Antioxidant capacity, acute and sub-acute oral toxicity, and in vivo anti-inflammatory effects of Tetradenia riparia hydroalcoholic extract.

Abstract

Tetradenia riparia (T. riparia) is a medicinal plant native to sub-Saharan Africa, traditionally used but has limited in vivo scientific validation. This study evaluated its antioxidant, toxicity, and anti-inflammatory effects using in vivo toxicity tests, paw edema, air pouch models, and vascular permeability assessment. Additionally, qualitative phytochemical analysis and quantitative measurements of total polyphenolic and flavonoid content were conducted. In vitro assays revealed significant concentrations of polyphenolic and flavonoid compounds, demonstrating notable radical scavenging activities in DPPH, phosphomolybdate, and FRAP assays. In vivo studies demonstrated that T. riparia extract showed no indications of acute or sub-acute oral toxicity, even when administered at the highest tested dosage of 5000 mg/kg body weight (LD50 > 5000 mg/kg). Toxicity assessments confirmed its safety, showing no fatalities, significant organ damage as evidenced by histopathological analysis, or substantial adverse effects on most hematological and biochemical parameters. The hydroalcoholic extract of T. riparia demonstrated a notable anti-inflammatory effect that increased with dosage. The inhibition percentage of paw edema by the extract was high at 3 hours, reaching 39.13 ± 8.78%. Nitric oxide (NO) inhibition at doses of 0.5 g/kg and 1 g/kg was recorded as 36.09 ± 2.13% and 49.96 ± 5.41%, respectively. Regarding vascular permeability, T. riparia extract significantly reduced dye leakage (p < 0.05 and p < 0.001), with inhibition percentages of 61.57% and 75.25% at doses of 0.5 g/kg and 1 g/kg, respectively. These findings highlight its promising potential as a treatment for inflammatory disorders. In conclusion, phytochemical analysis identified compounds, which are believed to be responsible for the pharmacological effects observed. Further studies are needed to investigate the chronic consumption of hydroalcoholic extract for long-term isolate bioactive compounds, understand their mechanisms, ensure comprehensive safety profiles for potential drug development, and elucidate their anti-inflammatory mechanism.