Diapolycopenedioic-acid-diglucosyl ester and keto-myxocoxanthin glucoside ester: Novel carotenoids derived from Exiguobacterium acetylicum S01 and evaluation of their anticancer and anti-inflammatory activities.

Inflammation is pivotal for the development of gastrointestinal cancer and linked to poor survival and limited therapeutic options. In this study, six structurally different carotenoids were isolated and identified from the methanolic extract of Exiguobacterium acetylicum S01 namely lycopene (Car-I), diapolycopenedioic-acid-diglucosyl-ester (Car-II), ß-carotene (Car-III), zeaxanthin (Car-IV), astaxanthin (Car-V), and keto-myxocoxanthin glucoside-ester (Car-VI). Further, their anti-cancer, anti-inflammatory, and antioxidant potentials were evaluated. The MTT assay was used to determine the effect of carotenoids on viability of colorectal cancer (HT-29) as well as peripheral blood mononuclear cells (PBMCs). Results revealed that all the six carotenoids were demonstrated a significant inhibition of HT-29 cells viability in a dose-dependent manner whereas there was no cytotoxic effect in PBMCs. The study also recorded that six carotenoids considerably inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) production, tumor necrosis factor-alpha (TNF-α), and lipid peroxidation in PBMCs. Moreover, antioxidant potentials of Car-II and Car-VI were significantly (p = 0.001) higher than ascorbic acid as determined by a 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Therefore, our results ascertained the role of carotenoids derived from E. acetylicum S01 in developing potential therapeutic agents for inflammation-associated cancer.

Supramolecular Surface Charge Regulation in Ionic Covalent Organic Nanosheets: Reversible Exfoliation and Controlled Bacterial Growth.

Poor control on the exfoliation of covalent organic frameworks (COFs) remains a disadvantage for their application as two-dimensional nanosheets. An equally important problem is the reversible control at the available surface charges on COFs. Herein, a strategy for the reversible exfoliation, re-stacking, and surface-charge control of a propidium iodide based ionic covalent organic framework, PI-TFP, using cucurbit[7]uril (CB[7]) induced molecular recognition, is reported. The surface charge on PI-TFP facilitates its initial self-exfoliation. However, complexation with CB[7] resulted in re-stacking with concomitant decrease in zeta potential from +28±3.0 to +0.004±0.003 mV. Addition of 1-adamantylamine hydrochloride (AD) facilitates decomplexation of PI-TFP from CB[7], resulting in exfoliation and an increase in zeta potential to +24±3.0 mV. Such control on the exfoliation, re-stacking, and the associated regulation of the surface charge in PI-TFP was exploited for controlling bacterial growth. Thus, the activity of E. coli and S. aureus bacteria obtained with the self-exfoliated PI-TFP could be reversibly controlled by the CB[7]/AD pair.

Synergistic activity of phenazines isolated from Pseudomonas aeruginosa in combination with azoles against Candida species.

Candidiasis infections are caused by yeasts from the genus Candida. The types of infection range from superficial to systemic. Treatment often requires antifungals such as the azoles; however, increased use of these drugs has led to the generation of yeasts with increased resistance to these drugs. Here, we describe the synergistic anticandidal activity of three phenazines-phenazine-1-ol, phenazine-1-carboxylic acid, and phenazine-1-carboxamide. These phenazines were purified from Pseudomonas aeruginosa in combination with three clinically used azoles-fluconazole, itraconazole, and clotrimazole. The synergistic anticandidal activities of phenazines and azoles were assessed using the checkerboard microdilution and time-kill methods. Study results show that the combined effects of phenazines and azoles were predominantly synergistic activity (fractional inhibitory concentration index <0.5). The time-kill study, which included a combination of the minimum inhibitory concentration of phenazines and azoles, showed growth of Candida species that was completely attenuated after 0-6 h of treatment. These results, which suggest that the activity of phenazines and azoles may be beneficial, have potential implications in delaying the development of resistance, as the anticandidal effect is achieved with lower concentrations of both agents (phenazines and azoles). The cytotoxicity of phenazines was also tested against a normal human cell line (foreskin normal fibroblast). No cytotoxicity was recorded at concentrations up to 200 µg/ml. The in vitro synergistic activity of phenazines and azoles against Candida species is reported here for the first time.

Fusarial wilt control and growth promotion of pigeon pea through bioactive metabolites produced by two plant growth promoting rhizobacteria.

The bioactive metabolites produced by two plant growth promoting rhizobacteria strains, a Pseudomonas aeruginosa strain RRLJ 04 and a Bacillus cereus strain BS 03, which showed growth promotion and disease control in pigeon pea against Fusarium udum, were isolated and screened for their efficacy to control fusarial wilt of pigeon pea under gnotobiotic and nursery condition. Bioactive metabolites viz., BM 1 and BM 2 from RRLJ 04 and BM 3 from BS 03 also showed in vitro antibiosis against F. udum. Seeds treated with 50 µl seed⁻¹ of BM 1, 30 µl seed⁻¹ of BM 2 and 70 µl seed⁻¹ of BM 3 and grown in pathogen infested soil showed suppression of wilt disease besides growth enhancement. Per cent disease control was 90 % with BM 2 application as compared to 87 and 83 %, respectively in BM 1 and BM 3 after 90 days of growth. BM 2 treated plants were more resistant to the pathogen as compared to the other fractions tested. Mycelial dry weight was found to be reduced on treatment with the bioactive metabolites. Formation of chlamydospore-like structures was observed in the pathogen mycelium treated with BM 3. The analytical studies confirmed that two of these metabolites are phenazine derivatives.

Chemical constituents from Chonemorpha fragrans roots and antibacterial activity studies of sarcorucinine D.

Nine non-alkaloid constituents viz., sitostenone (1), ß-sitosterol (2), naringenin (3), aromadendrin (4), matairesinol (5), vanillic acid (6), ferulic acid (7), protocatechuic acid (8) and sitosterol-3-O-ß-D-glucopyranoside (9) were isolated from the acetone extract as well as five alkaloids viz., japindine (10), sarcorucinine D (11), dictyophlebin (12), chonemorphine (13) and N-formylchonemorphine (14) were isolated from the ethanol extract of Chonemorpha fragrans roots. Except ß-sitosterol, all other non-alkaloid compounds and the alkaloid sarcorucinine D are being reported for the first time from C. fragrans. From the MIC and MBC values, it has been found that sarcorucinine D shows most promising antibacterial activity. Quantification of antibacterial activity as well as killing curve determinations were performed in order to confirm the efficacy of the compound. The cytotoxic activity studies revealed that it is nontoxic up to 100 µM concentration.

Optimization of submerged fermentation process for improved production of ß-carotene by Exiguobacterium acetylicum S01.

Carotenoids are natural pigments with substantial applications in nutraceutical, pharmaceutical, and food industries. In this study, optimization of the fermentation process for enhancement of ß-carotene and biomass production by Exiguobacterium acetylicum S01 was achieved by employing statistical designs including the Placket-Burman design (PBD) and response surface methodology (RSM). Among the seven variables investigated by two levels in PBD, glucose, peptone, pH and temperature were indicated as crucial variables (p < 0.0001) for ß-carotene and biomass productivity. Response surface methodology was further applied to evaluate the optimal concentrations of these four variables for maximum ß-carotene and biomass productivity. The optimized medium contained glucose 1.4 g/L, peptone 26.5 g/L, pH 8.5, and temperature 30 °C, respectively. A significant increase in ß-carotene (40.32 ± 2.55 mg/L) and biomass (2.19 ± 0.10 g/L) productivities in E. acetylicum S01 were achieved by using RSM, which was 3.47-fold and 2.36-fold higher in the optimized medium compared to the un-optimized medium. Further, the optimum fermentation condition in the 5-L bioreactor was achieved a maximal ß-carotene yield of 107.22 ± 5.78 mg/L within 96 h. Moreover, the expression levels of carotenoid biosynthetic genes (phytoene desaturase (CrtI) and phytoene synthase (CrtB)) were up-regulated (2.89-fold and 3.71-fold) in E. acetylicum under the optimized medium conditions. Overall, these results suggest that E. acetylicum S01 can be used as a promising microorganism for the commercial production of ß-carotene.

First report on isolation of 2,3,4-trihydroxy-5-methylacetophenone from palmyra palm (Borassus flabellifer Linn.) syrup, its antioxidant and antimicrobial properties.

The first report on isolation and characterization of 2,3,4-trihydroxy-5-methylacetophenone (1), nicotinamide (2), and uracil (3) from palmyra palm syrup is described. Total phenolic content (TPC) and Total flavonoid content (TFC) of palm syrup were 244.70±5.77(mggallic acid/kg of syrup) and 658.45±27.86(mg quercetin/kg of syrup), respectively. Compound 1 exhibited DPPH radical scavenging activity with an IC50 value of 20.02±0.14µM which was better than ascorbic acid (IC50=22.59±0.30µM). Compound 1 also showed broad spectrum antibacterial activity against Escherichia coli, Mycobacterium smegmatis, Staphylococcus aureus and Staphylococcus simulans.

Pseudopyronine B: A Potent Antimicrobial and Anticancer Molecule Isolated from a Pseudomonas mosselii.

In continuation of our search for new bioactive compounds from soil microbes, a fluorescent Pseudomonas strain isolated from paddy field soil of Kuttanad, Kerala, India was screened for the production of bioactive secondary metabolites. This strain was identified as Pseudomonas mosselii through 16S rDNA gene sequencing followed by BLAST analysis and the bioactive metabolites produced were purified by column chromatography (silica gel) and a pure bioactive secondary metabolite was isolated. This bioactive compound was identified as Pseudopyronine B by NMR and HR-ESI-MS. Pseudopyronine B recorded significant antimicrobial activity especially against Gram-positive bacteria and agriculturally important fungi. MTT assay was used for finding cell proliferation inhibition, and Pseudopyronine B recorded significant antitumor activity against non-small cell lung cancer cell (A549), and mouse melanoma cell (B16F10). The preliminary MTT assay results revealed that Pseudopyronine B recorded both dose- and time-dependent inhibition of the growth of test cancer cell lines. Pseudopyronine B induced apoptotic cell death in cancer cells as evidenced by Acridine orange/ethidium bromide and Hoechst staining, and this was further confirmed by flow cytometry analysis using Annexin V. Cell cycle analysis also supports apoptosis by inducing G2/M accumulation in both A549 and B16F10 cells. Pseudopyronine B treated cells recorded significant up-regulation of caspase 3 activity. Moreover, this compound recorded immunomodulatory activity by enhancing the proliferation of lymphocytes. The production of Pseudopyronine B by P. mosselii and its anticancer activity in A549 and B16F10 cell lines is reported here for the first time. The present study has a substantial influence on the information of Pseudopyronine B from P. mosselii as potential sources of novel drug molecule for the pharmaceutical companies, especially as potent antimicrobial and anticancer agent.

Two rhizobacterial strains, individually and in interactions with Rhizobium sp., enhance fusarial wilt control, growth, and yield in pigeon pea.

A Pseudomonas aeruginosa strain, RRLJ 04, and a Bacillus cereus strain, BS 03, were tested both individually and in combination with a Rhizobium strain, RH 2, for their ability to enhance plant growth and nodulation in pigeon pea (Cajanus cajan L.) under gnotobiotic, greenhouse and field conditions. Both of the rhizobacterial strains exhibited a positive effect on growth in terms of shoot height, root length, fresh and dry weight, nodulation and yield over the non-treated control. Co-inoculation of seeds with these strains and Rhizobium RH 2 also reduced the number of wilted plants, when grown in soil infested with Fusarium udum. Gnotobiotic studies confirmed that the suppression of wilt disease was due to the presence of the respective PGPR strains. Seed bacterization with drug-marked mutants of RRLJ 04 and BS 03 confirmed their ability to colonize and multiply along the roots. The results suggest that co-inoculation of these strains with Rhizobium strain RH 2 can be further exploited for enhanced growth, nodulation and yield in addition to control of fusarial wilt in pigeon pea.

Plant growth-promoting rhizobacterial strain-mediated induced systemic resistance in tea (Camellia sinensis (L.) O. Kuntze) through defense-related enzymes against brown root rot and charcoal stump rot.

Induction of systemic resistance in host plants through microbes and their bioactive metabolites are attaining popularity in modern agricultural practices. In this regard, individual application of two strains of Pseudomonas, RRLJ 134 and RRLJ 04, exhibited development of induced systemic resistance in tea plants against brown root rot and charcoal stump rot under split root experiments. The experimental findings also confirmed that the cuttings treated with fungal test pathogen and plant growth-promoting rhizobacteria (PGPR) strains survived longer as compared with pathogen-alone-treated cuttings. The enzyme level studies revealed that the presence of PGPR strains reduced the viscosity loss of cellulose and pectin by both the pathogens to a significant level. The activity of defense-related enzymes like L-phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase were also recorded higher in tea cuttings treated with PGPR strains in presence of pathogen. Crude bioactive metabolites isolated from these strains also showed in vitro antagonism against the test pathogens besides reducing the number of diseased plants under gnotobiotic conditions. These findings confirm the utilization of these two strains for induction of systemic resistance against two major root diseases in tea plants under plantation conditions.