Project description:Dioscorea cirrhosa is a plant that is used as a dye as well as in medicine. Many metabolites with pharmacological activity exist in the tubers of D. cirrhosa. However, little is known about the mechanism regulating biosynthesis in these metabolites. In this study, transcriptome and metabolome profiling were performed in four color tubers. A total of 531 metabolites, including 62 flavonoids, were identified. Epicatechin and proanthocyanin B2 were the key metabolites that exhibited high content levels in the four tubers. These metabolites were divided into nine classes with distinct change patterns. A total of 22,865 differentially expressed genes (DEGs) were identified by transcriptome analysis. Among these DEGs, we identified 67 candidate genes related to the flavonoid biosynthesis pathway and three genes that played pivotal roles in proanthocyanin (PA) synthesis. A weighted gene co-expression network analysis (WGCNA) revealed that the two modules, "MEblue" and "MEblack," were two key gene sets strongly associated with phenylpropanoid and flavonoid biosynthesis. We also found that the plant hormone signal transduction biological process exhibited activity in the late stage of tuber color formation. Additionally, we identified 37 hub transcript factors related to flavonoid biosynthesis, of which 24 were found to be highly associated with flavonoid pathway genes. In addition to the MYB-bHLH-WD40 (MBW) genes, we found that the plant hormone gene families exhibited high expression levels. This study provides a reference for understanding the synthesis of D. cirrhosa tuber metabolites at the molecular level and provides a foundation for the further development of D. cirrhosa related plant pigments as well as its further use in the pharmaceutical industry.
Project description:The aglycon form of the steroidal sapogenin furost -5-ene-3 beta, 22,26-triol, 3 beta- chacotrioside 26 beta-D-glucopyranoside was isolated from cell suspension cultures of Dioscorea deltoidea and its molecular structure was determined by mass spectrometry and 1H and 13C n.m.r. spectroscopy. From kinetic studies and incorporation experiments with [1-14C]acetate it was concluded that the steroidal compound (in the glycoside form) is an intermediate in vivo in diosgenin biosynthesis. It accumulated in growing cells of D. deltoidea and was metabolized to diosgenin (in the glycoside form, i.e. dioscin ) in non-dividing cells.
Project description:Dioscorea zingiberensis is a perennial herb famous for the production of diosgenin, which is a valuable initial material for the industrial synthesis of steroid drugs. Sterol C26-hydroxylases, such as TfCYP72A616 and PpCYP72A613, play an important role in the diosgenin biosynthesis pathway. In the present study, a novel gene, DzCYP72A12-4, was identified as C26-hydroxylase and was found to be involved in diosgenin biosynthesis, for the first time in D. zingiberensis, using comprehensive methods. Then, the diosgenin heterogenous biosynthesis pathway starting from cholesterol was created in stable transgenic tobacco (Nicotiana tabacum L.) harboring DzCYP90B71(QPZ88854), DzCYP90G6(QPZ88855) and DzCYP72A12-4. Meanwhile, diosgenin was detected in the transgenic tobacco using an ultra-performance liquid chromatography system (Vanquish UPLC 689, Thermo Fisher Scientific, Bremen, Germany) tandem MS (Q Exactive Hybrid Quadrupole-Orbitrap Mass Spectrometer, Thermo Fisher Scientific, Bremen, Germany). Further RT-qPCR analysis showed that DzCYP72A12-4 was highly expressed in both rhizomes and leaves and was upregulated under 15% polyethylene glycol (PEG) treatment, indicating that DzCYP72A12-4 may be related to drought resistance. In addition, the germination rate of the diosgenin-producing tobacco seeds was higher than that of the negative controls under 15% PEG pressure. In addition, the concentration of malonaldehyde (MDA) was lower in the diosgenin-producing tobacco seedlings than those of the control, indicating higher drought adaptability. The results of this study provide valuable information for further research on diosgenin biosynthesis in D. zingiberensis and its functions related to drought adaptability.
Project description:Diosgenin saponins isolated from Dioscorea species such as D. zingiberensis exhibit a broad spectrum of pharmacological activities. Diosgenin, the aglycone of diosgenin saponins, is an important starting material for the production of steroidal drugs. However, how plants produce diosgenin saponins and the origin and evolution of the diosgenin saponin biosynthetic pathway remain a mystery. Here we report a high-quality, 629-Mb genome of D. zingiberensis anchored on 10 chromosomes with 30 322 protein-coding genes. We reveal that diosgenin is synthesized in leaves ('source'), then converted into diosgenin saponins, and finally transported to rhizomes ('sink') for storage in plants. By evaluating the distribution and evolutionary patterns of diosgenin saponins in Dioscorea species, we find that diosgenin saponin-containing may be an ancestral trait in Dioscorea and is selectively retained. The results of comparative genomic analysis indicate that tandem duplication coupled with a whole-genome duplication event provided key evolutionary resources for the diosgenin saponin biosynthetic pathway in the D. zingiberensis genome. Furthermore, comparative transcriptome and metabolite analysis among 13 Dioscorea species suggests that specific gene expression patterns of pathway genes promote the differential evolution of the diosgenin saponin biosynthetic pathway in Dioscorea species. Our study provides important insights and valuable resources for further understanding the biosynthesis, evolution, and utilization of plant specialized metabolites such as diosgenin saponins.
Project description:BackgroundDiosgenin, mainly extracted from wild diosgenin-contained Dioscorea species, is a well-known starting material of steroidal and contraceptive drugs. However, due to large market demand and increasingly ecological damage, wild Dioscorea species resources available have been gradually declining. Therefore, identification of new potential ecological distribution of diosgenin-contained Dioscorea species is necessary for diosgenin production.MethodsIn this study, a large occurrence dataset (1808 data points) of diosgenin-contained Dioscorea species was obtained from Eastern Asia, Southern North America and Southern Africa. Along with the data for six critical environmental parameters and one soil factor, Geographic Information System for Global Medicinal Plant was applied to predict the potential suitable distribution of Dioscorea species.ResultsThe results showed that the potential distribution of these Dioscorea species covered a wide field, and that new ecological suitability areas were mainly distributed in the central region of South America, the southern part of the European and coastal region of Oceania. Jackknife test indicated that annual precipitation and annual mean radiation were the important climatic factors controlling the distribution of Dioscorea species.ConclusionsThe suitable areas and critical climatic factors will serve as a useful guide for diosgenin-contained Dioscorea species conservation and cultivation in ecological suitable areas.
Project description:Dioscorea villosa (wild yam) is native to North America and has been widely used as a natural alternative for estrogen replacement therapy to improve women's health as well as to treat inflammation, muscle spasm, and asthma. Diosgenin and dioscin (glycoside form of diosgenin) are reported to be the pharmacologically active compounds. Despite the reports of significant pharmacological properties of dioscin and diosgenin in conditions related to inflammation, cancer, diabetes, and gastrointestinal ailments, no reports are available on ADME properties of these compounds. This study was carried out to determine ADME properties of diosgenin and dioscin and their effects on major drug metabolizing enzymes (CYP 3A4, 2D6, 2C9, and 1A2). The stability was determined in simulated gastric and intestinal fluids (SGF, pH 1.2 and SIF, pH 6.8), and intestinal transport was evaluated in Caco-2 model. Phase I and phase II metabolic stability was determined in human liver microsomes and S9 fractions, respectively. Quantitative analysis of dioscin and diosgenin was performed by UPLC-MS system. Dioscin degraded up to 28.3 % in SGF and 12.4 % in SIF, which could be accounted for by its conversion to diosgenin (24.2 %. in SGF and 2.4 % in SIF). The depletion of diosgenin in SGF and SIF was < 10 %. Diosgenin was stable in HLM but disappeared in S9 fraction with a half-life of 11.3 min. In contrast, dioscin was stable in both HLM and S9 fractions. Dioscin showed higher permeability across Caco-2 monolayer with no significant efflux, while diosgenin was subjected to efflux mediated by P-glycoprotein. Diosgenin and dioscin inhibited CYP3A4 with IC50 values of 17 and 33 µM, respectively, while other CYP enzymes were not affected. In conclusion, dioscin showed better intestinal permeability. Conversion of dioscin to diosgenin was observed in both gastric and intestinal fluids. No phase I metabolism was detected for both compounds. The disappearance of diosgenin in S9 fraction indicated phase II metabolism.
Project description:Dioscorea nipponica rhizoma (DNR) is commonly used for the cure of hyperthyroidism resulting from Graves' disease (GD) or thyroid nodules. However, its therapeutic mechanism remains unclear. This study aimed to utilize network pharmacology integrated molecular docking and experimental verification to reveal the potential pharmacological mechanism of DNR against GD. First, the active componds of DNR were collected from the HERB database and a literature search was conducted. Then, according to multisource database, the predicted genes of DNR and GD were collected to generate networks. The analysis of protein-protein interaction and GO enrichment and KEGG pathway were employed to discover main mechanisms associated with therapeutic targets. Moreover, molecular docking simulation was applied in order to verify the interactions between the drug and target. Finally, our experiments validated the ameliorated effects of diosgenin, the main component of DNR, in terms of phosphorylation deactivation in IGF-1R, which in turn inhibited the phosphorylation and activation of PI3K-AKT and Rap1-MEK signaling pathways, promoting cell apoptosis and GD remission. Our present study provided a foundation for further investigation of the in-depth mechanisms of diosgenin in GD and will provide new scientific evidence for clinical application.
Project description:BackgroundYam (Dioscorea alata L.) is an important tuber crop and purple pigmented elite cultivar has recently become popular because of associated health benefits. Identifying candidate genes responsible for flavonoid biosynthesis pathway (FBP) will facilitate understanding the molecular mechanism of controlling pigment formation in yam tubers. Here, we used Illumina sequencing to characterize the transcriptome of tubers from elite purple-flesh cultivar (DP) and conventional white-flesh cultivar (DW) of yam. In this process, we also designed high quality molecular markers to assist molecular breeding for tuber trait improvement.ResultsA total of 125,123 unigenes were identified from the DP and DW cDNA libraries, of which about 49.5% (60,020 unigenes) were annotated by BLASTX analysis using the publicly available protein database. These unigenes were further annotated functionally and subject to biochemical pathway analysis. 511 genes were identified to be more than 2-fold (FDR < 0.05) differentially expressed between the two yam cultivars, of which 288 genes were up-regulated and 223 genes were down-regulated in the DP tubers. Transcriptome analysis detected 61 unigenes encoding multiple well-known enzymes in the FBP. Furthermore, the unigenes encoding chalcone isomerase (CHS), flavanone 3-hydroxylase (F3H), flavonoid 3'-monooxygenase (F3'H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX), and flavonol 3-O-glucosyltransferase (UF3GT) were found to be significantly up-regulated in the DP, implying that these genes were potentially associated with tuber color formation in this elite cultivar. The expression of these genes was further confirmed by qRT-PCR. Finally, 11,793 SSRs were successfully identified with these unigenes and 6,082 SSR markers were developed using Primer 3.ConclusionsThis study provides the first comprehensive transcriptomic dataset for yam tubers, which will significantly contribute to genomic research of this and other related species. Some key genes associated with purple-flesh trait were successfully identified, thus providing valuable information about molecular process of regulating pigment accumulation in elite yam tubers. In the future, this information might be directly used to genetically manipulate the conventional white-fleshed tuber cultivars to enable them to produce purple flesh. In addition, our SSR marker sets will facilitate identification of QTLs for various tuber traits in yam breeding programs.
Project description:The effects of the oligosaccharides from the endophytic fungus Fusarium oxysporum Dzf17 as elicitors on diosgenin production in cell suspension cultures of its host Dioscorea zingiberensis were investigated. Three oligosaccharides, DP4, DP7 and DP10, were purified from the oligosaccharide fractions DP2-5, DP5-8 and DP8-12, respectively, which were prepared from the water-extracted mycelial polysaccharide of the endophytic fungus F. oxysporum Dzf17. When the cell cultures were treated with fraction DP5-8 at 20 mg/L on day 26 and harvested on day 32, the maximum diosgenin yield (2.187 mg/L) was achieved, which was 5.65-fold of control (0.387 mg/L). When oligosaccharides DP4, DP7 and DP10 were individually added to 26-day-old D. zingiberensis cell cultures at concentrations of 2, 4, 6, 8 and 10 mg/L in medium, DP7 at 6 mg/L was found to significantly enhance diosgenin production, with a yield of 3.202 mg/L, which was 8.27-fold of control. When the cell cultures were treated with DP7 twice on days 24 and 26, and harvested on day 30, both diosgenin content and yield were significantly increased and reached the maximums of 1.159 mg/g dw and 4.843 mg/L, both of which were higher than those of single elicitation, and were 9.19- and 12.38-fold of control, respectively.
Project description:Response surface methodology (RSM) was utilized to optimize the ultrasonic-assisted extraction (UAE) of Dioscorea cirrhosa pigment (DCP). The results demonstrated that the yield of DCP is the highest (32.27%) when acetone volume fraction is 74%, extraction time is 31 min, and the temperature is 54 °C. Next, the effects of pH, temperature, light, metal ions, reductants and oxidants on the stability of DCP were further evaluated to confirm the best storage conditions of DCP. The results showed that DCP should be stored at a wide pH range of 3 to 9, below 80 °C and away from light. Metal ions such as Fe2+, Fe3+, and Ti4+ can destabilize DCP, while K+, Al3+, Ca2+, Cu2+, Mg2+, and Zn2+ have little impact on DCP. Moreover, DCP showed good anti-reduction and poor anti-oxidization properties. These results might provide the basic data and theoretical guidance for the application of DCP.