• Proceedings of the Plant Resources Society of Korea Conference
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• v.18 no.1
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• pp.41-51
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• 2005

We examined whether extracts from 14 local citrus spp. on Jeju Island (Korea) contained chemosensitizing activity that would increase the cytotoxic effect of vincristine(VCR) in drug-resistant cancer cells. We report that methanol extracts from fruits and flowers of some species had a chemosensitizing effect that reversed P-glycoprotein (Pgp)-mediated multidrug resistance (MDR). Using drug-sensitive AML-2/WT and drug-resistant AML-2/D100 in the absence of VCR in human acute myelogenous leukemia cells we found that fruit or flower extracts alone generally had low cytotoxicity $(IC_{50}>200\;{\mu}g/ml)$. In studies examining the effect of extracts on 120 ng/ml VCR cytotoxicity in drug-resistant AML-2/D100 cells, we found that immature fruit extracts had greater chemosensitizing activity than either extracts from mature fruit or flower. Of the 14 species examined, the immature fruit extract from Inchangkyool (Citrus ichangiensis) showed the hishest chemosensitizing index(CI) valus. Immature fruit extracts of Hongkyool(C. tachibana), Byungkyool(C. platymamma), Cheongkyool(C. nippokoreana) and Jinkyool (C. sunki) also strongly potentiated VCR cytotoxicity in AML-2/D100 cells. The chemosensitizing effect of peel extracts was 2-10-fold that of whole fruit extracts from Hongkyool (C. tachibana), Byungkyool (C. platymamma) and Inchangkyool (C. inchangiensis). The CI values for flower extracts were higher than those for mature fruit extracts, but lower than those for immature fruit extracts. These results indicate that immature citrus fruits contain compounds that do not exert their activity solely through cytotoxicity. In particular, Incahngkyool (C. inchangiensis), Byungkyool(C.platymamma), Cheongkyool(C. nippokoreana) and Hongkyool (C. tahibana) may be useful sources of chemosensitizing compounds.

• Korean Journal of Plant Resources
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• v.10 no.3
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• pp.213-220
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• 1997

The present study has been undertaken to characterize availability of citrus as a medicinal plant with antineoplastic property. The crude extracts from 40 species of fruits with 12 species of the local Citrus in Cheju island were evaluated on their potential activities against mouse P388 lymphocytic leukaemia in vitro. The percent cytotoxicity varied from 25.40 to 97.94% at a concentration of $100{\mu}g/mL$. Among 40 spp., 8 species showed high toxicity more than 90% against P388 cells and Cheongkyool(C. nippokoreana) exhibited the most cytotoxicity as 97.94%($IC_{50}=20.2{\mu}g/mL$). Nine varieties of C. junos were showed insiginicant cytotoxicity. In trifoliate orange, immature fruit was stronger than mature and peel extract showed higher cytotoxicity($IC_{50}=18{\mu}g/mL$) than the other tissues. Hexane fraction from methanol(MeOH) extract of trifoliate orange showed highly significant inhibition of cell growth($IC_{50}=3.9{\mu}g/mL$). In addition, its cytotoxicity increased remarkably from 3.95 to $0.40{\mu}g/mL$ as exposure time legthened. Cytotoxic activities of crude extracts were decreased considerably during a six months storage period. It was apparent that there is considerable variation in cytotoxicity, depending upon species, maturity and storage time of extracts. There was no meaningful cytotoxic difference between archicitrus and metacitrus in the genus Citrus.