Effect of triterpenoids isolated from the floral spikes of Betula platyphylla var. japonica on P-glycoprotein function.
One of the major causes of multidrug resistance (MDR) in cancer cells is over-expression of P-glycoprotein (P-gp). We studied the effects of 20 triterpenes isolated from the floral spikes of Betula platyphylla var. japonica ( B. platyphylla) on P-gp function based on our previous finding that some of them showed MDR reversing effects. We evaluated accumulations and effluxes of rhodamine 123 as a P-gp substrate with P-gp over-expressing KB-C2 cells. Among the 20 triterpenes, compounds 3, 4, 8, 9, 13, 15, and 20 increased rhodamine 123 accumulations in KB-C2 cells, and three ( 8, 13, and 20) of them also inhibited efflux of rhodamine 123 out of cells. In addition, compounds 13 and 20 showed a weak inhibitory activity of P-gp ATPase. These results suggested that MDR reversing effects of compounds 13 and 20 are partly involved in inhibition of P-gp ATPase.
Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan. mmsk@nupals.ac.jp
Michiko
M
Sekiya
Yoshiki
Y
Kashiwada
Tomohiro
T
Nabekura
Shuji
S
Kitagawa
Takashi
T
Yamagishi
Takako
T
Yokozawa
Takashi
T
Ichiyanagi
Yasumasa
Y
Ikeshiro
Yoshihisa
Y
Takaishi
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D029662:Betula; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D035263:Flowering Tops; D005456:Fluorescent Dyes; D006801:Humans; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D020112:Rhodamine 123; D014315:Triterpenes / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D005456:Fluorescent Dyes; D010936:Plant Extracts; D014315:Triterpenes; D020112:Rhodamine 123