Phytochemical Analyses of Mundulea Sericea, Tephrosia Uniflora (Leguminosae) and, Strebulus Usambarensis (Moracea) for Anti-infective and Cyctotoxic Principles

Abstract

Phytochemical analysis of the dichloromethane/methanol (1:1) extracts of Mundulea sericea and Tephrosia uniflora (both Leguminosae) and Strebulus usambarensis (Moraceae) yielded thirtyone compounds. Phytochemical analysis of S. usambarensis stems and roots resulted in the identification of three novel naphtho-benzofuran derivatives, named usambarin A (110), B (111), and C (112). Eight new naphthalene derivatives named usambarin D (113), E (114), F(115), G (116), H (117), I (118), and L (125), phenyl-1-benzoxepin derivative (120), two flavans (119 and 126), and four known compounds. Similarly, the analysis of the leaves and roots of M. sericea yielded ten known compounds; three flavanonols, two flavanols, an isoflavone, one rotenoid, two pterocarpans, and the sterol stigmasterol. Phytochemical investigation of the stems of T. uniflora also yielded one new -hydroxydihydrochalcone (134) and three known compounds (an isoflavone, -hydroxydihydrochalcone and a rotenoid). NMR, X-ray crystallography, UV spectroscopy, electronic circular dichroism and mass spectrometry were used to determine their structures. The crude extract of M. sericea roots exhibited antiplasmodial effect against chloroquine-resistant (W2) (IC50 of 0.6 μg/mL) and chloroquine-sensitive (3D7) (IC50 1.8 μg/mL) strains of Plasmodium falciparum. Among the major compounds from this plant, lupinifolinol (129) (IC50 values of 2.0 M for the W2 strain and 6.6 M for the 3D7 strain), and mundulinol (64) (IC50 of 5.9 μM against the W2 strain and 2.4 μM against the 3D7 strain) were active. The antileishmanial activity of selected compounds was tested against L. donovani strains, both antimony-sensitive (MHOM/IN/83/AG83) and antimony-resistant (MHOM/IN/89/GE1), of which sericetin (130) was active against antimony-sensitive (IC50 5.0 M) and antimony-resistant (IC50 38.0 μM) strains. Dehydrolupinifolinol (128) was also active against the antimony-sensitive strain (IC50 9.0 μM). The isolated compounds from S. usambarensis were tested against E. coli and B. subtilis. Usambarin D (113) had moderate antibacterial activity against B. subtilis (MIC = 9.0 M), however, the other compounds examined were inactive (MIC >100 M). All the tested compounds were inactive against E. coli. Some of the identified compounds from S. usambarensis and M. sericea were investigated for their cytotoxicity against; lung (A549), breast (MCF-7), immortal human hepatocytes non- cancerous (LO2), liver (HepG2), and human bronchial non-cancerous (BEAS-2B) cell lines. Usambarins A

(EC50 of 65 μM) and B (EC50 of 92 μM) were weakly cytotoxic against the breast cancer cell line, while compounds 114, 115, 119, 120, and 122 were not cytotoxic to MCF-7 with EC50 > 200 μM. The current study has revealed that M. sericea, S. usambarensis, and T. uniflora possess a spectrum of metabolites with unique structural features with potential in the development of antimalarial, anticancer, antibacterial and antileishmanial agents…………….