Bioefficacy and mode-of-action of aglaroxin A from Aglaia elaeagnoidea (syn. A. roxburghiana) against Helicoverpa armigera and Spodoptera litura

The bioefficacy of aglaroxin A from Aglaia elaeagnoidea (syn. A. roxburghiana) was assessed using the gram pod borer, Helicoverpa armigera (Hübner), and Asian armyworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). The compound exhibited strong growth inhibition in a diet bioassay, with 0.67 p.p.m: and 0.78 p.p.m. of the compound reducing growth by 50% in H. armigera and S. litura neonate larvae, respectively, whereas a growth inhibition of 95% was achieved at 2.36 p.p.m: and 2.41 p.p.m., respectively; this was comparable to azadirachtin treatments used as a control. Aglaroxin A was toxic to various stadia. Nutritional analysis revealed the antifeedant properties of the compound; however, nutritional indices indicated that the reduction in growth of the larvae was not entirely due to starvation, but partly due to the toxic effects of the ingested compound. This was further confirmed in topical treatments. When relative growth rate was plotted against relative consumption rate, the growth efficiency of larvae fed on a diet containing aglaroxin A was significantly less than that of control larvae. These results further indicate that aglaroxin A acts as both antifeedant and chronic toxin. Morphologically deformed or partially pupated insects were obtained after 5th instar larvae were treated with aglaroxin A. Such developmental inhibition during ecdysis was not due to depletion of the moulting hormone, as treated larvae, when provided with exogenous 20‐hydroxyecdysone, did not show any recovery from the effect. However, it is obvious from the present findings that aglaroxin A activity does not absolutely follow the pattern of azadirachtin or the more related compound rocaglamide known in lepidopterans.     

Limonoids from the fruits of Melia toosendan

Four (1–4) new and seven known limonoids were isolated from the EtOH extract of the fruits of Melia toosendan. The structures of the new compounds were established on the basis of spectroscopic methods to be 12-O-methyl-1-O-deacetylnimbolinin B (1), 12-O-methy-1-O-tigloyl-1-O-deacetylnimbolinin B (2), 12-O-ethylnimbolinin B (3), and 1-O-cinnamoyl-1-O-debenzoylohchinal (4). Additionally, two new tirucallane-type triterpenoids, named meliasenins S (5) and T (6), were obtained from the same fractions during purification of the limonoids.     

楝科树木营养贮藏蛋白质的研究

采用光学和电子显微镜技术及SDS-PAGE研究了营养贮藏蛋白质(VSPs)在楝科树木中的分布和超微结构;并采用免疫印迹技术,以大叶桃花心木(Swietenia macrophylla King)的21 kD VSP的抗血清检测楝科树木VSPs的免疫相关性.结果表明,在桃花心木亚科(Swietenioideae)的树木中普遍存在VSPs,但楝亚科(Melioidae)仅部分属的树木有VSPs而椿亚科(Cedreloideae)树木没有VSPs.VSPs在同一属树木中的分布是一致的.桃花心木亚科和楝亚科树木之间的VSPs几乎没有免疫相关性,但是在桃花心木亚科中,VSPs具有相对高的同源性.楝科树木VSPs的超微结构存在一定程度的差异,这可能与VSPs的种类不同有关.VSPs的分布、超微结构和免疫相关性可能是楝科树木的一个分类特征.     

Structural elucidation of limonoids and steroids from Trichilia connaroides

Six limonoids, trijugins D-H (1-5) and methyl 8alpha-hydroxy-8,30-dihydroangolensate (6), two degraded limonoids, trichiconnarins A and B (7-8), and a pregnane steroid, 3beta,4alpha-dihydroxypregnan-21-one (9), along with the known trijugin C (10) and 3beta,4alpha-dihydroxypregnan-16-one (11) were isolated from twigs and leaves of Trichilia connaroides. Their structures were established on the basis of extensive spectroscopic analysis.     

Chloroplast DNA phylogeography reveals colonization history of a Neotropical tree,Cedrela odorata L., in Mesoamerica

Spanish Cedar (Cedrela odorata L.) is a globally important timber species which has been severely exploited in Mesoamerica for over 200 years. Using polymerase chain reaction-restriction fragment length polymorphisms, its chloroplast (cp) DNA phylogeography was studied in Mesoamerica with samples from 29 populations in six countries. Five haplotypes were characterized, phylogenetically grouped into three lineages (Northern, Central and Southern). Spatial analysis of ordered genetic distance confirmed deviation from a pattern of isolation by distance. The geographically proximate Northern and Central cpDNA lineages were genetically the most differentiated, with the Southern lineage appearing between them on a minimum spanning tree. However, populations possessing Southern lineage haplotypes occupy distinct moist habitats, in contrast to populations possessing Northern and Central lineage haplotypes which occupy drier and more seasonal habitats. Given the known colonization of the proto-Mesoamerican peninsula by South American flora and fauna prior to the formation of the Isthmus of Panama, it seems most likely that the observed population structure in C. odorata results from repeated colonization of Mesoamerica from South American source populations. Such a model would imply an ancient, pre-Isthmian colonization of a dry-adapted type (possessing the Northern lineage or a prototype thereof), with a secondary colonization via the land bridge. Following this, a more recent (possibly post-Pleistocene) expansion of moist-adapted types possessing the Southern lineage from the south fits the known vegetation history of the region.     

An isoprenylated flavanone from leaves of Azadirachta indica

A new isoprenylated flavanone has been isolated from the leaves of Azadirachta indica and characterized as 8,3′-di-isoprenyl-5,7-dihydroxy-4′-methoxyflavanone on the basis of physical and spectroscopic evidence. This is the first report of an isoprenyl flavanone from the Meliaceae.     

楝科（Meliaceae）的地理分布

楝科为泛热带分布科,全世界有５１属,约５５０—６００种,分布于旧世界热带地区有４６属,热带美洲有８属．热带亚洲和热带非洲为楝科两大现代分布中心．中国楝科共１５属,６１种,占世界属总数的２９％,种总数的１０％。中国楝科的分布是在全球楝科分布区的边缘,主要分布于中国西南部及南部诸省,种类由西南向东南递减。中国楝科属的分布区类型可归为５类：１．热带亚洲、非洲和中南美洲间断分布（１属）;２．旧世界热带分布（３属）;３,热带亚洲至热带大洋洲分布（２属）;４．热带亚洲至热带非洲分布（１属）;５．热带亚洲分布（８属）。中国楝科种的分布区类型仅有２类：１．热带亚洲分布（３１种）;２．中国特有分布（３０种）。楝科植物的起源推断在早白垩纪。中国楝科植物由印度—马来西亚成分及特有成分组成。热带亚洲的楝科植物主要是通过中南半岛和中国云南。广西和海南等地发生联系,而菲律宾和台湾之间可有直接的联系。     

楝科植物柠檬素类化合物杀虫活性研究的新进展(英文)

植物中的次生代谢物是植物性杀虫剂的活性有效成分。关于来自楝科植物的柠檬素类化合物杀虫活性的研究近年来又有了新进展。这些化合物对许多种重要害虫具有驱避、拒食、毒杀、抑制生长发育等活性。来自楝属、印楝局的植物在杀虫活性、有活性种类数量方面高于其它属,米仔兰属、鹧鸪花属和香椿属的植物也有较高的杀虫活性。柠檬素类化合物的杀虫作用机制在本文中也做了综述。