ANTIFUNGAL ACTIVITIES OF SENNA ALATA EXTRACTS USING DIFFERENT METHODS OF EXTRACTION

Abstract

Many Thai medicinal plants have been used for the treatment of dermatomycotic infections, as recorded in Thai traditional texts. Some have been selected and recommended for the primary health care system in Thailand. Senna alata (L.) Roxb. has been used for a long time for the treatment of tinea versicolor and ringworm infections. Extracts were prepared in order to study the active ingredients and find scientific evidence for the herbal activities. Conventional methods using various solvents and soxhlet extraction yielded fractions with different properties. Lyophilization of the aqueous extract might limit the ingredients obtained. However, both methods differed in their yields: in the obtained percentage, appearance, properties and time and cost consumed. In addition, sonication was an alternative to acquire the active ingredients from the plants. With those different manipulations, it was of interest to demonstrate the different antifungal activities of S. alata. In this investigation, S. alata leaves were extracted by three different methods. Using a soxhlet apparatus, an 80 % ethanol extract (26.4 %) (A) was obtained. The extract was treated with HCl, which after further purification gave 7.3 % of crude anthraquinones (B). Lyophilization of water macerates yielded 10.1 % (C). In the third method, a 100-mg amount of pulverised leaves was sonicated with either 95 % ethanol (D) or water (E). After filtration, the residue was extracted for another two times in the same way. The filtrate was volume adjusted to 25 ml. All the extracts were investigated for their antifungal activities. On the basis of inhibitory zone, activities against dermatophytes and Candida albicans 36 and 26 clinical isolates, respectively, were established by an agar diffusion method. The extracts A, B and C (20 mg, each), D and E (80 µg, each) inhibited the dermatophytes by 13.8, 9.9, 21.9, 8.2 and 7.5 mm and C. albicans by 18.8, 10.7, 14.1, 10.1 and 7.2 mm, respectively. From TLC, the crude ethanol and ethanol sonicated extracts (A and D) of S. alata were shown to contain rhein (anthraquinone aglycone), while the lyophilized water extract (C), contained some polar compounds, which might be anthraquinone glycosides.