Oleanane and Stigmasterol-Type Triterpenoid Derivatives from the Stem Bark of Albizia gummifera and Their Antibacterial Activities

Chromatographic separation of methanol extract of stem bark of Albizia gummifera led to the isolation of two oleanane-type triterpenoids (1 and 2), a stigmasterol derivative (3), and stigmasterol (4). The structures of the compounds were elucidated based on 1D and 2D NMR spectroscopic data and comparing with reported literature values. The crude extract and the isolated compounds were evaluated for their antibacterial activities against five bacterial strains. Compounds 1, 2, and 4 showed marginal antibacterial activity with the growth inhibition zone ranging from 6.8 to 13.2 mm against the tested bacterial strains, with compounds 2 and 4 showing significant inhibition (13.0 and 13.2 mm) against S. flexneri and S. typhimurium, respectively. While, the standard drug, gentamycin showed inhibition zone 20.0 and 24.0 mm against S. flexneri and S. typhimurium, respectively

BIFLAVONOIDS FROM THE ROOTS OF RHUS RUSPOLII AND EVALUATIONS OF THEIR ANTIOXIDANT ACTIVITIES

Deresa DA, Abdissa Z, Gurmessa GT, et al. BIFLAVONOIDS FROM THE ROOTS OF RHUS RUSPOLII AND EVALUATIONS OF THEIR ANTIOXIDANT ACTIVITIES. Bulletin of the Chemical Society of Ethiopia . 2022;36(3):667-674.Biflavonoids are C-C or C-O-C linked flavonoid dimers with highly restricted presence in plant species. They are extensively reported to possess interesting pharmacological properties. The chromatographic fractionation and purification of CH2Cl2/MeOH (1:1) extract of the root of Rhus ruspolli led to the isolation of a new biflavonoid (1) along with four other known biflavonoids (2-5). The structure of the compounds were identified based on the analysis of NMR spectroscopic and mass spectrometric data and also in comparison with reported literature data. Compounds 2-5 were assayed for their antioxidant activity using DPPH and displayed potent in vitro antioxidant activities. The percentage radical scavenging activities were 78.32, 68.90, 93.22 and 92.00 for compounds 2-5, respectively. The highest activity was observed for compound 4 and 5 with IC50 values of 7.90 and 8.40, respectively, which are even greater than that of ascorbic acid (IC50 9.90). The high antioxidant activity of the compounds could be due to the presence of free hydroxyl groups in the flavonoids. The antioxidant activities of these compounds support the traditional uses of the plant in treatment of wound, ectoparasite and as antibacteria and indicates the potential use of these compounds as drug lead candidates