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.

Currently, algae arouse a growing interest in the pharmaceutical and cosmetic area due to the fact that they have a great diversity of bioactive compounds with the potential for pharmacological and nutraceutical applications. Due to lifestyle modifications brought on by rapid urbanization, diabetes mellitus, a metabolic illness, is the third largest cause of death globally. The hunt for an efficient natural-based antidiabetic therapy is crucial to battling diabetes and the associated consequences due to the unfavorable side effects of currently available antidiabetic medications. Finding the possible advantages of algae for the control of diabetes is crucial for the creation of natural drugs. Many of algae’s metabolic processes produce bioactive secondary metabolites, which give algae their diverse chemical and biological features. Numerous studies have demonstrated the antioxidant and antidiabetic benefits of algae, mostly by blocking carbohydrate hydrolyzing enzyme activity, such as α-amylase and α-glucosidase. Additionally, bioactive components from algae can lessen diabetic symptoms in vivo. Therefore, the current review concentrates on the role of various secondary bioactive substances found naturally in algae and their potential as antioxidants and antidiabetic materials, as well as the urgent need to apply these substances in the pharmaceutical industry.

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

Brown algae earned importance by virtue of their promising secondary metabolites of reasonable biological activities. Herein, the antioxidant, antimicrobial, and anticancer effects of crude extracts obtained from two Egyptian brown seaweeds, Sargassum linearifolium and Cystoseira crinita were evaluated. Phytochemical and GC-MS analyses revealed numerous active secondary metabolites in C. crinita cold methanolic extract (CCME) and S. linearifolium hot aqueous extract (SHAE). Both SHAE and CCME exhibited comparable DPPH (124.5 vs 125.6 µg/ml) and ABTS (257.1 vs 254.8 µg/ml) scavenging activities, respectively. Moreover, both crude extracts exhibited antimicrobial activity against various pathogenic microorganisms. Interestingly, employing MTT assay revealed cytotoxic effects of both extracts against a panel of cancer cells, where CCME showed a strong cytotoxic activity against MCF-7 cells (IC₅₀ = 18.0 ± 0.74 µg/ml), while SHAE exhibited a moderate effect (IC₅₀ = 31.1 ± 1.04 µg/ml). Increased mRNA and protein expression of Bax and Beclin-1 as well as the decreased expression of Bcl-2 revealed the ability of both extracts to induce apoptosis and autophagy in MCF-7 cells. Collectively, these findings provide evidence for antioxidant, antimicrobial, as well as anticancer effects driven by the two brown seaweeds that may underlay their plausible application in the therapeutic uses.