Effect of piperine on antifungal-resistant clinical isolates of Candida albicans and PLB1 expression

Abstract

Candida albicans is the most common cause of oral, cutaneous and vaginal Candidiasis which the incidence ranging up to 50% among those patients. Phospholipase proteins, genes like PLB1 act as virulence genes that code for C. albicans colonization and biofilm formation. Piperine is alkaloids content located in the seed of black pepper (Piper nigrum), and it has antimicrobial effects. This study aimed to study the effectiveness of piperine on resistant isolates of yeast isolated from patients with candidiasis. One hundred clinical samples were swabbed from oral and vaginal candidiasis patients who attended Baqubah teaching hospital in Iraq for a period of fourteen months, extending from December 2023 to January 2025. The samples are cultured using Sabouraud dextrose agar medium (SDA) at 37°C for 2-3 days. The identification of C. albicans was done by culturing it on HiChrom Candida agar medium, Vitek and SDA at 42°C for 2 days. Serial dilutions of Piperine, which were (2.5, 5, 10, 20, 40, 80, 160 and 320) µg/ml, were made for the treatment of the resistant isolates of C. albicans toward fluconazole (FLU) (25 µg) and nystatin (NY) (100 IU) antifungals. Real-time PCR technique was used for PLB1 gene expression of C. albicans isolates before and after treatment with piperine. Forty-two isolates were identified as Candida species (42.0%). According to the cultural and biochemical detection methods, sixteen (16 out of 42) isolates were identified as C. albicans. A statistically significant difference was observed between study groups of genders concerning the causes. Based on antifungal susceptibility testing, five isolates were resistant to two studied antifungals, with a percentage of 31.25%. The MIC of piperine (40 µg/mL) was affected on C. albicans isolates with ascending inhibition zones (5, 8, 9, 14 and 16) mm. The results of the RT-PCR technique revealed that PLB1 gene expression of resistance C. albicans isolates was reduced after treatment with piperine extract. This study concluded that these findings are primarily the detection of the piperine effect against the C. albicans isolated from patients with candidiasis. So, in the future, another study must be conducted with large samples of candidiasis and isolates of C. albicans.