Antioxidant, Anti-inflammatory, Analgesic Properties, and Phytochemical Characterization of Stem Bark Extract and Fractions of Anthocleista nobilis

BACKGROUND: Anthocleista nobilis (Loganiaceae) is used by Mbano people of Imo State, Nigeria, for the treatment of various ailments OBJECTIVE: The aim of this study is to evaluate the antioxidant, anti-inflammatory, and analgesic properties of the methanol extract, fractions, and subfractions of A. nobilis. MATERIALS AND METHODS: The powdered stem bark was extracted with methanol and sequentially fractionated into n-hexane, ethyl acetate, and butanol fractions. The constituents of the fractions were analyzed using high-pressure liquid chromatography (HPLC), and the components were identified by dereplication. Antioxidant potential of the extracts and fractions was investigated using 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging method. Anti-inflammatory and analgesic activities of the extract and fractions were also investigated using xylene-induced inflammation and acetic acid-induced writhing models, respectively. RESULTS: A total of five compounds isovitexin (R(t) = 18.77 min), isovitexin-2''-O-xyl (R(t) = 19.68 min), p-Hydroxybenzoic acid (R(t) = 11.88 min), Sarasinoside L (R(t) = 19.64 min), isovitexin (R(t) = 18.77), and apigenin monoglycoside (R(t) = 19.64 min) were identified by HPLC analysis and dereplication. The ethyl acetate fraction and subfraction elicited the best anti-inflammatory activity. The ethyl acetate subfraction also inhibited acetic acid-induced pain by 79% and 85.0% at the doses of 100 mg/kg and 200 mg/kg, respectively, which was better than 71.1% and 81.3% observed for diclofenac at similar doses. CONCLUSION: A. nobilis could be a potential source of anti-inflammatory and analgesic lead compounds. SUMMARY: The extract, fractions and subfractions of Anthocleista nobilis were screened or antioxidant, anti-inflammatory and Analgesic properties in vitro and in mice models. Some of the components were identified by dereplication after HPLC analysis. The results demonstrated potent anti-inflammatory and analgesic property of the extracts and fractions. The dereplication analysis also identified vitexin and related compounds. [Image: see text] Abbreviation used: HPLC: High performance Liquid Chromatography; VLC: Vacuum Liquid Chromatography; DPPH: 2,2-Diphenyl-1-pycrylhydrazine; SPSS: Statistical Package for the Social Sciences; ROS: Reactive Oxygen Species