Tetranortriterpenoids from Melia dubia

Two new tetranortriterpenoids, compositin and compositolide, have been isolated from leaves and seeds of Melia dubia. The structures of the two new compounds were determined by spectroscopic methods and chemical reactions.     

Limonoid extractives from Xylocarpus moluccensis

Further examination of the timber of Xylocarpus moluccensis has given three new compounds, xyloccensins G, H and I. Structures are deduced for G an     

Cross transferability of SSR markers to endangered Cedrela species that grow in Argentinean subtropical forests,as a valuable tool for population genetic studies

Species of Cedrela with a high economic value from Northwest and Northeastern Argentina are severely exploited. This work evaluates whether 51 nuclear SSRs, developed to study phylogenetically close species in the Meliaceae family (Cedrela odorata, Cedrela fissilis, Swietenia humilis and Swietenia macrophylla), can be used to study C. fissilis, Cedrela balansae, Cedrela saltensis and Cedrela angustifolia. A 62.8% of the total of 194 SSRs/species combinations showed a successful, homologous and cross-species amplification. As expected, a great success in SSRs transferability among Cedrela species was observed. Twenty-one screened SSRs showed a successful amplification pattern in all target species and many of them were polymorphic (9, 13, 13 and 7 SSRs for C. fissilis, C. balansae, C. saltensis and C. angustifolia, respectively). The high number of evaluated SSRs from the Cedrela genus and Meliaceae family, allowed us to obtain a suitable set of validated markers that are highly variable and easily scored, and also identify those which were less sturdy. We were able to retain a useful set of markers for three of the target species, but not for C. angustifolia. This could be due to its greater phylogenetic and morphological distances to the other three species. The lack of SSRs developed for our target species, transforms the transferred SSRs reported here in a valuable tool to monitor the genetic consequences of forest overexploitation on Cedrela species.     

Glabretal-type triterpenoids from Dysoxylum mollissimum

Dysoxylum mollissimum Blume, the accepted name of the species known by more than a dozen names has been extensively studied for its chemical constituents under the name Dysoxylum hainanense Merr. Congruent with the observation that the chemical constituents of this species might be affected by its geographic distribution, the leaf samples of this species from Quezon Province, Philippines were investigated. The dichloromethane extract of the air-dried leaves of D. mollissimum Blume afforded four new glabretal-type triterpenoids (1a–2b) along with the known compounds, 24,25-epoxy-3β,23-dihydroxy-7-tirucallene (3), squalene, polyprenol, linoleic acid and lutein. The structures of 1a–2b were elucidated by extensive 1D and 2D NMR spectroscopy and confirmed by mass spectrometry.     

In vitro shiro formation between the ectomycorrhizal basidiomycete Tricholoma matsutake and Cedrela herrerae in the Mahogany family (Meliaceae)

Tricholoma matsutake is an ectomycorrhizal basidiomycete that associates with Pinaceae plants, forming a rhizospheric mycelial aggregate called “shiro” from which the prized “matsutake” mushrooms form. Here we document that T. matsutake associates in vitro with Andean Cedrela herrerae (Meliaceae) via root endophyte interactions and efficiently forms shiro. C. herrerae produces many branches, leaves, and lateral roots in association with T. matsutake, unlike C. odorata, which grows in the tropics and produces few leaves and branches in association with the symbiont. This symbiosis may be a unique approach to culturing matsutake as well as to cultivating endangered plant species in vitro.     

中国分类学文献中Swietenia mahagoni之订正

通过调查,对Swietenia mahagoni的后选模式、S.macrophylla的主模式与中国分类学文献(如《植物分类学报》、《广州植物志》、《中国高等植物图鉴》、《云南植物志》、《广东植物志》、《中国植物志》和《中国高等植物》)的S.mahagoni作比较,证实中国分类学文献将S.mahagoni和S.macrophylla相混,上述分类学文献中的S.mahagon是S.macrophylla King。桃花心木(S.mahagoni(L.)Jacq.)的羽状复叶及小叶较短,小叶长度绝不超过10 cm,果卵球形,长度绝不超过15 cm;而大叶桃花心木(S.macrophylla King)的羽状复叶及小叶较长,总有一部分小叶的长度超过10 cm,果长卵球形,长12~22 cm。     

Antimalarial tetranortriterpenoids from the seeds of Lansium domesticum Corr

Five tetranortriterpenoids, domesticulide A-E (1-5), were isolated from seeds of Lansium domesticum Corr. together with 11 known triterpenoids (6-16). Their structures were elucidated by analysis of their spectroscopic data. Compounds 2, 3, 4, 7, 8, 10, 11, and 15 showed antimalarial activity against Plasmodium falciparum with IC(50)'s of 2.4-9.7 microg/ml.     

New pregnane steroids from Turraea pubescens

Three new pregnane steroids, 2beta,3beta,5beta-trihydroxy-pregn-20-en-6-one (1), 3beta-hydroxy-5alpha-pregn-7,20-dien-6-one (2), and 3beta-acetoxy-5alpha-pregn-7,20-dien-6-one (3) were isolated from the twigs and leaves of Turraea pubescens, and were structurally elucidated on the basis of spectroscopic data and chemical method.     

Imbibition of Swietenia macrophylla (Meliaceae) seeds: the role of stomata

BACKGROUND AND AIMS: The occurrence of stomata in seed coats is uncommon and there is limited information about their function(s). The aim of this study was to verify the distribution of stomata in seed coats of Swietenia macrophylla and to relate it to the imbibition process and aspects of the structure of the outer integument layers. METHODS: For the structural and ultrastructural studies, the seeds were processed using the usual techniques and studied under light and scanning electron microscopes. Histochemical tests were employed to identify the cell wall composition in the different seed coat portions. To assess the role of the stomata in the imbibition, non-impervious seeds were compared with partially impervious ones, in which only the embryo, median or hilar regions were left free. Further, the apoplastic pathway marker was employed to confirm the role of the stomata as sites of water passage during imbibition. KEY RESULTS: A positive relationship was observed between seed coat thickness and stomata density. The stomata were devoid of movement, with a large pore. They occurred in large numbers in the embryo region and extended with lower frequency towards the wing. Imbibition rates were related to stomata density, suggesting that the stomata act as preferential sites for water entry in the S. macrophylla seeds. CONCLUSIONS: At maturity, the stomata in the seed coat play a significant role in seed imbibition. The data may also infer that these permanently opened stomata have an important role in gas exchange during seed development, aiding embryo respiration.