Cytotoxicity and apoptosis induction of some selected marine bacteria metabolites

Crude Cell-Free Extract From Deinococcus radiodurans Exhibit Anticancer Activity by Inducing Apoptosis in Triple-Negative Breast Cancer Cells

Extremophilic organisms have the potential to tolerate extremely challenging environments of nature. This property can be accredited to its production of novel secondary metabolites that possess anticancer and other pharmaceutical values. The present study was aimed to investigate the anticancer activity of crude secondary metabolite extract (CSME) obtained from the radiation-tolerant bacterium Deinococcus radiodurans in triple-negative human breast carcinoma (MDA-MB-231) cells. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay showed the antiproliferative potential of CSME in MDA-MB-231 cells (IC₅₀ = 25 μg/ml) and MCF-7 cells (IC₅₀ = 10 μg/ml). Further, the CSME treatment led to the production of intracellular reactive oxygen species (ROS) and nuclear membrane alterations with the formation of apoptotic bodies in MDA-MB-231 cells. Considerable DNA damage and low antioxidant status were observed in CSME-treated MDA-MB-231 cells. The results also showed that the CSME treatment induced apoptotic markers expression in MDA-MB-231 cells. Western blot results illustrated significant upregulation of p53, caspase-3, and caspase-9 proteins expression. Then, we analyzed the presence of secondary metabolites which may be linked with antiproliferative potential of CSME by gas chromatography-mass spectrometry (GC-MS). The results illustrated the presence of 23 bioactive compounds some of which are already reported to possess anticancer properties. The study indicates that the CSME of D. radiodurans possess anticancer properties and exhibit the potential to be used as an anticancer agent.

A dual pH-sensitive liposomal system with charge-reversal and NO generation for overcoming multidrug resistance in cancer

In cancer therapy, chemotherapeutic drugs frequently encounter multidrug resistance (MDR) induced by the overexpression of drug transporters such as P-glycoprotein (P-gp). Herein, in order to overcome MDR and improve the effectiveness of chemotherapy, we developed a novel pH-sensitive charge-reversal and NO generation liposomal system by modifying a pH-sensitive polymer (PEG-PLL-DMA) on the surface of cationic liposomes for delivering a NO donor (DETA NONOate) and a chemotherapy drug (paclitaxel, PTX) into MDR cells. The proposed liposomal system (PTX/NO/DMA-L) exhibited a distinctive charge-reversal capacity, which was negatively charged under physiological conditions (pH 7.4) but could reverse to positive charge in a tumor microenvironment (pH 6.5) due to the cleavable amide linkages formed between PEG-PLL and DMA, leading to the improvement of cell uptake. Once arrived in the endosomes and lysosomes (pH 5.0), DETA NONOate was triggered to decompose and release NO, which further promoted the quick release of PTX and inhibited the P-gp mediated efflux. The charge-reversal, NO generation and NO-triggered rapid release of drugs could significantly increase the accumulation of PTX in tumors and eventually improve the antitumor efficacy. These results indicate that this dual pH-sensitive liposomal system is a highly promising approach for chemotherapy and may pave a new avenue for overcoming MDR in cancer.

Apoptotic role of marine sponge symbiont Bacillus subtilis NMK17 through the activation of caspase-3 in human breast cancer cell line

The aim of the present study was to evaluate the diverse potential biological activity of partially purified crude extract (PPCEBS) of marine Bacillus subtilis NMK17 associated with marine sponge Clathria frondifera. Symbionts were isolated from a marine sponge, only the potential strain which exhibited apoptosis was sequenced using 16S rRNA and extract of the active strain was subjected to purification using HPLC. The potential pro-apoptotic role of PPCEBS was investigated in MCF-7 human breast cancer cell line for cytotoxicity by MTT assay, which showed dose-dependent cytotoxicity on 24 h of exposure. The apoptotic findings demonstrated that PPCEBS significantly induces apoptosis, which was characterised by apoptotic morphological changes. Further, an increased expression of the Caspase 3 and Bax whereas decreased Bcl-2 was confirmed by immunofluorescence and western blotting analysis in MCF-7 cell line, which revealed that PPCEBS has potent apoptosis-inducing property. Added to the desirable apoptotic activity, PPCEBS exhibited excellent antibacterial and antioxidant activities too. The pharmacological effect of the marine sponge-associated bacteria from Gulf of Mannar India needs further attention in discovering new bioactive compounds. Our results suggested that the compounds present in the PPCEBS in marine bacterial B. subtilis NMK17 could be candidates for developing an apoptosis-specific drug with minimal toxicity. This study indicated that marine sponge-associated bacteria could be a good source to find the cytotoxic metabolites which would induce apoptosis and cause cancer cell death. Also, this study explores that marine natural products as a potential source of pharmaceuticals.

Therapeutic applications of bacterial pigments: a review of current status and future opportunities

Non-toxicity, biodegradability and non-carcinogenicity of the natural pigments, dyes and colorants make them an attractive source for human use. Bacterial pigments are colored metabolites secreted by bacteria under stress. The industrial uses of bacterial pigments have increased many folds because of several advantages over the synthetic pigments. Among natural resources, bacterial pigments are mostly preferred because of simple culturing and pigment extraction techniques, scaling up and being time economical. Generally, the bacterial pigments are safe for human use and therefore have a wide range of applications in pharmaceutical, textile, cosmetics and food industries. Therapeutic nature of the bacterial pigments is revealed because of their antimicrobial, anticancer, cytotoxic and remarkable antioxidant properties. Owing to the importance of bacterial pigments it was considered important to produce a comprehensive review of literature on the therapeutic and industrial potential of bacterial pigments. Extensive literature has been reviewed on the biomedical application of bacterial pigments while further opportunities and future challenges have been discussed.

Lysis of Antarctic algal strains by bacterial pathogen

The present paper describes the isolation, physiological and genetic characteristic of a bacterial agent which inhibits the growth of algae and causes death of laboratory cultures of Antarctic microalgal strains: prokaryotic cyanobacteria Synechocystis salina and green eukaryotic microalga Choricistis minor. The bacterial strain LB1 was isolated from algal damaged laboratory cultures of S. salina. It was established that this bacterium is obligate aerobic, Gram-positive, non-spore-forming, immotile, irregular rods with dimensions 0.3-2 μm. Our results showed that LB1 has algicidal effect to S. salina as well as to C. minor. Transmission electron microscopy observations confirmed the destruction of S. salina by the bacterium. Biochemical analysis of LB1 revealed positive reaction to D-glucose, catalase, hydrolysis of gelatin, acid production from: lactose, L-arabinose, L-ramnose, esculin and β-galactosidase. The partial sequence (1,404 bp) of the 16S rRNA gene of LB1 showed 99 % similarity with type strains of the genus Microbacterium. The results of the biochemical, antimicrobial and of 16S rRNA analysis of LB1 allowed us to identify LB1 as Microbacterium sp. Studying expression of pathogenicity of the bacteria to algal cultures will help to solve the problem of algal production for biotechnological purposes.

Cytotoxic and apoptotic evaluations of marine bacteria isolated from brine-seawater interface of the Red Sea

Background

High salinity and temperature combined with presence of heavy metals and low oxygen renders deep-sea anoxic brines of the Red Sea as one of the most extreme environments on Earth. The ability to adapt and survive in these extreme environments makes inhabiting bacteria interesting candidates for the search of novel bioactive molecules.

Methods

Total 20 i.e. lipophilic (chloroform) and hydrophilic (70% ethanol) extracts of marine bacteria isolated from brine-seawater interface of the Red Sea were tested for cytotoxic and apoptotic activity against three human cancer cell lines, i.e. HeLa (cervical carcinoma), MCF-7 (Breast Adenocarcinoma) and DU145 (Prostate carcinoma).

Results

Among these, twelve extracts were found to be very active after 24 hours of treatment, which were further evaluated for their cytotoxic and apoptotic effects at 48 hr. The extracts from the isolates P1-37B and P3-37A (Halomonas) and P1-17B (Sulfitobacter) have been found to be the most potent against tested cancer cell lines.

Conclusion

Overall, bacterial isolates from the Red Sea displayed promising results and can be explored further to find novel drug-like molecules. The cell line specific activity of the extracts may be attributed to the presence of different polarity compounds or the cancer type i.e. biological differences in cell lines and different mechanisms of action of programmed cell death prevalent in different cancer cell lines.

Antibacterial compounds from Planchonia careya leaf extracts

AIM OF THE STUDY

The leaves of Planchonia careya (F. Muell.) R. Knuth (Lecythidaceae) have been traditionally implemented in the treatment of wounds by the indigenous people of northern Australia, although the compounds responsible for the medicinal properties have not been identified. In this study, antibacterial compounds from the leaf extracts were isolated and characterized, and the biological activity of each compound was assessed.

MATERIALS AND METHODS

Compounds were isolated from the leaf extracts using HPLC-piloted activity-guided fractionation. The minimum inhibitory concentrations (MICs) were assessed with plate-hole diffusion assays, and the cytotoxicity was determined with MTT assays using monkey kidney epithelial (MA104) cells.

RESULTS

Six known compounds were isolated from the leaf extracts and were identified as 1, (+)-gallocatechin; 2, gallocatechin-(4alpha-->8)-gallocatechin; 3, 9(S)-hydroxy-10E,12Z-octadecadienoic acid (alpha-dimorphecolic acid); 4, 2alpha,3beta,24-trihydroxyolean-12-en-28-oic acid (hyptatic acid-A); 5, 3beta-O-cis-p-coumaroyltormentic acid; and 6, 3beta-O-trans-p-coumaroyltormentic acid. Compounds 5 and 6 were weakly selective for vancomycin-resistant Enterococcus (VRE) compared with eukaryotic cells, with an MIC of 59.4microg/mL and a 50% inhibitory concentration (IC(50)) of 72.0microg/mL for MA104 cells.

CONCLUSIONS

The isolation of six antibacterial compounds from the leaves of Planchonia careya validates the use of this species as a topical wound-healing remedy.