Diverse bioactive secondary metabolites from Phyllopentas schimperi (Hochst.) Y.D. Zhou & Q.F. Wang with chemophenetic significance

An extensive phytochemical study on the combined methanolic extracts from the stem barks and roots of Phyllopentas schimperi (Hochst.) Y. D. Zhou & Q. F. Wang (syn. Pentas schimperi (Hochst.) Wieringa) led to the isolation of a new anthraquinone, schimperiquinone C (1) along with nineteen known secondary metabolites 2–20. The structures of all the isolated compounds were elucidated through spectroscopic techniques including 2D NMR. The new compound and the less common secondary metabolites 2–17 were tested for their pharmacological properties. Compounds 4, 5 and 6 exhibited significant antioxidant and lipoxygenase inhibition activities, whereas compounds 2–5, 7–10, 12 and 17 had a potent urease inhibitory activity. Compounds 8 and 10 had the best urease inhibitory activities as compared to thiourea. Compounds 3, 9, 11, 12 and 17 are reported for the first time from the genus Pentas. The chemotaxonomic significance of the isolated compounds was discussed. Our results could be used for the chemotaxonomy of this species within the genus Pentas and for the Rubiaceae family. The obtained results suggested that some constituents from this plant may be used as such or in the form of their derivatives for the treatment of ulcer.