Correlation Phenolic Concentration to Antioxidant and Antibacterial Activities of Several Ethanolic extracts from Indonesia

Abstract

Increasing concerns on the adverse effect of synthetic antioxidants and the emergence of antibiotic-resistant Staphylococcus aureus have become two essential problems to be addressed. To tackle them, exploration of natural resources to discover novel antioxidants and/or antibacterial agents is urgently required. The aim of this research was to investigate the correlation of phenolic and flavonoid contents of extracts to their antioxidant and antibacterial activities. Green tea, green coffee, cocoa pod husks, bee pollen, and rosella calyces were processed and subjected to 80% ethanol-based maceration procedure to obtain extracts with appropriate condition. Each extract was examined for its phenolic and flavonoid concentrations using the Folin–Ciocalteau method and the aluminum chloride colorimetric assay, respectively. Further analysis on the free-radical scavenging potential and antibacterial/antibiofilm activity against S. aureus were carried out. Samples were found to contain total phenolics (TP) and total flavonoids (TF) at different concentrations. The highest level of TP and TF was identified in green tea extract and corresponded to the lowest IC50 against DPPH and the lowest MIC against S. aureus colonies or to their respective biofilm. In contrast, low amounts of TP and TF were found in cocoa pod husks and bee pollen which were further demonstrated high IC50 and high MIC. Collectively, our results suggested the linear correlation of phenolic- and flavonoid contents to the antioxidant and antibacterial/antibiofilm activities of plant extracts. The higher the phenolics and flavonoids level, the better the antioxidant and antibacterial/antibiofilm activities obtained from the corresponding extracts.

Green tea extract-mediated augmentation of imipenem antibacterial activity against Enterobacter cloacae clinical isolates

“…A summary of extraction yield, TPC, and EGCG content calculated from the obtained GTE are shown in Table 1. (Sartini et al, 2019). In addition, we also found that the GTE prepared in this study contained higher EGCG than our previous result (Sartini et al, 2019).…”

“…Green tea ethanolic extract, or referred to as green tea extract (GTE), was prepared based on the previously established method (Sartini et al, 2019) with slight modifications. Briefly, GTE was prepared by firstly extracting the coarse powder of green tea by ultrasound-assisted maceration method for 15 minutes using hexane (1:10) to eliminate non-polar compounds.…”

“…One of the suggested ways is by maintaining the use of existing antibiotics in combination with bioactive compounds from medicinal plants that could further improve the antibacterial activity of those antibiotics (Coutinho et al, 2008;Matias et al, 2011). It has been recently reported that certain phenolic compounds can increase the antibacterial activity of conventional antibiotics (Sartini et al, 2019). For example, the MICs of kanamycin, gentamycin, amikacin, neomycin were decreased as much as 87.5% or even 99.9% when they were used in combination with the flavonoid-rich ethanolic extract of Croton campestris leaves (Júnior et al, 2011).…”

“…One of the natural resources demonstrated to incite antimicrobial activity against some pathogenic bacteria is green tea (Sartini et al, 2019). The antibacterial properties of green tea are mainly attributed to the catechin and caffeine compounds (Scoparo et al, 2012;Bermejo et al, 2015).…”

Current State and Promising Opportunities on Pharmaceutical Approaches in the Treatment of Polymicrobial Diseases

“…Phenolic acids, tannins, coumarins, and quinines are among the phenolic compounds commonly extracted from medicinal plants and herbs [ 117 , 118 , 119 ]. Phenolic compounds such as curcumin, carvacrol, and thymol have been shown to inhibit the growth of Candida albicans , the causative agent of candidiasis.…”