Preparation of anthraquinone high-yielding Senna alata extract and its stability

A one-step purification of Senna alata (L.) Roxb. (Leguminosae) extract using silica gel vacuum chromatographic technique provided an anthraquinone high-yielding S. alata leaf extract. This method was capable of improving its anthraquinone content as well as antifungal activity against dermatophytes. The extract contained anthraquinone content up to 16.7% w/w, and exhibited antifungal activity against Trichophyton rubrum, T. mentagrophytes and Microsporum gypseum with minimum inhibitory concentration (MIC) values of 15.6, 62.5, and 250 μg/mL, respectively. Stability evaluations of the anthraquinone high-yielding extract in several conditions through a period of 4 months found that the extracts were stable either kept under light or protected from light. The extracts were also stable under 4 ± 2°C, 30 ± 2°C and an accelerated condition, at 45°C with 75% relative humidity. The aqueous solutions of the extracts, at pH 5.5 and 7, exhibited good stability. These results indicate that the anthraquinone high-yielding S. alata extract possessed satisfactory antifungal activity and stability for a further development of herbal medicines.