Kwanzoquinones A-G and other constituents of Hemerocallis fulva 'Kwanzo' roots and their activity against the human pathogenic trematode Schistosoma mansoni

Schistosomiasis is a debilitating disease caused by parasitic trematodes of the genus Schistosoma that afflicts 200 million people worldwide. Daylilies (Hemerocallis spp.) have been used in Asia for the treatment of schistosomiasis; however, the active principles have not been fully characterized. In our studies of Hemerocallis fulva 'Kwanzo' Kaempfer roots, we have isolated seven new anthraquinones, kwanzoquinones A (1), B (2), C (4), D (5), E (6), F (7), and G (9), two known anthraquinones, 2-hydroxychry sophanol (3) and rhein (8), one new naphthalene glycoside, 5-hydroxydianellin (11), one known naphthalene glycoside, dianellin (10), one known flavone, 6-methylluteolin (12), and a-tocopherol. The structures of the compounds were elucidated by spectroscopic and chemical methods. Compounds 1-11 and the monoacetates of kwanzoquinones A and B, 1a and 2a, respectively, were tested for their activity against multiple life-stages of Schistosoma mansoni. Compound 3 immobilized all cercariae within 15 s at 3.1 mug/mL. However, upon removal of the compound, 20% of the immobilized cercariae recovered after 24 h. In contrast, compound 6 immobilized cercariae within 12-14 min at 25 mug/mL. Following removal of the compound, all cercariae died within 24 h. The adult worms were also immobilized within 16 h by compounds 3 and 6 at 50 mug/mL. None of the compounds had an effect on the schistosomula stage. (C) 2002 Elsevier Science Ltd. All rights reserved.