Solvents efficacy on the extraction of bioactive compounds and antioxidant activity of Padina tetrastromatica and Gracilaria tenuistipitata seaweeds collected from Bangladesh

Title : Solvents efficacy on the extraction of bioactive compounds and antioxidant activity of Padina tetrastromatica and Gracilaria tenuistipitata seaweeds collected from Bangladesh

Abstract:

Seaweeds are now recognized as a treasure of bioactive compounds. Beneficial health effects of seaweeds vary with the different aspects especially geographical location of the seaweed. However, the seaweed of Bangladesh is still unexplored. So, this study was designed to explore the secondary metabolites and antioxidant activities of different solvent extracts (methanol, ethanol and water) of Padina tetrastromatica and Gracilaria tenuistipitata seaweeds. Here, we determined preliminary phytochemical composition, total phenolic content (TPC), total flavonoid content (TFC) and different antioxidant activity of crude extracts using different qualitative and quantitative in vitro assays. Overall, screening of phytochemicals revealed that both the seaweeds contain diverse type bioactive compounds including terpenoid, saponin, phlobatannin, cardiac glycosides, phenolic and flavonoid depending on the seaweed species and extraction solvents used. FT-IR spectroscopy also confirmed the presence of phenols, carboxylic acid, alkoxy, aromatics, alkene, amides and sulfonates at varying degree.  Antioxidant activity of extracts were evaluated by 1, 1-diphenyl-2- picrylhydrazyl (DPPH), 2, 2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), reducing power (RP), phosphomolybdenum, nitric oxide (NO) scavenging and hydrogen peroxide assays. Here, methanolic extract of P. tetrastromatica showed the highest amount of total phenolic content (85.61 mg of GA/g), total flavonoid content (41.77 mg of quercetin/g), which showed as potent antioxidant properties confirmed by DPPH (77.07%, IC₅₀=0.40 mg/ml), ABTS (77.65%, IC₅₀=1.33 mg/ml), RP (53.24 mg  AAE/g), phosphomolybdenum (31.58 mg  AAE/g), nitric oxide (70.64%, IC₅₀=0.75 mg/ml) and hydrogen peroxide (67.89%, IC₅₀=3.08 mg/ml) assays followed by ethanol and water. These results confirmed the presence of diverse type of chemical composition with its antioxidant activity in the seaweeds which will be useful for pharmacological as well as in functional food application.

Biography:

Mohammad Khairul Alam Sobuj received MS degree from Department of Fisheries Biology and Aquatic Environment, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur. He was working there as a research co-investigator under the supervision of S.M. Rafiquzzaman in the faculty lab on Seaweed. His working interest is to study about antioxidant activity, phytochemical analysis and isolation of bioactive compound, seaweed cultivation, seaweed biomass study, mangrove seaweed. He is now working as a Scientific Officer at under Ministry of Fisheries and Livestock. He has published 02 research articles in reputed journals.