Antibacterials from medicinal plants
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extended spectrum β-lactamases producing enteric bacteria (E. coli, Salmonella, Shigella and Klebsiella etc) and other multidrug resistant Pseudomonas, Campylobacter and Mycobacterium tuberculosis [21-25]. Antimicrobial activity of medicinal plants is widely spread and a large number of its secondary metabolites showed antimicrobial activity. There is a great structural diversity exist among antimicrobial phytocompounds [26]. Major groups of phytocompounds include essential oils and isolated compounds such as alkaloids, flavonoides, sesquiterpenes, lactones, diterpenes ,triterpenes or napthoquinones etc [27]. Considerable amount of work have been published on antimicrobial activity of medicinal plants from different parts of the world [14, 28-32]. Examples of such articles are from Brazil, Thailand, Turkey, India and so on [33-36]. Most of the studies are directed to see the activity against a variety of test bacteria including both pathogenic and non pathogenic strains. However, active compounds for antibacterial activity are yet to be determined in most of the cases. Encouraged with this trend of reports, many workers have made specific studies against pathogenic bacteria and also evaluated their therapeutic potential [37-39]. Similarly, several workers have made targeted screening against multidrug resistant bacteria such as methicillin resistant Staphylococcus aureus MRSA, VRE, Mycobacterium tuberculosis, Enteric bacteria and others[16, 27, 36, 40-43]. Some of the relevant studies are briefly summarized here. Hasegawa and workers demonstrated that various genoside and their aglycones isolated from Panx ginseng adversely affected efflux mediated tetracycline encoded resistance encoded by tetk genes in S. aureus clinical isolates. It was found that the tetracycline resistance was reversed by the non-toxic concentrations of these compounds [44]. Antibacterial activity of garlic and allicin was demonstrated against 40 strains of multiple drug resistance Shigella dysenteriae type 1, Shigella flexneri, enterotoxigenic E. coli and Vibrio cholerae [45]. In the same year, ajoene, a garlic derived sulphur containing compound had been isolated that prevent platelet aggregation, exhibited broad spectrum antimicrobial activity. Growth of S aureus and Lactobacillus platarum were inbibited by <20 ¾g/ml [126]. A compound z-4, 5, 7, 9 trithiadeo 1, 6 diane 9-oxide was isolated from oil macerated garlic extract. It showed broad antimicrobial activity against bacteria and yeast [46]. Furofuran lignans were isolated from the Propolis sp. The isolated lignan showed antibacterial activity against S. aureus and E. coli [47]. At our laboratory antimicrobial and phytochemical studies on 45 Indian medicinal plants against multidrug resistant human pathogens had been investigated. Among these, 40 plant extracts showed varied level of antimicrobial activity against one or more test bacteria. Overall broad spectrum antimicrobial