Bioassay-guided isolation of novel and selective urease inhibitors from Diospyros lotus / 中国天然药物

Two new dimeric naphthoquinones, 5',8'-dihydroxy-6,6'-dimethyl-7,3'-binaphthyl-1,4,1',4'-tetraone (1; Di-naphthodiospyrol D) and 5',8'-dihydroxy-5,8-dimethoxy-6,6'-dimethyl-7,3'-binaphthyl-1,4,1',4'-tetraone (2; Di-naphthodiospyrol E), along with known naphthoquinones diospyrin (3) and 8-hydroxy diospyrin (4) were isolated from the chloroform fraction of extract of Diospyros lotus roots. Their structures were elucidated by advanced spectroscopic analyses, including HSQC, HMBC, NOESY, and J-resolved NMR experiments. The fractions and compounds 1-4 were evaluated for urease activity and phosphodiesterase-I, carbonic anhydrase-II and α-chymotrypsin enzyme inhibitory activities. Compounds 1 and 2 and their corresponding fractions showed significant and selective inhibitory effects on urease activities. The IC values of 1 and 2 were 260.4 ± 6.37 and 381.4 ± 4.80 µmol·L, respectively, using thiourea (IC = 21 ± 0.11 µmol·L) as the standard inhibitor. This was the first report demonstrating that the naphthoquinones class showed urease inhibition.

The application of cystic cavity flushing technique in percutaneous ethanol sclerotherapy for thyroid colloid cysts / 介入放射学杂志

Objective To discuss the application of cystic cavity flushing technique in percutaneous ethanol sclerotherapy for the thyroid colloid cysts.Methods A total of 49 patients with thyroid colloid cysts were randomly divided into the study group (n=33) and the control group (n=16).Patients in the study group received cystic cavity flushing treatment by using saline together with α-chymotrypsin,which was followed by percutaneous ethanol injection (PEI).Patients in the control group underwent simple aspiration of cyst fluid followed by PEI.The residual cystic volume,the effective rate and the untoward effects were calculated at one,3 and 6 months after the treatment,and the results were compared between the two groups.Results Striking difference in the changes of postoperative residual cystic volume existed between the study group and the control group.The effective rate of PEI in the study group was 93.9％,which was obviously better than 68.8％ in the control group,the difference between the two groups was statistically significant (P＜0.05).No untoward effect was observed during the performance of aspiration of cyst fluid and flushing of cystic cavity.Nevertheless,bad side effect occurred in PEI procedure in both the study group (6.1％) and the control group (8.3％),but the difference was not statistically significant (P=0.75).Conclusion For the treatment of thyroid colloid cysts,the use of aspiration of cyst fluid together with cystic cavity flushing technique by using saline combined with α-chymotrypsin is safe and reliable,it can improve the curative effect of subsequent PEI.

Self-association of α-chymotrypsin: Effect of amino acids.

The concentration-dependent self-association of α-chymotrypsin is known to be influenced by various factors including the presence of small molecules and autolysis products. In this connection the effect of various amino acids on the self-association of α- chymotrypsin has been studied, as a point of interest, by measuring the sedimentation coefficient of α-chymotrypsin. The influence of an amino acid is seen to be governed by the nature of its side chain. Some amino acids do not affect the self-association of α- chymotrypsin at all while some affect it moderately and some others considerably. Functional groups such as the – OH group of Ser or the phenolic ring of Tyr do not seem to influence self-association behaviour. Based on these effects, amino acids could be categorized into 3 groups. Activity studies in the presence of amino acids indicate that the site of self-association and the active-site are probably mutually exclusive.