Antibacterial Potential and Apoptosis Induction by Pigments from the Endophyte Burkholderia sp. WYAT7.

Pigment from the endophyte Burkholderia sp. WYAT7 isolated from the medicinal plant Artemisia nilagirica (Clarke) Pamp. was extracted. The antibacterial efficacy of the crude pigment Y was assessed as a source of antibiotic against both Gram-positive and Gram-negative bacterial pathogens. The pigment Y exhibited a significant level of antibacterial activity against the tested pathogens Salmonella typhi (MTCC 733), Staphylococcus aureus (MTCC 1430), Pseudomonas aeruginosa (MTCC 2453), Klebsiella pneumoniae (MTCC 432), Escherichia coli (MTCC 1610), Salmonella paratyphi (3220), Bacillus subtilis (441) and Acinetobacter baumannii (12,889). The minimum inhibitory concentration of crude pigment extract Y for most of the bacterial pathogens tested was below or equal to 0.25 µg/mL and the minimum bactericidal concentration was below or equal to 0.5 µg/mL. In the cytotoxicity evaluation, crude pigment Y exhibited less toxicity toward normal cells lines (L929). Crude pigment extract Y also showed powerful anticancer activity toward melanoma cancer cells (A375). The IC50 value obtained was 68.08 µg/mL. Acridine orange (AO) and ethidium bromide (EB) double staining of cells treated with the pigment helped in the morphological assessment of nuclear condensation, apoptotic bodies and live cells. The DNA fragmentation analysis and caspase-9 quantification in the pigment-treated A375 cells determined the apoptosis activity mediated by the crude pigment extract Y. The compounds in the crude pigment extract Y was identified by HR-LCMS analysis. Further studies on the active compounds can lead to a rise in new drugs for cancer treatment and also against rising antibacterial resistant pathogens.

Bacterial endophytes from Artemisia nilagirica (Clarke) Pamp., with antibacterial efficacy against human pathogens.

A study was conducted to isolate and characterize endophytes from Artemisia nilagirica, a traditional medicinal plant. The plant was collected from Western Ghats, India. Endophytes isolated included Arthrobacter sp. WWAT1, Pseudomonas sp. WYAT2, Microbacterium sp. WYAT3, Psychrobacter sp. WBAT4, Enterobacter sp. WWAT5, Bacillus sp. WBAT6, Kosakonia cowanii WBAT7, Bacillus sp. WBAT8, Bacillus sp. WBAT9, Chromobacterium violaceum WVAT6, Serratia sp.WPAT8 and Burkholderia sp. WYAT7. Of these two bacteria, Chromobacterium violaceum strain WVAT6 and Burkholderia sp. strain WYAT exhibited antibacterial property against human pathogens. Similar to the environmental isolates, Burkholderia sp. WYAT7 showed pleomorphism and produced different enzymes, whereas like clinical strains they showed multidrug resistance, for their survival in different environmental conditions. Chromobacterium violaceum WVAT6 exhibited rod shape morphology and showed multiple drug resistance except to erythromycin, tetracycline and gentamicin antibiotics. Both produced biofilm and enzymes such as protease and lipase. The antimicrobial compounds from these endophytes may find application in the preparation of antimicrobial formulations.

Catechin rich butanol fraction extracted from Acacia catechu L. (a thirst quencher) exhibits immunostimulatory potential.

Acacia catechu L., (Fabaceae) named as "catechu" is a plant, the decoction of heartwood of which is daily consumed as thirst quencher by a good percentage of the population in South India. The plant is mainly distributed in India and other Asian countries. It has been used in Indian traditional medicine for the treatment of asthma, bronchitis, colic, diarrhea, boils, skin afflictions, sores and stomatitis. The present investigation was aimed to study the immunomodulatory effects of different fractions of ethanol extract of A. catechu heartwood and HPLC analysis of the active fraction. Three fractions namely, butanol, chloroform and ethyl acetate were prepared from ethanol extract of A. catechu heartwood. Each of these fractions was assessed for its immunomodulatory activity. In vivo immunomodulatory activity was analyzed by sheep red blood cells (SRBC) specific hemagglutinating antibody titer, plaque-forming cell assay and delayed type hypersensitivity (DTH) reaction in Swiss albino mice. In vitro immunomodulating potential of the fractions was studied using murine peritoneal macrophages and splenocytes. Non-specific immune functions such as phagocytosis (nitroblue tetrazolium reduction assay and cellular lysosomal enzyme assay), nitric oxide (NO) production and cytokine release (TNF-α and IL-10) were studied in macrophages. In addition, splenocyte proliferation was also studied. In the in vivo experiments, butanol and chloroform fractions showed an increase in antibody titer dose-dependently. At higher dose (400 mg/kg b. w.) treatment the butanol fraction produced an enhancement in the number of plaque-forming cells (antibody producing cells) in the spleen. SRBC induced DTH reaction was significantly increased with butanol fraction in a dose-dependent manner. Peritoneal macrophages showed an increased phagocytic response on treatment with butanol fraction (100 µg/mL) as evidenced by its effect on nitroblue tetrazolium reduction and cellular lysosomal enzyme activity. All three fractions inhibited the production of NO and the release of TNF-α. Interleukin-10 production was significantly increased after treatment with butanol fraction. High-performance liquid chromatography analysis of the butanol fraction showed the presence of high concentration of catechin. The results suggested that butanol fraction of ethanol extract of A. catechu heartwood had immunomodulatory effects on non-specific, humoral, and cell-mediated immune functions. This study may be useful in validating the rationality of daily consumption of decoction of A. catechu and also its use in traditional medicine system. The study also suggests the possible use of A. catechu in the immunostimulatory herbal preparations.