植源昆虫拒食剂苦皮藤种油化学成分的拒食效果

植源昆虫拒食剂苦皮藤种油化学成分的拒食效果南玉生,柯治国,卢令娴（中国科学院武汉植物研究所武汉４３００７４）关键词苦皮藤种油,菜青虫,二氢沉香呋喃ＴＨＥＡＮＴＩＦＥＥＤＩＮＧＥＦＦＥＣＴＳＯＦＴＨＥＣＨＥＭＩＣＡＬＣＯＭＰＯＳＩＴＩＯＮＳＯＦＡＮＧＬ...     

Pleurotus species convert monoterpenes to furanoterpenoids through 1,4-endoperoxides

Enzymatic synthesis of furanoterpenoids from β-myrcene and related monoterpenes was observed using a solubilised enzyme fraction of mycelium lyophilisates of several Pleurotus species. The initial enzymatic step, the incorporation of molecular oxygen into the conjugated 1,3-diene moiety, was similar to a 2 + 4 cycloaddition of 1,3-dienes with dienophilic ¹O₂, and was followed by a non-catalysed degradation sequence leading to the furans. The cyclic peroxides 3,6-dihydro-4-(2-(3,3-dimethyloxiran-2-yl)ethyl)-1,2-dioxine and 5-(3,6-dihydro-1,2-dioxin-4-yl)-2-methylpentan-2-ol were identified as key intermediates. Biotransformation of β-myrcene in ¹⁸O-labelled HEPES-buffer did not yield a detectable label in perillene, so a water addition to 3,10-epoxy-β-myrcenes as an alternative was ruled out. The pathway suggested presents a substantiated biogenetic scheme for the formation of monoterpenoid furans and opens biotechnological access to valuable natural flavour compounds, such as perillene and rosefurane. Only one metabolite, identified as the new natural compound 6-methyl-2-methylene-hept-5-enal, carried the ¹⁸O-label. The enzymatic formation of this compound through a 1,2-endoperoxide (3-(5-methyl-1-methylene-hex-4-enyl)-[1,2]-dioxetane) is suggested. The label may simply result from a chemical oxygen exchange between the carbonyl group and the ¹⁸O-labelled water.     

Synthesis,Stability, and Biological Evaluation of 1,3-Dihydrobenzo[c]furan Analogue of d4T and Its SATE Pronucleotide

Abstract

The anti-HIV activity and stability studies of 1,3-dihydrobenzo[c]furan analogue of d4T are reported. The corresponding mononucleoside phosphotriester derivative bearing a S-pivaloyl-2-thioethyl (tBuSATE) group, as biolabile phosphate protection, is also studied.     

Icacenone,a furanoditerpene with a pimarane skeleton from Icacina mannii

Icacenone was isolated from the roots of Icacina mannii. This new diterpene has a furane ring fused to a pimarane skeleton. Its structure was established by X-ray diffraction analysis. Its spectroscopic properties are also discussed.