Antimicrobial Activity and Chemical Constitution of the Crude Phenolic-Rich Extracts of Hibiscus sabdariffa Brassica oleracea and Beta vulgaris

摘要

Crude, phenolic-rich extracts (CPREs) were isolated from different sources, such as var. capitata f. rubra and ( and characterized. These CPREs showed potential antibacterial and antifungal activities. CPRE (HCPRE) is the most potent, as it inhibited all tested bacteria and fungi. Total anthocyanins content (TAC), total phenolic content (TPC) and total flavonoid content (TFC) were estimated in all three CPREs. contained 4.2 mg/100 g TAC, 2000 mg/100 g of TPC and 430 mg/100 g of TFC in a dry weight sample. GC–MS analysis of HCPRE showed 10 different active compounds that have antimicrobial effects against pathogenic bacteria and fungi, especially alcoholic compounds, triazine derivatives and esters. Scanning and transmission electron microscopy images of DSM 1104 and ATCC 43816 treated with HCPRE (50 μg/mL) exhibited signs of asymmetric, wrinkled exterior surfaces, cell deformations and loss of cell shapes; and adherence of lysed cell content led to cell clumping, malformations, blisters, cell depressions and diminished cell numbers. This indicates death of bacterial cells and loss of cell contents. EMCC516 ( , when treated with 100 μg/mL of HCPRE showed irregular cell organelles and cell vacuolation.