Antimicrobial Evaluation of Crude Methanolic Leaf Extracts from Selected Medicinal Plants Against Escherichia coli

Medicinal plants are used by almost 80% of the world’s population for their basic health care because of their low cost and ease in availability. Herbal drugs made from medicinal plants have been used from ancient times to treat various diseases and their antimicrobial properties make them a rich source of many potent drugs.

The use of herbal medicinal plants has always played a positive role in the control or prevention of diseases such as diabetes, heart disorders and various cancers. The genus Tagetes belongs to the Asteraceae family which presently comprises of 56 species, 27 biennials and 29 perennials. Tagetes species and chemo-types from its genus have been largely examined for biological active metabolites that can be used in industry and medicine. Compounds that have antimicrobial activity in the Tagetes minuta plant are said to be accumulated in the organs of the plant and their essential oils have not only antimicrobial effect but also insecticidal properties.

Disc Diffusion Method

Extracts from Tagetes minuta leaf flowers and stem extracted using methanol have shown to contain secondary metabolites including terpenes which are thought to be responsible for antibacterial activities. The genus Aloe is common in Kenya; with about 60 taxa recognized. Aloe species have antibacterial, antifungal, anticancer, antiviral and immunomodulatory properties. Aloe secundiflora other synonyms are; Aloe floramaculata, Aloe engleri and Aloe marsabitensis. Aloe secundiflora leaf components have been credited for antibacterial, antifungal and antiviral and antihelmintic medicinal properties. Herbalists from the Lake Victoria region have traditionally used Aloe secundiflora to treat ailments including chest problems, polio, malaria and stomach ache. Vernonieae is a tribe of about 1300 species of plant in the Asteraceae (compositae) family which mostly contains herbaceous plants. Vernonia laisopus decoctions from the stems and leaves have been traditionally been used by herbalist in East Africa to treat, malaria, worms and gastrointestinal problems. Its extracts have also been used in treating some of the sexually transmitted diseases in southern parts of Africa. Bulbine is a genus of plants in the family xanthorrhoeaceae and sub family asphodeloideae and its members are well known for their medicinal value. Bulbine plant has been used for medicinal purposes in the early stages of the eighteen century by Dutch and British settlers of South Africa in treating various ailments.