Toxicological study of various crude extracts of Hyoscyamus gallagheri native to Oman

Cancer is considered a major health issue all over the world for its high morbidity and mortality. Naturally obtained anticancer compounds have comparatively less side-effects, thus it remains a major focus for research. Hyoscyamus gallagheri (H. gallagheri), is one of the plants which have a useful source of bioactive metabolites. The present study is based on preparing plant extracts from the aerial parts of the herbal drug H. gallagheri with various polarities, determining their cytotoxicity and isolating the major cytotoxic compound from the highest active extract. A methanol extract was prepared by the Soxhlet extraction method. Then, it was processed with solvents of increasing polarities. Later, the extracts were evaluated for their cytotoxic activity by brine shrimp lethality assay (BSLA). The highest mass obtained was ethyl acetate and the highest cytotoxicity activity was observed in the ethyl acetate extract, While the lowest was water extract. Ethyl acetate extract was processed for isolation of cytotoxic compounds by different chromatographic methods to give nine fractions which were evaluated by BSLA. Among all, fractions No. 2, 3 and 4 showed significant activity against BSLA and the fractions were purified using preparative thin-layer chromatography (PTLC) to give four compounds (1-4). Only compound 1 showed high purity and appropriateness for NMR analysis. The compound was identified, and the structure was elucidated using 1D and 2D spectroscopy and was found to be 5,7,2',3',4' pentahydroxyflavanone (1). In conclusion, the isolated bioactive compound could be used as an anticancer agent.

Keywords: 1D; 2D NMR; Chromatography; Cytotoxic activity; Fractionation; Hyoscyamus gallagheri; Soxhlet extraction.