Antioxidant, anti-quorum sensing and anti-biofilm potential of ethanolic leaf extract of Phrynium capitatum and Dryptes indica

Objective: To investigate the antioxidant and anti-infective potential of Phrynium capitatum and Dryptes indica extract. Methods: The antioxidant potentials were determined by DPPH radical scavenging, reducing power, hydroxyl radical scavenging and total antioxidant assays. We further examined anti-quorum sensing activity and inhibition of synthesis of pathogenic factor of Chromobacterium violaceum and Pseudomonas aeruginosa PAO1. Bioactive compounds were determined using gas chromatography-mass spectrometry analysis. In silico analysis was conducted to determine the binding affinity of bioactive compounds of plant extracts for the quorum sensing regulatory receptor LasR. Results: DPPH assay showed that the ethanolic extract of Phrynium capitatum and Dryptes indica at 500 μg/mL showed (86.96 ± 4.07)% and (74.83 ± 3.47)% inhibition, respectively. Hydroxyl radical scavenging assay showed (73.17 ± 3.03)% and (62.63 ± 4.59)% activity, respectively. The ethanolic extract of Phrynium capitatum and Dryptes indica showed high level of attenuation of quorum sensing regulated pyocyanin production. Confocal laser scanning microscopic analysis revealed that the extracts had the potential to effectively inhibit biofilm formation of Pseudomonas aeruginosa. Molecular docking analysis showed a better binding affinity of bioactive compounds from the extracts for the structure of LasR protein of Pseudomonas aeruginosa. Conclusions: The ethanolic extracts of Phrynium capitatum and Dryptes indica possess antioxidant activity and the potential to inhibit the quorum sensing system and its regulatory irulence traits in Pseudomonas aeruginosa PAO1.

Determination of antioxidant activity of Hibiscus sabdariffa and Croton caudatus in Saccharomyces cerevisiae model system.

From ancient times, plants and plant derived products are exploited as a prominent source of folkloric medicines with tremendous therapeutic potential for an array of health disorders. In the present study, ethanolic leaf extract of Hibiscus sabdariffa and Croton caudatus were evaluated for free radical scavenging activity in Saccharomyces cerevisiae model system. H. sabdariffa and C. caudatus showed tremendous DPPH free radical scavenging potential with an IC50 value of 184.88 and 305.39 µg/mL respectively at a concentration of 500 µg/mL. The ethanolic leaf extract of H. sabdariffa and C. caudatus also showed significant hydoxyl radical scavenging and total antioxidant activity. Ascorbic acid was used as positive control. The in vitro antioxidant activity was further supported by in vivo studies using radical scavenging mechanism in S. cerevisiae wild type and its isogenic deletion strains sod1∆ and tsa1∆. The mutant yeast cells substantially scavenged the stress generated by H2O2 when supplemented with ethanolic leaf extract of H. sabdariffa and C. caudatus as evident from spot assays followed by fluorescence assay (DCF-DA) using fluorescence microscopic and intensity studies. H. sabdariffa and C.caudatus significantly neutralize the ROS level in yeast mutants with concomitant decrease in fluorescence intensity as compared to the untreated yeast cells. The results suggested the efficacy of H. sabdariffa and C. caudatus as potent antioxidants in yeast system and thus their futuristic applications in therapeutics.

Determination of antioxidant potential of Acacia nilotica leaf extract in oxidative stress response system of Saccharomyces cerevisiae.

BACKGROUND: From ancient times, plants and plant-derived products have been used as folkloric medicines for a variety of health disorders owing to their tremendous therapeutic potential. The present study aimed to determine the antioxidant efficacy of crude Acacia nilotica extract in the oxidative stress response system of Saccharomyces cerevisiae as a model organism. RESULTS: Acacia nilotica showed significant antioxidant activity, with IC50 values of 75.157 and 159.57 µg mL-1 for 2,2-diphenyl-1-picrylhydrazyl radical and hydroxyl radical scavenging activities respectively at a concentration of 500 µg mL-1 . The total antioxidant activity of A. nilotica showed an ascorbic acid equivalent of 152.79 ± 7.43 µg mL-1 . The presence of phytoconstituents such as phytol and α-tocopherol from gas chromatography/mass spectrometry analysis confirmed the potential of A. nilotica as an antioxidant. The results were validated using the stress response mechanism in S. cerevisiae wild type and its isogenic deletion strains sod1Δ and tsa1Δ. Acacia nilotica substantially neutralized reactive oxygen species generated by hydrogen peroxide in mutant strains, as evident from spot assay and fluorescence assay using fluorescence microscopy and intensity studies. CONCLUSION: The results suggested the efficacy of A. nilotica as a potent antioxidant in the S. cerevisiae system for the first time and its use in neutraceuticals/therapeutics. © 2017 Society of Chemical Industry.

Photo-induced and phytomediated synthesis of silver nanoparticles using Derris trifoliata leaf extract and its larvicidal activity against Aedes aegypti.

Due to the increased development of resistance of vectors against synthetic insecticides and chemical drugs, plant based insecticides serve as promising biocontrol agents for effective vector control. Green approach for the synthesis of nanoparticles has been attained using environmentally safe, non-toxic plant extracts. The present study was aimed to investigate the potent larvicidal activity of silver nanoparticles (AgNPs) produced by Derris trifoliata leaf extract in relation to the various concentrations of methanol and chloroform extracts for 24h against 3rd and 4th instar larvae of Aedes aegypti. AgNPs were synthesized using D. trifoliata leaf extract as reducing and stabilizing agent. Synthesized AgNPs were characterized by UV-Vis spectroscopy, FTIR spectroscopy, SEM, EDX, XRD and HRTEM. The size of AgNPs as estimated from the full width at half-maximum of (200) peak of silver was 16.13nm, the average crystalline size of the synthesized AgNPs was approximately 20nm, which was correlated with the HRTEM results (20nm). SEM and TEM images have shown the formation of polydispersed nanoparticles with an average size of 20nm. The FTIR spectra of AgNPs exhibited prominent peaks at 2360.7, 1606.2, 1095.6 and 785.9cm-1. The spectral peak observed at 1606.2, assigned to stretching vibration (C=O) in carbonyl compounds characterized by the presence of major constituents of flavonoids and terpenoids. The results obtained in FTIR spectroscopy correlated with the GC-MS analysis of methanol and chloroform extracts and indicates the presence of phytosteroids, flavonoids and terpenoids. The highest larvicidal activity was observed for the synthesized AgNPs against the 3rd instar larvae with LC50 values of 5.87mg/l and LC90 of 12.11mg/l, while against 4th instar larvae these values were7.00 and17.76mg/l respectively. The chloroform extracts also showed increased larvicidal activity than methanol extracts against 3rd instar larvae (LC50=54.42mg/l, LC90=140.83mg/l) and 4th instar larvae (LC50=62.47mg/l, LC90=145.06mg/l) of A. aegypti. Besides, the synthesized AgNPs also exhibited potent antibacterial activity against certain food borne pathogens. These results infer that the biologically synthesized AgNPs and organic solvent extracts have the potential to be used as an excellent eco-friendly approach for vector control against A. aegypti.