ABSTRACT
Oligopeptides are simple in composition, high in safety index and good in drug preparation, which are important components of biomedicine. However, due to the limitation of oligopeptide drug design theory and discovery pathways which are far less than other structural drugs, obtaining new bioactive oligopeptides is a hot and difficult topic in this field. As a natural oligopeptide library, Chinese materia medica (CMM) contains a large number of active oligopeptides. Oligopeptides of CMM have vital biological activities such as neuroprotection activity, liver protection activity, antitumor, anticoagulation, anti-oxidation, immunity enhancement, etc. In this paper, the sequence and biological activity of active oligopeptides discovered by scholars at home and abroad in the past 10 years were reviewed, and the relationship between active oligopeptides and classification of CMM was explored. It is preliminarily suggested that CMM such as tonifying deficiency drugs and promoting blood circulation and removing blood stasis are the sources of natural oligopeptides. There are many research results easy to be successful in the research and development of new oligopeptide drugs, which provides directions and ideas for the development of new active oligopeptide drugs.
ABSTRACT
The paper reviews theoretical basis,connotation,system design and application status of responsibility accounting research,summarizes the research status of public hospital liability accounting,and puts forward some suggestions on follow-up research and application.
ABSTRACT
OBJECTIVE To investigate the effect of steric hindrance on the acylation reaction of pentacyclic triterpenoids, taking glycyrrhetinic acid and oleanolic acid as examples. METHODS The parent nucleus of glycyrrhetinic acid and oleanolic acid were selected, for which the steric hindrance is different at the two carboxyl sites: one is non-angle, another is angle. The parent nucleus were combined with cyclopentylamine, cyclohexylamine, piperidine, and pyrrolidine, respectively. The four simple nitrogen-containing heterocycles are distinct from the four-membered or five-membered ring and the nitrogen atom is inside or outside the ring. By means of comparing and analyzing the acylation reaction results, the reasons influencing acylation reactions were explored. RESULTS Glycyrrhetinic acid had acylation reaction with four simple nitrogen-containing heterocycles normally, whereas oleanolic acid only formed a kind of intermediate active ester, “oleanolic acid-HOBt”, and no final target object could be obtained. CONCLUSION The effect of nitrogen-containing heterocycles on the acylation reaction is almost negligible, while the steric hindrance of different parent nucleuses has significant influence on the acylation reaction. This study is of reference significance for the acylation reaction of triterpenoid carboxyl groups.