Inhibitory Potential of Six Brown Algae from the Persian Gulf on α-Glucosidase and In Vivo Antidiabetic Effect of Sirophysalis Trinodis

BACKGROUND: Brown algae have gained worldwide attention due to their significant biological activities, such as antidiabetic properties. In the present study, the antidiabetic properties of six brown algae from the Persian Gulf were investigated. METHODS: An experimental study was conducted from 2017 to 2019 to examine the inhibitory effects of six brown algae against the α-glucosidase activity. Methanol (MeOH) and 80% MeOH extracts of Colpomenia sinuosa, Sargassum acinaciforme, Iyengaria stellata, Sirophysalis trinodis, and two accessions of Polycladia myrica were analyzed. The effect of 80% MeOH extracts of Sirophysalis trinodis on blood glucose levels in streptozotocin-induced diabetic rats was evaluated. Chemical constituents of brown algae were analyzed using thin-layer chromatography and liquid chromatography-mass spectrometry techniques. Data were analyzed using SPSS software, and P<0.05 was considered statistically significant. RESULTS: The 80% MeOH extracts of Iyengaria stellata (IC(50)=0.33±0.15 μg/mL) and Colpomenia sinuosa (IC(50)=3.50±0.75 μg/mL) as well as the MeOH extracts of Colpomenia sinuosa (IC(50)=3.31±0.44 μg/mL) exhibited stronger inhibitory effect on α-glucosidase than the acarbose (IC(50)=160.15±27.52 μg/mL, P<0.001). The 80% MeOH extracts of Sirophysalis trinodis reduced postprandial blood glucose levels in diabetic rats compared to the control group (P=0.037). Fucoxanthin was characterized as the major antidiabetic agent in most of the algal extracts. CONCLUSION: Sirophysalis trinodis is recommended as a novel source for isolation and identification of potential antidiabetic compounds due to its high in vivo and in vitro antidiabetic effects.