Ở Việt Nam, người ta chỉ biết đến bằng lăng như là thứ cây trồng làm cảnh, nhưng loại cây này có mặt trong những bài thuốc dân gian Philippines từ rất lâu.
acid corosolic |
Trích từ báo Soha
Một số sản phảm có chứa acid corosolic giúp hạ đường huyết
EVIPURE GLYCEMIC |
Thông tin tiếng anh cây bằng lăng giúp hạ đường huyết:
21.5 BANABA
Lagerstroemia speciosa, also called queen crepe myrtle, is an ornamental plant
widely cultivated as an avenue tree. The tea from the leaves has traditionally been
Diabetes and Angiogenesis 477
used in the Philippines as a folk medicine for the treatment and prevention of diabetes.
It is popularly known as Banaba [101]. The key chemical ingredients of L. speciosa
include corosolic acid, maslinic acid, ellagitannin (lagerstroemin), and valoneic acid.
Bioassay-guided fractionation of the banaba leaf extract culminated in identifying
corosolic acid as the active principle with hypoglycemic activity. It was shown to be a
glucose transport activator in Ehrlich ascites tumor cells [102]. Later studies have
shown that some other ingredients, with totally unrelated structures, were also
responsible for the activity of the whole extract. Lagerstroemin, flosin B, and reginin
A are a group of ellagitannins isolated from the leaves of L. speciosa that, much like
insulin, increased the rate of glucose uptake in rat adipocytes [103]. Lagerstroemin
also increased the Extracellular signal-regulated kinases (ERKs) activity in Chinese
hamster ovary cells expressing human insulin receptors [104]. These hypoglycemic
actions were reported to be caused by activation of the insulin receptors accompanied
by increased tyrosine-phosphorylation of the beta-subunit of the insulin receptors, a
mechanism different from that employed by insulin [104]. The aqueous extract of
banaba, which contains valoneic acid dilactone (VAD) and ellagic acid, may have a
dietary use for the prevention and treatment of hyperuricemia. These two ingredients
are potential inhibitors of xanthine oxidase (XOD), a key enzyme playing a role in
hyperuricemia, catalyzing the oxidation of hypoxanthine to xanthine and then to uric
acid [105]. The VAD was reported to be a potent alpha-amylase inhibitor [106].
The elevation of blood plasma glucose level in type II hereditary diabetic mice
(KK-AY/Ta Jcl) that were on a cellulose supplemented controlled diet was
suppressed almost entirely by swapping the controlled diet with a test diet
containing 5% hot water extract or resin purified hot water extract for five weeks
[107]. In KK-Ay mice, an animal model of type 2 diabetes, corosolic acid reduced
the blood glucose and significantly enhanced the translocation of the muscle
facilitative GLUT4 from low-density microsomal membrane to plasma membrane
causing a hypoglycemic effect in type 2 diabetes [108]. Insulin and some other drugs
upregulate both glucose transport and adipogenic activity (lipid biosynthesis) in
adipocytes and this results in weight gain as a serious side effect of diabetes
treatment. Banaba extracts, however, showed a desirable combination of glucose
uptake stimulatory activity and the absence of adipocyte differtiation activity in
addition to effective inhibition of induced adipocyte differtiation in 3T3-L1 cells
[109]. Dietary banaba extract exhibited antiobesity effect in obese mice from a
genetically diabetic strain (KK-Ay) [110].
The clinical antidiabetic activity of an aqueous ethanolic extract from the leaves
of L. speciosa standardized to 3% corosolic acid has been demonstrated in a single
blind cross over human clinical trial involving twenty two patients with mild noninsulin
dependent type II diabetes [111]. These patients were categorized into two
groups and treated with a placebo or a formulation containing banaba extract for four
weeks followed by four weeks of crossover. A daily dose of 9 tablets containing
1.125 g of standardized extract was administered to the treatment group. The mean
blood glucose levels dropped from 169.1 to 132.8 and 128 to 110 mg/dl in the two
groups during the banaba treatment period. A placebo controlled clinical study at the
Tokyo Jikeikai Medical School in Japan involving oral administration of
standardized banaba extract to 24 human subjects with mild cases of type II
478 Anti-Angiogenic Functional and Medicinal Foods
diabetes also demonstrated significant drop in average blood glucose compared to
the placebo group [112]. The recovery of blood glucose to the pre-treatment levels
was found to be slow, indicating a memory effect of banaba for blood glucose
control. In another clinical study [113] at the South Western Institute of Biomedical
Research in Brandenton, Florida, L. speciosa standardized to 1% corosolic acid
(Glucosol) was administered successively at the dose levels of 16, 32, and 48 mg/
day to type II diabetic patients for 2 weeks at each dose level, with an intermittent
2 week wash out period after each dose level. One group was given the drug in an oil
based soft gelatin formulation and the other group was supplemented with a dry
powder base in a two-piece hard gelatin capsule. The results confirmed the blood
glucose lowering effect found in the earlier studies and suggest that the soft gel
formulation has a better bioavailability than a dry-powder formulation. The
glucosolw in a soft gel capsule formulation showed a 30% decrease in blood glucose
levels compared to a 20% drop seen with the dry-powder filled hard gelatin capsule
formulation. The crossover study demonstrated a memory effect for blood glucose
control up to four weeks after the termination of the treatment with no signs of
adverse effects.
Trích từ sách: Anti-Angiogenic Functional and Medicinal Foods
Glucosol chứa 1% Corosolic Acid |
Không có nhận xét nào :
Đăng nhận xét