Sunday, June 20, 2010
Bioavailability and Antioxidant Effects of a Xanthone-Rich Mangosteen (Garcinia mangostana) Product in Humans
Oxidative damage is involved in many chronic diseases including those cited as the major causes of death in Western societies such as cardiovascular disorders and cancer. Antioxidants may prevent these degenerative processes by various mechanisms including the scavenging of free radicals. Intake of antioxidant supplements is associated with preventing oxidative damages. This study investigated the absorption and antioxidant effects of a xanthone-rich Mangosteen liquid in healthy human volunteers after the acute consumption of 59 mL of the supplement. The liquid contained Mangosteen, aloe vera, green tea, and multivitamins. Results indicated that α-mangostin and vitamins B2 and B5 were bioavailable, with observed Cmax at tmax of around 1 h. The antioxidant capacity measured with the oxygen radical absorbance capacity (ORAC) assay was increased with a maximum effect of 18% after 2 h, and the increased antioxidant level lasted at least 4 h. Overall, this study demonstrated the bioavailability of antioxidants from a xanthone-rich Mangosteen product and its in vivo antioxidant effects.
Thursday, June 3, 2010
Mulberry Leaf Extract (IMINOSOL®) helps control blood sugar and more……
Scientists in Japan have pinpointed a number of biologically active compounds in extracts of the leaves of the Mulberry, Morus alba. The Mulberry-leaf extract turns out to be effective in suppressing the progression of atherosclerosis, the buildup of cholesterol-rich plaque in our arteries. It does this, apparently, by inhibiting the oxidation of LDL-cholesterol (low-density lipoprotein, the “bad cholesterol”), which is a major factor in the development of atherosclerotic plaque.
The Japanese researchers reached this conclusion based on their observations of the antioxidant effects of the Mulberry extract on LDL-cholesterol taken from both rabbits and humans. They believe that the agents primarily (but not exclusively) responsible for this effect are two closely related compounds, isoquercitrin and astragalin. The former contains, as part of its molecular structure, the well-known antioxidant flavonoid quercetin, which is found in many foods and in a variety of nutritional supplements.
The antioxidant and antiatherosclerotic effects of Mulberry are gratifying, of course, but there’s more to the story than that. Mulberry leaves have long been used in Chinese medicine for the prevention and treatment of diabetes, because, as we now know, they contain chemical compounds that suppress high blood sugar levels (hyperglycemia) following a carbohydrate-rich meal. Controlling blood sugar (glucose) levels is vitally important. When these levels rise sharply, as they do after ingesting foods with a high glycemic index, such as potatoes or sweets, the body responds by producing more insulin to deal with the overload. But if this demand for more insulin occurs too strongly too often, the ability of the pancreas to produce enough insulin may become impaired, and our cells may become resistant to insulin as it tries to do its job of facilitating glucose transport through the cell walls. The result is insulin resistance, a dangerous condition that, if unchecked, leads to type 2 diabetes. Its primary cause is obesity.
A research group in Japan has found that white mulberry leaves contain compounds that inhibit these intestinal enzymes.In experiments with normal rats, they found that certain nitrogen-containing sugars in mulberry-leaf extract, notably one called 1-deoxynojirimycin, strongly inhibited the intestinal metabolism of disaccharides (especially sucrose), thereby restricting the amounts of monosaccharides that entered the circulation. They also found that pre treating the rats with Mulberry extract before feeding them carbohydrates significantly suppressed the normal postprandial (after-meal) rise in blood glucose levels.
This beneficial effect occurred in a dose-dependent manner. The doses were, however, very large: 0.1–0.5 g/kg of body weight, which, for a 70-kg (154-lb) human, would be 7–35 g. (A lower dose, 0.02 g/kg, corresponding to 1.4 g for a human, was ineffective.) Nonetheless, the researchers suggested that mulberry extract might be beneficial in preventing human diabetes by suppressing intestinal alpha-glucosidase activities.
The Indian researchers studied the effects of Mulberry on blood glucose levels, on blood lipid levels (cholesterol and triglycerides), and on lipid peroxidation in the cell membranes of erythrocytes (red blood cells). Their test subjects were 24 men, aged 40 to 60, with mild type 2 diabetes. The men were randomized to two groups: one group received two 500-mg capsules of powdered mulberry leaves three times daily, for a total of 3000 mg (3 g) daily, while the other group received a standard treatment with glibenclamide (more commonly called glyburide), an antidiabetic drug of the sulfonylurea type. The trial lasted for 4 weeks.
The results showed that, compared to glibenclamide, Mulberry significantly reduced fasting blood glucose levels in the diabetic men, indicating that it could be useful for controlling diabetes. Mulberry also significantly lowered the patients’ total cholesterol, LDL-cholesterol, and triglycerides, while significantly increasing their HDL-cholesterol (high-density lipoprotein, the “good cholesterol”). By contrast, glibenclamide’s only significant effect was to lower triglycerides.
In conclusion, the above studies provide preliminary data that suggest that mulberry therapy is capable of enhancing glycemic control in patients with type 2 diabetes. Our work suggests that serum and erythrocyte membrane lipids of diabetic patients were favorably affected by Mulberry therapy.
References
Doi K, Kojima T, Makino M, Kimura Y, Fujimoto Y. Studies on the constituents of the leaves of Morus alba L. Chem Pharm Bull 2001;49(2):151-3.
Doi K, Kojima T, Fujimoto Y. Mulberry leaf extract inhibits the oxidative modification of rabbit and human low-density lipoprotein. Biol Pharm Bull 2000; 23(9):1066-71.
Miyahara C, Miyazawa M, Satoh S, Sakai A, Mizusaki S. Inhibitory effects of mulberry leaf extract on postprandial hyperglycemia in normal rats. J Nutr Sci Vitaminol 2004; 50; 161-4.
Andallu B, Suryakantham V, Srikanthi BL, Reddy GK. Effect of mulberry (Morus indica L.) therapy on plasma and erythrocyte membrane lipids in patients with type 2 diabetes. Clin Chim Acta 2001; 314:47-53.
Vijayan K, Srivastava PP, Awasthi AK. Analysis of phylogenetic relationship among five mulberry (Morus) species using molecular markers. Genome 2004; 47:439-48.
The Japanese researchers reached this conclusion based on their observations of the antioxidant effects of the Mulberry extract on LDL-cholesterol taken from both rabbits and humans. They believe that the agents primarily (but not exclusively) responsible for this effect are two closely related compounds, isoquercitrin and astragalin. The former contains, as part of its molecular structure, the well-known antioxidant flavonoid quercetin, which is found in many foods and in a variety of nutritional supplements.
The antioxidant and antiatherosclerotic effects of Mulberry are gratifying, of course, but there’s more to the story than that. Mulberry leaves have long been used in Chinese medicine for the prevention and treatment of diabetes, because, as we now know, they contain chemical compounds that suppress high blood sugar levels (hyperglycemia) following a carbohydrate-rich meal. Controlling blood sugar (glucose) levels is vitally important. When these levels rise sharply, as they do after ingesting foods with a high glycemic index, such as potatoes or sweets, the body responds by producing more insulin to deal with the overload. But if this demand for more insulin occurs too strongly too often, the ability of the pancreas to produce enough insulin may become impaired, and our cells may become resistant to insulin as it tries to do its job of facilitating glucose transport through the cell walls. The result is insulin resistance, a dangerous condition that, if unchecked, leads to type 2 diabetes. Its primary cause is obesity.
A research group in Japan has found that white mulberry leaves contain compounds that inhibit these intestinal enzymes.In experiments with normal rats, they found that certain nitrogen-containing sugars in mulberry-leaf extract, notably one called 1-deoxynojirimycin, strongly inhibited the intestinal metabolism of disaccharides (especially sucrose), thereby restricting the amounts of monosaccharides that entered the circulation. They also found that pre treating the rats with Mulberry extract before feeding them carbohydrates significantly suppressed the normal postprandial (after-meal) rise in blood glucose levels.
This beneficial effect occurred in a dose-dependent manner. The doses were, however, very large: 0.1–0.5 g/kg of body weight, which, for a 70-kg (154-lb) human, would be 7–35 g. (A lower dose, 0.02 g/kg, corresponding to 1.4 g for a human, was ineffective.) Nonetheless, the researchers suggested that mulberry extract might be beneficial in preventing human diabetes by suppressing intestinal alpha-glucosidase activities.
The Indian researchers studied the effects of Mulberry on blood glucose levels, on blood lipid levels (cholesterol and triglycerides), and on lipid peroxidation in the cell membranes of erythrocytes (red blood cells). Their test subjects were 24 men, aged 40 to 60, with mild type 2 diabetes. The men were randomized to two groups: one group received two 500-mg capsules of powdered mulberry leaves three times daily, for a total of 3000 mg (3 g) daily, while the other group received a standard treatment with glibenclamide (more commonly called glyburide), an antidiabetic drug of the sulfonylurea type. The trial lasted for 4 weeks.
The results showed that, compared to glibenclamide, Mulberry significantly reduced fasting blood glucose levels in the diabetic men, indicating that it could be useful for controlling diabetes. Mulberry also significantly lowered the patients’ total cholesterol, LDL-cholesterol, and triglycerides, while significantly increasing their HDL-cholesterol (high-density lipoprotein, the “good cholesterol”). By contrast, glibenclamide’s only significant effect was to lower triglycerides.
In conclusion, the above studies provide preliminary data that suggest that mulberry therapy is capable of enhancing glycemic control in patients with type 2 diabetes. Our work suggests that serum and erythrocyte membrane lipids of diabetic patients were favorably affected by Mulberry therapy.
References
Doi K, Kojima T, Makino M, Kimura Y, Fujimoto Y. Studies on the constituents of the leaves of Morus alba L. Chem Pharm Bull 2001;49(2):151-3.
Doi K, Kojima T, Fujimoto Y. Mulberry leaf extract inhibits the oxidative modification of rabbit and human low-density lipoprotein. Biol Pharm Bull 2000; 23(9):1066-71.
Miyahara C, Miyazawa M, Satoh S, Sakai A, Mizusaki S. Inhibitory effects of mulberry leaf extract on postprandial hyperglycemia in normal rats. J Nutr Sci Vitaminol 2004; 50; 161-4.
Andallu B, Suryakantham V, Srikanthi BL, Reddy GK. Effect of mulberry (Morus indica L.) therapy on plasma and erythrocyte membrane lipids in patients with type 2 diabetes. Clin Chim Acta 2001; 314:47-53.
Vijayan K, Srivastava PP, Awasthi AK. Analysis of phylogenetic relationship among five mulberry (Morus) species using molecular markers. Genome 2004; 47:439-48.
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