Aging is an inevitable process featured by impaired functions at the molecular, cellular, tissue and organ scales. It is the major risk factor for the development and progression of several diseases, especially in elderly subjects. Many diseases have been related to aging susceptibility such as diabetes, cardiovascular diseases, osteoporosis, neurodegenerative diseases, and cancer (1).

Over the past decades, many assumptions have been proposed to unveil aging process mechanisms. For instance, in vitro dysregulation of the apoptotic pathway was proven to be involved in some aging processes. Additionally, epigenomic changes greatly affect cellular function and profoundly contribute to aging progression (1). Also, scientific evidence has indicated the free radical reactions that occur within the cells and tissues, representing the major contributor to the aging process (2, 3). Indeed, understanding the underpinning mechanisms is critical for developing effective strategies against age-related diseases.

The cosmetic market is highly growing. In 2019, it generated estimated revenues of 380.2 billion USD and is expected to reach up to 463.5 billion USD by 2027 with a relative annual growth going from 5.3 to 7% between 2021 and 2027 (4). Consequently, bioactive compounds extracted from natural sources as cosmetic ingredients are gaining attractiveness. For instance, phytochemicals with antioxidant activities, modulatory effects on molecular cell receptors and/or gene expression, and inhibitory effects on enzymatic activity have demonstrated their usefulness in counteracting cell aging (5).

In this context, many functional foods and dietary compounds were found to have anti-aging properties and health beneficial effects via regulation of numerous pathways, such as nutrition sensing and stress signaling, modulation of cellular metabolism, stress resistance, energy homeostasis, genome maintenance, and mitochondrial biogenesis. Notwithstanding this evidence, many of these natural compounds are yet to be explored for their potential in preventing or delaying aging related disorders (6).

Parsley (Petroselinum sativum) is a biennial aromatic plant from the Apiaceae family. It contains flavonoids and other phenolic compounds such as furanocoumarins, carotenoids, polyacetylenes, and its leaves are a great source of minerals as calcium, thiamin, riboflavin, potassium and iron and vitamins such as A, C, and niacin (7). It harbors essential oil in all parts, with phenylpropane and terpene compounds as major constituents. P. sativum also contains proteins (2–22%), fats (4%), sugars, among others (8). Compounds such myristicin, apiol, 1-allyl-2,3,4,5-tetramethoxybenzene, β-phellandrene, 1,3,8-p-menthatriene, β-pinene, terpinolene, apiin, oxypeucedanin and falcarinol are mostly isolated from P. sativum (9). However, this composition depends on several factors, such as plant tissue, variety, climate, and sampling method (10).

For hundreds of years, Mediterranean population used P. sativum as a medicinal plant. Traditionally, it is used to manage arterial hypertension, diabetes, renal diseases, and cardiovascular diseases in different countries (11–13). Indeed, recent in vitro and in vivo studies demonstrated that P. sativum elicits several biological and pharmacological activities such as diuretic, anti-urolithiasis, hypouricemic, hypolipidemic, hypotensive, antioxidant, anti-inflammatory, and antiplatelet effects (9). It also exhibits antimicrobial, laxative, anti-anemic, anti-otitis, menorrhagic, antihyperlipidemic, cytoprotective, antihepatotoxic, carminative, estrogenic and hyperuricemia activities (11).

Although P. sativum has been explored for a wide range of biological activities, its cosmeceutical potential has not been sufficiently studied so far. Thereby, herein, we annotated the chemical composition of the aqueous and ethanolic extracts of P. sativum using LC–MS/MS and investigated their anti-aging potential, wound healing ability, as well as antioxidant activity using in vitro, enzymatic, and cell-based approaches. Moreover, the antibacterial, anti-biofilm and inhibitory effect on microbial mobilities of Pseudomonas aeruginosa were assessed. The choice of studying this bacterium resides in its multi-resistance to conventional antibiotics and its ability to cause skin infection (14). The overall aim of this study is to provide valuable information on the potential of P. sativum as a source of dermo-cosmeceutical agents, addressing critical aspects of skin care and dermatological health mainly anti-aging properties, protection against induced skin-oxidative stress, wound healing capabilities, and anti-infectious attributes.

P. sativum is widely used as culinary herb, but it also boasts an array of potential health benefits that have been acknowledged over centuries. In this study, LC–MS/MS analysis of the aqueous and ethanolic extracts of P. sativum unveiled 47 secondary metabolites belonging to various classes of organic acids (e.g., oxoadipic acid, citric acid, maleic acid, malic acid, and succinic acid), phenolic acids (e.g., coumaric acid) and flavonoids (e.g., apigenin) (27, 29, 30). Similar findings were recently reported by Mallmann et al. (31) who identified 19 phenolic compounds in the methanolic extract (80%) of fresh P. sativum plants. The study showed that P. sativum is also rich in flavones, especially apigenin and its derivatives (31). Comparatively, the extracts obtained in the present study are rich in other phenolic acids, such as hydroxybenzoic acid, 3,4-dihydroxybenzoic acid and shikimic acid. Moreover, other aglycons were characterized along with their glycosidic and acetylated conjugations, such as isorhamnetin, diosmetin, quercetin, and kaempferol. In contrast, different types of polyphenols, mainly oleuropein, arbutin, myricetin, and naringin were recently revealed in the P. sativum hydro-ethanolic extract (32). The differences in the phytochemical composition are due to many factors, such as the geographical location, climate, soil type, growth stage, cultivation practices, and processing methods. These factors collectively shape the presence and concentration of the bioactive compounds, thus impacting therapeutic properties of the plant and its potential applications (10).

To the best of our knowledge, the cosmeceutical potential of P. sativum has not been sufficiently investigated. Thus, here we explored the beneficial effects of P. sativum aqueous and ethanolic extracts on skin aging process, wound healing, oxidative stress, and skin bacterial infections. Notably, the assessment of the extracts’ effect on HaCaT viability demonstrated a full biocompatibility for dermatological applications up to 100 μg/mL. More importantly, both extracts showed a strong in vitro antioxidant activity by DPPH and FRAP methods. These results were corroborated by antioxidant activity tested on a cell-based model, to evaluate the effects of P. sativum extracts on UVA stressed HaCaT cells where cell treatment with both extracts prior to UVA exposure resulted in a significant inhibition in intracellular ROS levels. The antioxidant activity of the aqueous extract was further confirmed by the inhibition of GSH depletion upon UVA radiation. Indeed, GSH is well known to be involved in the antioxidant defense system of the cells. However, a different behavior was observed for the ethanolic extract, as no protective effect was observed when cells were treated with the ethanolic extract and then irradiated by UVA radiations. Increased capacity of the aqueous P. sativum extract to prevent ROS and GSH depletion in UVA-irradiated HaCaT cells is probably due to the free radical scavenger activity of the plant phytochemicals (20). For instance, many preclinical investigations have provided evidence that apigenin, present in both extracts as a major compound, elicits positive impacts against UV-induced skin, dermatitis, vitiligo, wounds, skin aging, and skin cancer. This flavonoid primarily operates by impeding inflammation through the reduction of pro-inflammatory cytokines and internal inflammatory agents, alongside its antioxidative qualities that enhance the body’s natural defense mechanisms against oxidative stress (33).

Furthermore, P. sativum extracts were assessed for their capacity to inhibit skin aging-related enzymes. Skin aging is a complex process influenced by various factors, including enzymes like elastase, collagenase, hyaluronidase, and tyrosinase. Elastase and collagenase contribute to the breakdown of elastin and collagen fibers, crucial components necessary to maintain skin firmness and elasticity. Hyaluronidase degrades hyaluronic acid, a key molecule responsible for skin hydration and volume. Tyrosinase plays a role in melanin production, influencing pigmentation changes and age spots. The overactivity of these enzymes, coupled with natural reduction of repair mechanisms, results in an acceleration of skin aging by diminishing structural integrity, moisture retention, and even skin tone (34). Here, we showed that both extracts were potent for inhibiting in vitro enzymes’ activities to different extents. Interestingly, the ethanolic extract exhibited pronounced inhibitory effect (IC₅₀ = 2.03–12.54 μg/mL) against the four enzymes comparatively the reference compounds, namely Kojic acid and quercetin (IC₅₀ = 9.00–24.83 μg/mL). This could be explained by the synergistic action of the plant’s compounds to effectively imped the functioning of skin aging enzymes. Indeed, many of the identified phytoconstituents such as kaempferol, isorhamnetin, quercetin, and their analogous compounds have been previously shown to combat skin aging by exhibiting inhibitory effects against the aforementioned enzymes (34–37). The inhibitory impact of P. sativum extracts on skin enzymes is likely the result of multiple mechanisms. For instance, it has been shown that the essential zinc ion situated within the collagenase’s active site is pivotal for its operation, facilitating interaction with the inhibitor (38). Furthermore, the hydroxyl groups within polyphenols can engage with collagenase’s backbone or other functional side groups. Additionally, the hydrophobic interaction between the benzene ring in the polyphenolic compound’s structure and collagenase can induce conformational alterations, rendering the enzyme nonfunctional (39). Elsewhere, it was demonstrated that the application of P. sativum extract (50 μg/mL) to Human Dermal Fibroblasts (HDF) induced a significant decrease (up to 37.0%) in the protein expression levels of p-ERK and p-JNK, both known to be related to MMP1 gene expression by UVB exposure. These findings indicate that P. sativum extract potentially enhances wrinkle improvement by curbing the expression of the MMP1 gene, responsible for collagen breakdown. This effect is achieved through the hindrance of UVB-induced JNK phosphorylation (40).

Besides, a clinical trial provided evidence that the topical application of P. sativum resulted in a substantial reduction in the severity of epidermal melasma with comparable inhibitory effect to that of hydroquinone (41). Additionally, P. sativum leaf extract powder prepared at 4% was also reported to be effective in in vivo controlling of sebum. This effect was proposed to be attributed to the plant’s high vitamins content (C, A, B, E, K, and β-carotene) and minerals (magnesium, iron, phosphorus, manganese, sodium, potassium, sulfur, and calcium) (42, 43).

In this study, the effect of P. sativum extracts on HaCaT cells migration (in vitro) using the scratch assay was monitored and the aqueous extract significantly enhanced the wound closure (4.40-fold reduction), while no significant effect was observed with the ethanolic extract. Notably, this is the first study to demonstrate the in vitro wound healing effect of P. sativum. However, a recent study demonstrated that both the hydro-ethanolic and polyphenolic extracts of P. sativum resulted in substantial wound contraction in rats. After 25 days post-treatment period, the hydro-ethanolic extract exhibited the most pronounced healing effect, achieving up to 97% (32). This was attributed to the presence of bioactive compounds that facilitate repairing lesions and expediting cellular regeneration in impaired tissues. In fact, many medicinal plants (e.g., Curcuma longa, Centella asiatica, and Paeonia suffruticosa), along with their phytochemicals, are effectiveness in promoting wound healing. For instance, apigenin has been reported for its role in enhancing the wound healing process (44, 45). Furthermore, it has been reported that malic acid-enriched fractions from Sempervivum tectorum L. leaves promote cell proliferation and migration (46, 47). Therefore, it is plausible that the malic acid present in the P. sativum extracts may contribute to the wound healing process.

In addition to the skin aging and wound healing experiments, the antibacterial effects of P. sativum extracts against P. aeruginosa were investigated. The bacterium is an opportunistic pathogen that often displays multi-resistance to conventional antibiotics and is commonly associated to wound infections. In fact, when pathogens infiltrate a wound, they trigger an inflammatory response that can disrupt the orderly sequence of tissue repair. This leads to increased inflammation, delayed cell migration, impaired collagen synthesis, and compromised blood supply, all of which collectively hinder wound closure and tissue regeneration. Additionally, the presence of an infection can prolong the inflammatory phase, preventing the transition to subsequent healing stages (48, 49). Here, P. sativum extracts significantly and dose dependently inhibited P. aeruginosa growth. Precisely, the aqueous and ethanolic extracts at 100 mg/mL decreased bacterial growth by 72 and 75%, respectively. In addition, as P. aeruginosa can create robust biofilms, which sustain chronic infections, disrupt wound healing, and escalate the emergence of antibiotic resistance (50), the anti-biofilm capacity of the extracts was assessed and results revealed that the aqueous extract at 25 mg/mL significantly inhibited the biofilm up to 23% as well as the ethanol extract at 12.5 and 25 mg/mL which significantly decreased the biofilm by 57 and 80%, respectively. These results suggest that P. sativum phytocomponents hold potential for effectively contrasting P. aeruginosa’s biofilm formation during infections and thus impeding the adherence of bacterial communities to biological surfaces, in this case, the site of infection. In addition to biofilms, bacterial mobility assumes a crucial role in dictating the course of infection development. Bacteria employ various mechanisms such as flagella-driven twitching, swimming, or swarming to navigate the wound environment. These mobilities allow bacteria to colonize different wound surfaces and penetrate tissues (51, 52). The intricate interplay between bacterial mobility and the wound environment significantly impacts the severity, persistence, and treatment responsiveness of wound infections (53). Therefore, the effect of the extracts was assessed on the swarming and swimming mobilities of the bacterium on plates. Noteworthy, the aqueous extract was more potent in hindering P. aeruginosa mobilities comparatively to the ethanolic extract. At 25 mg/mL of the aqueous extract, the production of the bacterial pigment, pyocyanin, was completely inhibited. It is well established that P. aeruginosa only produces pyocyanin, therefore this is a diagnostic property of this bacterium. Pyocyanin, a redox-active phenazine compound, is a blue secondary metabolite found in sputum from P. aeruginosa infected tissues (54). This study demonstrated that P. sativum phytochemicals could target bacterial genes involved in biofilm formation and virulence factors production. Quercetin, a prominent constituent identified in the tested extracts, has previously demonstrated its efficacy in decreasing the expression levels of various quorum sensing genes namely lasR, lasI, rhlI, and rhlR exhibiting reductions of 68, 34, 57, and 50%, respectively (55). In the light of these findings, the potential of P. sativum phytoconstituents to counteract P. aeruginosa infections through its anti-quorum sensing effects holds promise through reducing bacterial growth rate, hindering biofilm formation and toxin production, and impeding bacterial colonization and infection within wound tissues.

Herein, P. sativum has been shown to be endowed with a wide range of cosmeceutical and dermatological properties. The phytochemical profiling of both extracts revealed the presence of a total of 47 phytocompounds belonging to diverse groups, namely organic and phenolic acids, and flavonoids. The plant was shown to be exempt of any cell toxicity, exhibited potent in vitro antioxidant activity, counteracted UVA-oxidative stress and GSH depletion in human keratinocytes, inhibited skin aging-related enzymes, enhanced wound healing process, inhibited the bacterial growth of P. aeruginosa, impaired biofilm formation, bacterial swimming and swarming, and the bacterial pigment (pyocyanin) production. These beneficial and protective effects are most likely due to the richness of the extracts in antioxidant compounds that enhance skin integrity, support collagen production, combat pathogens, and enhance the skin’s defense against oxidative stress. Nonetheless, additional investigations are imperative to uncover the complete capabilities of P. sativum, comprehend its modes of action and potential adverse effects on the skin, and develop efficient compositions to address diverse dermatological ailments.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

Ethical approval was not required for the studies on humans in accordance with the local legislation and institutional requirements because only commercially available established cell lines were used. Ethical approval was not required for the studies on animals in accordance with the local legislation and institutional requirements because only commercially available established cell lines were used.

IM: Investigation, Writing – original draft. PI: Investigation, Writing – original draft. HA: Investigation, Writing – original draft. WB: Investigation, Writing – original draft. NS: Investigation, Writing – original draft. AA: Writing – review & editing. DM: Investigation, Writing – review & editing. MS: Conceptualization, Validation, Writing – review & editing.