The anti-diabetic effect of eight Lagerstroemia speciosa leaf extracts based on the contents of ellagitannins and ellagic acid derivatives.

Previously, we have reported the opposite effects of compounds isolated from Lagerstroemia speciosa leaves on a glucose transport (GLUT4) assay. Ellagitannins from L. speciosa activated GLUT4, while ellagic acid derivatives showed an inhibitory effect. As part of our continuing research on anti-diabetic nutritional supplements, we herein compared the anti-diabetic effects of several extracts (LE1-8) from leaves of L. speciosa using different manufacturing processes based on the contents of ellagitannins and ellagic acid derivatives. Their anti-diabetic effects were evaluated through glucose uptake and adipocyte differentiation in 3T3-L1 cells in vitro as well as alloxan induced diabetic mice in vivo. These extracts were given to mice by gavage at doses of 0.25, 1.0, and 4.0 g per kg body weight once a day for 21 consecutive days. Results showed that LE1 (1.0 g kg-1), LE3 (1.0 or 4.0 g kg-1), LE4 (1.0 or 4.0 g kg-1), LE5 (0.25 or 1.0 or 4.0 g kg-1) and LE7 (1.0 or 4.0 g kg-1) showed significant anti-diabetic effects in alloxan-induced diabetic mice as indicated by the decreased levels of fasting blood glucose, body weight, serum biomarkers, tissue weight and body fat, and increased final insulin levels. LE8 (1.0 g kg-1) showed a moderate anti-diabetic effect as illustrated by the reduced fasting blood glucose level while LE2 and LE6 showed slight effects in alloxan-induced diabetic mice. The potential correlation of the content of ellagitannins, ellagic acid derivatives, and corosolic acid with the anti-diabetic activity was discussed.

Active compounds from Lagerstroemia speciosa, insulin-like glucose uptake-stimulatory/inhibitory and adipocyte differentiation-inhibitory activities in 3T3-L1 cells.

Seven ellagitannins, lagerstroemin (1), flosin B (2), stachyurin (3), casuarinin (4), casuariin (5), epipunicacortein A (6), and 2, 3-(S)-hexahydroxydiphenoyl-alpha/beta-D-glucose (7), together with one ellagic acid sulfate, 3-O-methyl-ellagic acid 4'-sulfate (8), ellagic acid (9), and four methyl ellagic acid derivatives, 3-O-methylellagic acid (10), 3,3'-di-O-methylellagic acid (11), 3,4,3'-tri-O-methylellagic acid (12), and 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (13), were identified by the bioassay-directed isolation from the leaves of Lagerstroemia speciosa (L.) Pers. The chemical structures of these components were established on the basis of one- and two-dimensional NMR and high-resolution mass spectroscopic analyses. Other known compounds, including corosolic acid, gallic acid, 4-hydroxybenzoic acid, 3-O-methylprotocatechuic acid, caffeic acid, p-coumaric acid, kaempferol, quercetin, and isoquercitrin, were also isolated from the same plant. The obtained ellagitannins exhibited strong activities in both stimulating insulin-like glucose uptake (1-5 and 7) and inhibiting adipocyte differentiation (1 and 4) in 3T3-L1 cells. Meanwhile, ellagic acid derivatives (10-13) showed an inhibitory effect on glucose transport assay. This study is the first to report an inhibitory effect for methyl ellagic acid derivatives.

Cimicifuga species identification by high performance liquid chromatography-photodiode array/mass spectrometric/evaporative light scattering detection for quality control of black cohosh products.

Black cohosh has become one of the most important herbal products in the US dietary supplements market. It is manufactured from roots and rhizomes of Cimicifuga racemosa (Ranunculaceae). Botanical identification of the raw starting material is a key step in the quality control of black cohosh preparations. The present report summarizes a fingerprinting approach based on high performance liquid chromatography-photodiode array/mass spectrometric/evaporative light scattering detection (HPLC-PDA/MS/ELSD) that has been developed and validated using a total of 10 Cimicifuga species. These include three North American species, Cimicifuga racemosa, Cimicifuga americana, Cimicifuga rubifolia, and seven Asian species, Cimicifuga acerina, Cimicifuga biternat, Cimicifuga dahurica, Cimicifuga heracleifolia, Cimicifuga japonica, Cimicifuga foetida, and Cimicifuga simplex. The chemotaxonomic distinctiveness of the HPLC fingerprints allows identification of all 10 Cimicifuga species. The triterpene glycoside cimigenol-3-O-arabinoside (3), cimifugin (12), and cimifugin-3-O-glucoside (18) were determined to be suitable species-specific markers for the distinction of C. racemosa from the other Cimicifuga species. In addition to identification, the fingerprint method provided insight into chemical interconversion processes occurring between the diverse triterpene glycosides contained in black cohosh. The reported method has proven its usefulness in the botanical standardization and quality control of black cohosh products.