Macrocarpal C isolated from <i>Eucalyptus globulus</i> inhibits dipeptidyl peptidase 4 in an aggregated form

<p>Dipeptidyl peptidase 4 (DPP-4) inhibitors are used for the treatment of type-2 diabetes mellitus. Various synthetic inhibitors have been developed to date, and plants containing natural DPP-4 inhibitors have also been identified. Here, 13 plant samples were tested for their DPP-4 inhibitory activity. Macrocarpals A–C were isolated from <i>Eucalyptus globulus</i> through activity-guided fractionation and shown to be DPP-4 inhibitors. Of these, macrocarpal C showed the highest inhibitory activity, demonstrating an inhibition curve characterised by a pronounced increase in activity within a narrow concentration range. Evaluation of macrocarpal C solution by turbidity, nuclear magnetic resonance spectroscopy and mass spectrometry indicated its aggregation, which may explain the characteristics of the inhibition curve. These findings will be valuable for further study of potential small molecule DPP-4 inhibitors.</p

Identification of α-glucosidase inhibitors from the leaves of <i>Pluchea indica</i> (L.) Less., a traditional Indonesian herb: promotion of natural product use

<div><p>A promising approach for treating diabetes mellitus (DM) is to decrease postprandial hyperglycaemia by suppressing carbohydrate digestion using α-glucosidase inhibitors. <i>Pluchea indica</i> leaf extracts possess inhibitory activity against intestinal maltase. Enzyme assay-guided fractionation by chromatography yielded five active caffeoylquinic acid derivatives (<b>1</b>–<b>5</b>). Their structures were elucidated by mass spectrometry and NMR analysis and completed by comparison with reference data. 3,5-Di-<i>O</i>-caffeoylquinic acid (<b>1</b>), 4,5-di-<i>O</i>-caffeoylquinic acid methyl ester (<b>2</b>), 3,4,5-tri-<i>O</i>-caffeoylquinic acid methyl ester (<b>3</b>), 3,4,5-tri-<i>O</i>-caffeoylquinic acid (<b>4</b>) and 1,3,4,5-tetra-<i>O</i>-caffeoylquinic acid (<b>5</b>) were isolated. Comparison of the activities of each isolate suggested that both methyl esterification of quinic acid and the number of caffeate groups in the molecule were important for the inhibitory activity. This study provides basic information for further examination of the suitability of <i>P. indica</i> as a functional food and medicinal supplement for the treatment and prevention of diabetes.</p></div

Structures of xylosylfructoside, and saccharides , and synthesized by kojibiose phosphorylase

<p><b>Copyright information:</b></p><p>Taken from "Three novel oligosaccharides synthesized using kojibiose phosphorylase"</p><p>http://journal.chemistrycentral.com/content/1/1/18</p><p>Chemistry Central Journal 2007;1():18-18.</p><p>Published online 28 Jun 2007</p><p>PMCID:PMC1994063.</p><p></p

Amphirionin‑4 with Potent Proliferation-Promoting Activity on Bone Marrow Stromal Cells from a Marine Dinoflagellate <i>Amphidinium</i> Species

A linear polyketide, amphirionin-4 (<b>1</b>), has been isolated from cultivated algal cells of the marine dinoflagellate <i>Amphidinium</i> species. The structure was elucidated on the basis of detailed analyses of 1D and 2D NMR data, and the absolute configurations of C-4 and C-8 were determined using the modified Mosher’s method. Amphirionin-4 (<b>1</b>) exhibited extremely potent proliferation-promoting activity on murine bone marrow stromal ST-2 cells (950% promotion) at a concentration of 0.1 ng/mL