Effect of Allium cepa on LAC۱ gene expression and physiological activities in Cryptococcus neoformans

Background and Purpose: This study aimed to investigate the effects of Allium cepa ethanolic extract (EAC) on Cryptococcus neoformans biological activities and LAC۱ gene expression.Materials and Methods: The minimum inhibitory concentration (MIC) of EAC was determined based on the Clinical and Laboratory Standards Institute M۲۷-A۴ method at a concentration range of ۱۲۵- ۴۰۰۰ µg/ml. The EAC synergism activity was determined in combination with fluconazole (FCZ) as an antifungal azole. Laccase activity, melanin production, and cell membrane ergosterol content of C. neoformans were assessed at the ۰.۵× MIC concentration of EAC (۱۰۰۰ μg/ml) and FCZ (۶۴μg/ml) by approved methods. The expression of the LAC۱ gene was studied in the fungus exposed to ۰.۵× MIC concentration of EAC and FCZ using the real-time polymerase chain reaction.Results: Based on obtained results, MIC of EAC and FCZ were ۲۰۰۰ and ۱۲۸ μg/ml,respectively. A combinatory effect was reported for FCZ and EAC by a fractional inhibitory concentration index of ۰.۲۵. The cell membrane ergosterol content was inhibited in EAC- and FCZ-treated C. neoformans by ۵۸.۲۵% and ۴۹.۸۵%, respectively.The laccase activity and melanin production were reduced in EAC-treated C. neoformans by ۴۵.۳۷% and ۵۱.۵۷%, and in FCZ-treated fungus by ۵۴.۶۴% and ۵۳.۶۸%, respectively.The expression of fungal LAC۱ at messenger RNA (mRNA) level was measured ۰.۴۶and ۰.۵۸ folds and significantly decreased in both EAC- and FCZ-treated C. neoformans at the ۰.۵×MIC concentration, respectively (p <۰.۰۵).Conclusion: The findings revealed that EAC contains inhibitory compounds which interact with biological activities in C. neoformans and thereby, it could be considered as a potential source for the development of novel antifungal drugs.

کلیدواژه ها:

Allium cepa ، Antifungal activity ، Cryptococcus neoformans ، Laccase ، LAC۱ gene expression