BINAPHTHALENONE GLYCOSIDES FROM AFRICAN CHEWING STICKS, DIOSPYROS LYCIOIDES

Our laboratory has engaged in the exploration of active antimicrobial principles present in chewing sticks commonly used by the African and Middle Eastern countries as a mechanical oral hygiene aid in place of tooth brushing. During this investigation, a methanol extract from the twigs of Diospyros lycioides, a Namibia tooth cleaning stick, demonst rated antimicrobial activity against common oral pathogens including S treptococcus mutans and Porphyromonas gingivalis (MICs 2.5 and 0.156 m g/mL). Subsequent fractionation and purification of this extract led t o the identification of two novel binaphathalenone glycosides: '-O-bet a-xylopyranosyl(1-->6)-beta-glucopyranoside (1) and i-O-beta-xylopyran osyl(1-->6)-beta-glucopyranoside (2). Their structures were establishe d using spectroscopic techniques. Examination of the antimicrobial act ivity of these two compounds revealed positive but only marginal growt h inhibition against the test cariogenic pathogens, S. sanguis and Str eptococcus mutans.