Application of essential oils of spices and medicinal herbs against Candida albicans

Abstract

Candida albicans is pathogenic yeast species present as a part of the normal microbiota mucosal surface oral and vaginal cavities and digestive tract of warm-blooded animals and humans, without causing any health problems. Intensive growth and infection can occur as a result of excessive use of broad-spectrum antibiotics, corticosteroids, in immunosuppressive individuals, so as under the influence of numerous external factors that weaken the body's defence system. Since antibiotics stimulate the growth of Candida albicans, treatment is based on the use of antimycotic drugs and dietary adjustments, when healing process can sometimes take several weeks. In addition, long-term use of antimycotic drugs causes side effects (nausea, vomiting, diarrhea) and their frequent use contributes development of resistant strains of Candida albicans, which further complicates curing. In order to alleviate treatment, recent years great interest is focused on finding and application of natural preparations, such as essential oils of spices and medicinal herbs, which possess numerous biological properties, including antifungal activity. The aim of this study was to evaluate the antifungal activity of essential oils of various spices and medicinal herbs against Candida albicans in order to find an alternative treatment for candidiasis. The antifungal activity of twenty essential oils and herbal tinctures was investigated by agar well diffusion and broth macrodilution methods, and the obtained results were compared with the effect of antimycotic drugs (nystatin) and commercial preparations present in the local marketplace. Based on the results obtained by the agar well diffusion method, undiluted essential oils and herbal tinctures can be divided into five groups, according to the diameter of inhibition zone they form. Very strong antifungal activity was observed with essential oils of oregano, basil, thyme and cinnamon, with a diameter of the inhibition zones greater than 40mm, while strong activity was also noticed with essential oil of lemon balm (34.5 mm). Essential oils of clove, ginger, mint, bay and lavender have shown moderate antifungal activity (20-30 mm) , while weak activity was registered with essential oils of rosemary, star anise and turmeric (16-20 mm). Very weak antifungal efficacy was observed with sage and immortelle essential oils (12-15 mm), while antifungal activity was not present with essential oils of frankincense and black pepper, as well with herbal tinctures of garlic and wild garlic. The lowest values for minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were achieved with essential oils which had very strong and strong antifungal activity determined by agar well diffusion method, as undiluted and diluted in 96% ethanol. According to the results obtained in this study, the essential oils of cinnamon, oregano, basil, thyme and lemon balm can be used, instead of nystatin, in infections caused by Candida albicans strains.