Trichilia silvatica extracts modulate the oxinflammatory response: an in vitro analysis

Plants belonging to the Meliaceae family, such as Trichilia silvatica C. DC., known as catiguá-branco, have attracted considerable interest in phytochemical research due to their diverse and significant secondary metabolites. Trichilia silvatica has traditionally been employed in Brazilian medicine to treat inflammatory disorders. Moreover, studies have reported its antioxidant and antimicrobial properties, highlighting its potential therapeutic applications.

This study aimed to evaluate the potential of Trichilia silvatica leaf and stem extracts in modulating OxInflammation in RAW264.7 macrophage cells following exposure to lipopolysaccharide (LPS) or hydrogen peroxide (H₂O₂) and to elucidate the underlying mechanisms of action.

The phytochemical composition of the extracts was characterized using thin-layer chromatography (TLC), HPLC equipped with a reversed-phase Hypersil C-18 column, and spectrophotometric method. Their antioxidant activity was evaluated using the 2,2-difenil-1-picrilhidrazil (DPPH) and Ferric Reducing Antioxidant Power (FRAP) assays. Cell viability was assessed via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, alongside the determination of catalase (CAT) and superoxide dismutase (SOD) enzyme activities, as well as nitric oxide (NO) production in cells treated with the extracts and subsequently stimulated with H₂O₂. Gene expression levels of Factor nuclear kappa B (NF-κB), Ciclooxygenase 2 (COX-2), Tumor necrosis factor alpha (TNF-α), Interleukin 10 (IL-10), and Hypoxia-inducible factor-1 (HIF-1) were quantified using RT-qPCR.

Trichilia silvatica extracts revealed the presence of terpenes/steroids, coumarins, condensed tannins, and phenolic acids, including chlorogenic and caffeic acids. The findings indicate that the leaf extract at 100 microg/ml and the stem extract at 100 microg/ml and 250 microg/ml preserved or enhanced cell viability, conferring protection against H₂O₂-induced oxidative stress. These concentrations significantly increased CAT activity, whereas SOD activity remained unaffected. Nitric oxide production was significantly reduced when cells were treated with 100 microg/ml and 250 microg/ml of both leaf and stem extracts. Moreover, FRAP value revealed an increase in antioxidant capacity at 250 microg/mL. Both leaf and stem extracts, at 100 microg/mL and 250 microg/mL, exhibited a DPPH radical scavenging capacity exceeding 75 % and downregulated the expression of pro-inflammatory cytokines, including NF-κB, TNF-α, and COX-2. Notably, the leaf extract at 250 microg/ml and the stem extract at 100 microg/mL upregulated the expression of IL-10 and H1F1.

These findings indicate that Trichilia silvatica extracts exhibit notable antioxidant activity, as evidenced by greater than 75 % inhibition of DPPH radicals and elevated FRAP values. Additionally, the extracts demonstrated anti-inflammatory properties by downregulating key pro-inflammatory mediators, including TNF-α, NF-κB, and COX-2, while upregulating the anti-inflammatory cytoline IL-10 and enhancing enhancing tissue oxygenation and nutrient supply through increased expression of HIF-1. These effects highlight the potential of T. silvatica extracts as therapeutic agents for managing inflammatory diseases associated with oxidative stress, thereby supporting their traditional medicinal use.