In the present studies, renewable and nontoxic biopolymer, pectin, was extracted from Indian red pomelo fruit peels and used for the synthesis of cerium oxide nanoparticles (CeO-NPs) having bio-therapeutic potential. The structural information of extracted pectin was investigated by FTIR and NMR spectroscopic techniques. Physicochemical characteristics of this pectin suggested its application in the synthesis of metal oxide nanoparticles. Using this pectin as a template, CeO-NPs were synthesized by simple, one step and eco-friendly approach. The UV-Vis spectrum of synthesized CeO-NPs exhibited a characteristic absorption peak at wavelength 345 nm, which can be assigned to its intrinsic band gap (3.59 eV) absorption. Photoluminescence measurements of CeO-NPs revealed that the broad emission was composed of seven different bands. FTIR analysis ensured involvement of pectin in the formation and stabilization of CeO-NPs. FT-Raman spectra showed a sharp Raman active mode peak at 461.8 cm due to a symmetrical stretching mode of Ce-O vibration. DLS, FESEM, EDX, and XRD analysis showed that the CeO-NPs prepared were polydispersed, spherical shaped with a cubic fluorite structure and average particle size ≤40 nm. These CeO-NPs displayed broad spectrum antimicrobial activity, antioxidant potential, and non-cytotoxic nature.

In the present study, microwave-assisted, optimized, instant, Terminalia bellirica fruit extract-mediated green synthesis of colloidal silver nanoparticles (AgNPs) has been reported. The synthesized AgNPs were characterized by UV–Vis spectroscopy, FTIR, Zetasizer, FESEM, EDX and XRD. The characteristic surface plasmon peak of reaction mixture at 406 nm confirmed the synthesis of AgNPs. The FTIR studies confirmed phytoconstituents were responsible for the synthesis and stability of AgNPs. The FESEM, EDX and XRD analysis revealed the presence of spherical silver nanoparticles of mean diameter ≤20.6 nm with face-centered cubic crystalline structure. These AgNPs showed notable catalytic activity in reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. The synthesized AgNPs showed potential antibacterial and antibiofilm activity against bacterial pathogens like Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. Thus, these synthesized AgNPs can open avenues for the development of AgNP-based efficient nanocatalyst and potent nanomedicine in future.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-016-0589-1) contains supplementary material, which is available to authorized users.

Bioactivity of a microbial pigment, extracted from fermented broth of culture marine Pseudomonas aeruginosa was screened for anticancer activity against human skin melanoma cell line SK-MEL-2. Upon characterisation, the pigment was confirmed as Phenazine-1-carboxylic acid (PCA). The PCA was found effective against SK-MEL-2 cell line at low concentration (GI50 value <10 μg/mL). Reduced cell density and cell shrinkage with typical morphological changes such as rounding of cells with loss/breaking of cell membrane were seen in SK-MEL-2 cells treated with PCA and Adriamycin. The pigment exhibited UV-B protecting activity as calculated by in vitro spectrophotometric assay and potentiated sun protection factor of commercial sunscreen lotion. Moreover, the pigment was non-toxic up to concentration of 100 ppm as assessed erythrocyte haemolysis assay. These results suggest that microbial pigment PCA could be effective and promising in the treatment as well as prevention of melanoma skin cancers.

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Phenazines, a nitrogen containing heterocyclic antibiotic biosynthesized by a diverse range of bacteria. Owing its enormous importance as (1) electron shuttles to alternate terminal acceptors in bacteria, (2) modify cellular redox states to modify host response, (3) contributing to biofilm formation and cell signaling, as well as (4) biotechnological applications such as environmental sensor, microbial fuel cell, antitumor, and biocontrol activity attracted attention of scientific community to target phenazine as lead molecule. Similarly, emerging application of phenazines insisted high productivity fermentative process. Current chapter focuses on sources of natural phenazines and impact of nutritional as well as environmental dynamics on fermentative production of phenazine in different bacteria.

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