Effect of chloroform extracts from Longdan Xiegan decoction in inhibiting hydrolytic enzyme activity of Candida albicans isolated from VVC patients

Abstract

To investigate the inhibitory effect and mechanism of chloroform extracts from Longdan Xiegan decoction(CELX) against hydrolytic enzymes activity of Candida albicans isolated from vulvovaginal candidiasis(VVC) patients. Secreted aspartyl proteinase(Sap), phospholipase(PL) and lipase(Lip) positive strains were identified from 15 strains of C. albicans with milk culture medium, egg yolk culture medium and tween-80 medium, respectively. Then, the activities of Sap, PL, and Lip were detected in the above media. qRT-PCR was used to detect the changes in gene expressions of aspartic protease(SAP1-7,10), phospholipase B(PLB1-2) and lipase(LIP3-6). Secreted aspartyl proteinase and phospholipase of 15 VVC clinical strains were positive, and lipase of 11 strains were positive. Compared with the blank control group, the drug CELX-containing medium(milk medium, egg yolk culture medium, tween-80 medium) experiment showed that the sedimentation of colonies decreased gradually in each culture medium with the increase of CELX dose. When the concentration of CELX was 256 mg•L⁻¹, the colony almost disappeared, which indicated the enzyme activity was significantly weakened. The results of qRT-PCR showed that SAP1, SAP2, SAP3, SAP4, SAP7, SAP9 and SAP10 were down-regulated by 62%, 55%, 62%, 84%, 61%, 51%, 68%, respectively, except for SAP5 and SAP6; and PLB1, LIP3, LIP4, LIP6 were down-regulated by 67%, 51%, 54%, 55%, respectively. The findings suggested that CELX may inhibit the activities of Sap, PL, and Lip, which are important virulence factors of C. albicans.