Polyphenols in selected marine algae and aromatic herbs with antimicrobial properties: A comparative study

Abstract

The increasing resistance of bacteria toward commercial antibiotics recommends offering various natural products as potent alternatives. In this study, polyphenols including flavonoids and phenolic compounds were detected in the sampled seaweeds: Corallina officinalis, Ulva lactuca, and Pterocladia capillacea, abundant in the Egyptian marine environment, and the aromatic herbs: Ocimum basilicum, Mentha longifolia, and Salvia officinalis, abundant in the Egyptian market. Phenolics were detected in different concentrations in seaweed and aromatic herbs, where the highest values were recorded for cinnamic acid (0.0213 mg/g), followed by the ellagic acid concentration (0.0152 mg/g) in S. officinalis. In addition, the highest values of flavonoids were estimated as 87.8258 for Kaempferol in O. basilicum. The antibacterial activity of algal and herbal extracts was evaluated. As revealed, Staphylococcus aureus ATCC 25923 was the most affected strain by all extracts. The algal extracts recorded considerable values against S. aureus ATCC 25923 (i.e., 16 mm by P. capillacea extract) and Pseudomonas aeruginosa ATCC 9027 (i.e., 44 mm by C. officinalis extract). The aromatic herbal extracts also exhibited high antibacterial activity against S. aureus ATCC 25923 (34–38 mm). These extracts showed high activities against P. aeruginosa ATCC 9027 (34–40 mm). The C. officinalis crude extract was then fractioned by preparative TLC plates and afforded three materials: 1, 2, and 3, where Rf = 0.44, 0.29, and 0.11, respectively. The most abundant spots were scraped and collected from 12 TLC sheets to detect their antibacterial activities against the same pathogens compared to the Ciprofloxacin antibiotic. However, spot 1 showed the highest inhibition.