Antimicrobial and Antibiofilm Potentials of Methanolic Extract from Cultivated Tropical Hibiscus (Hibiscus rosa sinensis L.) Flower

Using natural antimicrobials to treat microbial infections is one of the hopeful alternatives to combating antibiotic-resistant strains throughout the world. In this work, the antimicrobial and antibiofilm properties of methanolic extract derived from tropical hibiscus flower were investigated against a variety of microbial pathogens. Results showed that the extract contained considerable amounts of anthocyanins, polyphenols, and flavonoids. Furthermore, the extract contained high amounts of volatile compounds: Disulfide, di-tert-dodecyl (11.378%), Tridecanol, 2-ethyl-2-methyl- (11.940%), Didodecyl phthalate (13.701%), Eicosane (14.532%), and Octane, 2-methyl- (15.242%). Interestingly, the growth, cell morphology, and biofilms of the tested pathogenic bacteria were highly affected by the extract. High sensitivity towards the extract was exhibited by the tested bacteria: Staphylococcus aureus (36±0.1 mm), Micrococcus luteus (45±0.5 mm), Escherichia coli (45±0.15 mm), and Klebsiella pneumonia (40±0.5 mm), with MIC values of 1, 0.5, 0.5 and 1 mg/mL, respectively. The extract inhibited the formation of biofilm in Staphylococcus aureus, Micrococcus luteus, Escherichia coli and Klebsiella pneumonia by 46.4, 47.6, 46.3 and 38.4% respectively. The strongest antifungal activity of the extract was against Fusarium solani (34.7%) and Alternaria phragmospora (33.8%) at 8 mg/mL. The findings of this study indicated that tropical hibiscus flower extract may be promising for the development and design of natural antimicrobial alternatives.