Synthetic and biological studies on a cyclopolypeptide of plant origin

Objective: A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling oftetrapep-tide units Boc-Leu-Pro-Trp-Leu-Ome and Boc-Ile-Ala-Ala-Gly-Ome after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment.Methods: Solution phase technique was adopted for the synthesis of cyclooctapeptide--sarcodactylamide.Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz.Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-Ome and Ala-Gly-Ome.Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method.The structure of synthesized cyclopolypeptide was elucidated by FTIR,1H NMR,13C NMR,FABMS spectral data and elemental analysis.The newly synthesized peptide was evaluated for dif-ferent pharmacological activities including antimicrobial,anthelmintic and cytotoxic activities.Results: Synthesis of sarcodac-tylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide (DCC) as coupling agent.Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines,in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis,Pontoscotex corethruses and Eudrilus sp.Moreover,cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa,in comparison to standard drugs griseofulvin and ciprofloxacin.Conclusion: Solution phase technique employing DCC and triethylamine (TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide.N-methyl morpholine (NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.     

Developmental links of very early phonological and language skills to second grade reading outcomes: strong to accuracy but only minor to fluency

The authors examined second grade reading accuracy and fluency and their associations via letter knowledge to phonological and language predictors assessed at 3.5, 4.5, and 5.5 years in children in the Jyv?skyl? Longitudinal Study of Dyslexia. Structural equation modeling showed that a developmentally highly stable factor (early phonological and language processing [EPLP]) behind key dyslexia predictors (i.e., phonological awareness, short-term memory, rapid naming, vocabulary, and pseudoword repetition) could already be identified at 3.5 years. EPLP was significantly associated with reading and spelling accuracy and by age with letter knowledge. However, EPLP had only a minor link with reading fluency, which was additionally explained by early letter knowledge. The results show that reading accuracy is well predicted by early phonological and language skills. Variation in fluent reading skills is not well explained by early skills, suggesting factors other than phonological core skills. Future research is suggested to explore the factors behind the development of fast and accurate decoding skills.     

会开汽车的儿子

儿子从小就喜欢汽车,现在他正在学开车。说来可能你们不会相信,这位小司机今年才刚刚4岁。并且,他开的并不是玩具汽车,也不是把什么椅子倒转来,装模作样地开着玩,而是地地道道坐在福特汽车的驾驶座上,像模像样地操纵着方向盘,完全像个有着丰富经验的老驾驶员。     

提高國家對學校視導工作的作用

共產黨對於國家的監督事業,對於檢查黨與政府指示的執行情况的工作,始終是極其重視的。蘇聯共產黨第十九次代表大會,就非常注意國家監督與檢查工作的問题。只有自上而下的檢查和自下而上的檢查相結合,黨與非黨羣眾的檢查相結合,才能保證及時地消除我們組織和機關工作中的缺點,才能創造條件、及時地而準確地執行决議和指示。因此,代表大會號召領導機關,在進行檢查執行情况的工作時,要依靠廣大的勞動羣眾,依靠黨、工會和青年團組織,依靠地方蘇維埃的積極分子。第十九次黨代表大會的這些指示,對於教育機關來說也有着巨大的意義。國民教育工作中存在的嚴重缺點,在很大程度上是由於國家監督薄弱和對黨與政府指示的執行情况檢查不够的結果。     

英国文学的新时代

《当代文学简介》是布斯在云南大学的讲稿,这里选译了其中的第一讲:“英国文学的新时代”和第十二讲:“威廉·萨默赛特·毛姆。”第一讲是英国当代文学概述,以后各讲均为作家评介,今后将继续选译部分作家评介。     

谈谈如何总结和推广先进教育经验

教师们整天埋头工作,有时觉得自已的工作没有什么独到之处,没有什么经验可谈,其实,任何一个认真工作的人,都一定会在他的工作中积累一些值得别人学习的东西。有时教师又觉得自已工作得已经满不错了,于是就产生了沾沾自喜的情绪,不去严格要求自已,但当他看到了别人的先进经验,并把它拿来衡量自己的工作时就会发现,原来自已的工作还不足     

关于中值定理应用的探讨

结合实例探讨了中值定理在解题中的应用,归纳了运用中值定理的基本步骤和技巧.     

阿尔泰语民族树木崇拜概略

中外学者们早就注意到了阿尔泰语系各民族那早还在保留着一种原始的树木崇拜的现象。这种现象存在于东起兴安岭、长白山,西至阿尔泰、天山,北及西伯利亚、北冰洋,南延内蒙古高原的广阔地域。     

关键词:语法教学

如果你希望一个写文章不通的人看了两本语法书就把文章写通,一个不会写文章的人看了两本语法书就会写文章,那你一定要失望.语法万能和语法无能是两种极端的看法,但后者常常是由前者转变过来的. ——吕叔湘《语法三问》,《语文学习》,1953年第8期