Phytochemical and antimicrobial studies on some Nigerian medicinal plants

Abstract

Medicinal plants are employed in traditional medicine for diverse uses such as in the treatment or  management of disease conditions like malaria, diabetes, sickle-cell anaemia, tumors, inflammations,  cardiac troubles, mental disorders and especially microbial infections. There is an ever growing need to  subject these ethnomedicinal uses to scientific scrutiny. Hence, the phytochemical and antimicrobial  studies on some plants found in the Nigeria were undertaken. The phytochemical screening revealed that all the twenty plants tested negative for anthraquinones while only Acalypha indica gave a positive  reaction for cyanogenic glycosides. However, each plant either demonstrated the presence or absence of alkaloids, saponins, tannins, cardiac glycosides, terpenes and flavonoids. All but the extract of A. indica strongly inhibited the growths of B. subtilis and S. aureus. Also, extracts of Pycnanthus angolensis,  Ageratum conyzoides, Rinorea dentata, Tridax procumbens and Viscum albium gave very weak  antibacterial activities against E. coli while most of the plant extracts were generally inactive against K. pneumoniae, Ps. aeruginosa, S. typhi and S. dysentriae. Surprisingly, more than ten of the plant extracts tested demonstrated some anti-candidal activity notably amongst which are Bryophyllum pinnatum, Carica papaya and Centrosema pulmieri. Cardiac glycosides, terpenes, flavonoids and tannins had been reported to have demonstrated antimicrobial activities in previous studies. The results of the   antimicrobial tests have lent some scientific credence to some of uses of these plants in the treatment or management of infections, especially those of microbial origin.

Keywords: Phytochemical; Antimicrobial; Extracts; Antibacterial; Anticandidal