Biofunctional effects of thiohemiaminal-type dimeric sesquiterpene alkaloids from Nuphar plants

Abstract

Dimeric sesquiterpene thioalkaloids from the rhizomes of Nuphar pumilum exhibited immunosuppressive effects using a sheep erythrocyte plaque forming cell (PFC) assay, as well as an anti-metastasis effect, and rapid apoptosis-inducing effects in tumor cell lines. In particular, dimeric sesquiterpene thioalkaloids with a hydroxy group (6-hydroxythiobinupharidine, 6,6′-dihydroxythiobinupharidine, 6-hydroxythionuphlu-tine B) showed substantial effects, whereas dimeric sesquiterpene thioalkaloids lacking the hydroxy group (thiobinupharidine, thionuphlutine B, 6′-hydroxythionuphlutine B, neothiobinupharidine, thionuphlutine B β-sulfoxide, neothiobinupharidine β-sulfoxide) and monomeric sesquiterpene alkaloids (nupharidine, 7-epi-deoxynupharidine, nupharolutine) showed weak activity. In this review, we summarize our studies of the biofunctional effects of these alkaloids.