Diphlorethohydroxycarmalol isolated from Ishige okamurae, a brown algae, a potent alpha-glucosidase and alpha-amylase inhibitor, alleviates postprandial hyperglycemia in diabetic mice

Biological activities and potential health benefits of fucoxanthin derived from marine brown algae

The importance of marine algae as sources of functional ingredients has been well recognized due to their valuable health beneficial effects. Therefore, isolation and investigation of novel bioactive ingredients with biological activities from marine algae have attracted great attention. Among functional ingredients identified from marine algae, fucoxanthin has received particular interest. Fucoxanthin has been attributed with extraordinary potential for protecting the organism against a wide range of diseases and has considerable potential and promising applications in human health. Fucoxanthin has been reported to exhibit various beneficial biological activities such as antioxidant, anticancer, anti-inflammatory, antiobesity, and neuroprotective activities. In this chapter, the currently available scientific literatures regarding the most significant activities of fucoxanthin are summarized.

Inhibitory effects of estrogens on digestive enzymes, insulin deficiency, and pancreas toxicity in diabetic rats

Diabetes mellitus, with its attendant disorders and dysfunctional behaviors, constitutes a growing concern to the population of the world. With this concern in mind, the present study investigated the anti-diabetic and hypolipedimic potential of 17β-estradiol (called E2), particularly in terms of its inhibitory effects on maltase, sucrase, lactase, and lipase activities in the intestine of surviving diabetic rats. The findings revealed that this supplement helped protect the β cells of the rats from death and damage. Interestingly, E2 induced considerable decreases of 29%, 46%, 42%, and 84% in the activities of intestinal maltase, lactase, sucrase, and lipase, respectively. The E2 extract also decreased the glucose, triglyceride, and total cholesterol rates in the plasma of diabetic rats by 39%, 27%, and 53%, respectively, and increased the HDL-cholesterol level by 74%, which helped maintain the homeostasis of blood lipid. When compared to those of the untreated diabetic rats, the superoxide dismutase, catalase, and glutathione peroxidase levels in the pancreas of the rats treated with this supplement were also enhanced by 330%, 170%, and 301%, respectively. A significant decrease was also observed in the lipid peroxidation level and lactate dehydrogenase activity in the pancreas of diabetic rats after E2 administration. Overall, the findings presented in this study demonstrate that E2 has both a promising potential with regard to the inhibition of intestinal maltase, sucrase, lactase, and lipase activities, and a valuable hypoglycemic and hypolipidemic function, which make it a potential strong candidate for industrial application as apharmacological agent for the treatment and prevention of hyperlipidemia, obesity, and cardiovascular diseases.

Dieckol isolated from Ecklonia cava inhibits alpha-glucosidase and alpha-amylase in vitro and alleviates postprandial hyperglycemia in streptozotocin-induced diabetic mice

This study was designed to investigate whether dieckol may inhibit α-glucosidase and alpha-amylase activities, and alleviate postprandial hyperglycemia in streptozotocin-induced diabetic mice. Dieckol isolated from Ecklonia cava, brown algae, evidenced prominent inhibitory effect against alpha-glucosidase and alpha-amylase. The IC(50) values of dieckol against alpha-glucosidase and alpha-amylase were 0.24 and 0.66 mM, respectively, which evidenced the higher activities than that of acarbose. Dieckol did not exert any cytotoxic effect in human umbilical vein endothelial cells (HUVECs) at various concentrations (from 0.33 to 2.69 mM). The increase of postprandial blood glucose levels were significantly suppressed in the dieckol administered group than those in the streptozotocin-induced diabetic or normal mice. Moreover, the area under curve (AUC) was significantly reduced via dieckol administration (259 versus 483 mmol min/l) in the diabetic mice as well as it delays absorption of dietary carbohydrates. Therefore, these result indicated that dieckol might be a potent inhibitor for α-glucosidase and α-amylase.

Protective effect of diphlorethohydroxycarmalol isolated from Ishige okamurae against high glucose-induced-oxidative stress in human umbilical vein endothelial cells

In the present study, the protective effect of diphlorethohydroxycarmalol (DPHC) isolated from Ishige okamurae, a brown algae, on high glucose-induced-oxidative stress was investigated using human umbilical vein endothelial cells (HUVECs). High concentration of glucose (30 mM) treatment induced cytotoxicity whereas DPHC prevented cells from high glucose-induced damage; restoring cell viability was significantly increased. In addition, the lipid peroxidation, intracellular reactive oxygen species (ROS), and nitric oxide (NO) levels induced by high glucose treatment were effectively inhibited by addition of DPHC in a dose-dependent manner. DPHC also suppressed the over-expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins as well as nuclear factor-kappa B (NF-kappaB) activation induced by high glucose in HUVECs. These finding indicate that DPHC might be used as potential pharmaceutical agent which will reduce the damage caused by high glucose-induced-oxidative stress associated with diabetes.

Assessment of antioxidant capacity and cytotoxicity of selected Malaysian plants

Thirteen Malaysian plants; Artocarpus champeden, Azadirachta indica, Fragaria x ananassa, Garcinia mangostana, Lawsonia inermis, Mangifera indica, Nephelium lappaceum, Nephelium mutobile, Peltophorum pterocarpum, Psidium guajava and Syzygium aqueum, selected for their use in traditional medicine, were subjected to a variety of assays. Antioxidant capability, total phenolic content, elemental composition, as well as it cytotoxity to several cell lines of the aqueous and ethanolic extracts from different parts of these selected Malaysian plants were determined. In general, the ethanolic extracts were better free radical scavengers than the aqueous extracts and some of the tested extracts were even more potent than a commercial grape seed preparation. Similar results were seen in the lipid peroxidation inhibition studies. Our findings also showed a strong correlation of antioxidant activity with the total phenolic content. These extracts when tested for its heavy metals content, were found to be below permissible value for nutraceutical application. In addition, most of the extracts were found not cytotoxic to 3T3 and 4T1 cells at concentrations as high as 100 μg/mL. We conclude that although traditionally these plants are used in the aqueous form, its commercial preparation could be achieved using ethanol since a high total phenolic content and antioxidant activity is associated with this method of preparation.

Protective effects of enzymatic digest from Ecklonia cava against high glucose-induced oxidative stress in human umbilical vein endothelial cells

BACKGROUND

Antioxidants can prevent pathological damage caused by hyperglycaemia-induced oxidative stress associated with diabetes. In the present study, we investigated whether the brown alga Ecklonia cava has protective effects against high glucose-induced oxidative stress in Human umbilical vein endothelial cells (HUVECs). For that purpose, we prepared an enzymatic digest from E. cava (ECC) by using the carbohydrate, Celluclast.

RESULTS

High glucose treatment induced HUVECs cell death, but ECC, at a concentration of 10 or 100 microg mL(-1), significantly inhibited the high glucose-induced cytotoxicity. Furthermore, treatment with ECC dose-dependently decreased thiobarbituric acid reactive substances (TBARS), intracellular generation of reactive oxygen species, and the nitric oxide level increased by high glucose. In addition, ECC treatment increased activities of antioxidant enzymes including catalase, superoxide dismutase and glutathione peroxidase in high-glucose pretreated HUVECs. High glucose levels induced the overexpression of inducible nitric oxide synthase, cyclooxygenase-2 and nuclear factor-kappa B proteins in HUVECs, but ECC treatment reduced the overexpression of these proteins.

CONCLUSION

These results suggest that ECC is a potential therapeutic agent that will reduce the damage caused by hyperglycaemia-induced oxidative stress associated with diabetes.