Antinociceptive and anti-arthritic effects of aqueous whole plant extract of Trianthema portulacastrum in rodents: Possible mechanisms of action

Abstract

Ethnopharmacological relevanceTrianthema portulacastrum L. (Aizoaceae) is used in traditional African Medicine for the treatment of various illnesses including dropsy, inflammation and rheumatism. Aim of the studyThis study was designed to investigate the anti-nociceptive and anti-arthritic properties of the aqueous whole plant extract of Trianthema portulacastrum (AETP), possible mechanisms of action and characterize some of the active constituents. Materials and methodsAntinociceptive activity was evaluated using the acetic acid-induced writhing and hot plate tests in mice. The carrageenan test was used to induce a transient inflammation while arthritis was induced with complete Freund’s adjuvant (CFA) in rats. On completion of CFA-induced arthritis macroscopic observations, the rats were euthanized to isolate the spleen, liver and limbs for estimation of oxidative stress and histological analysis. ResultsAETP (10, 50, or 250 mg/kg; p.o.) produced significant (p < 0.05) and dose-dependent inhibition (41.10, 50.40, and 67.10%, respectively) of writhing response elicited by acetic acid. Also, increased pain threshold of supraspinally mediated nociceptive behaviour, with peak maximum possible effect (MPE) obtained at 250 mg/kg (22.98%; 30 min post-treatment). However, the pre-treatment of mice with Nitro-L-arginine (L-NNA) or naloxone reversed AETP-induced antinociception. In another experiment, AETP produced time course inhibition of carrageenan-induced paw oedema with peak effect (50.60%) at 250 mg/kg as well as significant reduction in CFA-induced arthritis by 58.56%, on day 27 and arthritic index (26.84%). Similarly, AETP attenuated CFA-induced MDA generation and deficit in antioxidant enzyme activities. Histological analysis of rat joints revealed a reduction in the synovial hyperplasia and mononuclear infiltration induced by CFA in AETP treated groups. ConclusionFindings from this study showed that T. portulacastrum possesses anti-nociceptive action through nitrergic and opioidergic signalling as well as anti-arthritic effect through enhancement of antioxidant defense system and inhibition of release or actions of inflammatory mediators.