Rawiya H. Alasbahi1 (Ph. D. / Pharmacy), Lyle E. Craker (Professor Ph. D. /Agronomy & Plant Genetics) and Saida Safiyeva (MSc / Pharmacy)
Laboratories for Natural Products, Medicinal and Aromatic Plants, University of Massachusetts, Amherst, MA 01003-0910 USA
Essential oils play a role as potential antimicrobial agents for preservative purposes in food and cosmetic industries, for crop protection, and several medicinal applications (e.g. mouthwash, dental practice, aromatherapy). Antimicrobial, antifungal and
antioxidant activities in essential oils have been reported in a number of studies (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15). Moreover, the use of essential oils as antimicrobial agents could afford satisfaction, as they are generally inexpensive, biodegradable and non-toxic (16). Researches on the bioactivity of essential oils and their role in Yemeni traditional medicine are lacking. The present study was therefore undertaken to test the antimicrobial activity of essential oils extracted from some Yemeni medicinal plants, Acacia harala Gifri & Thulin sp. nov. aff. ehrenbergiana Hayne., bark (Fabaceae), a recently identified native Yemeni medicinal plant (17); Acalypha fruticosa Forsk., leaves (Euphorbiaceae);
Capparis cartilaginea Decne, leaves (Capparaceae); Indigofera sedgewickiana Vatke & Hildebr., leaves (Fabaceae) and Plectranthus cf. barbatus leaves and stems (Labiatae). Determination of the antimicrobial activity of a number of extracts of different polarities prepared from the above-mentioned plant tissues has been reported in our pervious work (18). However, screening their essential oils for antimicrobial activity was carried out to assess the role of essential oils in the overall antimicrobial activity of the tested plants, and to help providing scientific justification for the utilization of these plants in traditional medicine.
Materials and Methods
The plants used in this study, bark of Acacia harala, leaves of Acalypha fruticosa, leaves of Capparis cartilaginea, leaves of Indigofera sedgewickiana and leaves and stems of Plectranthus cf. barbatus were collected in Abyan, Taiz, and Yaffee Heights, Republic of Yemen. The first four