Zaleya pentandra L. produces anti-arthritic effects by downregulating IL-6, NF-κB, and TNF-α and mitigating oxidative...

Zaleya pentandra L. (Aizoaceae) is traditionally used to treat various ailments including inflammatory conditions, but the literature is scant regarding its role in chronic inflammation. Therefore, the current study aimed to provide evidence and mechanistic understanding of extracts of the plant in chronic inflammatory conditions.

The powdered dried aerial parts were sequentially macerated in hexane, chloroform and methanol. The extracts were investigated for anti-inflammatory activity using albumin denaturation inhibition, membrane stabilization, and anti-proteinase assays. The extract showing higher activity was then investigated for anti-arthritic activity at 300 and 600 mg/kg doses using Complete Freund's Adjuvant (CFA)-induced arthritic rats. Arthritis was induced in the right hind paw of all rats, except control, by injecting a single dose of CFA (0.1 mL). After 7 days, the arthritic rats were treated daily by the extract and standard for 21 days. The body weight and paw size were measured weekly. On the last day of the study, the animals were assessed for analgesia and motor coordination. The blood, liver and sciatic nerve of each animal were subjected to the estimation of biochemical, oxidative and inflammatory markers, and histopathology. Finally, the extract was analyzed by HPLC to identify chemical constituents.

The anti-inflammatory activity of methanol extract was higher compared to other extracts in all the in vitro models (p < 0.05). In the CFA induced arthritic rats, both doses of the methanol extract reduced paw inflammation comparable to the standard (p > 0.05). The biochemical parameters and oxidative stress markers were restored in the extract-treated groups compared to the disease control (p < 0.05). The extract significantly downregulated proinflammatory markers (IL-6, NF-κB, and TNF-α) in the sciatic nerve compared to the disease control (p < 0.05). Histopathological examination revealed improved pannus formation, bone erosion, and inflammation in the ankle joint of extract-treated rats. Likewise, a marked reduction in inflammation was found in the sciatic nerve sections of the extract-treated rats. The methanol extract was found to contain nineteen phenolic compounds.

The methanol extract of Z. pentandra exerts anti-arthritic effects, potentially through the modulation of inflammatory pathways and mitigation of oxidative stress-induced tissue damage. These findings provide evidence to the traditional anti-inflammatory use of the plant.