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!6s 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 LC_(50)were calculated using Statistical software SPSS.The Biomedical studies including the cardiac assay and organ toxicity assessment were carried out in Zebraiish.Results:The bioactive anti-MRSA small molecule A,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 A_2 was 30μg/mL but,the inhibitory concentration of the MRSA in the infected embryo was 32-34μg/mL for TLC purified molecule A,with LC_(50)mean value was61.504μg/mL.Zebrafish toxicity was assessed in 48-60μg/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 40μg/mL and control was 42.33-42.67 for 15 seconds which significantly showed that the anti-MRSA molecule A_2 did not affected the HBR.Conclusions:Anti-MRSA molecule from Streptomyces sp PVRK-I was isolated and biomedical studies in Zebrafish model assessed that the molecule was non toxic at the minimal inhibitory concentration of MRSA.

Cynodon dactylon andSida acuta extracts impact on the function of the cardiovascular system in zebrafish embryos

The aim of the present study was to screen cardioactive herbs from Western Ghats of India. The heart beat rate （HBR） and blood flow during systole and diastole were tested in zebrafish embryos. We found that Cynodon dactylon （C. dactylon） induced increases in the HBR in zebrafish embryos with a HBR of （3.968±0.344） beats/ s, which was significantly higher than that caused by betamethosone [（3.770±0.344） beats/s]. The EC50 value of C. dactylon was 3.738 μg/mL. The methanolic extract of Sida acuta （S. acuta） led to decreases in the HBR in zebrafish embryos [（1.877 ±0.079） beats/s], which was greater than that caused by nebivolol （positive control）. The EC50 value of Sida acuta was 1.195 μg/mL. The untreated embryos had a HBR of （2.685±0.160） beats/s at 3 d post fertilization （dpf）. The velocities of blood flow during the cardiac cycle were （2,291.667 ±72.169） μm/s for the control, （4,250± 125.000） μm/s for C. dactylon and （1,083.333±72.169） μm/s for S. acuta. The LC50 values were 32.6 μg/mL for C. dactylon and 20.9 μg/mL for S. acuta. In addition, the extracts exhibited no chemical genetic effects in the drug dosage range tested. In conclusion, we developed an assay that can measure changes in cardiac function in response to herbal small molecules and determine the cardiogenic effects by microvideography.

Antimicrobial silver nanoparticle induces organ deformities in the developing Zebrafish (Danio rerio) embryos

Silver Nanoparticles were synthesized by Esche- richia coli using Silver nitrate in the growth me-dium and characterized in X-Ray Diffraction, UV-Vis Spectrophotometer and Scanning Electron Microscope. They exhibited antimicrobial activity against human pathogens except Escherichia Coli. Nanoparticles were impregnated in yarn and ana-lyzed for their inhibition in the broth culture. The Minimal Inhibitory Concentratio was calculated for the human pathogens in Microtitre plate. The toxicity assessment of the nanoparticles in the embry-onic Zebrafish showed many organogensis deformi-ties like cardiac malformations, eye and head edema, tail and trunk flexure were observed in the organ system of the developing embryos for 1 to 5 day post fertilization in different concentrations of Ag Nanoparticles. The Organogenesis disruptive effects were found in 14 - 20 ng/ml of silver nanoparticles but the inhibition was found in 4-10ng/ml for the pathogens in vitro and 10ng/ml in embryos. Nevertheless, in Cardiac assay, the Heart Beat rates were calculated as 42 - 45 for 15 Sec in the concentrations ranging from 10 - 20 ng/ml of Silver nanoparticles. The blood flows, rhythmicity, contractility of heart beat rates were observed normal. The Mean value of blood Cell counting did not showed any notable effects in the Nanoparticle treated Zebrafish embryos and control. The LC50 value for the Biosynthesized nanoparticle was at 22 ng/ml in all the developmental stages of the em-bryos. Our results shows silver nanoparticles dis-rupts the normal organogenesis during development and further detailed studies are needed to prove silver nanopartcles are an antimicrobial agent for use in humans.