Translocation and accumulation of nicotine via distinct spatio-temporal regulation of nicotine transporters in Nicotiana tabacum

In plants, secondary metabolites play important roles in adaptation to the environment. Nicotine, a pyridine alkaloid in Nicotiana tabacum, functions as chemical barrier against herbivores. Nicotine produced in the root undergoes long-distance transport and accumulates mainly in the leaves. Since production of such defensive compounds is costly, plants must regulate the allocation of the products to their tissues; however, the molecular mechanism of nicotine translocation remains unclear. Our recent studies identified a novel multidrug and toxic compound extrusion (MATE)-type nicotine transporter, JAT2 (jasmonate-inducible alkaloid transporter 2). This transporter is specifically expressed in leaves, localizes to the tonoplast, and transports nicotine as its substrate. The specific induction of JAT2 expression in leaves by methyl jasmonate (MeJA) treatment suggests that this transporter plays an important role in nicotine distribution to leaves, especially under herbivore attack, by transporting nicotine into the vacuole. Considering JAT2, together with the previously identified MATE transporters JAT1, MATE1, and MATE2, and the PUP (purine permease) transporter NUP1 (nicotine uptake permease1), we show a model of nicotine translocation and accumulation via distinct spatio-temporal regulation of nicotine transporter expression. Furthermore, we discuss the possible role of nicotine transporters in determining outcrossing rates and seed production.     

长序虎皮楠果实中的一个新的生物碱（英文）

从长序虎皮楠（Daphniphyllum longeracemosum）果实的甲醇提取物中分离得到一个新的虎皮楠生物碱和三个已知的环烯醚萜苷型虎皮楠生物碱。通过现代波谱解析技术鉴定为daphlongeranine F（1）,caldaphnidine F（2）,daphcalycinosidine B（3）and daphcalycinosidine C（4）。其中,三个环烯醚萜苷虎皮楠生物碱系首次从该种分离得到。     

Knockdown of berberine bridge enzyme by RNAi accumulates (<Emphasis Type="Italic">S</Emphasis>)-reticuline and activates a silent pathway in cultured California poppy cells

Reticuline is a key compound in the biosynthetic pathway for isoquinoline alkaloids in plants, which include morphine, codeine and berberine. We established cultured California poppy (Eschscholzia californica) cells, in which berberine bridge enzyme (BBE) was knocked down by RNA interference, to accumulate the important key intermediate reticuline. Both BBE mRNA accumulation and enzyme activity were effectively suppressed in transgenic cells. In these transgenic cells, end-products of isoquinoline alkaloid biosynthesis, such as sanguinarine, were considerably reduced and reticuline was accumulated at a maximum level of 310 μg/g-fresh weight. In addition, 1 g-fresh weight of these cells secreted significant amounts of reticuline into the medium, with a maximum level of 6 mg/20 mL culture medium. These cells also produced a methylated derivative of reticuline, laudanine, which could scarcely be detected in control cells. We discuss the potential application of RNAi technology in metabolic modification and the flexibility of plant secondary metabolism.     

Spermatinamine, the first natural product inhibitor of isoprenylcysteine carboxyl methyltransferase, a new cancer target

Isoprenylcysteine methyltransferase (Icmt) catalyzes the carboxyl methylation of oncogenic proteins in the final step of a series of post-translational modifications. The inhibition of Icmt provides an attractive and novel anticancer target. A natural product high-throughput screening campaign was conducted to discover inhibitors of Icmt. The Australian marine sponge, Pseudoceratina sp., yielded spermatinamine, a novel alkaloid with a bromotyrosyl-spermine-bromotyrosyl sequence, as the bioactive constituent. Its structure was determined by 1D and 2D NMR spectroscopy. Spermatinamine is the first natural product inhibitor of Icmt.     

土壤不同水分条件对长春花(Catharanthus roseus)生活史型的影响

为了研究土壤中不同水分条件对长春花生活史型形成及生理代谢的影响,设置对照、轻度干旱、中度干旱和重度干旱等土壤水分梯度,对长春花(Catharanthus roseus(L.)G.Don)幼苗进行处理。对长春花形态指标进行聚类分析发现选择的20个聚类实体被分为2组,第1组为对照(CK)和轻度干旱(LD)处理的植株,第2组为中度干旱(MD)和重度干旱(HD)处理的植株。运用主成分分析(Principal component analysis,PCA)方法对不同土壤水分条件下长春花营养生长(Vegetative growth,V)、有性生殖(Sexual reproduction,S)和无性繁殖(Clone reproduction,C)等3类15种性状进行统计。结果显示,长春花在对照条件下生活史型为V0.39S0.54C0.07,轻度干旱为V0.36S0.50C0.14,中度干旱为V0.53S0.27C0.20,重度干旱为V0.45S0.09C0.46,干旱程度加强显著提高了无性繁殖的比重,降低了有性生殖的比例。同时,对长春花中文朵灵、长春质碱和脱水长春碱等生物碱的含量进行了动态测定,发现重度干旱下的文朵灵、长春质碱和脱水长春碱的含量在16d时分别是对照水平的1.5倍、2.3倍和3.1倍,表明干旱胁迫诱导生物碱积累,为长春花高效栽培提供了理论依据。     

微波辅助提取荷叶生物碱条件的优化

对荷叶中主要生理活性物质生物碱的提取条件进行了初步研究,以稀盐酸水为溶剂结合微波照射浸渍提取,获得了较优化的提取工艺,即用pH2.5 HCl、微波辅助处理2.5 min、固液比1:40、提取温度90℃、提取时间3 h,可得荷叶生物碱量172.63μg.g-1。     

Asymmetric synthesis of phenanthroindolizidine alkaloids with hydroxyl group at the C14 position and evaluation of their antitumor activities

The asymmetric total synthesis of the strongly cytotoxic phenanthroindolizidine alkaloid 3 was achieved. Using the same route, various derivatives were also synthesized. Cytotoxicity of those synthetic compounds was evaluated and compounds 19, 23, and 27 demonstrated potent cytotoxicities similar to that of 3. The in vivo antitumor efficacy of selected compounds was also evaluated and 23 demonstrated moderate antitumor efficacy.     

Synthesis of phenanthroindolizidine alkaloids and evaluation of their antitumor activities and toxicities

We previously reported that phenanthroindolizidine alkaloid 3 and its derivatives had markedly potent in vitro cytotoxicity. However, they had low in vivo antitumor activities and high in vivo toxicities, which was a serious problem. To address this problem, new phenanthroindolizidine derivatives were synthesized and their antitumor activities and toxicities were evaluated. This study describes the relationship between the chemical structures, antitumor activities, and toxicities of these phenanthroindolizidine derivatives. Based on its properties, compound 8 was found to be the most suitable potential antitumor agent.     

延胡索的化学成分研究(英文)

采用现代分离技术和方法,从延胡索根茎中分离得到17个化合物,通过波谱分析鉴定其结构。包括11个生物碱类化合物,二氢白屈菜红碱(1)、去氢紫堇碱(2)、四氢非洲防己胺(3)、异紫堇球碱(4)、紫堇碱(5)、四氢黄连碱(6)、药根碱(7)、黄连碱(8)、小檗碱(12)、巴马汀(13)和延胡索乙素(14);2个蒽醌类化合物,大黄素(9)和大黄素甲醚(10);1个三萜类化合物,即3β-羟基-齐墩果烷-111,3(18)-二烯-28-酸(11)和3个甾醇类化合物,豆甾醇(15)、β-谷甾醇(16)和胡萝卜苷(17)。其中,化合物9～11首次从该属植物中分离得到,1首次从该种中分离得到。