Nutraceutical, Antioxidant, Antimicrobial Properties of Pyropia vietnamensis (Tanaka et Pham-Hong Ho) J.E. Sutherl. et Monotilla

Background: Pyropia genus is one of the most nutritionally rich marine algae which contain various bioactive compounds. Among Indian Pyropia species, Pyropia vietnamensis (P. vietnamensis), which was earlier known as Porphyra vietnamensis has recently documented with various reports. The present work is designed to evaluate the radical scavenging, nutraceutical and microbicidal properties of Pyropia vietnamensis. Methods: P. vietnamensis was collected from the coastal region of Maharashtra, namely Harihareshwar. Dried algal material was extracted with different solvents. Nutritional parameters such as fatty acids, minerals, dietary fibers, vitamins, lipids, ash content and protein were measured as per the standard protocol (WHO guidelines). Folin-Ciocalteu and aluminum chloride colorimetric procedures were used to estimate total phenolic content and total flavonoid content. Free radical scavenging activity was assessed using 2,2-diphenyl-1-picrylhydrazyl, nitric oxide and superoxide anion (O2¯) assays. Antimicrobial activity was investigated by in vitro microdilution procedure to estimate minimum inhibitory concentration and minimum bacterial concentration, against Gram-- positive bacterium (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, and Proteus vulgaris). Results: Nutritional analysis revealed that Pyropia vietnamensis contained a considerable amount of dietary fiber, protein, carbohydrate, methyl palmitate, magnesium, sulphur and sodium. Total phenolic content and total flavonoid content of methanolic fractions (913±21.7, 128±11.7) were more than an aqueous fraction (841±21.2, 3.7±11.1). Aqueous and ethyl acetate fractions showed significant antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (65.5±1.2 μg/mL, 68.3±1.6 μg/mL), nitric oxide (71.5±3.5 μg/mL, 52.3±1.9 μg/mL), and O2¯ (50.6±1.02 μg/mL, 62.1±1.03μg/mL) free radicals. Aqueous, methanolic and ethyl acetate fractions had the highest total antibacterial activity with minimum inhibitory concentration as 110–490 μg/mL and minimum bacterial concentration as 248–689 μg/mL against one Gram-positive and three Gram-negative microorganisms. Conclusion: Aqueous, ethyl acetate, and methanolic fractions of Pyropia vietnamensis exhibited good antimicrobial spectrum and antioxidant activity. This could be useful in preventing various oxidative stresses and pathogenic microbial strains.