Bioactive Natural Products from Two Sudanese Medicinal Plants Diospyros mespiliformis and Croton zambesicus
Ietidal E. Mohamed, El Bushra E. El Nur, Muhammad I. Choudhary and Shamsun N. Khan
University of Khartoum, Faculty of Science, Department of Botany, Khartoum, Sudan
H.E.J. Research Institute of Chemistry, International center for Chemical and Biological Sciences, University of Karachi, Karachi- 75270, Pakistan
Abstract: Phytochemical investigations were performed in two plant species used in Sudanese traditional medicines to treat different illnesses, Diospyros mespiliformis and Croton zambesicus. The investigations revealed compounds of triterpenes (lupane series), one trihydroxyflavone and one diterpene. The compounds have been isolated and identified using various chromatographic and spectroscopic techniques. These were lupeol (1), betulinic acid (2), betulin (3) and lupenone (4) from Diospyros mespiliformis. Compounds 1, 2, 3 in addition to diterpene ent -kaurane-3β, 16β, 17-triol (5) and vitexin (6) were re-isolated from Croton zambesicus. However,compound 5 and 6 were isolated for the first time from this source.The pure isolated compounds and semi-synthesized acetates 1Ac, 2Ac and 3Ac, which were prepared from compounds 1, 2 and 3 respectively, were subjected to two bioassays: α- glucosidase enzyme inhibition assay and antioxidant activity. Compounds, 1, 1Ac, 3 and 4 showed a marked α-glucosidase inhibitory potential, while compound 6 exhibited strong antioxidant activity.
Keywords: Croton zambiescus; Diospyros mespiliformis; antioxidant; α-glucosidase; triterpenes;vitexin; ent –kaurane.
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