Bioactive Chemical Constituent Analysis, in vitro Antioxidant and Antimicrobial Activity of Whole Plant Methanol Extracts of Ulva lactuca Linn

Aims: To analyse the bioactive chemical constituents and evaluate in vitro antioxidant and antimicrobial activities of whole plant methanol extracts of Ulva lactuca Linn.

Study Design: Preliminary phytochemical screening, Gas Chromatography-Mass Spectrometry (GC-MS) analysis, evaluation of antioxidant and antimicrobial activities.

Place and Duration of Study: Veterinary University Training and Research Centre, Ramanathapuram-623503, Department of Botany, A.V.V.M Sri Pushpam college, Poondi, Thanjavur-613503 and K.M.C.H college of pharmacy, Kovai Estate, Kalapatti Road, Coimbatore-641048. The studies were carried out during August-December 2016.

Methodology: Phytochemical constituents were identified by qualitative and GC-MS analysis. In vitro antioxidant activity of the extracts were studied using DPPH radical scavenging assay, total phenol and total flavonoid content determination assays. Antimicrobial activity was investigated by disc diffusion technique.

Results: Phytochemical screening of methanol extracts showed positive results for alkaloids, flavonoids, phenols, tannins, terpenoids, glycosides, steroids, proteins and negative results for saponins and cardiac glycosides. GC-MS analysis revealed the presence of 10 compounds in Ulva lactuca methanolic extracts and some of the phytocomponents screened were terpenoids, fatty acid derivatives and aliphatic hydrocarbons and many of them have antioxidant, anti-inflammatory, antimicrobial and anticancer actions. Methanolic plant extract showed significant antioxidant activity under DPPH free radical scavenging activity, total phenol and total flavonoid content determination assay. In disc diffusion technique among six bacterial species, methanol extract showed potent activity against three Gram positive (Bacillus subtilis, Corynebacterium diphtheriae and Staphylococcus aureus) and three Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Salmonella paratyphi). The extracts were more potent towards fungal isolates (Aspergillus niger and Aspergillus fumigatus) and no activity reported in Candida albicans.

Conclusion: The results demonstrate that methanolic extracts of whole plant of U. lactuca can be used as a potential source of antioxidant and antimicrobial agent.