An investigation of the in vitro transport of Sceletium tortuosum alkaloids across porcine buccal, sublingual and intestinal membranes
Sceletium tortuosum (L.) N.E.Br. is indigenous to South Africa and has traditionally been used for its mood enhancing properties. Recently, products containing S. tortuosum have become increasingly popular and are commonly administered as tablets, capsules, teas, decoctions or tinctures, while the dried plant material has traditionally been masticated and the resulting extracts swallowed. In this study, the in vitro transport of four major S. tortuosum alkaloids across porcine intestinal, sublingual and buccal mucosa in their pure form as well as in the form of three different crude extracts; water, methanol and an acid-base alkaloid-enriched extract, was evaluated.
The permeability of mesembrine across intestinal tissue was higher than that of the highly permeable reference compound, caffeine, in its pure form as well as in the form of crude extracts. The intestinal permeability of mesembranol was similar to that of caffeine, while that of mesembrenol and mesembrenone was lower than that of caffeine but much higher than that of the poorly permeable reference compound, atenolol. In general, the permeability of the alkaloids was lower across the sublingual and the buccal tissues than across the intestinal tissue. However, comparing the transport of the alkaloids with that of the reference compounds there are indications that absorption from the oral cavity may contribute considerably to the overall bioavailability of the alkaloids when the plant material is chewed. The results from this study predict relatively good bioavailability of the alkaloids of S. tortuosum in purified or crude extract form when administered orally.