The effect of hydrostatic pressure on the thermal stability of DNA hairpins

DNA hairpins consist of two distinct structural domains: a double stranded stem and a single-stranded loop that connect the two strands of the stem. Previous studies of short DNA hairpins have revealed that loop and stem sequences can significantly affect the thermodynamic stability of short DNA hairpins. In this work we present the effect of hydrostatic pressure on the helix-coil transition temperature (T_M) for 11 16-base, hairpin-forming DNA oligonucleotides. All of the samples form a hairpin with a 6-base pair stem and a four-base loop. In addition, the four base pairs at the end of the stem distal from the loop are the same for every molecule. We have varied loop sequence and identity of the two duplex base pairs adjacent to the loop. Using the change in UV absorption to monitor the conformational state of the oligonucleotide the hairpin-coil transition temperature of these molecules was studied as a function of sodium ion concentration and pressure. From these data we calculated the volume change accompanying the transition. Model-dependent (van't Hoff) transition parameters such as ΔH_vH and transition volume (ΔV) were estimated from the analysis of conformational transitions. Experiments revealed that the ΔV for denaturation of these molecules range from − 2.35 to + 6.74 cm³ mol⁻¹. The expansibility (ΔΔV/ΔT) and the pressure dependence of cation release are also presented. The difference in the volume change for this transition is related to the differences in the hydration of these molecules.     

Composition and biovariability of Deverra scoparia volatile oil and its potential use as a source of bioactive phthalide components

Chemical biodiversity of essential oils of natural populations of Deverra scoparia growing in different regions in Algeria, and spreading from of semiarid to Saharan territories, was assessed. More than 60 compounds were identified by GC and GC-MS. Both phenylpropanoids and phathalids classes of bioactive components in leaves part were exhibiting drastic variations: (0.77–59.46%) and (0.04–28.55%), respectively. More specifically, the following bioactive components reached a very high level for this plant species: myristicin “up to 58.19%”, dill apiole “up to 25.52%” and (Z)-ligustilide “up to 27.5%”. Seven major compounds identified for the flowers part were varying from very low to very high percentages: α-pinene (2.49–42.32%), sabinene + β-pinene (1.11–30.31%), α-phellandrene (0.99–20.63%), p-cymene (0.0–44.22%), limonene (0.0–42.99%), myristicin (0.03–58.19%) and dill apiole (0.4–25.52%). Similarly, for the stems part, larges variations of both major and minor components were also registered: α-pinene (17.97–53.25%), sabinene + β-pinene (3.44–24.99%), α-phellandrene (0.75–10.32%), limonene (1.35–59.68%), terpinen-4-ol (0.29–15.85%) and spathulenol (0.46–11.29%). Agglomerative Hierarchical Cluster analysis was conducted, showing the existence of two main groups. Obtained data for volatile components in each plant part gave an insight of the existence of simultaneous clear and large biodiversity of the chemical profiles of the studied plant parts.     

米碎花茎枝的化学成分研究

为探讨山茶科（Theaceae）柃木属植物米碎花（Eurya chinensis R. Brown）茎枝的化学成分,从米碎花茎枝95%乙醇提取物中分离得到8个化合物,根据现代波谱技术和文献对照,鉴定其结构分别为：高根二醇（1）、白桦酸（2）、木栓酮（3）、羽扇豆醇（4）、β-谷甾醇（5）、豆甾醇（6）、邻羟基苯甲醛（7）、正二十九烷醇（8）。所有化合物均为首次从该植物中分离得到。     

Viburnum tinus L.: Investigation on its spontaneous emission at different phenological stages

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Dendrocyin: an isocucurbitacin with novel cyclic side chain from Dendrosicyos socotrana

Dendrosicyos socotrana Balf.f. is a unique species (Cucurbitaceae) native to Socotra island in the horn of Africa. From the chloroform extract of the stems, A new isocucurbitacin (Dendrocyin) with unusual cyclization in the side chain; 24beta-ethoxy-20-25-epoxy-3alpha,16alpha-dihydroxy-9-methyl-19-norlanost-5(6) ene-2,11,22-trione has been isolated alongside isocucurbitacin R. Their structural configuration were established by usual spectroscopic (1H NMR, 13C NMR and DEPT) and two-dimensional NMR techniques (1H-1H Cosy, HMBC and HMQC).     

瑞香狼毒茎叶化学成分研究

新鲜瑞香狼毒（Ｓｔｅｌｅｒａｃｈａｍａｅｊａｓｍｅ）茎叶经正己烷提取,脱腊后进行ＧＣＭＳＤＳ联用分析,鉴定出２０个化合物。主要成分为正十八烷;正十九烷;２,６,１０,１４四甲基十六烷;十六烷酸;十六烷酸甲酯;十六烷酸乙酯;９,１２,１５十八碳三烯酸甲酯;９,１２十八碳二烯酸;９,１２,１５十八碳三烯酸和十八烷酸。     

Bioactive Coumarins from the Stems of Clausena emarginata

Five new coumarins, clauemarmarins I – M ( 1 – 4 ), together with 10 known analogs ( 5 – 14 ), were isolated from the stems of Clausena emarginata. Compounds 8 – 13 were obtained from this plant for the first time. Their structures were established and elucidated by comprehensive analysis of spectroscopic data. The absolute configurations of 1 – 4 were further determined by their electronic circular dichroism spectroscopy. Compounds 5 , 7 , 12 , and 14 exhibited inhibitory effects on LPS‐induced NO production. Compounds 5 – 7 showed selective neuroprotective effects in Aβ_{25 – 35} model at 10 μm .     

Xanthine oxidase inhibitory effects of the constituents of Chrysanthemum morifolium stems

The flowers of Chrysanthemum morifolium Ramat. (family: Asteraceae) are used in Traditional Chinese Medicine to treat fever, cold and swelling. However the aerial part is considered as agriculture waste and the chemical and pharmacological information is scanty. From the stems of this plant, four new compounds named as morineoliganosides A (1), B (2), C (3) and heterophyllol-1-O-β-d-glucopyranoside A (4) together with 27 known isolates (5–31), including flavonoids and caffeoylquinic acids were isolated. Their structures were elucidated by chemical and spectroscopic methods The inhibitory effects on xanthine oxidase of these compounds have been determined. This research provided a scientific development and utilization of C. morifolium stems.     

Triterpenoids with antimicrobial activity from Drypetes inaequalis

The air-dried stems and ripe fruit of Drypetes inaequalis Hutch. (Euphorbiaceae) were studied. Four triterpene derivatives, characterized as lup-20(29)-en-3β,6α-diol, 3β-acetoxylup-20(29)-en-6α-ol, 3β-caffeoyloxylup-20(29)-en-6α-ol and 28-β d-glucopyranosyl-30-methyl 3β-hydroxyolean-12-en-28,30-dioate along with 10 known compounds were isolated from the whole stems. One triterpene, characterized as 3α-hydroxyfriedelan-25-al along with six known compounds were isolated from the ripe fruit. Their structures were established on the basis of spectroscopic analysis and chemical evidence. The triterpenes were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria, and two of them appeared to be modestly active.     

Epicuticular wax structures on stems and comparison between stems and leaves – A survey

The cuticle, forming the outermost layer of plant tissues and being in direct contact with the environment, consists of waxes and cutin. Waxes are hydrophobic substances that are divided in two groups: intra- and epicuticular, depending on their localisation. Epicuticular waxes appear as smooth coverings, however, many plants also produce superimposed wax structures of a crystalline nature. While studies of waxes have almost exclusively focused on leaves, here a survey of epicuticular wax structures on stems is presented. The stem surface of 343 higher plant taxa, representing 80 families, was examined using scanning electron microscopy. The adaxial and abaxial surfaces of leaves of 319 taxa were also examined to determine the relationship between wax structures on stems and leaves. Wax structures are classified, described and discussed. The results of the study indicate that stems exhibit the same main wax crystal types that have been described for leaves. Seventy percent of the examined taxa produced wax crystals on their stems. In ∼24% of the taxa, wax crystals were absent on leaves and found only on stems. In plant taxa that produce wax crystals, 40% exhibit the same type on either side of their leaves and on their stem. However, a much stronger morphological similarity exists between crystal shapes present on the adaxial and abaxial surfaces of leaves than between those present on the stem and those on leaves. In general, these observations suggest that stems are quite different than leaves in terms of their epicuticular wax structures.