RESUMO
CONTEXT: The phytochemical study and biological activities of Astragalus armatus Willd. subsp. numidicus (Fabaceae) pods, an endemic shrub of Maghreb, are reported. OBJECTIVE: This study isolates the secondary metabolites and determines the bioactivities of Astragalus armatus pods. MATERIALS AND METHODS: The chloroform, ethyl acetate and n-butanol extracts of hydro-ethanolic extracts were studied. Antioxidant activity was investigated using DPPH and ABTS radical scavenging, CUPRAC and ferrous chelating assays at concentrations ranging from 3 to 200 µg/mL. Anticholinesterase activity was determined against acetylcholinesterase and butyrylcholinesterase enzymes at 50, 100 and 200 µg/mL. Antibacterial activity was performed according to minimum inhibitory concentration (MIC) method. Carbon clearance method in albino mice was used for the phagocytic activity at concentrations 50, 70 and 100 mg/kg body weight. Spectroscopic techniques were used to elucidate the compounds. RESULTS: Ethyl acetate extract afforded a flavonoid (1) while the n-butanol extract gave four flavonoids (2-5), a cyclitol (6) and a cycloartane-type saponin (7). The ethyl acetate extract exhibited highest antioxidant activity in DPPH (IC50: 67.90 ± 0.57 µg/mL), ABTS (IC50: 11.30 ± 0.09 µg/mL) and CUPRAC (A0.50: 50.60 ± 0.9 µg/mL) assays. The chloroform extract exhibited the best antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, each with 80 µg/mL MIC values. The n-butanol extract enhanced phagocytic activity. DISCUSSION AND CONCLUSION: Isorhamnetin (1), isorhamnetin-3-O-α-l-rhamnopyranosyl-(1 â 6)-ß-d-galactopyranoside (2), isorhamnetin-3-O-ß-d-apiofuranosyl-(1 â 2)-[α-l-rhamnopyranosyl-(1 â 6)]-ß-d-galactopyranoside (3), kaempferol-3-O-(2,6-di-O-α-l-rhamnopyranosyl)-ß-d-galactopyranoside (4), kaempferol-3-O-(2,6-di-O-α-l-rhamnopyranosyl)-ß-d-glucopyranoside (5), pinitol (6) and cyclomacroside D (7) were isolated whereas 1, 2, 6 and 7 are reported for the first time from A. armatus.
