Pollen morphology of Diosma and Coleonema (Rutaceae: Diosminae) and its taxonomic implications

The pollen morphology of Diosma and Coleonema of the taxonomically problematic subtribe Diosminae (Rutaceae) was investigated to determine its taxonomic relevance. Pollen of 26 of the 28 species of Diosma and of each of the eight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticulate, could be distinguished. In contrast, exine sculpturing shows interspecific variation in Coleonema and three distinct types, striate, reticulate and perforate, could be discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support macromorphological evidence that suggests the generic re-classification of the Diosminae.     

利用扁桃斑鸠菊叶发酵高产粗毛纤孔菌胞外多糖的条件优化及其抗氧化活性研究

粗毛纤孔菌胞外多糖是粗毛纤孔菌液体发酵的重要活性代谢产物,但采用常规的发酵方法,粗毛纤孔菌胞外多糖的产量较低。为更好地获取粗毛纤孔菌胞外多糖,本文采用双向液体发酵的方法,通过向发酵培养基中添加适量的扁桃斑鸠菊叶粉末,来提高粗毛纤孔菌胞外多糖的产量,并对优化得到的胞外多糖抗氧化活性进行了研究。以发酵液中胞外多糖含量为指标,采用单因素实验和正交实验优化发酵条件;采用红外光谱对胞外多糖的结构特征进行分析;通过测定胞外多糖对ABTS、DPPH和羟基自由基的清除率来了解其抗氧化活性。结果表明,最优发酵条件为:扁桃斑鸠菊叶粉末添加量0.5g/L、发酵时间10d、pH 6.5、接种量5.0mL,在此条件下,粗毛纤孔菌胞外多糖的产量达到(2.34±0.25)mg/mL,与未添加扁桃斑鸠菊叶的空白组相比,其胞外多糖产量提高了约216.22%;红外分析与抗氧化活性实验结果表明,添加扁桃斑鸠菊叶后的胞外多糖与未添加扁桃斑鸠菊叶的胞外多糖红外主要吸收峰一致,并且对ABTS、DPPH以及羟基自由基清除能力相近。本研究结果表明扁桃斑鸠菊叶能够有效地提高粗毛纤孔菌胞外多糖的产量,为其他珍稀食药用菌胞外多糖的高效生产提供了新思路。     

毒根斑鸠菊中的一个新倍半萜的分离与鉴定

为了更好的研究毒根斑鸠菊(Vernonia cumingiana Benth)叶茎的化学成分与活性测定,利用硅胶柱层析、Sephadex LH-20等柱色谱技术对毒根斑鸠菊叶茎提取物进行了分离,并采用现代波谱学技术(1 H NMR、13C NMR、HMBC、HMQC等)及X-射线单晶衍射技术并根据其理化性质鉴定了七个化...     

Structural and immunological studies of a pectin and a pectic arabinogalactan from Vernonia kotschyana Sch. Bip. ex Walp. (Asteraceae)

Two polysaccharides, a pectin (Vk100A2b) and a pectic arabinogalactan (Vk100A2a) with mean Mw 2 x 10(4) and 1.15 x 10(6)Da, respectively, were isolated from the dried powdered roots of Vernonia kotschyana Sch. Bip. ex Walp. by hot water extraction followed by fractionation on DEAE-Sepharose fast flow and Sephacryl S-400 HR. The pectin showed low-complement fixation activity and no influence on proliferation of B or T cells, while the pectic arabinogalactan showed a potent, dose-dependent complement fixation activity and a T cell independent induction of B-cell proliferation. Both polysaccharides induced chemotaxis of human macrophages, T cells and NK cells. exo-alpha-L-arabinofuranosidase and exo-beta-D-galactosidase digestion followed by component sugar and methylation analysis indicated that Vk100A2a consisted of a highly branched rhamnogalacturonan core with approximately 50% of the rhamnose 1,2,4-substituted, side chains rich in terminal-, 1,5-linked and 1,3,5-branched arabinose and terminal-, 1,4-, 1,6-linked and 1,3,6-branched galactose. The enzyme resistant part of Vk100A2a still showed strong complement fixating activity, suggesting that this activity may at least in part be expressed by carbohydrate structures present in the enzyme resistant, inner portion of the polymer.     

Synthesis of novel cationic bolaamphiphiles from vernonia oil and their aggregated structures

The present study describes the synthesis of a novel class of vesicle-forming bolaamphiphiles with choline ester head groups. These bolaamphiphiles were derived from vernonia oil, whose main constituent is vernolic acid, a fatty acid with a unique combination of epoxy, carboxy and unsaturated double bonds. A series of bolaamphiphiles containing amido or ester groups within the hydrophobic domain were synthesized from N,N'-alkylenebis (vernolamides) and alpha,omega-alkylene divernolate ester in a two-stage synthesis comprising opening of the epoxy ring with chloroacetic acid, followed by quaternization with N,N-dimethylaminoethyl acetate to form choline ester head groups. The products were characterized by FT-IR, (1)H and (13)C NMR, and ESI-MS. Vesicles prepared from these bolaamphiphiles have the potential to serve as a targeted drug delivery systems with selective decapsulation in the presence of the enzyme acetylcholine esterase, resulting in site-specific release of the drug.     

Sesquiterpene lactones — insect feeding deterrents in Vernonia

Larval feeding tests were run to determine the preference of six species of Lepidoptera for two species of Vernonia which produce sesquiterpene lactones and one which has lost the ability to produce these bitter principles. Significant differences between the feeding preferences of the insect species were observed. Further feeding tests were run with a Vernonia leaf powder medium to determine how interspecific chemical differences influenced these preferences. The sesquiterpene lactone, glaucolide-A, was found to reduce larval feeding when incorporated in a Vernonia powder-agar medium. The amount of insect feeding was inversely proportional to the concentration of glaucolide-A in the medium.     

Cloning and functional analysis of two type 1 diacylglycerol acyltransferases from Vernonia galamensis

Vernonia galamensis accumulates vernolic acid (cis-12-epoxyoctadeca-cis-9-enoic acid) as the major fatty acid in its seed oil. Such epoxy fatty acids are useful in a number of industrial applications. Successful genetic engineering of commercial oilseed crops to produce high levels of vernolic acid depends on a better understanding of the source plant enzymes for vernolic acid accumulation. Developing V. galamensis seed microsome assays demonstrate that diacylglycerol acyltransferase (DGAT), an enzyme for the final step of triacylglycerol synthesis, has a strong substrate preference for vernolic acid bearing substrates including acyl-CoA and diacylglycerol. There are two classes of DGATs known as DGAT1 and DGAT2. Here we report on the isolation, characterization, and functional analysis of two DGAT1 cDNAs from V. galamensis (VgDGAT1a and VgDGAT1b). VgDGAT1a and VgDGAT1b are expressed in all plant tissues examined with highest expression in developing seeds. Enzymatic assays using isolated microsomes from transformed yeast show that VgDGAT1a and VgDGAT1b have the same DGAT activity levels and substrate specificities. Oleoyl-CoA and sn-1,2-dioleoylglycerol are preferred substrates over vernoloyl-CoA and sn-1,2-divernoloylglycerol. This data indicates that the two VgDGAT1s are functional, but not likely to be responsible for the selective accumulation of vernolic acid in V. galamensis seed oil.     

New vernocuminosides from the stem barks of Vernonia cumingiana Benth

Seven new stigmastane-type steroidal glycosides, vernocuminosides A-G (1-7), have been isolated from the stem barks of Vernonia cumingiana Benth. The structural elucidation and stereochemistry determination were achieved by spectroscopic and chemical methods including 1D and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, and NOE) experiments, especially the employment of Snatzke's method expressed by the induced circular dichroism spectra. Anti-inflammatory activities and cytotoxicities of compounds 1-7 were evaluated.     

Antibacterial Flavonoids and Other Compounds from the Aerial Parts of Vernonia guineensis Benth. (Asteraceae)

An extensive phytochemical study of the aerial parts of Vernonia guineensis Benth. (Asteraceae) led to the isolation of a new flavone, vernoguinoflavone and a naturally isolated glycerol ester, eicosanoic acid 2‐hydroxy‐1,3‐propanediyl ester, together with eighteen known secondary metabolites including quercetin, luteolin, vernopicrin, vernomelitensin, β‐amyrin, oleanolic acid, ursolic acid, lupeol, betulinic acid, β‐carotene, a mixture of stigmasterol and β‐sitosterol, β‐sitosterol‐3‐O‐β‐D‐glucoside, 2,3‐dihydroxypropyl heptacosanoate, pentacosanoic acid, docosan‐1‐ol, tritriacontan‐1‐ol, and heptatriacontan‐1‐ol. Eleven compounds are reported herein for the first time from this species. The structures of these compounds were elucidated on the basis of extensive spectroscopic analyses, particularly 1D and 2D NMR, and HR‐ESI‐MS and by comparison of their data with those reported in the literature. The crude extract, fractions and some isolated compounds were evaluated for their antibacterial activity against Gram‐negative bacteria: Escherichia coli (ATCC 25922), Shigella flexineri (NR 518), Salmonella muenchen, Salmonella typhimurium and Salmonella typhi (ATCC 19430). All the tested compounds demonstrated inhibitory activities against the tested enteric bacteria with MIC values ranging from 3.12 to 100 μg/ml. Three flavonoids isolated from the most active fraction demonstrated the best bioactivities against Escherichia coli, Salmonella muenchen and Salmonella typhimurium with MIC values ranging from 3.12 to 25 μg/mL.     

Microbial transformation of zaluzanin-D

Microbial transformation of zaluzanin-D using different fungi gave 11,13-dihydrozaluzanin-C, zaluzanin-C, 4,16,11,13 - tetrahydro zaluzanin-C, estafiatone, dihydroestafiatol and dihydroestafiatone.