RESUMEN
INTRODUCTION: α-Glucosidase inhibitors form an essential basis for the development of novel drugs in diabetes type 2 treatment. Searching for α-glucosidase inhibitors in plants, TLC bioautographic assays have been established and improved within the last years. In traditional medicine, extracts from the leaves of Justicia secunda Vahl are used to treat diabetes mellitus symptoms. OBJECTIVE: To screen for α-glucosidase inhibitors in J. secunda via HPTLC bioautography. Methodology - Extracts from the leaves of J. secunda and fractions thereof were evaluated in terms of their α-glucosidase inhibiting potential by subjecting them to HPTLC bioautography. The aqueous (AQ) fraction deriving from the methanol extract was further fractionated via column chromatography on polystyrene Diaion® HP-20. Two AQ subfractions revealed active compounds, which were isolated via preparative HPTLC and semipreparative HPLC. Their identification and structure elucidation was achieved employing HPLC-ESI-MSn , HRESI-MS, and NMR analyses. RESULTS: α-Glucosidase inhibitors were visualised as white zones on violet background on the TLC plate. The crude water extract, the methanol extract, and the methanol extract derived AQ fraction showed α-glucosidase inhibiting effects. In the latter, two diastereomeric mixtures responsible for the α-glucosidase inhibition were enriched. They were identified as the novel 2-caffeoyloxy-4-hydroxy-glutaric acid and the diastereomers secundarellone B and C. CONCLUSION: The current study presents the α-glucosidase inhibiting potential of J. secunda supporting its traditional medicinal use in diabetes mellitus treatment. HPTLC bioautography screening for α-glucosidase inhibitors provides a simple and effective method for the investigation of complex samples, such as plant extracts. Copyright © 2016 John Wiley & Sons, Ltd.
Asunto(s)
Acanthaceae/química , Cromatografía en Capa Delgada/métodos , Inhibidores de Glicósido Hidrolasas/farmacologíaRESUMEN
Single-chain surfactants usually emulsify and stabilize oily substances into droplets in an aqueous solution. Here, we report a coassembly system, in which single types of anionic or non-ionic surfactants emulsify a class of water-soluble nonamphiphilic organic salts with fused aromatic rings in aqueous solutions. The nonamphiphilic organic salts are in turn promoted to form droplets of water-based liquid crystals (chromonic liquid crystals) encapsulated by single-chain surfactants. The droplets, stabilized against coalescence by encapsulated in a layer (or layers) of single chain surfactants, are of both nonspherical tactoid (elongated ellipsoid with pointy ends) and spherical shapes. The tactoids have an average long axis of â¼9 µm and a short axis of â¼3.5 µm with the liquid crystal aligning parallel to the droplet surface. The spherical droplets are 5-10 µm in diameter and have the liquid crystal aligning perpendicular to the droplet surface and a point defect in the center. Cationic and zwitterionic surfactants studied in this work did not promote the organic salt to form droplets. These results illustrate the complex interplay of self-association and thermodynamic incompatibility of molecules in water, which can cause new assembly behavior, including potential formation of vesicles or other assemblies, from surfactants that usually form only micelles. These unprecedented tactoidal shaped droplets also provide potential for the fabrication of new soft organic microcapsules.