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Currently, the chemically synthesized carotenoid pigments, fulfill the needs of the consumers and industries. However, owing to their toxic effects, the use of such chemical oriented pigment products have limitations by restrictions of usage; and such restrictions have necessitated finding ecofriendly alternative pigments. By the way, bacteria, fungi and plants are the prospective alternative natural resources for the production of pigments, similar to carotenoids. Carotenoids are natural pigments that are used widely in nutraceutical, food and pharma industries. Lately, the biological production of carotenoids from microbes has been receiving greater attention and in this aspect, the studies on bacterial sources are emerging proportionally. During a screening process of pigmented strains, the bacterial strain, Dietzia maris AURCCBT01 was isolated and on further study found it to be a producer of canthaxanthin. The process parameters for biomass and canthaxanthin production were statistically optimized using response surface methodology. The effect of process parameters, namely glucose (5–20 g/L), NaCl (0.2 – 1.0 g/L) and pH (5 – 7) on the biomass and canthaxanthin production were studied. The optimal conditions for biomass and canthaxanthin production were glucose, 12.5 g/L; NaCl, 0.6 g/L and pH, 7 resulting in the highest canthaxanthin yield of 2997 µg/L and biomass of 3.03 g/L. The results exposed that these three process variables had greater influence on the production of canthaxanthin by the strain Dietzia maris AURCCBT01. The scale-up study was carried out in a jar fermenter under the optimized conditions. The maximum production for canthaxanthin and biomass was 3103 µg/L, 3.2 g/L was achieved respectively, and the results are encouraging for optimization under industrial conditions.

The present study was undertaken to investigate the anticancer activity of flexirubin produced by Chryseobacterium artocarpi CECT8497 and to explore its mechanism of action. The effect of flexirubin on cell proliferation of MCF-7 cells were evaluated by 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyl-tetrazolium bromide (MTT), sulforhodamine B (SRB) and lactate dehydrogenase (LDH) assays. Cell apoptosis was detected by DNA fragmentation and expression of apoptosis-related genes were assessed by RT-PCR. The study was further designed to appraise the anticancer activity of flexirubin against 7,12-di methylbenz(a)anthracene (DMBA) induced breast cancer in Sprague Dawley rats for 120 days. Treatment of cells at various concentrations (25 to 400 μg/ml) inhibited cell viability in a dose dependent manner. IC50 values of flexirubin on human breast cancer MCF-7 cells obtained by MTT, SRB and LDH were 62, 71 and 48 μM respectively. DNA fragmentation was observed in MCF-7 cell line at 45 and 90 μg/ml concentration, while no DNA fragmentation was observed in untreated cells. Flexirubin treated cells exhibited considerable decrease in the level of anti-apoptotic protein BCL-2, a strong indication that the intrinsic apoptotic pathway may play a role in MCF-7 cells. The expression of p53, caspase 3 and BCL-2 was induced by flexirubin in a dose and time dependent manner. The compound flexirubin showed good affinity to the receptor due to more lipophilic character and hydrogen bonding. The results obtained in the molecular docking studies showed good correlation with in vitro and in vivo activity. Molecular docking showed that flexirubin was effective to control the over expression of anti-apoptotic protein MCL-1, suggesting its possible applications in cancer treatment. Our findings implement that flexirubin is a potential chemo-preventive agent against human breast cancer.

AIM Nano-biotechnologically synthesizing silver nanoparticles via canthaxanthin pigment extracted from Dietzia maris AURCCBT01 and assessing their cytotoxic therapeutic potential against human keratinocyte cell line (HaCaT) were the key objectives of this study. METHODS AND RESULTS The pigment extracted from D. maris AURCCBT01 was identified as canthaxanthin using UV-VIS spectroscopy, FTIR, NMR (1 H NMR and 13 C NMR) and MS. Canthaxanthin, treated with silver nitrate solution, produced canthaxanthin-mediated silver nanoparticles and they were characterized by UV-VIS spectroscopy, FTIR, XRD, FESEM-EDX and TEM-SAED techniques. UV-VIS spectroscopy pointed out an absorption band at 420 nm, relating to the surface plasmon resonance of silver nanoparticles. FTIR findings suggested that the diverse functional groups of canthaxanthin bio-molecules played a significant task in capping the silver nanoparticles. XRD analysis exhibited 40·20 nm for the crystal size of nanoparticles. FESEM and TEM exhibited that the biosynthesized silver nanoparticles were spherical in shape with crystalline nature and the particle size was 40-50 nm. Moreover, the cytotoxicity assessment of the synthesized nanoparticles in HaCaT revealed significant cytotoxicity in the cultured cells with an IC50 value of 43 µg ml-1 . CONCLUSION Stable silver nanoparticles synthesized using canthaxanthin from D. maris AURCCBT01 were found effective for application in wound healing activity. SIGNIFICANCE AND IMPACT OF THE STUDY Biosynthesized silver nanoparticles via canthaxanthin bacterial pigment exhibited their cytotoxicity effect in HaCaT and testified their eventual therapeutic potential in the wound healing activity with no side effects in a cost effective and eco-friendly process.

As an investigative study, the potent bacterium Serratia marcescens SB08 was screened from the enteric gut of sulfur butterfly (Kricogonia lyside). Its pigment potential was tested, and the pigment was identified as prodigiosin by structural studies using High Performance Liquid Chromatography (HPLC), Gas Chromatography–Mass Spectroscopy (GC–MS), Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). Various conditions, including pH, reaction time, temperature, color intensity, and fastness properties, were studied for pure silk, China silk, and cotton yarns, and the conditions for effective dyeing were optimized. Further, the pigment’s antimicrobial pursuit was tested to counter the common pathogens Bacillus subtilis MTCC2388, Escherichia coli MTCC443, Klebsiella pneumonia MTCC109, Proteus vulgaris MTCC1771, and Pseudomonas aeruginosa MTCC1688. The pigment was largely effectual and exhibited utmost zones of inhibition, thus demonstrating the finest antimicrobial effect against the microbes tested. The textile yarn materials soaked with this intrinsic dye pigment also exhibited antimicrobial action.

A bacterial strain was isolated from an oil-contaminated site and on its’ further characterization, exhibited the potential of synthesising metabolites and the ability to degrade crude oil. Its’ morphological, biochemical and 16S rRNA analysis suggested that the bacterium belongs to Dietzia maris AURCCBT01. This strain rapidly grew in the medium supplemented with n-alkanes C14, C18, C20, C28 and C32 utilizing them as a sole carbon source and produced a maximum canthaxanthin pigment of 971.37 µg/L in the n-C14 supplemented medium and produced the lowest pigment yield of 389.48 µg/L in the n-C-32 supplemented medium. Moreover, the strain effectively degraded 91.87% of crude oil in 7 days. The emulsification activity of the strain was 25% with the highest cell surface hydrophobicity (70.26%) and it showed a decrease in surface tension, indicating that the biosurfactant production lowers the surface tension. This is the first report on the characterization of the strain, Dietzia maris AURCCBT01 and its’ novelty of alkane degradation and simultaneous production of canthaxanthin pigment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02807-7.

Novel benzimidazoquinoline derivative (AVT) was synthesized through a substitution reaction and characterized by various spectral techniques. Analyzing the optical properties of AVT under absorption and emission spectral studies in different environments exclusively with respect to solvents and pH, intriguing characteristics viz. aggregation induced emission enhancement (AIEE) in the THF solvent and ‘On-Off’ pH sensing were found at neutral pH. Sensing nature of AVT with diverse metal ions and bovine serum albumin (BSA) was also studied. Among the metal ions, Fe 3 + ion alone tunes the fluorescence intensity of AVT probe in aqueous medium from “turn-on” to “turn-off” through ligand (probe) to metal charge transfer (LMCT) mechanism. The probe AVT in aqueous medium interacts strongly with BSA due to Fluorescence Resonance Energy Transfer (FRET) and the conformational change in BSA was further analyzed using synchronous fluorescence techniques. Docking study of AVT with BSA reveals that the active site of binding is tryptophan residue which is also supported by the experimental results. Interestingly, fluorescent AVT probe in cells was examined through cellular imaging studies using BT-549 and MDA-MB-231 cells. Thus, the single molecule probe based detection of multiple species and stimuli were described.

A novel compound 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline 3 bearing a tri-quinoline moiety has been synthesized from 2-chloro-3,6-dimethyl quinoline 1 and 8-hydroxy quinoline 2 using dry acetone and K 2 CO 3 as a base. 3 has been characterized by using FT-IR, FT-Raman, UV–Vis, 1 H NMR, 13 C NMR spectra and single crystal X-ray diffraction methods. We have also made a combined experimental and theoretical study on the molecular structure, vibrational spectra, NMR, FT-IR, FT-Raman and UV–Vis spectra of 2-chloro-3,6-bis-(quinolin-8-yloxymethyl)-quinoline. The theoretical studies of the title compound have been evaluated by using density functional theory calculations using B3LYP/6-31+G(d,p) and M06-2X/6-31+G(d,p) level of theories. The calculated theoretical values were found to be in good agreement with the experimental findings. The single crystal structure 3 crystallized in the orthorhombic space group Pna 2 1 . The compound 3 exhibits higher cytotoxicity in human cervical cancer cell lines (HeLa) than human breast cancer cell lines (MCF7).

The structure of 3-bromomethyl-2-chloro-quinoline crystallizes in the triclinic crystal space group P‘1 with unit cell parameters a=6.587(2), b=7.278(3), c=10.442(3) Å, a= 83.59(3)°, b= 75.42(2)°, g= 77.39(3)°, Z= 2, V= 471.9(3)Å3. The structure has converged to a final R-value of 0.0734. The phenyl Ring-B has normal geometry while the pyridine Ring-A has slightly distorted conformation. The asymmetry parameter calculations, i.e., DC2 and DCs for the pyridine ring indicates that the structure is planar. There exists one intramolecular hydrogen bonded interaction of the type C-H…Cl and one C-H…N intermolecular interaction. The structure is stabilized by Van der Waals forces.

A one-pot synthesis of benzimidazoles by condensing naphthyl or quinoline aldehyde with benzene-1,2-diamine has been reported. IR, 1H and 13C NMR, mass spectral, and CHN analyses were used to elucidate the structures of the products. The molecular structural correlation in the optical properties of the quinoline and naphthalene benzimidazoles was explored. The fluorescence quantum yield ([Formula: see text]) and time-resolved fluorescent lifetime of the quinoline benzimidazoles derivatives were estimated. The influence of solvent polarity and pH on the optical property of quinoline derivatives was illustrated. To explore the bioanalytical applicability, the thermal stability by TG–DTA analysis and the cytogenetic analysis of 3-(1H-benzoimidazol-2-yl)-2-chloro-8-methyl-quinoline (1b) compound were carried out. The fluorescent staining ability of 1b was analyzed and also compared with the normal Gram staining in the bacterium.

In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ((1)H NMR and (13)C NMR), UV-Vis, and LC-MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV-Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36μgmL(-1). This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent.

Two independent molecules of the title compound, C17H12ClN3, are present in the structure. The angle between the planes defined by the atoms of the benzimidazole unit and the quinoline unit are 45.2 (3) and 44.0 (3)°, indicating an essentially identical conformation for both molecules. Each of the independent molecules is linked with a symmetry equivalent by an intermolecular N—H...N hydrogen bond involving the two benzimidazole N atoms, to form chains in the crystallographic c direction.

In the title compound, C20H19N3O3, the interplanar angle between the benzimidazole unit and the quinoline unit is 25.1 (2)°. Two different hydrogen bonds involving the hydroxy group and the imidazole unit are present. An intramolecular N—H...O hydrogen bond links the hydroxy group of the side chain with the imidazole unit, forming a 12-membered ring, and an intermolecular O—H...N hydrogen bond links the molecules, forming chains in the crystallographic b direction.