Lipophilic pigments and fatty acids from the aerial parts of certain plant species of the genus Limonium. VII

Pigments and lipids from the aerial parts of six plant species from the genus Limonium (Plumbaginaceae, Limoniacea) were studied. Xanthophylls dominated among the carotinoids; chlorophyll, the chlorophylls, according to spectrophotometry. Unsaturated fatty acids, the content of which reached 80%, dominated in all samples according to GC. The principal fatty acids were 18:1 and 18:2. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 412–414, September–October, 2006.     

Magnetic molecularly imprinted specific solid‐phase extraction for determination of dihydroquercetin from Larix griffithiana using HPLC

The naturally occurring quercetin flavonoid, dihydroquercetin, is widely distributed in plant tissues and has a variety of biological activities. Herein, a magnetic molecularly imprinted solid‐phase extraction was tailor made for selective determination of dihydroquercetin in Larix griffithiana using high‐performance liquid chromatography. Amino‐functionalized core‐shell magnetic nanoparticles were prepared and characterized using scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and infrared spectroscopy. The polymer had an average diameter of 250 ± 2.56 nm and exhibited good stability and adsorption for template molecule, which is enriched by hydrogen bonding interaction. Multiple factors for extraction, including loading, washing, elution solvents, and extraction time, were optimized. The limit of detection was 1.23 μg/g. The precision determined at various concentration of dihydroquercetin was less than 4% and the mean recovery was between 74.64 and 101.80%. It has therefore been shown that this protocol can be used as an alternative extraction to quantify dihydroquercetin in L. griffithiana and purify quercetin flavonoid from other complex matrices.     

最优回归设计在落叶松遗传转化体系主导因子优化筛选试验中的应用

阐述了 3 1 1 -A最优回归设计的数学模型 ,并利用此模型对落叶松遗传转化体系中主导因子 2 .4-D、BA、KT的浓度水平进行了优化筛选 ,获得了最佳水平组合及最佳胚性愈伤组织发生量 .结果表明 ,最优回归设计是一种科学、合理、实用的优化培养基的方法 .     

Modification of Arabinogalactan Isolated from Larix sibirica Ledeb. into Sulfated Derivatives with the Controlled Molecular Weights

The process of sulfation of arabinogalactan—a natural polysaccharide from Larix sibirica Ledeb.—with sulfamic acid in 1,4-dioxane using different activators has been studied for the first time. The dynamics of the molecular weight of sulfated arabinogalactan upon variation in the temperature and time of sulfation of arabinogalactan with sulfamic acid in 1,4-dioxane has been investigated. It has been found that, as the sulfation time increases from 10 to 90 min, the molecular weights of the reaction products grow due to the introduction of sulfate groups without significant destruction of the initial polymer and sulfation products. Sulfation at 95 °C for 20 min yields the products with a higher molecular weight than in the case of sulfation at 85 °C, which is related to an increase in the sulfation rate; however, during the further process occurring under these conditions, sulfation is accompanied by the destruction and the molecular weight of the sulfated polymer decreases. The numerical optimization of arabinogalactan sulfation process has been performed. It has been shown that the optimal parameters for obtaining a product with a high sulfur content are a sulfamic acid amount of 20 mmol per 1 g of arabinogalactan, a process temperature of 85 °C, and a process time of 2.5 h.     

一阶混合型积分微分方程的周期边值问题

在有一般化的上下解的条件下,研究了一阶混合型积分微分方程的周期边值问题的可解性和最小最大解的存在性。讨论基于迭合度方法,单调迭代方法和新的比较定理。     

Two new oplopane sesquiterpenes from Artemisia gmelinii Web. ex Stechm.

Two new oplopane sesquiterpenes, gmelinin A（1） and gmelinin B（2）, were isolated from Artemisia gmelinii Web. ex Stechm. Their structures were established by spectroscopic techniques（mainly 1D and2 D NMR） and application of the modified Mosher method.     

Effect of waterlogging on carbon isotope discrimination during photosynthesis in Larix gmelinii

Soil moisture is a major factor controlling carbon isotope discrimination (Δ¹³C), which has been demonstrated to decrease under dry conditions in many studies; however, few studies on Δ¹³C under waterlogging condition have been conducted. In this study, a pot experiment was conducted with Larix gmelinii, a major larch species in the east Siberian Taiga, to investigate the effect of waterlogging on Δ¹³C during photosynthesis. Assimilation rate and Δ¹³C_RD (instantaneous Δ¹³C calculated with Rayleigh distillation equation) decreased drastically soon after waterlogging, followed by recovery in their values, which was caused by a change in stomatal conductance. Thereafter, assimilation rate decreased gradually, whereas Δ¹³C_RD decreased more gently. These results were thought to be caused by the decrease in both stomatal conductance and carboxylation. Our results indicate that extreme wet events may cause a decrease in Δ¹³C, which is important information for detecting flooding events in the past using tree-ring isotope analyses and for studying impacts of flooding on plants in areas where waterlogging might occur.     

POSSIBILITIES AND LIMITATIONS OF USING HISTORIC PROVENANCE TESTS TO INFER FOREST SPECIES GROWTH RESPONSES TO CLIMATE CHANGE

Abstract. Under projected changes in global climate, the growth and survival of existing forests will depend on their ability to adjust physiologically in response to environmental change. Quantifying their capacity to adjust and whether the response is species‐ or population‐specific is important to guide forest management strategies. New analyses of historic provenance tests data are yielding relevant insights about these responses. Yet, differences between the objectives used to design the experiments and current objectives impose limitations to what can be learned from them. Our objectives are (i) to discuss the possibilities and limitations of using such data to quantify growth responses to changes in climate and (ii) to present a modeling approach that creates a species‐ and population‐specific model. We illustrate the modeling approach for Larix occidentalis Nutt. We conclude that the reanalysis of historic provenance tests data can lead to the identification of species that have population‐specific growth responses to changes in climate, provide estimates of optimum transfer distance for populations and species, and provide estimates of growth changes under different climate change scenarios. Using mixed‐effects modeling techniques is a sound statistical approach to overcome some of the limitations of the data.     

Quantitative antioxidant activity of the ethylacetate extract of Larix sibirica bark and its individual components

The antioxidant [AO] properties of the ethylacetate extract of Larix sibirica bark and the flavonoids quercetin and dihydroquercetin found in it were studied using a model radical-chain oxidation of propan-2-ol in the kinetic regime. The quantitative characteristics of their AO activity were determined as effective rate constants fk_ln. It was found that dihydroquercetin had the highest AO activity among the studied natural compounds. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 131–133, March–April, 2006.     

Lipids from Bud Meristem of Larix sibirica

The total lipids were isolated from meristematic bud tissues of Larix sibirica L. and cell membrane complexes. Their group composition was established. The dynamics of seasonal variation were studied. The principal lipids were found to be polar lipids residing in the membranes. Lipids in membranes were largely (up to 75% of the mass) replaced in winter by proteinaceous material. The principal lipids in the membranes were phospholipids.