Bioactive Natural Products from Two Sudanese Medicinal Plants Diospyros mespiliformis and Croton zambesicus

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 and3 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 6exhibited strong antioxidant activity.