Assessment of extracts from red yeast rice for herb-drug interaction by in-vitro and in-vivo assays.

Red yeast rice (RYR) is made by fermenting the yeast Monascus purpureus over rice. It is a source of natural red food colorants, a food garnish and a traditional medication. Results of the current study demonstrated that polar fractions of the RYR preparations contained herbal-drug interaction activity, which if left unremoved, enhanced P-glycoprotein activity and inhibited the major drug metabolizing cytochromes P450, i,e, CYP 1A2, 2C9 and 3A4.

Oral absorption and antitussive activity of tuberostemonine alkaloids from the roots of Stemona tuberosa.

The intestinal absorption of four stereoisomers of tuberostemonine-type alkaloids, neotuberostemonine (1), tuberostemonine (2), tuberostemonine H (3), and tuberostemonine J (4), isolated from the antitussive Chinese medicinal herb Radix Stemonae, and the IN VIVO antitussive activity of alkaloids 1, 2 and 3 were investigated in the current study. All three alkaloids exhibited dose-dependent inhibitory effects on citric acid-induced cough in guinea pigs after intraperitoneal administration. Alkaloid 2 had the same potency via both oral and intraperitoneal dosing, 1 exhibited significantly lower oral activity than that following intraperitoneal application, while 3 did not show oral activity.