The Influence of Chestnut Extract and Its Components on Antibacterial Activity against .

Increasing antimicrobial resistance has caused a great interest in natural products as alternatives or potentiators of antibiotics. The objective of this study was to isolate individual tannins from crude chestnut extract as well as to determine the influence of both crude extracts (tannic acid extract, chestnut extract) and individual pure tannins (gallic acid, vescalin, vescalagin, castalin, castalagin) on the growth of Gram-positive bacteria. Their antibacterial activity was monitored by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) as well as the duration of the lag phase, growth rate and generation time.

Antimicrobial Properties of Different Hop () Genotypes.

The antimicrobial activity of hop extracts obtained from different hop genotypes were investigated against and . In this study the pure xanthohumol, purified β-acids rich fraction, as well as α-acids with β-acids rich fraction were used to test antimicrobial activity against and ; whereby, the antimicrobial activity of different hop extracts against was studied for the first time. Microbial susceptibility to purified hydroacetonic extracts from different hop varieties was investigated by the broth microdilution assay to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC).

The influence of pH on UV/Vis spectra of gallic and ellagic acid: A combined experimental and computational study.

The pH dependence of the UV/Vis spectrum of gallic and ellagic acid was measured in a buffer-free solution to obtain reliable data at wavelengths bellow 230 nm. UV/Vis absorption spectra were also calculated for all possible ionised species of gallic and ellagic acid using time dependent density functional theory (TD-DFT). From pK values of gallic and ellagic acid the molar fraction of different ionised species was calculated for each pH value.

Generation Times of Prolong with Increasing Tannin Concentration while the Lag Phase Extends Exponentially.

The current study examines the effect of tannins and tannin extracts on the lag phase duration, growth rate, and generation time of . Effects of castalagin, vescalagin, gallic acid, Colistizer, tannic acid as well as chestnut, mimosa, and quebracho extracts were determined on 's growth phases using the broth microdilution method and obtained by turbidimetric measurements. responds to the stress caused by the investigated antimicrobial agents with reduced growth rates, longer generation times, and extended lag phases.

The Effect of Growth Medium Strength on Minimum Inhibitory Concentrations of Tannins and Tannin Extracts against .

In this study the effect of growth medium strength on the minimum inhibitory concentration (MIC) of different tannins and tannin extracts against was systematically investigated for the first time. Three pure compounds (vescalagin, castalagin and gallic acid) and five extracts (chestnut, quebracho, mimosa, Colistizer and tannic acid) were studied. Broth microdilution was assayed and bacteria were grown using different growth medium strengths varying from half to double the concentration recommended by the producer.