1H- and 13C-nmr assignments of phyllanthin and hypophyllanthin: lignans that enhance cytotoxic responses with cultured multidrug-resistant cells
Somanabandhu, A.; Nitayangkura, S.; Mahidol, C.; Ruchirawat, S.; Likhitwitayawuid, K.; Shieh, H.L.; Chai, H.; Pezzuto, J.M.; Cordell, G.A.
Journal of Natural Products 56(2): 233-239
1993
ISSN/ISBN: 0163-3864 PMID: 8385184 Document Number: 168
Complete H-nmr data and unambiguous assignments of the 13C-nmr spectra of phyllanthin [1] and hypophyllanthin [2] were obtained through extensive nmr studies, including homonuclear COSY, homonuclear decoupling, APT, HETCOR, nOe difference, selective INEPT, and COLOC experiments. The absolute configuration of hypophyllanthin [2] was determined by cd. Neither of these lignans demonstrated significant cytotoxic activity when evaluated with a battery of cultured mammalian cells, but both were found to enhance the cytotoxic response mediated by vinblastine with multidrug-resistant KB cells. In addition, 1 was found to displace the binding of vinblastine with membrane vesicles derived from this cell line, suggesting an interaction with the P-glycoprotein.
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