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Aims: The ethnobotanical herb Hygrophila spinosa T. Anders (Acanthaceae) is native to India and used in traditional ayurvedic medicines for its pharmacologically important phytochemicals. This study aims to isolate and characterize the culturable bacterial endophytes of H. spinosa and evaluate their antimicrobial properties. Place and Duration of Study: The experiments were performed in the Department of Botany, Serampore College, Serampore as well as in the Microbiology Laboratory, Department of Botany, University of Calcutta, Kolkata during 2011 to 2012. Methodology: Bacterial endophytes were isolated from healthy plant tissues following surface sterilization and plating on nutrient agar, glycerol asparagine agar and tryptic soy agar. They were characterized physio-biochemically following standard microbiological and biochemical methods. The endophytes were screened for production of antimicrobial compounds following cross-streak assay against test strains Bacillus subtilis, B. cereus, Escherichia coli, Pseudomonas cepacia, Klebsiella pneumoniae and Staphylococcus aureus on nutrient agar plates. Results: Eleven phenotypically distinguishable bacterial endophytes were isolated from surface sterilized leaf, stem and root tissues and Shannon Weaver diversity index clearly revealed more diverse (0.83) types of endophytes in leaves than in stem (0.48) and root (0.41) tissues. Physio-biochemical features of the isolates clearly indicated distinct variation in their sugar fermentation profiles along with NaCl tolerance. The endophytes produced important enzymes like catalase, amylase, gelatinase, nitrate reductase and lipase. The bacterial isolates belonged to the genera Bacillus, Paenibacillus, Pseudomonas, Ralstonia, Staphylococcus, Micrococcus and Acidomonas. Antibiotic sensitivity profile, however, have indicated that the isolates were mostly resistant to amoxycillin and bacitracin, while they were highly susceptible to tetracycline followed by neomycin and streptomycin. Interestingly, the bacterial endophytes of H. spinosa give a definite stamp on their antimicrobial activity against E. coli and K. pneumoniae followed by S. aureus. Two isolates, Paenibacillus HGS 202 and Acidomonas HGR 302 obtained from stem and root segments respectively showed antimicrobial activity against B. subtilis, B. cereus, E. coli, K. pneumoniae and S. aureus. Conclusion: This study identified 11 bacterial endophytes harbored by the leaves, stem and root of H. spinosa which demonstrated antibacterial activity against Gram-positive as well as Gram-negative bacterial strains. Moreover these endophytic bacterial isolates could be exploited as sources of antibacterial substances.
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Therapeutic effect of ethanolic extract of Hygrophila spinosa in gentamicin-induced nephrotoxic model of kidney injury in male Sprague-Dawley rats was studied. Rats were administered with gentamicin at a dose of 80 mg/kg intraperitoneally (ip) to induce nephrotoxicity. Kidney function was assessed by measuring serum creatinine and urea. Kidney superoxide dismutase, lipid peroxidation, catalase and reduced glutathione were also measured in control and treated rats. H. spinosa extract showed free radical scavenging activities at doses of 50 and 250 mg/kg with a predominant activity at 250 mg/kg. The ethanolic extract also caused a reduction in serum creatinine and urea levels. Histopathological studies were conducted to confirm the therapeutic action of the plant extract. The results demonstrated that the ethanolic extract of whole plant of H. spinosa evinced the therapeutic effect and inhibited gentamicin-induced proximal tubular necrosis.
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Purpose: Hygrophila spinosa T. Anders (Acanthaceae) is commonly used in the traditional system of medicine for the treatment of inflammation; pain; jaundice; rheumatism; arthritis; anaemia; etc. In the present study; we investigated the anti-inflammatory and antipyretic activities of the petroleum ether; chloroform; alcoholic and aqueous extracts of the leaf of this plant. Methods: The anti-inflammatory activity of the various extracts was studied based on their effects on carrageenan-induced paw oedema in rats while antipyretic activity was evaluated on the basis of their effect on Brewer's yeast-induced pyrexia in rats. The extracts were screened for alkaloids; steroids; proteins; flavonoids; saponins; mucilage; carbohydrates; organic acids; fats and oils. Results: Preliminary phytochemical screening revealed the presence of alkaloids; steroids; proteins; flavonoids; fats and oils; tannins; mucilage and organic acids in the leaves of H. spinosa. Chloroform and alcoholic extracts of leaves of H. spinosa produced significant (p 0.05 and p 0.01) anti-inflammatory and antipyretic activities in a dose-dependent manner. On the other hand; petroleum ether and aqueous extracts did not show significant anti- inflammatory and antipyretic activities. The maximum anti-inflammatory activities produced by chloroform and alcoholic extracts (400 mg/kg) were 33.7and 47.5; respectively. These two extracts also reduced elevated body temperature in rats at 200 and 400 mg/kg body weight doses throughout the observation period of 6h .Conclusion: Chloroform and alcoholic extracts of H. spinosa leaves have anti-inflammatory and antipyretic activities