Medicinal plants have been the major resources for therapeutic agents for remedy of many diseases. In the present investigation, antimicrobial activity of aqueous and methanol extracts of green and black tea (Camellia sinensis) against intestinal pathogens was studied by well diffusion method and minimum inhibitory concentration. About twenty six intestinal strains which include E.coli, Salmonella spp., Shigella spp. and Vibrio spp. were isolated from diarrheal samples. Results showed that methanol extracts of both green tea and black tea revealed higher inhibitory activity on intestinal bacteria than aqueous extracts. At the concentration of 12.0 mg/ml 8/12 (66%) of Salmonella spp., 06/08 (75%) of Shigella spp. and 02/04 (50%) of Vibrio spp. were sensitive to green tea aqueous extracts. All the isolates (100%) were sensitive to the green tea methanol extracts concentration of 3.0, 6.0, 12, 24 and 48 mg/ml and exhibited zone size ranging from 1.0-37 mm. The MIC of green tea for E.coli was found to be 3.0mg/ml, for Salmonella spp. was 6.0 mg/ml for aqueous and 12.0 mg/ml for methanol extract. For Shigella spp and Vibrio spp. it was 12.0 and 6.0mg/ml respectively. Our findings revealed that methanol extracts of green tea exhibited strong antibacterial activity on intestinal pathogens. Thus the extracts of tea leaves can be used as an alternative drug against intestinal pathogens without having any side effects. Green tea and black tea extracts are safe and can be a supplement for other systems of medicines for the treatment of intestinal diseases caused by bacteria.
Many researchers regard somatic embryogenesis as a system of choice for in vitro propagation of superior varieties of crops such as coffee, mango, datepalm, and rose. While there are advantages, commercialization has not been possible so far in coffee, mango, and rose. The work highlights some reasons for this and feasible alternatives. We have established somatic embryogenesis in four elite Indian arabica coffee genotypes. Plantlets (3500) of all the four varieties are now being field-evaluated. The cost of producing these propagules is 15 times the seedling cost at present. A major constraint is the long time (6 months) needed to reach the five-leaf stage in vitro prior to release for acclimatization. This period can be reduced to 2 months using exvitro development after the two leaf stage. There are many reports of somatic embryogenesis in mango. Results on establishing free-living plantlets have not been encouraging.We found a number of abnormalities in the shape of the somatic embryos in cv. Rumani. However, except for the “rod”-shaped ones (that lacked cotyledonary expansion), all embryos germinated satisfactorily (75% rooting).We have encouraging results in reducing the time required to generate suitable plantlets for field acclimatization and in standardizing the procedures for grafting. Our laboratory has developed methods for ex vitro germination of mature embryos in datepalm,which yield more numbers of free-living plantlets (50%–60%) in only 3 months with an average of four leaves per plant. This compared favorably with in vitro germination that takes 6 months and produces plantlets with one or two leaves only. A novel protocol for obtaining somatic embryogenesis in rose from petal derived calli was developed by us (Murali et al., 1996). The number of embryos induced was too low for commercial application. [Murali et al., 1996. Euphytica 91:271–275].
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