新疆松萝属地衣的研究

松萝属地衣在世界范围内是研究比较深入。本文概述了松萝属地衣在新疆的研究历史及现状,阐述了新疆松萝属地衣的物种鉴定、所含地衣物质及其药用价值,以及松萝酸和松萝多糖等的相关研究进展,并对松萝属地衣研究的发展趋势作了展望。     

新疆北部松萝属地衣生态分布与地理区系成分分析

根据多年的实地调查资料和前人研究资料,对新疆北部松萝属地衣的种类以及它们的分布区、区系特征和垂直分布进行了初步研究。结果表明,分布在新疆北部的松萝属地衣共有22种,主要分布在天山和阿勒泰山,生长在树皮、树枝和朽木上。根据它们对环境的适应特征和选择性,将新疆北部松萝属地衣的主要地理成分分为环极北极及北方成分、北美-欧洲成分、世界广布种、北美成分、环极低北极及北方成分、欧洲成分、东亚—北美成分等7种。研究还发现分布在阿勒泰山和天山的松萝属地衣的垂直分布有明显的差异。阿勒泰山的地衣分布海拔比较高,分布范围比较广泛。     

脐鳞属地衣一个新种(英文)

本文描述了脐鳞属地衣一个新种:褐脐鳞。这个新种类似红脐鳞,但地衣体上表面为灰褐色并且不合松萝酸。本种与泡状脐鳞的区别是不含富马原岛衣酸及地理分布的差异。     

脐鳞属地衣一个新种

本文描述了脐鳞属地衣一个新种：褐脐鳞。 这个新种类似红脐鳞,但地衣体上表面为灰褐色并且不含松萝酸。本种与泡状脐鳞的区别是不含富马原岛衣酸及地理分布的差异。     

松萝酸的结构修饰与生物活性研究进展

松萝酸是一种二苯并呋喃类衍生物,为地衣植物的特有成分,具有抗菌、抗病毒、抗肿瘤等生物活性。为增强松萝酸的生物活性及溶解性,学者们对其开展了大量的结构修饰与改造,发现了一些更具有潜在研究价值的松萝酸衍生物。本文综述了松萝酸结构修饰、生物活性和构效关系的研究,为松萝酸衍生物类药物的开发提供参考。     

太白山药用地衣的种质资源及其化学成分的研究概况

地衣是低等植物的重要类群,为菌藻共生体,全世界已知有500多属26 000余种,中国有232属1 766种.我国历代本草记载药用地衣约200种,著名的有石蕊、松萝等,秦岭太白山有药用地衣37种,其中常用13种.其主要成分为地衣多糖和地衣酸,具有抗肿瘤、抗辐射及抗菌等生物活性,太白山药用地衣是陕西民间中草药的重要组成部分,具有一定的开发应用潜力.     

黄梅属地衣2个中国新记录种

黄梅属(Xanthoparmelia)是广泛分布于中国西北干旱半干旱地区的叶状地衣,生长在岩石和土壤表面。文章以1991-2017年采自天山东部和准噶尔盆地不同生态系统中的黄梅属地衣标本为研究材料,用形态学、解剖学、生物化学以及分子系统学方法,对其进行分类学研究。结果表明:(1)发现了黄梅属地衣的2个中国新记录种:即绿皮黄梅(Xanthoparmelia chlorochroa)和怀俄明黄梅(X.wyomingica)。(2)绿皮黄梅和怀俄明黄梅的地衣体上表面光泽、呈淡绿色至黄绿色,缺乏裂芽、粉芽,下表面暗褐色,且绿皮黄梅地衣体上表面有大量的白斑,裂片线性至亚线性、不规则分枝、重叠,假根多、单一至分枝,而怀俄明黄梅地衣体裂片密集重叠、亚线性,假根少、单一,但二者均未见子囊盘。(3)TLC法检测显示,绿皮黄梅衣含合水杨嗪酸、肺衣酸、水杨嗪酸及松萝酸;怀俄明黄梅含共水杨嗪酸、降斑点酸、水杨嗪酸及松萝酸。(4)ITS rDNA系统发育分析表明,这两个中国新记录种地衣分布在黄梅衣属中,绿皮黄梅和旱黄梅形成一个姊妹群并且和散生黄梅形成单系分支;怀俄明黄梅形成了一个独立单系分支。文中对这两新记录种地衣进行了详细描述,并提供了它们的分布、生境和地衣体的彩色图片。标本现存于新疆大学“中国西北干旱区地衣研究中心”标本室(XJU)。     

硬枝树花中4个单体化合物的抑菌活性

研究了从硬枝树花中提取得到的4个单体化合物松萝酸(usnic acid)、去甲环萝酸(evernic acid)、巴尔巴地衣酸(barbatic acid)和水杨嗪酸(salazinic acid)对大肠杆菌、沙门氏菌、金黄色葡萄球菌、枯草芽孢杆菌4种细菌及甜瓜根腐病菌、禾谷镰刀病菌、番茄灰霉病菌3种植物病原菌的抑制能力。结果表明,水杨嗪酸对大肠杆菌的抑制能力较强,对枯草芽孢杆菌几乎无抑制作用。松萝酸对大肠杆菌和枯草芽孢杆菌基本无抑制作用。高浓度的去甲环萝酸对大肠杆菌及金黄色葡萄球菌的抑制效果较好。巴尔巴地衣酸对4种细菌的抑制作用不强。水杨嗪酸对3种植物病原菌的抑制效果明显,去甲环萝酸对3种植物病原菌的抑菌效果较好,巴尔巴地衣酸对番茄灰霉病菌的抑制能力较好,而松萝酸对植物病原菌的抑制能力较弱。     

松萝酸提取工艺的研究

以破茎松萝为材料,分别以碱水或碱醇直接提取、制备松萝酸钠,并对松萝酸钠提取影响因素进行探究。对所得提取物进行分离和定性鉴定,并利用高效液相层析技术测定提取物中松萝酸的含量。通过单因素实验考察了NaOH和Na2CO3浓度对松萝酸提取的影响,用HPLC测定不同浓度碱液提取物中松萝酸的含量。实验结果说明,1.5%NaOH和75%乙醇+4%Na2CO3提取松萝酸效果较好,松萝酸提取得率最高,分别为1.75%和1.99%,破茎松萝材料中松萝酸含量为2.4%。     

Usnic acid

Since its first isolation in 1844, usnic acid [2,6-diacetyl-7,9-dihydroxy-8,9b-dimethyl-1,3(2H,9bH)-dibenzo-furandione] has become the most extensively studied lichen metabolite and one of the few that is commercially available. Usnic acid is uniquely found in lichens, and is especially abundant in genera such as Alectoria, Cladonia, Usnea, Lecanora, Ramalina and Evernia. Many lichens and extracts containing usnic acid have been utilized for medicinal, perfumery, cosmetic as well as ecological applications. Usnic acid as a pure substance has been formulated in creams, toothpaste, mouthwash, deodorants and sunscreen products, in some cases as an active principle, in others as a preservative. In addition to antimicrobial activity against human and plant pathogens, usnic acid has been shown to exhibit antiviral, antiprotozoal, antiproliferative, anti-inflammatory and analgesic activity. Ecological effects, such as antigrowth, antiherbivore and anti-insect properties, have also been demonstrated. A difference in biological activity has in some cases been observed between the two enantiomeric forms of usnic acid. Recently health food supplements containing usnic acid have been promoted for use in weight reduction, with little scientific support. The emphasis of the current review is on the chemistry and biological activity of usnic acid and its derivatives in addition to rational and ecologically acceptable methods for provision of this natural compound on a large scale.     

The chemoenzymatic synthesis of usnic acid

Usnic acid, a highly functionalized dibenzofuran, is a polyketide secondary metabolite produced by several species of lichens. Synthesis of usnic acid from commercially available starting material was accomplished in two steps. The synthesis involves the methylation of phloracetophenone followed by oxidation with horseradish peroxidase. This work will lay the foundation for further biosynthetic studies on usnic acid.     

Identification and quantitation of usnic acid from the lichen Usnea species of Anatolia and antimicrobial activity

Six species of lichens, such as Usnea florida, Usnea barbata, Usnea longissima, Usnea rigida, Usnea hirta and Usnea subflorida, were collected from different areas of Anatolia (district of Antalya, Karabük, Qankiri, Giresun and Trabzon) in Turkey. Their usnic acid amounts in acetone extracts were determined by HPLC. In addition, antimicrobial activities of these extracts were determined against Escherichia coli (ATCC 35218), Enterococcus faecalis (RSKK 508), Proteus mirabilis (Pasteur Ens. 235), Staphylococcus aureus, Bacillus subtilis and Bacillus megaterium. It was shown that with increasing amount of usnic acid, the antimicrobial activity increased. Usnic acid contents of Usnea species varied between 0.22-6.49% of dry weight.     

Response of the lichen-eating moth <Emphasis Type="Italic">Cleorodes lichenaria</Emphasis> larvae to varying amounts of usnic acid in the lichens

Lichens are characterized by a great variety of secondary metabolites. The function of these substances remains partly unknown. In this study, we propose that some of these metabolites may expel insect herbivores. To test this hypothesis, we reared larvae of the lichenivorous moth Cleorodes lichenaria on three selected lichens, Cladonia arbuscula subsp. mitis, Usnea hirta, and Usnea dasypoga. In experimental setup, the secondary metabolite usnic acid was removed from the lichens with acetone prior to feeding, whereas a control was left untreated. On all three lichens, removal of usnic acid from the lichens using acetone significantly prolonged survival of larvae and increased their viability. Larvae reared on control lichens contained significantly more usnic acid than those reared on treated lichens, both in their biomass and their faeces. These results support the hypothesis that usnic acid serves as a repellent against insect feeding, besides its well established functions of UV protection and antimicrobial properties.     

Anti-viral activity of (−)- and (+)-usnic acids and their derivatives against influenza virus A(H1N1)2009

Influenza is a widespread respiratory infection. Every year it causes epidemics, quickly spreading from country to country, or even pandemics, involving a significant part of the human population of the earth. Being a highly variable infection, influenza easy accumulates the resistance mutations to many antivirals.Usnic acid, a dibenzofuran originally isolated from lichens belongs to the secondary metabolites and has a broad spectrum of biological activity. In humans, it can act as an anti-inflammatory, antimitotic, antineoplasic, antibacterial, and antimycotic agent. In this work we studied for the first time the antiviral activity of usnic acid and its derivatives against the pandemic influenza virus A(H1N1)pdm09. A total of 26 compounds representing (+) and (?) isomers of usnic acid and their derivates were tested for cytotoxicity and anti-viral activity in MDCK cells by microtetrazolium test and virus yield assay, respectively. Based on the results obtained, 50% cytotoxic dose (CTD₅₀) and 50% effective dose (ED₅₀) and selectivity index (SI) were calculated for each compound. Eleven of them were found to have SI higher than 10 (highest value 37.3). Absolute configuration was shown to have critical significance for the anti-viral activity. With minor exceptions, in the pair of enantiomers, (?)-usnic acid was more active comparing to (+)-isomer, but its biological activity was reversed after the usnic acid was chemically modified. Based on the obtained results, derivatives of usnic acid should be considered as prospective compounds for further optimization as anti-influenza substances.     

Lichen secondary metabolites affect growth of <Emphasis Type="Italic">Physcomitrella patens</Emphasis> by allelopathy

Lichen secondary metabolites can function as allelochemicals and affect the development and growth of neighboring bryophytes, fungi, vascular plants, microorganisms, and even other lichens. Lichen overgrowth on bryophytes is frequently observed in nature even though mosses grow faster than lichens, but there is still little information on the interactions between lichens and bryophytes.In the present study, we used extracts from six lichen thalli containing secondary metabolites like usnic acid, protocetraric acid, atranorin, lecanoric acid, nortistic acid, and thamnolic acid. To observe the influence of these metabolites on bryophytes, the moss Physcomitrella patens was cultivated for 5 weeks under laboratory conditions and treated with lichen extracts. Toxicity of natural mixtures of secondary metabolites was tested at three selected doses (0.001, 0.01, and 0.1 %). When the mixture contained substantial amounts of usnic acid, we observed growth inhibition of protonemata and reduced development of gametophores. Significant differences in cell lengths and widths were also noticed. Furthermore, usnic acid had a strong effect on cell division in protonemata suggesting a strong impact on the early stages of bryophyte development by allelochemicals contained in the lichen secondary metabolites.Biological activities of lichen secondary metabolites were confirmed in several studies such as antiviral, antibacterial, antitumor, antiherbivore, antioxidant, antipyretic, and analgetic action or photoprotection. This work aimed to expand the knowledge on allelopathic effects on bryophyte growth.     

Effect of (+)-usnic acid on mitochondrial functions as measured by mitochondria-specific oligonucleotide microarray in liver of B6C3F1 mice

Usnic acid is a lichen metabolite used as a weight-loss dietary supplement due to its uncoupling action on mitochondria. However, its use has been associated with severe liver disorders in some individuals. Animal studies conducted thus far evaluated the effects of usnic acid on mitochondria primarily by measuring the rate of oxygen consumption and/or ATP generation. To obtain further insight into usnic acid-mediated effects on mitochondria, we examined the expression levels of 542 genes associated with mitochondrial structure and functions in liver of B6C3F₁ female mice using a mitochondria-specific microarray. Beginning at 8 weeks of age, mice received usnic acid at 0, 60, 180, and 600 ppm in ground, irradiated 5LG6 diet for 14 days. Microarray analysis showed a significant effect of usnic acid on the expression of several genes only at the highest dose of 600 ppm. A prominent finding of the study was a significant induction of genes associated with complexes I through IV of the electron transport chain. Moreover, several genes involved in fatty acid oxidation, the Krebs cycle, apoptosis, and membrane transporters were over-expressed. Usnic acid is a lipophilic weak acid that can diffuse through mitochondrial membranes and cause a proton leak (uncoupling). The up-regulation of complexes I–IV may be a compensatory mechanism to maintain the proton gradient across the mitochondrial inner membrane. In addition, induction of fatty acid oxidation and the Krebs cycle may be an adaptive response to uncoupling of mitochondria.     

The phenolic compounds in <Emphasis Type="Italic">Cladonia</Emphasis> lichens are not antimicrobial in soils

According to classic text books on lichen biology, the phenolic secondary chemicals in lichens have antibiotic effects on soil microorganisms and mycorrhizal fungi in ecosystems. However, the experimental evidence for this under natural conditions is still relatively scarce. We examined some of the assumptions behind the concept of antimicrobial effects of lichen secondary substances: (1) the secondary substances of Cladonia stellaris, usnic and perlatolic acids, are leached out from the lichens by rainwater; (2) these substances inhibit the microbial activity of soil, and; (3) since they are extremely resistant to microbial decomposition, the soil underneath a continuous lichen mat is enriched in usnic and perlatolic acids. Our results did not support any of these assumptions. The evidence for the antimicrobial activity of lichen secondary substances seems to be weak in comparison to other suggested functions such as light filtering and herbivore protection. We suggest that it is time to re-evaluate the evidence for the antimicrobial ecological role of lichen secondary substances in natural systems.