Standard Antibiotics Gentamicin Research Articles

Exploring the Antibacterial Properties of Vernonia amygdalina (Bitter Leaf) Extract: A Potential Alternative to Conventional Antibiotics

As part of the ongoing search for potent and resistance-free antibacterial medicinal plants, this study aimed to evaluate the antibacterial properties of the plant extract of Vernonia amygdalina, commonly known as bitter leaf. Standard procedures were used to provide a potential cheap alternative to conventional medication for treating bacterial infections. The aqueous extract of V. amygdalina leaves was prepared and subjected to phytochemical screening, which revealed the presence of tannins, phlobatannins, saponins, terpenoids, cardiac glycosides and alkaloids. The antibacterial activity of the extract was tested against the gram-positive bacterium Staphylococcus aureus and the gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli using the agar well diffusion method. The extract showed moderate antibacterial activity, exhibiting 10 mm and 8 mm zones of inhibition against S. aureus and P. aeruginosa respectively at a concentration of 20 mg/ml. However, it displayed no activity against E. coli. In comparison, the standard antibiotic gentamicin produced larger zones of inhibition of 33.5 mm, 27 mm, and 23.5 mm against the respective test organisms. The results suggest that V. amygdalina extract had greater antibacterial activity on the gram-positive S. aureus than on the gram-negative microorganisms tested. The presence of phytochemicals like tannins, saponins and alkaloids in the extract may contribute to its antibacterial properties. Further research is warranted to fully elucidate the medicinal potential of V. amygdalina and isolate the active compounds responsible for the observed antimicrobial effects. Overall, the findings provide a scientific basis for the traditional use of this plant in treating bacterial infections. Keywords: Vernonia amygdalina, Antibacterial activity, Phytochemicals, Antimicrobial resistance, Traditional. medicine

One-pot multicomponent synthesis of 4-((2H-chromen-3-yl)/(2-phenyl-2H-chromen-3-yl)methylene)-3-methylisoxazol-5(4H)-ones and evaluation of their antibacterial activity

An efficient synthesis of a series of 4-((2H-chromen-3-yl)/(2-phenyl-2H-chromen-3-yl)methylene)-3-methylisoxazol-5(4H)-ones has been developed via one-pot multicomponent addition of ethyl acetoacetate, hydroxylamine hydrochloride and 2H-chromene-3-carbaldehydes using DABCO as organocatalyst in refluxing ethanol. The reaction acted as a cyclocondensation between ethyl acetoacetate, hydroxylamine hydrochloride and 2H-chromenealdehyde, resulting into chromenyl isoxazolone. This mild cost-effective hetero-cyclization was obtained by simple crystallization with comparatively high yields and purity with good substrate scope adequacy. All the synthesized compounds were subsequently evaluated for in vitro anti-bacterial assay against Gram-negative (Escherichia coli and Klebsiella pneumoniae) and Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) pathogenic bacteria in comparison to the standard antibiotic Gentamicin. Compounds 21f and 21h found to have potent inhibitory activity against E. coli having ZI at 18 mm and 19 mm each corresponding to a MIC of 6.25 (μg/ml), respectively. SAR and molecular docking revealed compounds 21f and 21h having –Cl and –Br group displayed improved halogen and hydrogen bond-interaction with bacterial DNA gyrase of E. coli (PDBID:1KZN) having binding affinity of −8.8 kcal/mol respectively.

Aryl fluorosulfate analogues as potent antimicrobial agents: SAR, cytotoxicity and docking studies

A series of aryl fluorosulfate analogues (1–37) were synthesized and tested for in vitro antibacterial and antifungal studies, and validated by docking studies. The compounds 9, 12, 14, 19, 25, 26, 35, 36 and 37 exhibited superior antibacterial potency against tested bacterial strains, while compounds 2, 4, 5, 15, 35, 36 and 37 were found to have better antifungal activity against tested fungal strains, compared to standard antibiotic gentamicin and ketoconazole respectively. Among all the synthesized 37 analogs, compounds 25, 26, 35, 36 and 37 displayed excellent anti-biofilm property against Staphylococcus aureus. The structure–activity relationship (SAR) revealed that the antimicrobial activity depends upon the presence of –OSO2F group and slender effect of different substituent’s on the phenyl rings. The electron donating (OCH3) groups in analogs increase the antibacterial activity, and interestingly the electron withdrawing (Cl, NO2, F and Br) groups increase the antifungal activity (except compound 35, 36 and 37). The mechanism of potent compounds showed membrane damage on bacteria confirmed by SEM. Compounds 35, 36 and 37 exhibited highest glide g-scores in molecular docking studies and validated the biocidal property.

Endo-symbiont mediated synthesis of gold nanobactericides and their activity against human pathogenic bacteria

Synthesis of gold nanobactericides (AuNBs) were achieved by treating 1mM chloroaurate with cell free supernatant of Aneurinibacillus migulanus. Formation of AuNBs was initially was monitored with change in colour to ruby red. Further confirmation was assessed with UV–visible spectra with maximum absorption occurring at 510nm. Transmission electron microscopy (TEM) analysis revealed the polydispersity of AuNBs with size distribution ranging from 10 to 60nm with an average size of 30nm. Crystalline nature was studied using X-ray diffraction which exhibited characteristic peaks indexed to Bragg's reflection at 2θ angle which confers (111), (200), (220), and (311) planes suggesting AuNBs were face-centred cubic. Fourier transform infrared spectroscopy (FTIR) analysis revealed absorption peaks occurring at 3341cm−1, 1635cm−1 and 670cm−1 which corresponds to functional groups attributing to synthesis. The antibacterial efficacy of AuNBs was tested against selective human pathogenic bacteria and activity was measured as zone of inhibition by using disc and well diffusion. Bactericidal activity was interpreted with standard antibiotics gentamicin and kanamycin. Micro broth dilution assay expressed the minimal concentration of AuNBs to inhibit the growth of test pathogens. Highest activity was observed against Pseudomonas aeruginosa (MTCC 7903) with 21.00±0.57mm compared to other pathogens. The possible mode of action of AuNBs on DNA was carried out with in vitro assay as preliminary test against pathogenic DNA isolated from P. aeruginosa. Further studies will be interesting enough to reveal the exact interactive mechanism of AuNBs with DNA. Overall study contributes towards biogenic synthesis of AuNBs as one of the alternative in combating drug resistant pathogens.

Phytochemical and Antibacterial Properties of Ethanolic Seed Extracts of Chrysophyllum albidum (African Star Apple)

Phytochemical and antibacterial properties of ethanolic extract of the seeds of African Star Apple (Chrysophyllum albidum) were investigated. The phytochemical result revealed the presence of saponins, carbohydrates, flavonoids, quinones, cardiac glycosides, fatty acids and terpenoids. The antibacterial activity was studied using agar well diffusion method at different concentrations against six pathogenic bacterial strains, three Gram-positive (Staphylococcus aureus, Micrococcus varians and Bacillus cereus) and three Gram-negative (Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris). Significant inhibitory activities were exhibited by the ethanolic seed extracts for all test organisms except Bacillus cereus. Zone of inhibition of the crude ethanolic extract was correlated with that of a standard antibiotic Gentamicin, for antibacterial activity. The results indicated a notable inhibition of the bacterial growth.

Evaluation of antidiarrheal activity of ethanolic extract of Holarrhena antidysenterica seeds in rats.

Aim:The present study was conducted to evaluate the antidiarrheal effect of ethanolic extract of Holarrhena antidysenterica (Family - Apocynaceae) seeds against induced diarrhea in Wistar albino rats.Materials and Methods:The extract was evaluated for castor oil and Escherichia coli induced diarrhea. Extract was given at 100, 200, 400 mg/kg body wt. orally in both protocols. Standard antidiarrheal Loperamide was used at 5 mg/kg body wt. orally in castor oil induced protocol, while standard antibiotic Gentamicin at 8 mg/kg body wt. intraperitoneally was used in E. coli induced diarrhea. In castor oil induced protocol, the percentage inhibition of defecation was calculated for each group, whereas in E. coli induced protocol, change in fecal consistency, and body weight was recorded for each individual rat for 3 days.Results:The severity of castor oil induced diarrhea was reduced significantly (p<0.05) with H. antidysenterica seeds extract at 200 and 400 mg/kg body wt. which showed equivalent effectiveness like that of Loperamide treated groups. Similarly in E. coli induced diarrhea protocol, the mean change in body weight was significantly (p<0.05) higher in positive control, whereas no significant variation was observed in negative control, Gentamicin treated and H. antidysenterica treated group at 200 mg/kg and 400 mg/kg body wt., respectively.Conclusion:The study concluded that ethanolic extract of H. antidysenterica seeds effectively controlled diarrhea and decreased the severity of clinical signs of castor oil and E. coli induced diarrhea in Wistar rats.

Antibacterial activity of Eleutherine bulbosa against multidrug-resistant bacteria

Abstract Background Recent interest in plant-based medicine is justified, as synthetic antioxidants and antibiotics suffer from several drawbacks. Plant extracts have been shown to possess health promoting properties, and they exert no selective physiological pressure on the pathogens that can result in development of drug resistance. The aim of this study was to investigate the antibacterial activity of Eleutherine bulbosa plant extracts against a series of multidrug-resistant (MDR) bacteria by calculating zones of inhibition, minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs) and time–kill kinetics. Methods Dried bulb powder of E. bulbosa was extracted with five solvents (ethyl acetate, chloroform, butanol, ethanol and water) to select the best extractant for subsequent isolation of bioactive compounds to use against a battery of MDR bacteria. Results Butanol was found to be the best extractant with an MIC ranging from 46 μg/mL to 187 μg/mL. Butanol and aqueous extracts showed higher zones of inhibition in comparison with standard antibiotics gentamicin and ciprofloxacin. Thin layer chromatography (TLC)-bioautography was carried out with the butanol extract against Staphylococcus aureus and Shigella boydii . A synergistic effect was established against S. boydii by combining the chloroform extract with gentamicin. Conclusion The bulb extracts of E. bulbosa exhibited significant antibacterial activity. Further study is necessary to characterize the antibacterial compounds of this plant for use in clinical applications.

Antimicrobial, antioxidant and phytochemical investigation of Balanites aegyptiaca (L.) Del. edible fruit from Sudan

The methanol extract of the fruit (edible mesocarp) of Balanites aegyptiaca (L.) Del., a popular plant from Sudan, widely employed in Sudanese folk medicine was screened for antimicrobial, antioxidant and some active phytochemical compounds. The extract showed the presence of saponin, terpenoids, phenolic compounds and alkaloids. The methanolic extract of the fruits extracted from B. aegyptiaca exhibited a strong antioxidant activity in the DPPH assay and a potent capacity in preventing linoleic acid oxidation. Methanol extracts (50 and 100 mg/ml) were tested on several microbial strains using agar-well diffusion, minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC) and minimum fungal concentration (MFC) methods. These experiments were performed on ten bacterial strains (five Gram-positives and five Gram-negatives) and four fungal strains. Methanol extracts, particularly at concentration of 100 mg/ml was found to be active against all bacterial and fungal strains and it was comparable to standard antibiotics Gentamicin and Amphotericin B. These findings support some of the traditional applications of the fruit of B. aegyptiaca against microbial aliments. It is therefore recommended that further studies regarding fractionation, separation and purification of these active antimicrobial compounds are required, in addition to toxicological evaluation in vivo.

COMBINATION EFFECTS BETWEE N HIBISCUS SABDARIFFA AND QUERCUS INFECTORIA EXTRACTS AGAINST SEVERAL GRAM NEGATIVE BACTERIA

The antibacterial activities of Hibiscus sabdariffa and Quercus infectoria extracts were screend against 5 spicies of Gram negative bacteria, Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens, Proteus vulgaris and Klebsiella pneumonia. Calyces of Hibiscus sabdariffa and nutgalls of Quercus infectoria were extracted in acetone using a soxhlet apparatus. Extracts of the plants showed high antibacterial activities on all types of bacteria tested using the disc diffusion method and comparing with the standard antibiotics Gentamicin and cephalexin . The combined effect of the two extracts was also studied against the tester bacteria, and found increase the inhibition zone diameters at all concentrations, except in S. marcescens which was inhibited at concentrations from 200-6.25 mg/ml and Pr.vulgaris which appeared more sensitive against the combination between the two extracts. The calculated inhibition zone reached 25 mm using the concentration 200 mg/ml which is greater than the control effects. The study also determined the Minimum Inhibitiory Concentration MIC of the two extracts and the combination between them. The bacteria also showed high sensitivity against the extract combination,with Pr. vulgaris was also more sensitive than other bacteria. The calculated MIC reached 0.0625 mg/ml meanwhile. K. pneumonia appeared less sensitivity, the calculated MIC was 0.125 mg/ml.