Polyphenol-Rich Extracts from Brown Macroalgae Lessonia trabeculate Attenuate Hyperglycemia and Modulate Gut Microbiota in High-Fat Diet and Streptozotocin-Induced Diabetic Rats

The effects of yam gruel on lowering fasted blood glucose in T2DM rats

“…After 6 weeks, all rats were fasted for 12 h. The rats in the model group were intraperitoneally injected with 1% streptozotocin (STZ) solution twice at a dose of 25 mg/kg (interval 2 days) while the NC group received an intraperitoneal injection of citric acid buffer at the same dose. After 1 week of observation, blood samples were collected from the tail vein once a day for two consecutive days and FBG ≥ 11.1 mmol/L was determined as a standard for T2DM rat [17]. T2DM rats were randomly divided into three subgroups: (1) DM (normal saline, n = 8), (2) DM + yam gruel (yam gruel, n = 7), and (3) DM + metformin (metformin, as a positive control, 100 mg/kg/day, n = 8).…”

Bioactive Properties of Marine Phenolics

“…The presence of benzoic and cinnamic acids has been reported, particularly in brown seaweeds, which also present flavonoids [ 20 , 103 ]. Brown seaweeds present higher contents of benzoic and cinnamic acids (1 mg/g) than red (0.2 3 mg/g) and green (0.01–0.9 mg/g) seaweeds [ 26 , 104 , 105 ].…”

“…Five isolated phlorotannins from E. cava , fucodiphloroethol G, dieckol, 6,6′-bieckol, 7-phloroeckol, phlorofucofuroeckol-A, have shown a marked α-glucosidase inhibition with 19.5 μM, 10.8 μM, 22.2 μM, 49.5 μM and 19.7 μM, respectively, as well as some α-amylase inhibitory effect with IC 50 values of >500 μM, 125 μM, >500 μM, 250 μM and >500 μM, respectively [ 165 ]. Phlorotannins extracted from A. nodosum [ 166 , 167 ], Alaria marginata and Fucus distichus [ 168 ] are also able to inhibit α-amylase and α-glucosidase, while those of F. vesiculosus [ 160 ] and L. trabeculate [ 103 ] inhibit α-glucosidase activity, and L. trabeculate [ 103 ] inhibits lipase activity ( Table 4 ). Generally, seaweed extracts and isolated compounds exhibited more inhibitory potency towards α-glucosidase compared to α-amylase (see IC 50 values in Table 4 ), which is desirable since high inhibition of α-amylase activity has been suggested to cause abnormal fermentation of undigested carbohydrates by the colonic microbiota [ 169 ].…”

“…Another recent study showed the capacity of a polyphenol-rich extracts from the brown macroalgae Lessonia trabeculata to attenuate hyperglycemia in high-fat diet and STZ-induced diabetic C57BL/6J rats treated for 4 weeks (200 mg/kg bw/day). Lower fasting blood glucose and insulin levels, as well as a better serum lipid profile and antioxidant stress parameters compared with the diabetic control group, were observed [ 103 ]. Similarly, a water-ethanolic extract of green macroalgae E. prolifera rich in flavonoids showed antidiabetic activity, by improving oral glucose tolerance and insulin sensitivity, decreasing fasting blood glucose levels and protecting kidney and liver from high sucrose–fat diet on STZ-induced diabetic mice treated with 150 mg/kg bw/day of the assayed extract for 4 weeks.…”

“…Kappaphycus also modulated the balance between Firmicutes and Bacteroidetes in the gut, which could serve as a potential mechanism to reverse MetS through selective inhibition of obesogenic gut bacteria and promote healthy gut bacteria [ 226 ]. Polyphenol-rich extracts from L. trabeculate attenuated hyperglycemia in high-fat diet and STZ-induced diabetic rats [ 103 ], as aforementioned. Higher Bacteroidetes , Odoribacter and Muribaculum abundances, lower Proteobacteria abundances, as well as a reduced Firmicutes/Bacteroidetes ratio, were observed in the polyphenol supplemented group in comparison with untreated diabetic rats.…”