Neurological activities of lapachol and its furano derivatives from Kigelia africana

Abstract

This study was carried out to investigate some neurological activities of lapachol and other chemical constituents isolated from Kigelia africana in male albino mice using elevated plus-maze (EPM) test, open-field test (OFT), and forced swimming test (FST). The anxiolytic-like and antidepressant effects of these constituents were compared to known active anxiolytic (diazepam, 2 mg/kg) and antidepressant (imipramine, 15 mg/kg) reference drugs. The compounds 1 [50 mg/kg, intraperitoneally (i.p.)] and 3 (100 mg/kg, i.p.) significantly increased the number of lines crossed in the OFT and the duration of immobility in the FST, indicating a possible antidepressant activity, but no significant effect was observed in the EPM test. The compound 4 (100 mg/kg, i.p.) significantly increased the time spent on the open arms, but the increase in number of open arms entries was not significant in the EPM test. Meanwhile, the duration of the immobility time was significant and quite close to that of the standard drug, imipramine used in the FST. The compound 5 (100 mg/kg, i.p.) substantially increased the time spent and entries into open arms of the EPM, and reduced the time spent and entries into closed arms, when compared with saline controls (P < 0.05). This compound also increased the exploratory activity of the mice as well as the swimming duration in the OFT and FST, respectively. These results indicate that among the compounds tested, quinones displayed significant anxiolytic and/or antidepressant effects at all doses tested. Kojic acid, a fungal metabolite whose structure was unambiguously confirmed by single-crystal X-ray studies, is also isolated for the first time from K. africana, suggesting that it is a possible taxonomic marker in the biogenesis of the quinone skeleton.