Effect of melatonin derivatives on Candida albicans

Method: 2-pyrazine carbonyl melatonin (2-PCM) was synthesized by using dicyclohexylcarbodiimide as catalyst, fractionated by analytical thin layer chromatography and chemically identified by using Nuclear Magnetic Resonance method. 10³ Colony forming unit (CFU)/ml of Candida albicans strain ATCC MYA-2876 (SC5314) was cultured in the presence of 500, 1,500 or 2,000 µg/ml melatonin, 2-PCM or 0.8, 1.7 or 2.4% dimethyl sulfoxide (DMSO) at 37°C for 24 hrs, subsequently 10-fold serial dilutions were prepared using phosphate buffer saline; each solution was finally plated into Sabouraud dextrose agar at 37°C for another 24 hrs to examine anticandidal effect. Comparisons between CFU/ml between groups were conducted by Analysis of Variance (ANOVA) and post hoc analysis by t-test.

Result: Methods used to synthesis 2-PCM were successful. The results from plate count experiments showed that 1,500 µg/ml and 2,000 µg/ml of 2-PCM and melatonin significantly reduced quantity of C. albicans (p < 0.05) compared to control as well as 1.7% and 2.4% of DMSO which used as a solvent of those two agents.

Conclusion: Within the limits of this in vitro study, Melatonin and 2-PCM have dose-dependent anti-candidal effect. Therefore, further study is needed to confirm and investigate the mechanism involved in the inhibitory activity of 2-PCM against C. albicans.