title: The antifungal activity and membrane-disruptive action of dioscin extracted from Dioscorea nipponica.
abstract: Dioscin is a kind of steroidal saponin isolated from the root bark of wild yam Dioscorea nipponica. We investigated the antifungal effect of dioscin against different fungal strains and its antifungal mechanism(s) in Candida albicans cells. Using the propidium iodide assay and calcein-leakage measurement, we confirmed that dioscin caused fungal membrane damage. Furthermore, we evaluated the ability of dioscin to disrupt the plasma membrane potential, using 3,3'-dipropylthiadicarbocyanine iodide [DiSC(3)(5)] and bis-(1,3-dibarbituric acid)-trimethine oxanol [DiBAC(4)(3)]. Cells stained with the dyes had a significant increase in fluorescent intensity after exposure to dioscin, indicating that dioscin has an effect on the membrane potential. To visualize the effect of dioscin on the cell membrane, we synthesized rhodamine-labeled giant unilamellar vesicles (GUVs) mimicking the outer leaflet of the plasma membrane of C. albicans. As seen in the result, the membrane disruptive action of dioscin caused morphological change and rhodamine leakage of the GUVs. In three-dimensional contour-plot analysis using flow cytometry, we observed a decrease in cell size, which is in agreement with our result from the GUV assay. These results suggest that dioscin exerts a considerable antifungal activity by disrupting the structure in membrane after invading into the fungal membrane, resulting in fungal cell death.
authors.affiliation: Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Jaeyong
authors.initials: J
authors.lastname: Cho
authors.forename: Hyemin
authors.initials: H
authors.lastname: Choi
authors.forename: Juneyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Mi-Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Ho-Yong
authors.initials: HY
authors.lastname: Sohn
authors.forename: Dong Gun
authors.initials: DG
authors.lastname: Lee
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001703:Biophysics / Q000379:methods; D002176:Candida albicans / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects; D027742:Dioscorea / Q000378:metabolism*; D004144:Diosgenin / Q000031:analogs & derivatives* / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry / Q000379:methods; D005452:Fluoresceins / Q000737:chemistry; D008564:Membrane Potentials / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence / Q000379:methods; D010936:Plant Extracts / Q000378:metabolism; D011419:Propidium / Q000494:pharmacology; D012235:Rhodamines / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000935:Antifungal Agents; D005452:Fluoresceins; D010936:Plant Extracts; D012235:Rhodamines; D011419:Propidium; C019357:dioscin; D004144:Diosgenin; C007740:fluorexon