Antimicrobial, Antioxidant, Anticancer Activity and Phytochemical Analysis of the Red Alga, Laurencia papillosa

Background and Objective: Marine macro-algae contain bioactive compounds and can produce a great variety of secondary metabolites useful to human health. The present study was meant to evaluate the biological activities of extracts from the red alga, Laurencia papillosa (L. papillosa). Materials and Methods: The dichloromethane, dichloromethane: methanol (1:1 v/v), methanol and water were used to obtain the algal extract. The antimicrobial activity of the different extracts was evaluated against gram-positive bacteria (Staphylococcus aureus (S. aureus), Staphylococcus saprophyticus and Streptococcus agaloctiae) and gram-negative bacteria (Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Proteus mirabilis (P. mirabilis)) and two fungal strains (Candida albicans and Candida tropicalis (C. tropicalis)) by the well diffusion method. The algal extract was assayed for DPPH radical scavenging activity and MTT cell viability using HCT-116 colon cancer. The phytochemical composition of L. papillosa was studied. The FT-IR and GC-MS analysis were performed for the most effective algal extract. Results: The dichloromethane: methanol (1:1) extract revealed a wide range of antimicrobial activity against tested pathogens, which mostly inhibited the growth of P. aeruginosa, S. aureus, C. tropicalis, E. coli and P. mirabilis with inhibition zones range of 13-15 mm. The algal extracts exhibited bactericidal effect against the tested strains at the ratio of MBC/MIC >= 2.0. Among the algal extracts, dichloromethane: methanol (1:1) exhibited the highest antioxidant and anticancer activities with a very low IC50 (110.8 and 196 mu g mL(-1), respectively). The pigments, protein, carbohydrates, lipid, total phenolic, flavonoid and tannin contents of alga were assayed. The FTIR analysis of extract revealed the presence of alcohols, phenols, ester and alkanes. The results indicated the presence of long chain unsaturated and saturated fatty acids with the dominance of palmitic acid (53.3%). Conclusion: The results indicated that L. papillosa contains different biologically active compounds and can act as a promising antioxidant, antimicrobial, anticancer agents and may represent an application in the therapeutic uses.