Characterization of Culturable Actinomycetes Associated with Halophytic Rhizosphere as Potential Source of Antibiotics

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - The global-scale failure of bacterial drug resistance calls for an urgent need to develop novel antibiotics....     

Isolation of a small molecule with anti-MRSA activity from a mangrove symbiont Streptomyces sp. PVRK-1 and its biomedical studies in Zebrafish embryos

Objective

The aim of the present study was to isolate the anti-MRSA (Methicillin Resistant Staphylococcus aureus) molecule from the Mangrove symbiont Streptomyces and its biomedical studies in Zebrafish embryos.

Methods

MRSA was isolated from the pus samples of Colachal hospitals and confirmed by amplification of mecA gene. Anti-MRSA molecule producing strain was identified by 16s rRNA gene sequencing. Anti-MRSA compound production was optimized by Solid State Fermentation (SSF) and the purification of the active molecule was carried out by TLC and RP-HPLC. The inhibitory concentration and LC₅₀ were calculated using Statistical software SPSS. The Biomedical studies including the cardiac assay and organ toxicity assessment were carried out in Zebrafish.

Results

The bioactive anti-MRSA small molecule A₂ was purified by TLC with Rf value of 0.37 with 1.389 retention time at RP-HPLC. The Inhibitory Concentration of the purified molecule A₂ was 30 µg/mL but, the inhibitory concentration of the MRSA in the infected embryo was 32-34 µg/mL for TLC purified molecule A₂ with LC₅₀ mean value was 61.504 µg/mL. Zebrafish toxicity was assessed in 48-60 µg/mL by observing the physiological deformities and the heart beat rates (HBR) of embryos for anti MRSA molecule showed the mean of 41.33-41.67 HBR/15 seconds for 40 µg/mL and control was 42.33-42.67 for 15 seconds which significantly showed that the anti-MRSA molecule A₂ did not affected the HBR.

Conclusions

Anti-MRSA molecule from Streptomyces sp PVRK-1 was isolated and biomedical studies in Zebrafish model assessed that the molecule was non toxic at the minimal inhibitory concentration of MRSA.     

Chemical genetic effects of Sargassum wightii during embryonic development in zebrafish

Objective:Phenotype based small molecule discovery is a category of chemical genetic study. The aim of this study was to observe the phytochemical based genetic effects of Sargassum wightii during organogenesis in embryonic zebrafish.Results:Initially, cardiac bulging was found in 2 dpf to 3 dpf (days post fertilization), then bradycardia and tubular heart were observed in the next 8 h, which also showed the reduction in the heart beat rates. The phenotypic mutation effects of bre, has, dou yan, heg and you were observed in the 3 dpf and 4 dpf of the extract treated zebrafish embryos.Conclusions:This study demonstrated that the phytomolecules from S. wightii exhibited potential molecular switches on the developmental process, which might have significant role in understanding the development based chemical genetic studies in zebrafish.KEY WORDS: Chemical genetics, phytomolecules, small molecules screening, tubular heart, zebrafish     

In vitro study on α-amylase inhibitory activity of an Indian medicinal plant, Phyllanthus amarus

Objective:

The objective of this study was to evaluate the α-amylase inhibitory activity of different extracts of Phyllanthus amarus against porcine pancreatic amylase in vitro.

Materials and Methods:

The plant extracts were prepared sequentially with ethanol, chloroform, and hexane. Each extract was evaporated using rotary evaporator, under reduced pressure. Different concentrations (10, 20, 40, 60, 80, and 100 μg/mL) of each extract were made by using dimethyl sulfoxide (DMSO) and subjected to α-amylase inhibitory assay using starch azure as a substrate. The absorbance was read at 595 nm using spectrophotometer. Using this method, the percentage of α-amylase inhibitory activity and IC₅₀values of each extract was calculated.

Results:

The chloroform extract failed to inhibit α-amylase activity. However, the ethanol and hexane extracts of P. amarus exhibited appreciable α-amylase inhibitory activity with an IC50 values 36.05 ± 4.01 μg/mL and 48.92 ± 3.43 μg/mL, respectively, when compared with acarbose (IC₅₀value 83.33 ± 0.34 μg/mL).

Conclusion:

This study supports the ayurvedic concept that ethanol and hexane extracts of P. amarus exhibit considerable α-amylase inhibitory activities. Further, this study supports its usage in ethnomedicines for management of diabetes.