Phenolic compounds among the bioactive molecules in Ginkgo biloba L.

The interest for natural antioxidants has been increasing over the years. Phenolic compounds comprise a very large group of biologically active molecules, being appreciated for their beneficial effects on health (physiologically active compounds with anti-allergic, antiatherogenic, antimicrobial, antithrombotic, anti-inflammatory, antioxidant, cardioprotective and vasodilatory effects) [1-3]. The aim of the present study was to evaluate the phenolic compounds of Ginkgo biloba L. (infusion and methanol/water extract), widely used in traditional medicine and in dietary supplements. Twenty-five compounds were detected, eighteen of which were flavonoids, one phenolic acid, five terpene lactones and one unknown compound. However, among the twenty-five compounds detected, compounds 1, 2, 4-6 and 12, associated to ginkgolides, were not quantified due their low UV absorption and possible interferences in the complex matrix of G. biloba extracts, as well as the unavailability of commercial gingkolide standards. Regarding the quantified phenolic compounds, flavonoids were the main group present, being two kaempferol derivatives the major compounds found: kaempferol-3-0-dirhamnosylglucoside and kaempferol-3-O-rutinoside. The infusion presented lower quantities than the methanol/water extract, probably due to the high temperatures applied to obtain the first preparation that could have destroyed some thermal sensitive compounds, but also due to the lower extraction time.