Inhibition of carotenoid pigmentation in Rhodotorula species by Terbinafine Ali Zarei

Introduction: Terbinafine is a synthetic allylamine antifungal and inhibit ergostrole synthesis by inhibiting squalene epoxidase. It is mainly effective on the dermatophytes however it is also effective against several yeast such as Candida and Rhodotorula species. Carotenoid biosynthesis is a feature of the Rhodotorula species that is aerobes and the air flow rate in the culture is an essential factor to assimilate the substrate. The main aim of the present study was to determine the effect of terbinafine on the carotenoid biosynthesis in Rhodotorula species. Materials & Methods: 28 strains of Rhodotorula including R. glutinis (26), and R. mucilaginosa (2) were examined to determine sensitivity to terbinafine and carotenoid biosynthesis inhibition. All strains were inoculated in 5ml of Sabouraud dextrose broth and incubated at ambient temperature at the shaker for 4 days. Then cultures were centrifuged at 1500g for 15min, washed twice with PBS and adjusted to 1MacFarland. Antifungal activity was measured using a serial dilutions of terbinafine from 256-4 μg/ml. Results: In the present study, 7.7% of strains were inhibited at <64μg/ml of terbinafine followed by 61.6% at 64-32μg/ml and 30.8% at ≥16μg/ml. In addition the production of red carotenoid in the most strains of Rhodotorula (53.8%) was inhibited at 32μg/ml. However terbinafine could not inhibit red pigmentation at 7.7% of strains. Discussion: Terbinafine has inhibitory effect on the red pigmentation in Rhodotorula strains and this effect is displayed at different concentrations.

Carotenoid pigment; Rhodotorula Species; Terbinafine