Abstract In this study crude extracts of Turbinaria decurrens, Padina pavonica, Sargassum muticum and Sargassum acinarium (Phaeophyta); Ulva lactuca (Chlorophyta) and Pterocladia capillacea (Rhodophyta) seaweeds were tested to evaluate their antioxidant properties and antidiabetic potential on α-amylase and α-glucosidase starch hydrolyzing enzymes. The results showed that all analyzed seaweeds exhibited antioxidant effects using DPPH (2,2-Diphenyl-1-picrylhydrazyl), reducing power and total antioxidant capacity assays in addition to antidiabetic activity that all depended on the species and the extract solvent. Among the tested extracts, acetone extract of Turbinaria decurrens showed the highest antioxidant activity and inhibitory effects for α-amylase (96.1%) and α-glucosidase (97.4%), respectively which was related with its total phenolic content and antioxidant activity. In vitro, the extract showed no toxicity against fibroblast normal cell lines at lower concentration of 250 µg/ml. Gas Chromatography-Mass Spectrum analysis (GC-MS) of this acetone extract showed the presence of different bioactive compounds mainly cyclotrisiloxane, hexamethyl which could be responsible for its antioxidant and antidiabetic activities. The study results suggest that brown seaweeds especially T. decurrens can be used as antioxidant ingredients and as potent reducing drug for postprandial hyperglycemia.
Abstract The ethyl acetate, n hexane and methanol extracts of six cyanobacterial species isolated from paddy fields in Egypt were assessed for their antimicrobial activity, using disc diffusion method. Oscillatoria acuminata, Oscillatoria amphigranulata and Spirulina platensis methanolic extracts showed the highest inhibition zones. Minimum inhibitory concentration of O. amphigranulata extract recorded lower values using agar streak dilution method. O. acuminata methanolic extract exhibited the highest antioxidant activity (6.58 and 34.60 % using DPPH (2, 2- diphenyl-1- picrylhydrazyl) and ABTS+ (2, 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) methods, respectively, followed by O. amphigranulata then S. platensis. Similarly, O. acuminata methanolic extract showed very strong cytotoxicity activity against HepG2 and HCT-116 cell lines and strong activity with MCF-7 cell lines. O. amphigranulata extract showed strong cytotoxicity for HepG2 and HCT-116 as well as moderate cytotoxicity for MCF-7 cell line. Whereas, S. platensis extract exhibited moderate cytotoxicity for all cell lines. Results of gas chromatography/mass spectroscopy analysis pointed out that the potential activity of these cyanobacterial extracts might be attributed to a synergistic effect between their pronounced contents of fatty acids, alkaloids, phytol, hydrocarbons, phenolics and phthalates, especially fatty acids. We recommend cyanobacteria as a rich source of natural products with potent pharmacological and medical applications.
Abstract The present study investigated the biochemical composition of three seaweeds; Ulva fasciata (Chlorophyta), Sargassum linifolium (Phaeophyta) and Corallina officinalis (Rhodophyta). Total chlorophyll content was maximum in U. fasciata (34.06mg/g dry wt.) while carotenoid content was the highest in C. officinalis (3.8 mg/g dry wt.). The uppermost level of carbohydrates was (27.98% of dry wt.) in C. officinalis and proteins were maximum (14.89%) in S. linifolium. Aspartic, glutamic, alanine, leucine and proline were common amino acids in the three tested species. The polyunsaturated ω6 and ω3 essential fatty acids were recorded in S. linifolium (3.28%) and in U. fasciata (3.18%). The results showed that U. fasciata contained the highest amounts of lipids (2.96%), phenols (11.95mgGA/g dry wt.), flavonoid (7.04 mgCA/g dry wt.) and ascorbic acid (4.11mg/100g), respectively. β-Carotene was maximum (3940.12 IU/100 g) in C. officinalis. DPPH antioxidant activities were the highest in U. fasciata (81.3%) followed by S. linifolium (79.8%) then C. officinalis (72.6%). Among the 12 analyzed minerals, most of them were high in S. linifolium in which ion quotient ratio was the smallest (0.343). Since these algal species are common in the Egyptian coastal waters, their biochemical composition and antioxidant activities made them promising candidates for nutritional, pharmaceutical and medicinal applications.