In vitro antibacterial activity of Hibiscus rosa sinensis, Chrysanthemum indicum, and Calendulaofficinalis flower extracts against Gram negative and Gram positive food poisoning bacteria

Safely management of food spoilage and foodborne illness is primarily achieved by applying chemical additives that have adverse effects along with health risk, increment chemical in food, and reduced bacterial susceptibility to antimicrobials. In the present study, antimicrobial efficacy of extracts from 3 different flowers (Hibiscusrosa sinensis, Chrysanthemum indicum, and Calendula officinalis) was examined towards seven food poisoning bacterial strains, four gram-positive strains (Staphylococcus aureus MTCC 87, Bacillus cereus MTCC 430, Clostridium perfringens MTCC 450, Listeria monocytogenes MTCC 657), and three gram-negative strains (Escherichia coli MTCC 43, Salmonella typhi MTCC 1264 and Pseudomonas aeruginosa MTCC424) using well diffusion assay. Aqueous extracts from all three of the flowers were similarly efficient with variable antimicrobial efficiency against the examined bacterial strains, while ethanol and methanol extracts from C.officinalis were highly efficient against all tested pathogenic bacteria. Ethanolic extract of C. indicum was the most efficient flower extract after C. officinalis against C. perfringens, L. monocytogenes, and S. typhi. H. rosa sinensis ethanol extract exhibited bactericidal action against S. aureus, B. cereus, and P. aeruginosa. For most extracts, the minimum inhibitory concentration (MIC) ranged from 3.75 to 7.5% and minimum bactericidal concentration (MBC) of 1.87-3.75% except for C. perfringens, and L. monocytogenes those were less sensitive with MIC 20%, and MBC 20%. Such flower extracts, which are potentially efficient, would be utilized to manage foodborne illness and protect food items from spoilage and minimize safety hazards generated due to chemically preservatives.