NF-κB is a principal transcription factor involved in regulating the gene expression of more than thousand regulatory proteins, including certain pro-inflammatory cytokines. These cytokines further induce the transcription of adhesion molecules, critical in leukocyte infiltration and transmigration to the site of injury and inflammation (Barnes and Karin, 1997; Tak and Firestein, 2001; Akira et al., 2006). Early studies on NF-κB has confirmed its role in gene regulation of the Igκ light chain and numerous other regulatory genes responsible for carrying out normal physiological functions, including immune modulation, acute inflammatory response, cell differentiation and apoptosis (Baeuerle and Baltimore, 1996; Yamamoto and Gaynor, 2001a; Karin et al., 2006). Five mammalian proteins have been recognized in NF-κB activation pathway: NF-κB (p50 and its precursor p105), NF-κB2 (p52 and its precursor p100), p65 (RelA), RelB, and c-Rel. These proteins can interact with each other as homo- or heterodimers, depending upon their active or latent state. A Rel homology domain is characteristically present on all the NF-κB members, which encompasses a nuclear localization array for binding of specific DNA sequences, sites for dimerization, and interface with inhibitory IκB proteins. In the cytoplasm, these inhibitory proteins (IκBα, IκBβ, IκBε, and Bcl-3) are non-covalently bonded to the NF-κB dimer keeping it in an inactive state. Upon receiving the stimulus, 26S proteosome seeks the help of IκB kinases for the phosphorylation and polyubiquition of IκB (Karin and Ben-Neriah, 2000; Broide et al., 2005). This makes the way for promoter genes to interact with nuclear localization site and activates the transcriptional factors. This activation permits NF-κB to be translocated into the nucleus, followed by the transcription of numerous cytokines pro-inflammatory cytokines (IL-1, IL-2, IL-6, IL-12, TNFα), chemokines (IL-8, Rantes, MCP-1, MIP-1α, eotaxin), cell adhesion molecules (ICAM-1 and VCAM-1) acute phase proteins (SAA, CRP), and the inducible enzymes, nitric oxide synthetase (iNOS) and cyclooxygenase (COX-2) (Barnes and Karin, 1997; Tak and Firestein, 2001; Yamamoto and Gaynor, 2001a; Gordon and Taylor, 2005). Henceforth, NF-κB activation can be inculpated for the production of numerous immunomudulators, responsible for many inflammatory diseases. Clinical data has suggested that elevated expression of these inflammatory mediators have been observed in inflamed synovial tissues, hence leading to the development and progression of rheumatoid arthritis (Marok et al., 1996). Moreover, overexpressed COX-2 expression contributes to the prostanoids production, which further promotes the synthesis of IL-1 and TNFα, leading to chronic inflammatory diseases. Thus, the natural product with NF-κB inhibitory activity represents a potential therapeutic alternative in treating inflammation (Barnes and Karin, 1997; Yamamoto and Gaynor, 2001b).

Numerous Annonaceae species have been investigated for the inhibitory activity on NF-kB pathway. For example, styryl lactones from the genus Goniothalamus are secondary metabolites with either 5-or 6-membered lactones (De Fátima et al., 2006) with several reported bioactivities including cytotoxicity, apoptosis, and anti-inflammatory (De Fátima et al., 2006; Kuo et al., 2011). In recent work of Orlikova et al. (2013), goniothalamin (1) (GTN) (Figure 1) a styryl-lactone isolated from the Goniothalamus macrophyllus was evaluated on TNF-α induced NF-κB activation. GTN inhibited the TNF-α induced NF-κB activation in K562 chronic myelogenous leukemia cells at a concentration of 5 μM. Moreover, GTN also prevented NF-κB binding with its DNA transcription factors. Translocation of the p50/p65 heterodimer to the nucleus was down regulated and TNF-α activated interleukin 8 (IL-8) expression was also significantly reduced. Furthermore, in a phytochemical evaluation of Indonesian plant species, methanolic extract of Alphonsea javanica showed potent anti-inflammatory activity by inhibiting NF-κB activation in raw macrophage 264.7 cells (Johnson et al., 2013). Moreover, IκBα phosphorylation was also significantly reduced. This phytochemical analysis suggested that reported activity was due to the presence of an styryl lactone, altholactone (2) (Figure 1). However, according to Taha et al. (2014) methanolic bark extract of Pseuduvaria monticola have shown insignificant results in anti-diabetic evaluation studies. Other parameters including, NF-κB translocation were also evaluated on pancreatic insulinoma cells of mice. Test extract failed to show inhibitory activity against TNF induced NF-κB translocation. However, Shih et al. (2010) reported a completely different anti-inflammatory activity of Polyalthia longifolia. Since microglia mediated inflammation is involved in the pathway responsible for neuronal cell death in neurodegenerative diseases (Gebicke-Haerter, 2001). Hence, this study was carried out to evaluate the effects of P. longifolia var. pendul isolate, 6-hydroxycleroda-3,13-dien-15,16- olide (3)(PL3) (Figure 1) on LPS induced microglial inflammation. PL3 (3) successfully decreased the cell viability in neuroblastoma SH-SY5Y cells. Subsequently, it decreased the activity of NF-κB and the degradation of IκBα. PL3(3) also boosted HO-1 expression, which is a known cytoprotective and anti-inflammatory enzyme. Moreover, microglial activation is also associated with the complete or partial loss of dopaminergic neurons in Parkinson's disease (PD) (McGeer and McGeer, 2004; Suzumura et al., 2006; Block et al., 2007). Hence, if early measures are taken to suppress the microglial activation, then it would be an important step in suppressing the progression of PD. α- asarone (4) (Figure 1), an active constituent found in few Annonaceae species, has proved to beneficial in the early treatment of PD (López et al., 1993; Silva et al., 2007; Kim et al., 2015). Kim et al. (2015) reported that α-asarone(4) decreased the pro- inflammatory cytokine production in LPS induced BV-2 cells. The detailed mechanistic study revealed that reported activity of α-asarone was due to the inhibition of NF-κB, by blocking degradation of Ik-B signaling in BV-2 microglial cells. Moreover, in a recent study it was suggested that methanolic extract of A. reticulata have shown significant neuro-protective response in H₂O₂ induced neuronal damage in SHSY5Y cells and DRG neuronal cells. After the completion of the drug treatment the levels of pro-inflammatory cytokines, iNOS, and NF-κB activation was significantly reduced in a dose dependent manner. Hence it was concluded from this study methanolic extract of A. reticulata has potential to inhibit neuronal inflammation, neurogenic pain, and oxidative stress by inhibiting NF-κB inflammatory pathway (Kandimalla et al., 2017).

NF-κB activation is accountable for the development and progression of solid and hemopoietic malignancies (Van Waes, 2007; Yang F. et al., 2012). Therefore, NF-κB is often referred as an oncogene as well. Although, NF-κB activation is not a pre-requisite for tumor, but it plays an important role in moderating inflammation, setting up the tumor microenvironment and stimulating immunomodulatory cells including, pro and anti-inflammatory cytokines, and chemokine production (Mantovani et al., 2008, 2010; Grivennikov et al., 2010). Here, two pathological conditions have been stated as examples to signify the role of NF-κB activation in inflammation leading to cancer. The first example is Colitis-associated colon cancer (CAC) a classical inflammation-driven cancer and, secondly, hepatitis C induced hepatic cancer is the most prominent examples of inflammation leading to cancer (Greten et al., 2004; Pikarsky et al., 2004). Henceforth, the agents with the tenacity to subdue the NF-κB translocation are of major interest due to their dual action on inflammation and cancer development (Zhang et al., 2005; Opferman, 2008; Cheng et al., 2012). Moghadamtousi et al. (2014a) evaluated the ethyl acetic acid extract of A. muricata (leaves) (AMEAE) on A549 lung cancer cells. Cell viability study demonstrated the specific cytotoxic impact of AMEAE toward A549, with an IC₅₀ of 5.09 ± 0.41 μg/mL after 72 h of treatment. In addition, AMEAE also inhibited the translocation of NF-κB from the cytoplasm to nucleus. Apropos to last study reported, Pieme et al. (2014) suggested that the presences of phenolic compounds are the key elements for the reported NF-κB activity of A. muricata (Duraipandiyan et al., 2006; Jiménez et al., 2014; Solomon-Wisdom et al., 2014).

The association between the PGs and inflammation was acknowledged in 1971. While two research groups reported that inhibiting the PGE₂ production through COX enzyme is responsible for the anti-inflammatory activity of Asprin (Smith and Willis, 1971; Moncada et al., 1976). Later the discovery of two different isoforms of COX enzyme COX 1 and COX 2 further highlighted the role of PGs in inflammation. COX-1 is constitutive, expressed on platelets and gastric partial cells, responsible for modulating platelet aggregation and maintaining the gastric mucosal protective lining. Whereas, COX-2 is an inducible enzyme with cell-specific distribution. COX-2 activation give rise to prostaglandins responsible for producing classical sign and symptoms of inflammation including, hyperalgesia and swelling (Harrington et al., 2008; Rouzer and Marnett, 2009). Numerous internal and external factors including stress growth factors, mitogens, and inflammatory cytokines may cause the up regulations of COX-2 gene expression. This up regulation may give rise to development and progression of chronic inflammation, angiogenesis, and cancer metastasis (Williams et al., 1999; Dannenberg et al., 2001). Henceforth, natural products with COX-2 inhibitory activity and downregulation of over expressed COX-2 expression can be a noteworthy pharmacological therapeutic options for treatment inflammatory conditions.

Annonaceous acetogenins are usually 35–77 carbon compounds, produced by polyketide pathway (Liaw et al., 2010). First acetogenins was discovered in 1982 and ever since series of investigation has been carried on this fascinating class of natural product due to its unique structure and versatile bio-activities (Chang and Wu, 2001; Kojima and Tanaka, 2009; de Sousa et al., 2010; Chen et al., 2012; Zhang et al., 2015). In the quest to explore phytochemicals with COX 2 inhibitory activity, isodesacetyluvaricin (5) (Figure 1), an annonaceous acetogenin from Annona glabra was evaluated on A431 carcinoma cells (Wu et al., 2012). The addition of 25 μg/mL of Epidermal Growth Factor (EGF) resulted in increased expression of COX-2 mRNA, without effecting COX-1. Upon addition of isodesacetyluvaricin (5), expression of COX-2 mRNA was significantly reduced in a dose dependent manner, without affecting COX 1 expression. Upon further investigation, it was proposed that selective COX-2 inhibition was due to the suppression of promotor activity of element binding factor (CREB) and the nuclear factor of activated T cells (NFAT) responsible for the EGF-mediated transcriptional activation of COX-2 (Duque et al., 2005; Yiu and Toker, 2006). Isodesacetyluvaricin(5) significantly inhibited (P < 0.05) CREB and NFAT at a concentration ranging 1–5 μM further cementing the proposed mechanism. However, an alternative mechanism was also proposed, involving the phosphorylation of CREB by protein kinase A- dependent Rap1-extracellular-signal-related kinase and dephosphorylation of NFAT (Iñiguez et al., 2000; Chun and Surh, 2004). Alkaloid (compound 1; name not specified by author) isolated from Fissistigma cavaleriei root showed corresponding activity (Yang Z. et al., 2012). Colorimetric screening assay revealed that compound 1 has significant angiogenic property due to its selective COX-2 inhibition. Subsequently, Hu et al. (2008) further supported the COX-2 inhibitory activity of Fissistigma oldhamii. 7′-(3′, 4′-Dihydroxyphenyl)-n-[(4-methoxyphenyl) ethyl] propenamide (Z23) (6) (Figure 1) isolated from the leaves of F. oldhamii reduced the COX 2 gene expression in LPS induced Raw 256.7 macrophage cells. Moreover, Aquila et al. (2009) reported that cycloartane triterpene, berenjenol (7) (Figure 1) isolated from Oxandra xylopioides, significantly (p < 0.05) decreased the COX-2 gene expression at 50 μM.

Mitrella kentia is a tree-climbing liana from Annonaceae family. It is proposed that it possesses significant anti-inflammatory activity due to presence various bioactive compounds including, isoquinoline alkaloids, chalcones, and essential oils. Saadawi et al. (2012) evaluated the PGE₂ inhibitory activity of M. kentii using highly sensitive radioimmunoassay technique. Among all the isolated compounds chrysin (8) (Figure 1) showed dose dependent PGE₂ inhibition with an IC₅₀ value of 25.5 μM. Results from another report further supported the corresponding M. kenti activity against PGE₂. Desmosdumotin C (9) (Figure 1) a new isolated bioactive compound from M. kentii revealed gastro-protective activity by decreasing gastric ulcers area, edema, and leukocyte infiltration, which could be attributed intervention with anti H pylori and COX-2 inhibitory pathway (Sidahmed et al., 2013).

PAF plays a significant role in carrying out several physiological functions. Unfortunately when body faces mechanical stress, trauma or exposed to toxin the concentrations of PAF rises significantly. These elevated levels may give rise to numerous pathophysiological conditions such as inflammation (Stafforini et al., 2003), allergy (Petersen et al., 1997), asthma (Kasperska-Zajac et al., 2008), and thrombosis (Zhang et al., 2001). Lately, it is proposed that in order to carry out its pathophysiological functions it is imperative for PAF to specifically binds to its receptors (Esquenazi and Bazan, 2010). Therefore, compounds with PAF receptor antagonistic activity can be used as a good therapeutic option to treat PAF associated inflammatory condition (Moharam et al., 2010b). Moreover, PAF and prostanoins share common pathway hence TXA₂ may acts as a PAF mediator and produce the symptoms associated with PAF elevations (Badr et al., 1989). In addition, increased PGE₂ synthesis was observed in PAF treated rat meningeal cells suggesting its role in the prostanoids secondary production (Arribas-Gómez et al., 1995).

A few species of Annonaceae have displayed compelling PAF receptor antagonistic activity. For instance, Jantan et al. (2005) evaluated PAF inhibitory activity of 49 methanolic extracts from 37 Malaysian indigenous plant species. Their inhibitory effects were evaluated using ³H-PAF as a ligand. 6 Zingiberaceae species, two Cinnamomum species and one Annonaceae species (Goniothalamus malayanus) were reported as novel PAF antagonists, as they exhibited noteworthy inhibitory effects with IC₅₀ values ranging from 1.2 to 18.4 μg/mL. Furthermore, two alkaloids and aporphine alkaloids isolated from the twigs of Mitrephora vulpine were evaluated using ³H-PAF ligand model (Moharam et al., 2010b). Out of all the isolated compounds phylligenin (10) and quebrachitol (11) (Figure 1) managed to antagonize PAF receptor in concentration depended manner with IC₅₀ values of 13.1 and 42.2 μM, respectively. Whereas, the phylligen have an IC₅₀ value comparable to cedrol (10.2 μM), a potent PAF antagonist. In continuation to previous work Moharam et al. (2010a) focused on the essential oils isolated from five Goniothalamus species (G. tapisoides, G. velutinus, G. clemensii, G. tapis, and G. woodii). Essential oil from the bark of G. clemensii, G. woodii, G. velutinus, and the root oil of G. tapis were able to show significant antagonist activity with IC₅₀ values ranging from 3.5 to 10.5 μg/ml. It was proposed that the presence of sesquiterpenes and sesquiterpenoids were responsible for producing potent PAF receptor antagonistic activity. Furthermore, Nordin et al. (2012) highlighted the similar bioactivity of E. pulchrum first time ever. Among the extracts examined, ethyl acetate extract has shown superior antagonist activity with 85.6% inhibition. Moreover, liriodenine (12), cleistopholine (13) and dehydroanonaine 1-(2′, 3′, 4′-trimethoxyphenyl)hexan-1-ol(14) (Figure 1) isolated compounds from the same fraction were the strongest to antagonize PAF receptor with an IC₅₀ values of 26.6, 50.2, and 45.4 μM, respectively. Saadawi et al. (2012) reported that polycarpol (15) and acetylmelodorinol (16) (Figure 1) isolated from Mitrella kentii (Bl.) have shown similar dose dependent inhibitory effects with IC₅₀ values of 24.3 and 24.5 μM, respectively. Faria Lua Figueiredo et al. (1999) reported parallel activity for magnolin (17), epiyangambin (18), yangambin (19) (Figure 1) and furofuranic lignans isolated from leaves of Rollinia deliciosa.

Numerous vascular diseases are often supplemented with inflammation, which may affect the production of peroxynitrite and protein nitration and may lead to irreversible DNA damage and apoptosis (Beckman and Koppenol, 1996; Zamora et al., 2000). Three different isoforms are involved in the production of Nitric oxide in various parts of the body. Neuronal NOS (nNOS, ³NOS1) is produced by both autonomic and peripheral nervous system to serve as a neurotransmitter and to support inter and intra neuronal communication. Chromosomes 12 carry the gene coding for nNOS. While, endothelial NOS (eNOS) and inducible NOS (iNOS, NOS₂) is constitutively expressed isoenzyme principally produced from endothelial cells. Chromosome 7 and 17 are responsible for carrying an encoded gene for the iNOS and eNOS respectively. Elevated intracellular Ca² levels are required for the activation of both enzymes. But unlike eNOS, iNOS bind with Ca²⁺ calmodulin more tightly with non-covalent bond hence making the deactivation of iNOS considerably difficult. This leads to the continuous and unstoppable overproduction of iNOS in the body (Alderton et al., 2001; Aktan, 2004; Pautz et al., 2010). Normally, low levels of NO are essential for the body to regulate and maintain the vascular permeability and homeostasis. However, if the production of NO exceeds the normal levels then it may lead to the pathogenesis of cardio vascular disorders such as hypertension, heart failure, and atherosclerosis (Cooke and Dzau, 1997; Albrecht et al., 2003). Inflamed human endothelium can contribute to increased iNOS activity up to three- to five-fold beyond its baseline concentrations (Zhang et al., 2007; Brovkovych et al., 2011). Moreover, numerous reports have indicated that eNOS can mimic iNOS activity depending upon the nature and intensity of the stimulus, but more work need to be done to elucidate the mechanism behind this interchangeable behaviors of eNOS (Cirino et al., 2003).

There are several reports in the literature that show that Annonaceae species has a potent iNOS inhibitory activity. Recently Hu et al. (2007) reported that 7-(3,4- dihydroxyphenyl)-N-[(4-methoxyphenyl) ethyl] propenamide (Z23) (6) (Figure 1) from F. oldhamii exhibited dual action of decreasing the T cell activation and the production of iNOS in in vivo model of type II bovine collagen induced arthritis. In the light of this study, it was suggested that anti-inflammatory effect of Z23, is through modulating the synthesis of several inflammatory mediators and cytokines involved in the inflammatory process. In conclusion, Z23 has the potential to be a therapeutic option for numerous inflammatory diseases, where the overproduction of NOS and inflammatory cytokines are responsible for development and progression of the disease, e.g., rheumatoid arthritis. Moreover, Adewole and Caxton-Martins (2006) evaluated the corresponding activity of aqueous leave extract of A. muricata on streptozotocin induced (STZ)-diabetic rats. The extracts were intra-peritoneally injected to the rats (100 mg/kg) starting from 5 days after the administration of STZ and stopped on the 30th day of the study period. While control group of rats was injected with same amount of citrate buffer. Histophathological evaluation and bioassay results revealed that A. muricata significantly (p < 0.05) reduced the glucose and iNOS level in a dose dependent manner. Hence in the light of this study it can be concluded that A. muricata has beneficial effects on pancreatic tissues subjected to STZ-induced oxidative stress. Likewise the recent work of Nhiem et al. (2015) reported three new ent-kaurane diterpenoids and five known isolates from the fruit extract of A. glabra and they were evaluated for anti-inflammatory activity. After 24 h of incubation with the isolates, 7β,17-dihydroxy-ent-kaur-15-en-19-oic acid 19-O-β-D-glucopyranoside ester (20) (Figure 1) inhibitory activity was the most significant with the IC₅₀ value of 0.01 μM. Similarly, Shirwaikar et al. (2004) focused on Annona Squamosa, commonly known as custard apple. Several antioxidant-screening models were used to evaluate the free radical scavenging activity of the leaves of A. squamosa. Leave ethanolic extract had the highest scavenging activity against 2,2-azinobis- (3-ethylbenzothiazoline- 6- sulphonate) (ABTS) up to 99.07% followed by the scavenging of the stable radical 1, 1-diphenyl, 2- picryl hydrazyl (DPPH) (89.77%), and nitric oxide radical (73.64%) at 1,000 μg/ml. These findings signify the therapeutic potential of Annona species in traditional medicine.

Xylopia parviflora is a tall tree distributed in East and Central Africa. It is very famous for its traditional uses in coastal regions against stomach disorders, headaches and fever (Nishiyama et al., 2006). Kuate et al. (2011) evaluated the possibility of using X. parviflora seed as a food source of natural antioxidant. Several bioassays were performed on water, ethanolic, and hydro-ethanolic extracts to evaluate the anti-oxidant and free radical scavenging activity. All extracts have shown significant (p < 0.05) dose dependent NO inhibition, compared to the control group. However, high test NO inhibition was observed with hydo-ethanolic extract, decreasing the iNOS production upto 87% with IC₅₀ range of 20–50 μM. The anti-oxidant activity of X. parviflora was further supported by the late work of Woguem et al. (2014). This study focused on the essential oils hydro distilled from the fruits of X. parviflora. In order to evaluate the anti-oxidant and anti-inflammatory activity of X. parviflora, LPS induced raw macrophage 264.7 cell were incubated with essential oils for 24 h. Results suggested that cells treated with X. parviflora essential oils have shown decreased NO production in a dose dependent manner exhibiting a potential anti-inflammatory activity.

In recent years, utilization of anti-oxidants has been significantly increased due to its positive role in the management of numerous diseases (Halliwell, 2006). Monodora tenuifolia have already been exploited commercially either as anti-oxidant additives or nutritional supplements (Pourmorad et al., 2006). To validate the anti-oxidant activity of M. tenuifolia Njoku (2007) administered diethyl ether fraction and seed extracts to rats systemically. Since the diazotization of nitrite with sulphanilamide, formation of choromophore followed by coupling with napthethylene diamine served as a marker of NO scavenging activity (Villagra et al., 2007). M. tenuifolia seed extract, pet- ether extract and the diethyl ether fraction were able to inhibit the formation of chormophore in a dose dependent manner. Although, the exact pathway of free radical scavenging activity was not completely understood but it was proposed that activity reported was probably due to the high occurrence of anti-oxidant vitamins and flavonoids. Moreover, no toxicity sign were observed up to a dose level of 5,000 mg/kg body weight. Moreover, 15 known and three new megastigmane glycosides were isolated from Miliusa balansae and were tested on LPS induced RAW 264.7 macrophage cells (Thao et al., 2015). milbaside A and B (21) and C (22) (Figure 1) were most effective among all isolated compounds, with inhibition values of 98.5 ± 1.6, 90.9 ± 7.8, 84.8 ± 3.5%, respectively. Rest of the compounds either had weak or failed to show any activity on tested concentration (10.0, 20.0, and 40.0 μM).

Polyalthia longifolia var. pendula, commonly known as “Indian Mast Tree” is widely distributed in tropical and subtropical regions. Due to its ability to reduce noise pollution it is extensively cultivated in several Asian countries, specially in Taiwan (Ghosh et al., 2008). In an effort to explore isolates from Taiwanese medicinal plants with anti-inflammatory activity, Wu T. H. et al. (2014) evaluated P. longifolia isolates and fruit extracts for iNOS inhibitory activity. Results from present study suggested that 16-hydroxycleroda-3,13-dien-15,16-olide (23) and 16-oxocleroda-3,13-dien-15-oic acid (24) (Figure 1) has significantly (P < 0.05) reduced NO production at 10 μg/mL, with 81.1 and 86.3%, inhibition, respectively. Similarly, Saha et al. (2008) conducted a study on Bangladeshi medicinal Plants (Hibiscus mutabilis, Leucas aspera, Ixora coccinea, and P. longifolia). Ethanolic extract of all the tested species showed dose dependent NO direct scavenging activity in following manner L. aspera > I. coccinea > H. mutabilis > P. longifolia. Although, the activity reported for P. longifolia was least potential among all the tested extract with 70.67% with IC₅₀ of 167.08 μg/ml but its inhibitory activity can be considered significant when compared to positive control (ascorbic acid with 74.56% inhibition). In another account, Johnson et al. (2013) stated that Alphonsea javanica Scheff decreased the expression of eight pro-inflammatory cytokines/enzymes (0.8–5.0 μM) including iNOS. Then again, Aquila et al. (2009) reported similar activity of berenjenol (7) (Figure 1), isolated from Oxandra cf. xylopioides. The anti-inflammatory activity was assessed on sub chronic inflammation induced by repetitive application of 12-O-tetradecanoyl-phorbol-13-acetate (57% inhibition, 7 × 1 μmol/ear). While it reduced the expression of iNOS by 80% at 50 μM. Hence suggesting that these species can be used as potent and novel therapeutic agent for scavenging of NO and the regulation of pathological conditions caused by excessive generation of NO and by product.

ROS are usually characterized as incompletely reduced metabolites of oxygen that have potent oxidizing potentials (Casteilla et al., 2001; Mittal et al., 2014). ROS actions can be variant depending upon their concentrations. At high concentrations, ROS are injurious to body but at low concentrations, ROS serve as intricate signaling functions (Taniyama and Griendling, 2003; DelloStritto et al., 2016). Under normal circumstances, the human body produces numerous antioxidants such as catalase and glutathione peroxidase, in order to balance out the deleterious effects of ROS. However, in certain inflammatory conditions, this balance is disturbed due to the excessive generation of ROS (Drake et al., 1998; Cominelli, 2004; Reuter et al., 2010). In other way, neutrophils produce a large quantity of ROS at the site of inflammation in order to fight against the foreign bodies. As a result lipid peroxides are produced which gives rise to pathophysiological changes associated with an oxidative stress (Wolfreys and Oliveira, 1997; Dabrowski et al., 1999; Aprioku, 2013). This physiological response is known as oxidative burst. It provides support to host defense, but it can also result in collateral destruction of host tissues (Chen and Junger, 2012). Henceforth, suppression of the excessive pathophysiological activation of neutrophils can be used to treat inflammatory diseases. A few studies including Barreca et al. (2011) evaluated the antioxidant activity of ethanolic, methanolic, and dimethyl formammide extracts of Annona cherimola on hydrogen peroxide induced lymphocytes. Although, all extracts showed significant antioxidant and ferric reducing potential but highest scavenging activity was reported for dimethyl formammide extract against DPPH, ABTS and O2-. Whereas ethanolic extract was reported to have highest activity against tert-butyl hydroperoxide induced lipid peroxidation. Invariably in the light of the fact that various antioxidants also possess antimutagenic activity, Ravikumar et al. (2008) focused on screening antimutagenic and antioxidant activity of Polyalthiam cerasoides. Antioxidant activity was evaluated based on inhibitory activity on hydroxyl radical, superoxide radical, DPPH free radical scavenging and Fe³⁺reducing properties. Results suggested that methanolic extract inhibited DPPH and superoxide anion in a dose dependent manner. Moreover, similar activity was reported against hydroxyl radicals produced by the reaction of Fe³⁺-EDTA together with H₂O₂ and ascorbic acid. In addition, by reducing Fe³⁺ to Fe²⁺ ions the methanolic extract had exhibited strong reducing potential. These results clearly indicate that methanolic extract of P. cerasoides have powerful anti-oxidant and reducing potential. Likewise, Hwang et al. (2009) reported similar activity of isopedicin, a flavanone derived from F. oldhamii. Results suggested that isopedicin decreased superoxide anion production in FMLP stimulated RAW macrophage with an IC₅₀ value of 0.34 ± 0.03 μM. In addition, phosphodiesterase inhibition enhanced the activity of PKA and cAMP. Moreover, FMLP induced kinase and c-Jun N-terminal kinase phosphorylation was inhibited by isopedicin. However, isopedicin was unable to reverse the FMLP induced calcium mobilization and p38 mitogen activated protein kinase phosphorylation. Hence it is proposed that antioxidant activity of isopedicin is due to the elevation of cellular cAMP and activation of PKA through its inhibition of cAMP-specific PDE. Numerous other species of Annonaceae can produce similar super oxide anion generation and elastrase inhibitory activity in micro-molar concentration. For instance, Chang et al. (2006) isolated a novel clerodane diterpenoid 16-hydroxycleroda-13-ene-15,16-olide-3-one (25) (Figure 1) along with other known 23 compounds from the methanolic extract of P. longifolia leaves. Anti-inflammatory activities of isolated compounds were evaluated on formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (FMLB/CB) stimulated superoxide generation in neutrophils. 16-oxocleroda-3,13E-dien-15-oic acid methyl ester (26) and 16-hydroxycleroda-3, 13(14)E-dien-15-oic acid (27) (Figure 1) exhibited significant inhibitory activity against both models with IC₅₀ value of 0.6 ± 0.09 and 1.49 ± 0.28 μg/mL, respectively. In continuation of previously mentioned work by Liou et al. (2014), member of same research group investigated phyto constituents from the leaves of Polyalthia parviflora. Parvistones (28) (Figure 1), a styryllactones and two 6S configuration derivative inhibited fMLP/CB-induced superoxide anion generation and elastase release. Likewise, Chan et al. (2013) isolated a new melodamide A(29) (Figure 1) phenolic amide along with 12 known compounds from the methanolic leave extract of Melodorum fruticosum. Melodamide A (29) has shown significant inhibitory activity with IC₅₀ value of 5.19 μM against both O⁻² and elastase. However, synthetic derivative of melodamide A(29) with a 2-bromo substitution on ring A failed to show any substantial anti-oxidant activity. Similarly, in recent work of Hsu et al. (2016) seven compounds including 3-methyl-4, 5-dihydro-oxepine (flexuvaroxepine A) (30) (Figure 1), four polyoxygenated cyclohexene and two polyoxygenated cyclohexene derivatives, together with four known flavones were isolated from methanolic extract of Uvaria flexuosa. All isolated compound were evaluated against superoxide anion generation and elastase release. Out of all the isolated compounds flexuvarol B (31) and chrysin (8) (Figure 1) have shown significant inhibitory activity against elastase release and superoxide anion generation with IC₅₀ of 2.25–5.55 μM. Similarly, Njoku (2007) reported anti-oxidant activity for the seed extract of M. tenuifolia. He reported that seed extracts were able to inhibit lipid peroxidation and free radical generation in liver homogenate in a dose dependent manner.

More than few reports have called attention to other mechanism related with the flavonoids of A. dioica. This study focused on the several aspects including anti-proliferative, antioxidant, and anti-inflammatory activity of A. dioica (Formagio et al., 2013a). DPPH assay was employed in order to evaluate the free radical scavenging activity of four fractions including hexane, chloroform, ethyl acetate and hydromethanol fraction. Furthermore carrageenan induced paw edema test was used for the further evaluation. Results suggested that ethyl acetate and hydromethanol fractions were most potent among all the tested fractions with an IC₅₀ of 8.53 and 10.57 μg/mL, respectively. Whereas, methanolic extract was able to significantly reduce the carrageenan-induced edema in dose and time dependent manner (30–300 mg/kg). It was concluded that A. dioica St. and several other species of Annonacea family have a unique mechanism of suppressing the transmigration and phagocytosis by polymorphonuclear leukocytes (PMNs) and helps in the alleviation of unnecessary and deleterious production of ROS, hyperalgesia, and other classical symptoms of inflammation. In succession of his previous work, Formagio et al. (2013b) further evaluated the essential oils, hydrodistillated form the leaves of Annona sylvatica. Carrageenan induced paw edema test was employed to assess the anti-inflammatory activity. Upon oral administration of essential oils, potent anti-inflammatory and antioxidant activity was reported. It was proposed that the presence of z-caryophyllene (44) and β-maliene (46) (Figure 1) in essential oil was responsible for potential anti-oxidant activity. Moreover, several other phytochemical classes including chalcone have been reported to share similar activity. Somsrisa et al. (2013) managed to isolated one new dihydrochalcone derivative 4′, 6′-dihydroxy-2′,4-dimethoxy-5′-(2″-hydroxybenzyl)dihydrochalcone (32) and one known dihydrochalcone, 4′, 6′-dihydroxy-2′,4- dimethoxydihydrochalcone (32) (Figure 1) from the twig and leaves of Cyathostemma argenteum. Ethyl phenylpropiolate was applied tropically on the inner and outer part of the ear of rats to induce ear edema. Dose of 1 mg/ear test compounds were also applied tropically just before the application of irritant to evaluate their analgesic activity. A significant time dependent inhibition was observed for both isolated compounds at a dose of 1 mg/ear. Hence concluding that both compounds are very effective in an acute phase of inflammation and has the ability to antagonize or decrease the vascular permeability of inflammatory mediators including histamine, serotonin, bradykinin, and prostaglandin (PGs). Chavan et al. (2012) reported similar activity for a diterpines, kaur-16-en-19-oic acid (34) (Figure 1) isolated from the bark of Annona reticulate. Hot plate method was employed to assess the analgesic activity. Whereas anti-inflammatory activity was evaluated using carrageenan induced rat paw edema assay. Significant analgesic and anti-inflammatory activity was reported for kaur-16-en-19-oic acid (34), at doses of 10 and 20 mg/kg. This study points out a lead anti-inflammatory compound, which should be further explored for therapeutics.

In the last few decades exceptional progress has been made for the development of new anti-inflammatory and analgesic drugs. However, we are far behind from finding an ideal class of drug with maximum efficacy and minimum side effects. As a part of this effort Vendramini-Costa et al. (2014) evaluated a styryl-lacton, goniothalamin (1) (Figure 1) widely distributed among the genus Goniothalamus. Results suggested that Goniothalamus has significantly reduced the carrageenan induced paw edema in mice. Moreover, effective concentrations were also evaluated for its potential toxicity and results suggested that no sign of toxicity was observed at effective concentrations. Moreover, Meiocarpidium lepidotum has exhibited significant analgesic and anti-inflammatory activity in mice and rat (Meddah et al., 2013). Tail flick tests, acetic acid- induced writhing, carrageenan-induced hyperalgesia in mice were employed for the evaluation of anti-inflammatory activity. Paw edema was significantly reduced after the administration of extract. Moreover, acetic acid induced writhings and tail-flicks were significantly (p < 0.001) reduced at 1 mg/kg dose. Hence, proving a very potent analgesic and anti-inflammatory activity at small concentrations. Moreover, the intra-peritonial injection of methanolic fruit extract of D. chrysocarpa in rat model have shown significant analgesic and anti-inflammatory activity in a dose dependent manner (Almeida et al., 2012). At dose range of 100, 200, and 400 mg/kg acetic-acid-induced abdominal writhes were significantly reduced. Moreover, significant results were also recorded for hot-plate test and formalin test. It was proposed that corresponding activity reported is due to its dual action on peripheral and central nervous system. Additionally, Ishola et al. (2016) reported similar activity for hydro-ethanolic seed extract of Monodora myristica. It completely inhibited the xylene induced ear edema. Significant increase in threshold and decrease in acetic induce abdominal writings were observed in a dose dependent manner at concentration range of 50–200 mg/kg. Hence, this study provides scientific evidence for the use of M. myristica in traditional medicine for pain management. In the latest work of Popoola et al. (2016) focused three plant species commonly used for their indigenous anti-cancer activity. In this present study anti-oxidative and anti-inflammatory activity of Garcinia kola Heckel (stem bark), Uvaria chamae (root), and Olax subscorpioidea (root) were evaluated using in vivo inflammatory models. Formaldehyde and carrageenan induced rat paw edema was significantly reduced by all three species, in a time dependent manner. Maximum inhibitory activity was observed at 400 mg/kg when compared with the reference drugs. Thus, this study provides some scientific evidence of the usage of these three species in traditional anti-cancer and anti-inflammatory regimens. Seangphakdee et al. (2013) reported similar anti-inflammatory activity for poly-oxygenated cyclohexane zeylenol (35) (Figure 1) isolated from Uvaria grandiflora. Anti-inflammatory activity of zeylenol (35) was evaluated on rats using ear edema assay. Zeylenol (35) reduced the ear edema in a time dependent manner; activity recorded was equivalent to positive control, phenylbutazone. Results suggested that the test compound is effective against acute phase inflammation and able to inhibit the synthesis or release of various inflammatory mediators (histamine, serotonin, bradikinine, prostaglandin) responsible for producing vasodilation. Moreover, the mice treated with essential oil with the leave of Xylopia laevigata have also significantly (P < 0.05 and P < 0.001) reduced formalin induced abdominal writhing (Queiroz et al., 2014). Whereas, oral administration of essential oils decreased carrageenan-induced peritonitis and paws edema. Hence providing the scientific evidence to the traditional use of X. laevigata as anti-inflammatory remedy.

According to Bulua et al. (2011) “mitochondrial ROS (mtROS) act as signaling elements to induce pro-inflammatory cytokine production” (Nakahira et al., 2011; Zhou et al., 2011). This self-explanatory statement highlights the role of ROS in the production of pro-inflammatory cytokines. TNF-α is a major cytokine, responsible for inducing various other proinflammatory cytokines. Using its pyrogic activity TNF- α can induce mononuclear cells to produce inflammatory mediators like iNOS and ROS. These inflammatory mediators can further induce the production of TNF- α simultaneously. This leads to the production of IL-1 and IL-6 and proinflammatory cytokines and chemokines by activation of NF-κB (De Simone et al., 2015; Chen et al., 2016). Tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) are pro-inflammatory cytokines released by stimulated macrophages to augment the inflammatory response and injure cells and its surroundings (Whiteley et al., 2009; Olefsky and Glass, 2010). Hence decreasing the TNF-α and IL-6 levels may repress tissue injury caused by the inflammation. For instance fruit and seed extract from A. squamosa decreased TNF-α and IL-6 levels in LPS-stimulated macrophages (Yang et al., 2002). Similar activity was reported by Chuang et al. (2008) for Annona montana. The study was conducted to evaluate four new cyclomontanins isolated from the methanolic extract of A. montana seeds. LPS induced murine macrophage J774A.1 cells were used to evaluate the cytokines production inhibitory activity of cyclomontanins. Results suggest that maximum TNF-α and IL-6 inhibitory activity was reported for cyclomontanin A (36) and cyclomontanin C (37) (Figure 1). Although, cyclomontanin D (38) and annomuricatin C (37) (Figure 1) inhibitory activity is at relatively higher concentration (30 μg/mL). However, upon stimulating the cells with Pam3Cys cyclomontanin D exhibited dose dependent inhibition at various concentrations 3, 5, 10, 30, and 50 μg/mL. These results demonstrated a potent anti-inflammatory activity of synthetic analogs of cyclopeptides but lacks accuracy to pin point the exact mechanism of inhibition. Dellai et al. (2010) reported similar activity of cyclic peptides isolated from the seeds of A. squamosa. cyclosquamosin D (39) and met-cherimolacyclopeptide B (40) (Figure 1) and their analogs were evaluated using well established enzyme-linked immunosorbent assay (ELISA). Fourteen synthetic analogs were prepared from cyclosquamosin D (39) (Figure 1), few of them failed to show any bioactivity and hence they were included as a negative control. Whereas, few synthetic compounds were able to show superior activity then the natural products. Three analogs were able to suppress the IL-6 and TNF α equally. Moreover, no activity was reported for the natural cyclic peptide cherimolacyclopeptide B and met-cherimolacyclopeptide. Whereas, their analogs were able to significantly reduce the production of TNF-a and IL-6 in LPS induced macrophage cells. Two new cyclic peptides, fanlizhicyclopeptide A (41) and fanlizhicyclopeptide B (42) (Figure 1) isolated from the fruit of A. squamosa reported similar activity (Wu P. et al., 2014). Fanlizhicyclopeptide A (41) and fanlizhicyclopeptide B(42) (Figure 1) were able to reduce the secretion of TNF α by 32 and 27%. However, IL-6 activity was more pronounced then TNF α with 51 and 57% inhibition. Few years later Ge et al. (2013) demonstrated that aristololactam (43) (Figure 1) an alkaloid extracted from F. oldhamii against TNF-a and IL-6. From the results, the ethanol extract and its CHCl₃, EtOAc, and n-BuOH-soluble parts showed significant inhibitory effects against LPS-induced IL-6 production, and the CHCl₃-soluble part inhibited TNF- α production. As mentioned before 7′-(3′, 4′-dihydroxyphenyl)-n-[(4-methoxyphenyl) ethyl] propenamide (Z23) (6) (Figure 1) from F. oldhamii, have shown significant inhibitory activity against nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2). In the same study, Hu et al. (2008) reported that Z23 was able to produce more pronounce effect on TNF- α then IL-6. Moreover, in recent study of Vendramini-Costa et al. (2017) evaluated the cytokines inhibitor activity of goniothalamin (1) in colitis-associated cancer (CAC) and dextran sulfate sodium (DSS) induced-colitis mice model. Results indicate that goniothalamin decreased the gene expression of IL 1β, TNF-α, IL-6, IL-23A, IL-22, and IL-17A. Moreover, IL-6, IL-17, and TNF-α production was also significantly reduced in tumor tissue. It was concluded from this data that GTN could be a potential candidate for the treatment of progression and development of colon rectal cancer due to its potent anti-inflammatory activity. Rojano et al. (2007) indicated one new and unusual cycloartane triterpene, berenjenol (1) (Figure 1) and its three synthetic derivative isolated from the leaves of Oxandra xylopioides. Test compounds were co-incubated with LPS induced RAW 264.7 macrophages. Whereas, the inhibitory activity of the test compound was evaluated using ELISA kit. Isoespintanol (Figure 1), a synthetic derivative of berenjenol (1) had decreased IL-1 production by 72% at 100 μM and reduced IL-1 mRNA synthesis.

In very interesting study conducted by López et al. (2009), reported anti leishmanial and anti-inflammatory activity of eight extracts and essential oil from the leaves and seeds of Xylopia discrete. Results from this study suggested that Xylopia discrete failed to produce any significant effect on IL-10 IL-12 and TNF α. However, rise in level of monocyte chemotactic protein 1 (MCP-1) was observed in infected macrophages. This rise of MCP-1 caused to decrease the number of Leishmania parasites in infected cells. The proposed mechanism involves modulating the levels of MCP-1, which is responsible for the prophylactic function in maintaining cytokines level (Brandonisio et al., 2002; Dey et al., 2007). Usually, macrophage produce pro-inflammatory cytokines plus MCP-1 to induces the production of IL-12 and inhibiting IL-10 and TGF-β. Th1 phenotype was provoked in response to treatment with MCP-1, macrophage inflammatory protein supports prophylactic role to these chemokines to control of Leishmania parasites. This study suggests that X. discreta possesses antileishmanicidal potential due to its immunomodulatory activity. But more work need to be done in vivo models in order to confirm these bioactivities.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.