Interaction between a novel folate receptor targeted rhaponticin conjugate and human serum albumin by molecular spectroscopy / 国际药学研究杂志

Objective To investigate the affinity and interaction of a folate receptor targeted rhapontion(RHA)conjugate (FRHA)with human serum albumins(HSA). Method The interaction between FRHA and HSA under physiological conditions was investigated by fluorescence spectroscopy,UV-visual(vis)spectroscopy and circular dichroism(CD)spectroscopy. Great attempts were made to investigate their interaction mechanism regarding the quenching mechanism,the specific binding site,the type of inter-action force,and the effect of FRHA on the micro-environmental and conformational changes in HSA molecules. Results The forma-tion of the complex of FRHA-HSA would lead to fluorescence quenching. The corresponding values of Ka were 1.4322 × 105,1.1793 × 105,0.9334 × 105 and 0.7896 × 105 L/mol when the temperature were 298,302,306,and 310 K,respectively. The enthalpy change (ΔH)and entropy change(ΔS)were calculated to be-38.772 kJ/mol and-31.39 J/(mol·K),indicating that van der Waals force and hydrogen bonds played major roles in stabilizing the complex. Conclusion The interaction process of the formation of FRHA-HSA is spontaneous. The negative values of enthalpy change(ΔH)and entropy change(ΔS)indicate that van der Waals force and hydrogen bonds play major roles in stabilizing the complex. The conformational investigation reveals theα-helical structure is decreased and the microenvironment of HSA is changed upon the addition of FRHA. The fluorescence quenching of HSA caused by FRHA is static quenching. Furthermore,the results of site marker competitive experiment suggest that FRHA binds to the sub-domainⅡA of HSA.

Progress on chemical components and diuretic mechanisms of traditional Chinese diuretic medicines Poria cocos,Cortex Poriae, Polyporus umbellatus and Alisma orientalis / 中国药理学与毒理学杂志

Poria cocos,Cortex Poriae,Polyporusumbellatusand Alisma orientalisare common tra-ditionaI Chinese diuretic medicines. According to reported Iiterature,P.cocostriterpenes and poIysaccha-rides,steroids and tetracycIic triterpenes are the main chemicaI components of P.cocos,its epidermis, Pol.umbellatusand A.orientalis,respectiveIy. most of these diuretic drugs contain tetracycIic triterpenes and steroids,which have a simiIar structure to aIdosterone nucIeus structure. Therefore,this characteris-tic may reveaI their diuretic mechanisms. The tetracycIic triterpenes and steroids may exert diuretic effect through competitive inhibition of aIdosterone receptors in different parts of tubuIar reabsorption to increase urine output. The present articIe reviewed the chemicaI components of these diuretic Chinese medicines. Furthermore,their bioactive components and action mechanisms were aIso anaIyzed and discussed.