The antibacterial activities of different plant extracts and few essential oils were evaluated in the laboratory by agar-gel diffusion and disc diffusion techniques against bacteria belonging to four genera. The four strains of bacteria are Bacillus cereus, Staphylococcus aureus, Escherichia coli I and Escherichia coli II. Leaf extracts from the plants Bougainvillea spectabilis wild (Nyctaginaceae), Tagetus erecta (Compositae), and Breynia retusa (Euphorbiaceae), and the essential oils at concentration of 3.0% (w/v)—pine, clove, eucalyptus, tagetus, and neem were the test compounds. Results from the antibacterial tests demonstrated that all the essential oils except neem oil and B. retusa extract (at 500 mg/ml concentration) have an excellent inhibitory effect against bacteria at a fixed dosage of 50 ml. These results suggest that these plant materials have potential as antibacterial compounds and can be exploited for medicinal purpose.
Historically, plants have provided a good source of anti-infective agents. The antimicrobial activity of oils and extracts has been recognized for many years, particularly essential oils and their components are becoming increasingly popular as naturally occurring germicidal agents. The antimicrobial activity of plant oils and extracts has formed the basis of many applications, including raw and processed food preservations, pharmaceuticals alternative medicines, and natural therapies (Reynolds, 1996; Lis-Balchin and Deans, 1997). Today, plant materials are present in or have provided the models for 50% of western drugs (Robbers et al., 1996). Many commercially proven drugs used in modern medicine were initially used in crude form in traditional or folk healing practices or for other purposes that suggested potentially useful biological activity. The primary benefits of using plant-derived medicines are that they are relatively safer than synthetic alternatives, offering profound therapeutic benefits and more affordable treatment. Some studies have concentrated exclusively on one oil or one microorganism. While these data are useful, the reports are not directly comparable due to methodological differences such as choice of plant extracts, test microorganisms, and antimicrobial test methods (Janssen et al., 1987). The Indian subcontinent is rich with a vast array of medicinal and aromatic plants, which have been in use since ancient times in drug preparations and for disease curing purposes. Several essential oils and plant products are yet to be evaluated against different microorganisms to find their use as antimicrobial agents. |
