Anti-inflammatory effects of Solanum procumbens on a low dose complete Freund's adjuvant-induced arthritis rat model

Objective: To investigate the anti-inflammatory and analgesic effects of Solanum procumbens on complete Freund's adjuvant-induced arthritis rat models. Methods: We isolated and identified five compounds in the ethanol-soluble Solanum procumbens extract (SP) with anti-inflammatory effects, including ursolic acid, β-sitosterol, hexadecanoic acid, cis-vaccenic acid, and vanillic acid. Additionally, we investigated the anti-inflammatory effects of SP on rheumatoid arthritis symptoms, including paw volumes, local temperatures, withdrawal latency, and mechanical withdrawal threshold at the hind paw and white blood cell (WBC) number from complete Freund's adjuvant-induced arthritis rat models. Results: We have successfully established a complete Freund's adjuvant-induced arthritis rat model at a low dose (1 mg/mL). SP extract significantly reduced paw volumes (P<0.05), prolonged withdrawal latencies (P<0.05), decreased local temperature, and increased the mechanical withdrawal threshold (P<0.05), but only SP extract at the dose of 300 mg/kg significantly decreased WBC numbers. Conclusions: SP extract could be a potential medication candidate with anti-inflammatory effects for arthritis, but it requires further investigation into the mechanism of the SP and its effectiveness on other models as well as clinical trials.