In vitro anti-yeast effect of Nigella sativa seed quinones

Abstract

N. sativa L. seeds (Ranunculaceae), commonly known as black seed or black cumin, have been traditionally used as a curative remedy for numerous disorders as well as spice and food preservative. Several pharmacological activities of the seeds have been attributed to the quinone constituents of its volatile oil, particularly to thymoquinone (TQ). Thymohydroquinone (THQ) and dithymoquinone (DTQ). Although many of the biological effects, e.g. antibacterial, antiparasitic and anti-inflammatory have been widely investigated in the past [1], antifungal activity of the plant has been rarely assessed [2]. In this study we describe the in vitro inhibitory effect of N. sativa quinones on growth of human pathogenic and food spoilage yeasts, namely on Candida albicans, Debaryomyces hansenii, Kluyveromyces marxianus, Pichia anomala, Saccharomyces cerevisiae, and Yarrowia lipolytica using the broth microdilution method [3]. For the tests purposes TQ was purchased from Sigma-Aldrich (CZ), whereas DTQ and THQ were synthesized from TQ according to the previously described methods [4,5]. The results showed that TQ and THQ possessed inhibitory effect against all yeasts tested in this study at concentrations of 64µg/ml and below, except THQ, which inhibited the growth of C. albicans strains with MICs value 256µg/ml. The strongest antimicrobial effect showed TQ and THQ, inhibiting the growth of Z. microellipsoides with minimum inhibitory concentration 8µg/ml. DTQ possessed no inhibitory activity. Regarding to our results, we suggest TQ and THQ as a perspective anti-yeast agents for possible applications in pharmaceutical or food industry.