Study On Thermal Conversion Products

Iridoid compounds have four biosynthetic pathways and there are four types of iridoids in the plants, including iridoid alcohols, 4-demethy iridoid alcohols,secoiridoid alcohols, and secoiridoid lactones. In order to research the conversion products, transformation way and rule of the iridoids totally, our research group selected four representative iridoid compounds and studied their conversion products.This paper undertook the work of loganic acid, which was a kind of iridoid alcohol compounds.At first, we determined the content of loganic acid in G. macrophylla, V baillonii, G. rigescens(â… ), G. rigescens(â…¡) and S. nux-vomica this five kinds of medicinal plants by HPLC, and choosed G. macrophylla as the raw material to extract Loganic acid. Secondly, the roots of 50 kg G. macrophylla were isolated through various chromatographic techniques and at last 190.1 g loganic acid was obtained after purification, whose content was more than 98%. In order to explore the transformation conditions of loganic acid, it was heated in hot water at different pH. The result showed that loganic acid produced various components when pH<5and the conversion products were most abundant at pH=1. Then 30 g loganic acid were heated in hot water at pH=1 and the water-soluble part was subjected to further chemical studies. As an initial result, four compounds were separated and two compounds were confirmed, including a new one named as Loganivarisin A( 1) and a known one identified as Isoboonein( 2), by various spectroscopy analysis.Furthermore, we deduced the probably transformation way of Loganivarisin A and Isoboonein in theory.This study might lay a theoretical foundation for a overall knowledge of the conversion products of iridoids. In practice, our research achievements might have great influence on the producing, processing drugs, quality control,pharmacological activities and clinical application of the drugs containing loganic acid.At last, we summarized the researches on structure and category,pharmacological activities, distribution, extracting and separating methods and methods of content determination of iridoids by consulting the literatures.