Antidepressant screening and flavonoids isolation from Eremostachys laciniata (L) Bunge

Eremostachys laciniata (L) Bunge (Lamiaceae), a rich source of flavonoids, has been investigated for chemical constituents and in vivo antidepressant property using forced swim test (FST) model. Five important compounds were isolated, including luteolin (1), apigenin (2), 5,8-dihydroxy-6,7-dimethoxyflavone (3), 5,7-dihydroxy-6,8-dimethoxyflavone (4) and luteolin 7-O-beta-glucoside (5). Compound 3 and 4 were isolated for the first time from the plant. A profound antidepressant action was observed for the crude extract at low doses, followed by a state of depression at higher doses. The initial antidepressant-like property of the plant may be attributed to the presence of apigenin like compounds; where as, an increase in immobility time observed at higher doses of the extract may be due to the sedative and calming effect of luteolin present in the plant. E. laciniata may be a potential source for the isolation of important natural products with antidepressant-like properties.