Flavonoid Glycosides and Cannabinoids from Cannabis Pollen

Cannabis sativa L. is one of the oldest plants known in medicine and one that has been most studied with respect to its phytochemistry (Turner et al., 1980). Currently, a total of 483 constituents have been identified in cannabis of which 66 are cannabinoids (Ross et al., 1995). About 20 flavonoids have been reported to be present in the cannabis plant as aglycones or as conjugated O-glycosides or C-glycosides (Paris et al., 1973, 1975; Gellert et al., 1974; Turner et al., 1980; Ross and ElSohly, 1995). The exact structure of most of the glycosides has not been not determined because of the uncertainty of the exact linkage and/or the number of sugar moieties present. Paris et al. (1975) reported the detection of two flavonoids in the extracts of pollen grain from C. sativa, which provided, upon acid hydrolysis, two genins identified as apigenin and luteolin, indicating the presence of the respective O-glycosides in the pollen. Flavonoid glycosides are claimed to be of benefit in treating conditions characterised by capillary bleeding and are also known as powerful antioxidants (Dewick, 2002). Flavonol glycosides are known to have inhibitory activities against HIV-1 reverse transcriptase and HIV-1 integrase (Tewtrakul et al., 2002). The purpose of the present investigation was to study the composition of the flavonoids and cannabinoids present in the pollen grains of cannabis. Pollen grains collected from male plants of C. sativa were successively extracted with n-hexane and methanol. The hexane extract was analysed by GC-FID and GC-MS using 4-androstene-3, 17-dione as the internal standard (Ross et al., 1995); 16 cannabinoids could be identified and quantified. Repeated CC over silica gel of the methanol extract, followed by reversed-phase HPLC and separation over Sephadex LH-20 afforded the 3-Osophorosides of kaempferol and of quercetin.