Ellagitannins from Lagerstroemia speciosa as Activators of Glucose Transport in Fat Cells

Hattori, Takeo; Maruyama, Haruko; Kasai, Royji; Hattori, Katsuji; Takasuga, Shunsuke; Hazeki, Osamu; Yamasaki, Kazuo; Tanaka, Takashi

doi:10.1055/s-2002-20251

Cited by 79 publications

(64 citation statements)

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“…In agreement with the result in a previous study (5), treatment of rat adipocytes with lagerstroemin increased the 2DG uptake of the cells in a dose-dependent manner (Fig. 1A).…”

Section: Resultssupporting

confidence: 93%

“…Lagerstroemin was isolated from the leaves of Lagerstroemia speciosa (Banaba) collected on a mountain in the Zambales, Philippines, as reported previously (5). Chinese hamster ovary cells (CHO cells) and the CHO cells overexpressing human insulin receptors (CHO-IR cells) were generously given to us by Dr. Yousuke Ebina (University of Tokushima).…”

Section: Methodsmentioning

confidence: 99%

“…Another biologically active compound contained in the banaba leaves is lagerstroemin. The compound increases the glucose uptake of rat adipocytes, physiological target cells of insulin (5). However, it is not known whether the insulin-like action of lagerstroemin is elicited solely on the glucose transport system or broadly on the insulin-regulated cellular events.…”

Section: Introductionmentioning

confidence: 99%

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Activation of Insulin Receptors by Lagerstroemin

et al. 2003

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Abstract. Lagerstroemin, an ellagitannin isolated from the leaves of Lagerstroemia speciosa (L.) Pers. (Lythraceae), was examined for its biological activities. In rat adipocytes, the compound increased the rate of glucose uptake and decreased the isoproterenol-induced glycerol release. In Chinese hamster ovary cells expressing human insulin receptors, it increased the Erk activity. These insulin-like actions were accompanied by the increased tyrosine-phosphorylation of the b-subunit of the insulin receptors. Tryptic digestion of the extracellular sites of the insulin receptors markedly increased the effective concentrations of insulin without changing those of lagerstroemin. Thus lagerstroemin was considered to cause its insulin-like actions by a mechanism different from that employed by insulin.

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“…In agreement with the result in a previous study (5), treatment of rat adipocytes with lagerstroemin increased the 2DG uptake of the cells in a dose-dependent manner (Fig. 1A).…”

Section: Resultssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Activation of Insulin Receptors by Lagerstroemin

et al. 2003

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“…The solvents with higher ethanol ratio has been used to extract corosolic acid during the extraction process of banaba leaves, and the ethanol extracted banaba leaves that contain 1% of corosolic acid has been commercialized. However, other researchers [14,19] propose that the antidiabetic compound of these extracts is not corosolic acid which is hydrophobic material, but another polyphenol which is hydrophilic material as the water extracted banaba extracts that rarely contain corosolic acid showed higher antidiabetic effects. On the other hand, guava water extracts are known to have antidiabetic effects such as decreasing plasma sugar level and restraining the activity of carbohydrate hydrolyzing enzyme [21,22].…”

Section: Discussionmentioning

confidence: 98%

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confidence: 99%

Antidiabetic Effects of Leaves Extracts of Psidium guajava L. and Lagerstroemia speciosa L. in STZ-induced Rats

2009

Journal of Life Science

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Guava (Psidium guajava L.) and banaba (Lagerstroemia speciosa L.) are well known as medicinal plants for their antidiabetic effects. These contain a great deal of polyphenol compound and work on the treatment of diabetes mellitus effectively. In this study, the extracts of guava and banaba are consumed by streptozotocin (STZ) induced diabetic rats to compare the antidiabetic effects. According to the comparison result, the glucose level of those STZ-induced diabetic rats has decreased by 19-32%, total cholesterol by 24-46%, triglyceride by 22-67% and free fatty acid by 49-71% approximately compared to the diabetic rats, while the generation of insulin and the recovery of beta cells have increased. However, the result showed that the antidiabetic effect of guava extracts was higher than that of banaba extracts. This is because the hydrophilic polyphenol compounds contained in banaba leaves were not extracted during the ethanol extraction process, and the antidiabetic activity of the extracted corosolic acid was low to surprise.Key words : Guava (Psidium guajava), banaba (Lagerstroemia speciosa), polyphenol, anti-diabetic effects *Corresponding author *Tel：+82-51-510-2262, Fax：+82-51-510-3736 *E-mail : wcchoi@pusan.ac.kr Introduction Diabetes mellitus (DM) causes the chronical metabolism disorder which makes approx. 4% of the world population suffer and this figure is expected to increase to 5.4% [16]. Hyperglycemia triggered by DM is usually caused due to the decrease in insulin secretion, decrease in glucose utilization of tissue and increase in the generation of glucose. Hyperglycemia's symptoms include obsessive thirst, glucosuria, polyuria, lipemia and hunger, and if left without treatment, this can result in patient's death due to critical ketoacidosis [27].For ages, many countries have applied traditional medical plants to treat hyperglycemia and diabetes mellitus [1,6,13,26], and more than 400 plants have been reported with their glucose reduction effects [2]. Recently the interest on medical plants is getting high as oral agents used to treat DM cause various side effects [4,15] while taking traditional medical plants in a natural form of extracts show treatment effect as good as that of therapeutic agents without side effects.In general, traditional medical plants contain a wide range of polyphenol compounds such as flavonoids, glycosides and terpenoids, which are effective in treating DM [5,7,31]. However, the amount and efficacy of polyphenol compounds may differ depending on extraction methods. If the ethanol extraction method is used, polyphenol compounds can hardly extracted.Psidium guajava L. known as guava is a representative medical plant that has antidiabetic effects and the interest on guava has been increased recently. Guava leaves contain a variety of polyphenol compounds such as polyphenol [25], terpenoids [3,23], flavonoids [20] and tannins [29]. And it was reported that guava leaves have antidiabetic effects direct and indirect through controlling glucose increase [22] and carbohydrate hyd...

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