Coumarin-monoterpenes from Gerbera anandria (Linn.) Sch.-Bip and their neuroprotective activity.

Thirty-two undescribed coumarin-monoterpenes, including the first report of six pairs of enantiomeric and twenty congeners, were isolated from the petroleum ether extract of the stems of Gerbera anandria (Linn.) Sch.-Bip. Structurally, these compounds represented C3-substituted 5-methyl-4-hydroxycoumarin-monoterpenes. Among them, 1-7 and 10-24 were rare 5-methylcoumarin-monoterpenes formed through a furan ring. Their chemical structures and absolute configurations were determined by comprehensive analysis of spectroscopic data, including HRESIMS, 1D and 2D NMR spectroscopic data, Mosher's method, ECD calculations and single crystal X-ray diffraction. Furthermore, biological studies revealed that compounds 1-3, 3a, 5, 5a, 11-12, 21-22 and 26 had the neuroprotective effects on scopolamine-induced injury in PC12 cells. Notably, 3 exhibited the strongest neuroprotective activity with the cell viability values of 77.24%. Meanwhile, pretreatment with 3 significantly downregulate apoptosis and reactive oxygen species (ROS) production, as well as strengthen antioxidant enzyme activities (MDA and SOD). Moreover, pretreatment with 3 also could attenuate the down-regulation of HO-1 and Nrf2 induced by scopolamine. In conclusion, these results demonstrated that these compounds possessed the protective effects on scopolamine-injured PC12 cells through anti-apoptotic and anti-oxidant activities.

Transcriptomes analysis reveals novel insight into the molecular mechanisms of somatic embryogenesis in Hevea brasiliensis.

BACKGROUND: Somatic embryogenesis (SE) is a promising technology for plant vegetative propagation, which has an important role in tree breeding. Though rubber tree (Hevea brasiliensis Muell. Arg.) SE has been founded, few late SE-related genes have been identified and the molecular regulation mechanisms of late SE are still not well understood. RESULTS: In this study, the transcriptomes of embryogenic callus (EC), primary embryo (PE), cotyledonary embryo (CE), abnormal embryo (AE), mature cotyledonary embryo (MCE) and withered abnormal embryo (WAE) were analyzed. A total of 887,852,416 clean reads were generated, 85.92% of them were mapped to the rubber tree genome. The de novo assembly generated 36,937 unigenes. The differentially expressed genes (DEGs) were identified in the pairwise comparisons of CE vs. AE and MCE vs. WAE, respectively. The specific common DEGs were mainly involved in the phytohormones signaling pathway, biosynthesis of phenylpropanoid and starch and sucrose metabolism. Among them, hormone signal transduction related genes were significantly enriched, especially the auxin signaling factors (AUX-like1, GH3.1, SAUR32-like, IAA9-like, IAA14-like, IAA27-like, IAA28-like and ARF5-like). The transcription factors including WRKY40, WRKY70, MYBS3-like, MYB1R1-like, AIL6 and bHLH93-like were characterized as molecular markers for rubber tree late SE. CML13, CML36, CAM-7, SERK1 and LEAD-29-like were also related to rubber tree late SE. In addition, histone modification had crucial roles during rubber tree late SE. CONCLUSIONS: This study provides important information to elucidate the molecular regulation during rubber tree late SE.

Tobacco rattle virus-induced gene silencing in Hevea brasiliensis.

Virus-induced gene silencing (VIGS) is a powerful gene-silencing tool that has been intensively applied in plants. To data, the application of VIGS in rubber tree has not yet been reported. In this study, we described the efficient gene silencing in rubber tree by VIGS. The gene encoding Hevea brasiliensis phytoene desaturase (HbPDS) was identified in rubber tree genome. Small interfering RNAs from HbPDS and the silencing gene fragment were predicted and a length of 399 bp was selected to be tested. We showed that the tobacco rattle virus (TRV)-VIGS could induce effective HbPDS silencing in rubber tree. This study was the first to report VIGS in rubber tree. The present TRV-VIGS method could be used to perform reverse genetic approaches to identify unknown gene functions and might be further applied to produce gene silenced rubber tree plants, to advance functional gene of rubber tree.

Identification of histone methylation modifiers and their expression patterns during somatic embryogenesis in Hevea brasiliensis.

Histone methylation plays a crucial role in various biological processes, from heterochromatin formation to transcriptional regulation. Currently, no information is available regarding histone methylation modifiers in the important rubber-producing plant Hevea brasiliensis. Here, we identified 47 histone methyltransferase (HMT) genes and 25 histone demethylase (HDM) genes as possible members of the histone methylation modifiers in the rubber tree genome. According to the structural features of HMT and HDM, the HbHMTs were classified into two groups (HbPRMs and HbSDGs), the HbHDMs have two groups (HbLSDs and HbJMJs). Expression patterns were analyzed in five different tissues and at different phases of somatic embryogenesis. HbSDG10, 21, 25, 33, HbJMJ2, 18, 20 were with high expression at different phases of somatic embryogenesis. HbSDG10,14, 20, 21, 33 and HbPRMT4 were expressed highly in anther, HbSDG14, 20, 21, 22, 23, 33, 35 and HbPRMT1 HbJMJ7 and HbLSD1, 2, 3, 4 showed high expression levels in callus. HbSDG1, 7, 10, 13, 14, 18, 19, 21, 22, 23, 35, HbPRMT1, 8, HbJMJ5, 7, 11, 16, 20 and HbLSD2, 3, 4 were expressed highly in somatic embryo. HbSDG10, 21, 25, 33, HbLSD2, 3 were expressed highly in bud of regenerated plant. The analyses reveal that HbHMTs and HbHDMs exhibit different expression patterns at different phases during somatic embryogenesis, implying that some HbHMTs and HbHDMs play important roles during somatic embryogenesis. This study provide fundamental information for further studies on histone methylation in Hevea brasiliensis.

The 14-3-3 protein HbGF14a interacts with a RING zinc finger protein to regulate expression of the rubber transferase gene in Hevea brasiliensis.

Hevea brasiliensis is a key commercial source of natural rubber (cis 1,4-polyisoprene). In H. brasiliensis, rubber transferase is responsible for cis-1,4-polymerization of isoprene units from isopentenyl diphosphate and thus affects the yield of rubber. Little is known about the regulatory mechanisms of the rubber transferase gene at a molecular level. In this study we show that the 5'UTR intron of the promoter of the rubber transferase gene (HRT2) suppresses the expression of HRT2. A H. brasiliensis RING zinc finger protein (designated as HbRZFP1) was able to interact specifically with the HRT2 promoter to down-regulate its transcription in vivo. A 14-3-3 protein (named as HbGF14a) was identified as interacting with HbRZFP1, both in yeast and in planta. Transient co-expression of HbGF14a and HbRZFP1-encoding cDNAs resulted in HbRZFP1-mediated HRT2 transcription inhibition being relieved. HbGF14a repressed the protein-DNA binding of HbRZFP1 with the HRT2 promoter in yeast. We propose a regulatory mechanism by which the binding of HbGF14a to HbRZFP1 interferes with the interaction of HbRZFP1 with the HRT2 promoter, thereby repressing the protein-DNA binding between them. This study provides new insights into the role of HbGF14a in mediating expression of the rubber transferase gene in Hevea brasiliensis.

Identification, characterization and expression analysis of genes involved in steroidal saponin biosynthesis in Dracaena cambodiana.

Dracaena cambodiana is a traditional medicinal plant used for producing dragon's blood. The plants and dragon's blood of D. cambodiana contain a rich variety of steroidal saponins. However, little is known about steroidal saponin biosynthesis and its regulation in D. cambodiana. Here, 122 genes encoding enzymes involved in steroidal saponin biosynthesis were identified based on transcriptome data, with 29 of them containing complete open reading frames (ORF). Transcript expression analysis revealed that several genes related to steroidal saponin biosynthesis showed distinct tissue-specific expression patterns; the expression levels of genes encoding the key enzymes involved in the biosynthesis and early modification of steroidal saponins were significantly down-regulated in the stems in response to the inducer of dragon's blood, exhibiting positive correlations with the content of steroidal saponins. These results provide insights on the steroidal saponins biosynthetic pathway and mechanisms underlying induced formation of dragon's blood in D. cambodiana.

[Chemical constituents from ethyl acetate-soluble extraction of Valeriana jatamansi].

Application of a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, macroporous adsorbent resin, and reversed-phase HPLC, led to the isolation of 173 compounds including irdidoids, monoterpenes, sesquiterpenes, triterpenes, lignans, flavonoids, and simple aromatic derivatives from the ethyl acetate-soluble fraction of the whole plants of Valeriana jatamansi(Valerianaceae), and their structures were elucidated by spectroscopic methods including 1D, 2D NMR UV, IR, and MS techniques. Among them, 77 compounds were new. In previous reports, we have described the isolation, structure elucidation, and bioactivities of 68 new and 25 known compounds. As a consequence, we herein reported the isolation and structure elucidation of the remaining 9 new and 71 known compounds, the structure revision of valeriotriate A(8a), as well as cytotoxicity of some compounds.

Isolation, Structure Elucidation, and Absolute Configuration of Highly Oxygenated Germacranolides from Carpesium cernuum.

The new highly oxygenated germacranolides cernuumolides A-J (1-10) and the known compounds 11-20 were isolated from Carpesium cernuum. Among these compounds, 1-4 are 11-methoxymethylgermacranolides and 5-7 as well as 11-17 are 2,9-hemiacetal-linked germacranolides. Their structures were elucidated using NMR and HRESIMS analyses, and X-ray diffraction studies were used to confirm the absolute configurations of 1, 2, 5, 6, 8, and 9. Cernuumolides A-J were evaluated for their in vitro cytotoxicity against the A549, HCT116, MDA-MB-231, and BEL7404 cell lines, and 8 exhibited moderate cytotoxicity with IC50 values in the 0.87-2.02 µM range.

Chemical Constituents from Campylotropis hirtella.

A phytochemical investigation on the roots of Campylotropis hirtella afforded nine new isoflavones (3-9, 12, 15), two new isoflavans (10 and 11), one new coumestan (1), and three new prenylated benzoic acid derivatives (2, 13, 14), together with twenty-four known compounds. Their structures were established by spectroscopic analysis and circular dichroism data. The isolated compounds were also evaluated for their antibacterial activities against Enterococcus faecalis, Salmonella gallinarum, Streptococcus suis, Streptococcus agalactiae, Aeromonas hydrophila, Pseudomonas aeruginosa, Bacillus subtilis, Riemerella anatipestifer, and Vibrio alginolyticus.

Identification and characterization of MAGO and Y14 genes in Hevea brasiliensis.

Mago nashi (MAGO) and Y14 proteins are highly conserved among eukaryotes. In this study, we identified two MAGO (designated as HbMAGO1 andHbMAGO2) and two Y14 (designated as HbY14aand HbY14b) genes in the rubber tree (Hevea brasiliensis) genome annotation. Multiple amino acid sequence alignments predicted that HbMAGO and HbY14 proteins are structurally similar to homologous proteins from other species. Tissue-specific expression profiles showed that HbMAGO and HbY14 genes were expressed in at least one of the tissues (bark, flower, latex, leaf and root) examined. HbMAGOs and HbY14s were predominately located in the nucleus and were found to interact in yeast two-hybrid analysis (YTH) and bimolecular fluorescence complementation (BiFC) assays. HbMAGOs and HbY14s showed the highest transcription in latex and were regulated by ethylene and jasmonate. Interaction between HbMAGO2 and gp91phox (a large subunit of nicotinamide adenine dinucleotide phosphate) was identified using YTH and BiFC assays. These findings suggested that HbMAGO may be involved in the aggregation of rubber particles in H. brasiliensis.

Eight pairs of epimeric triterpenoids involving a characteristic spiro-E/F ring from Abies faxoniana.

Five pairs of new epimeric lanostane-type triterpenoids, abiespirones A-D (1-4) and G (7), two pairs of new epimeric cycloartane-type triterpenoids, abiespirones E and F (5, 6), and a pair of new epimeric 7(8→9)abeo-spirolanostane abiespirones H (8) with spiro-B/C and -E/F ring systems were isolated from Abies faxoniana as inseparable mixtures of C-23 epimers in a specific proportion. The HPLC plots showed that each purified isomer rapidly equilibrated with the C-23 epimer in solution. The structures of compounds 1-8 were elucidated by analysis of the NMR spectra and single-crystal X-ray diffraction. Compound 6 showed cytotoxicity against three hepatoma cell lines, namely, HepG2, Huh7, and SMMC7721, with IC50 values of 9.8, 7.5, and 10.7 µM, respectively, but exerted low cytotoxicity on normal QSG7701 hepatic cells, indicating its selective cytotoxicity for hepatoma cells. Compound 6 arrests the cell cycle at G2/M and induces cell apoptosis in Huh7 cells. In addition, the generation of reactive oxygen species (ROS) was detected in Huh7 cells when treated with compound 6, and a ROS scavenger partly blocked the effects of compound 6-induced Huh7 cell death, suggesting that compound 6-induced apoptosis is associated with elevated levels of ROS in Huh7 cells.

Molecular characterization of HbCZF1, a Hevea brasiliensis CCCH-type zinc finger protein that regulates hmg1.

KEY MESSAGE: The HbCZF1 protein binds to the hmg1 promoter in yeast and this interaction was confirmed in vitro. The hmg1 promoter was activated in transgenic plants by HbCZF1. Biosynthesis of natural rubber is known to be based on the mevalonate pathway in Hevea brasiliensis. The final step in the mevalonate production is catalyzed by the branch point enzyme, 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGR), which shunts HMG-CoA into the isoprenoid pathway, leading to the synthesis of natural rubber. However, molecular regulation of HMGR expression is not known. To study the transcriptional regulation of HMGR, the yeast one-hybrid experiment was performed to screen the latex cDNA library using the hmg1 (one of the three HMGR in H. brasiliensis) promoter as bait. One cDNA that encodes the CCCH-type zinc finger protein, designated as HbCZF1, was isolated from H. brasiliensis. HbCZF1 interacted with the hmg1 promoter in yeast one-hybrid system and in vitro. HbCZF1 contains a 1110 bp open reading frame that encodes 369 amino acids. The deduced HbCZF1 protein was predicted to possess a typical C-X7-C-X5-C3-H CCCH motif and RNA recognition motif. HbCZF1 was predominant in the latex, but little expression was detected in the leaves, barks, and roots. Furthermore, in transgenic tobacco plants, over-expression of HbCZF1 highly activated the hmg1 promoter. These results suggested that HbCZF1 may participate in the regulation of natural rubber biosynthesis in H. brasiliensis.

Genome-wide identification and characterization of WRKY gene family in Hevea brasiliensis.

WRKY proteins constitute a large family of transcription factors. In this study, we identified 81 WRKY genes (named HbWRKY1 to HbWRKY81) in the latest rubber tree genome. Tissue-specific expression profiles showed that 74 HbWRKYs were expressed in at least one of the tissues and the other 7 genes showed very low expression in all tissues tested, which suggested that HbWRKYs took part in many cellular processes. The responses of 20 selected HbWRKYs to jasmonic acid (JA) and ethylene (ET) were analyzed in the latex. 17 HbWRKYs responded to at least one treatment, which included 15 HbWRKYs responding to JA treatment, 15 HbWRKYs to ET, which suggested that these HbWRKYs were regulated by JA and ET. We also observed that HbWRKY3, 14, and 55 bind HbSRPP promoter and activate the transcription in yeast. This study suggests that HbWRKY proteins maybe involved in the transcriptional regulation of nature rubber biosynthesis.

Three decomposition products of valepotriates from Valeriana jatamansi and their cytotoxic activity.

Three new decomposition products of valepotriates, valtrals A-C (1-3), and two known products, baldrinal and homobaldrinal, are formed during the isolation procedure of the ethanol extract of the whole plants of Valeriana jatamansi. Their structures were determined by spectroscopic methods including IR, MS, 1D, and 2D NMR experiments. Compounds 1-3 showed selective cytotoxicity against metastatic prostate cancer (PC-3M) and colon cancer (HCT-8) cell lines.

Structure Conservation and Differential Expression of Farnesyl Diphosphate Synthase Genes in Euphorbiaceous Plants.

Farnesyl diphosphate synthase (FPS) is a key enzyme of isoprenoids biosynthesis. However, knowledge of the FPSs of euphorbiaceous species is limited. In this study, ten FPSs were identified in four euphorbiaceous plants. These FPSs exhibited similar exon/intron structure. The deduced FPS proteins showed close identities and exhibited the typical structure of plant FPS. The members of the FPS family exhibit tissue expression patterns that vary among several euphorbiaceous plant species under normal growth conditions. The expression profiles reveal spatial and temporal variations in the expression of FPSs of different tissues from Euphorbiaceous plants. Our results revealed wide conservation of FPSs and diverse expression in euphorbiaceous plants during growth and development.

Molecular and functional characterization of the HbSRPP promoter in response to hormones and abiotic stresses.

Small rubber particle protein (SRPP) is a major component of Hevea brasiliensis latex, and obviously participates in the biosynthesis of natural rubber. However, little information is available about regulation of SRPP gene expression. In this study, the promoter region of HbSRPP was isolated and characterized. Its sequence included regulatory elements predicted to be responsive to hormones and other environmental cues. Promoter deletion analysis revealed that 219 nucleotides (nt) upstream of the transcription start site were sufficient for expression. The region from -1,055 to -219 nt positively regulated expression induced by methyl jasmonate (MeJA), abscisic acid (ABA), and wounding; the region from -734 to -528 nt positively regulated expression induced by gibberellic acid (GA); the region from -734 to -219 nt positively regulated expression induced by heat; the region from -1,055 to -4 negatively regulated expression induced by cold; the region from -219 to -4 nt was associated with negative regulation of expression induced by ABA and wounding; the region from -528 to -4 nt negatively regulated expression induced by GA. These results suggest the activity of the HbSRPP promoter is regulated by MeJA, ABA, GA, cold, heat, and wounding.

Molecular characterization of the Jatropha curcas JcR1MYB1 gene encoding a putative R1-MYB transcription factor.

The cDNA encoding the R1-MYB transcription factor, designated as JcR1MYB1, was isolated from Jatropha curcas using rapid amplification of cDNA ends. JcR1MYB1 contains a 951 bp open reading frame that encodes 316 amino acids. The deduced JcR1MYB1 protein was predicted to possess the conserved, 56-amino acid-long DNA-binding domain, which consists of a single helix-turn-helix module and usually occurs in R1-MYBs. JcR1MYB1 is a member of the R1-MYB transcription factor subfamily. A subcellular localization study confirmed the nuclear localization of JcR1MYB1. Expression analysis showed that JcR1MYB1 transcripts accumulated in various examined tissues, with high expression levels in the root and low levels in the stem. JcR1MYB1 transcription was up-regulated by polyethylene glycol, NaCl, and cold treatments, as well as by abscisic acid, jasmonic acid, and ethylene treatment. Analysis of transgenic tobacco plants over-expressing JcR1MYB1 indicates an inportant function for this gene in salt stress.

Reprogramming of DNA methylation and changes of gene expression in grafted Hevea brasiliensis.

Rubber tree (Hevea brasiliensis) is reproduced by bud grafting for commercial planting, but significant intraclonal variations exist in bud-grafted clones. DNA methylation changes related to grafting may be partly responsible for intraclonal variations. In the current study, whole-genome DNA methylation profiles of grafted rubber tree plants (GPs) and their donor plants (DPs) were evaluated by whole-genome bisulfite sequencing. Data showed that DNA methylation was downregulated and DNA methylations in CG, CHG, and CHH sequences were reprogrammed in GPs, suggesting that grafting induced the reprogramming of DNA methylation. A total of 5,939 differentially methylated genes (DMGs) were identified by comparing fractional methylation levels between GPs and DPs. Transcriptional analysis revealed that there were 9,798 differentially expressed genes (DEGs) in the DP and GP comparison. A total of 1,698 overlapping genes between DEGs and DMGs were identified. These overlapping genes were markedly enriched in the metabolic pathway and biosynthesis of secondary metabolites by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Global DNA methylation and transcriptional analyses revealed that reprogramming of DNA methylation is correlated with gene expression in grafted rubber trees. The study provides a whole-genome methylome of rubber trees and an insight into the molecular mechanisms underlying the intraclonal variations existing in the commercial planting of grafted rubber trees.

New phenylbutenoids and terpene glycosides from Ginkgo biloba leaves.

Our continued works on the chemical constituents of Ginkgo biloba (G. biloba) leaves has led to the isolation of two novel phenylbutenoids (1, 2), along with five previously unidentified terpene glycosides (3-7). Among them, compounds 1 and 2 represent unique (Z)-phenylbutenoids, 3-6 are megastigmane glycosides, and 7 is identified as a rare bilobanone glycoside (Fig. 1). This study marks the first reported isolation of phenylbutenoid and bilobanone glycoside from G. biloba. The chemical structures of these compounds were elucidated through extensive spectroscopic analysis, including HR-ESI-MS and various 1D and 2D NMR experiments. Furthermore, the absolute configurations of these molecules were determined using Mosher's method, ECD experiments, and Cu-Kα X-ray crystallographic analyses.

Kinase inhibit region of SOCS3 attenuates IL6-induced proliferation and astrocytic differentiation of neural stem cells via cross talk between signaling pathways.

AIMS: Efficiency of neural stem cells (NSCs) therapy for brain injury is restricted by astrogliosis around the damaged region, in which JAK2/STAT3 signaling plays a key role. The SOCS3 that can directly inhibit JAK/STAT3 pathway. Here, we investigated the effects of a fusion peptide that combined kinase inhibitory region (KIR) of SOCS3 and virus trans-activator of transcription (TAT) on biological behavior of cultured NSCs under inflammatory conditions. METHODS: NSCs were isolated from embryonic brain of SD rats, TAT-KIR was synthesized, and penetration rate was evaluated by flow cytometry (FACS). CCK8, immunostaining, and FACS were used to detected of TAT-KIR on the proliferation of NSCs. The expressions of GFAP and ß tubulin III positive cells induced by IL6 with/without TAT-KIR were examined by immunostaining and Western blotting to observe the NSCs differentiation, and the effect of TAT-KIR on signaling cross talk was observed by Western blotting. RESULTS: Penetration rate of TAT-KIR into primary cultured NSCs was up to 94%. TAT-KIR did not affect the growth and viability of NSCs. It significantly reduced the NSCs proliferation that enhanced by IL-6 stimulation via blocking the cell cycle progression from the G0/G1 to S phase. In addition, TAT-KIR attenuated astrocytic differentiation and kept high level of neuronal differentiation derived from IL-6-induced NSCs. The fate of NSCs differentiation under inflammatory conditions was affected by TAT-KIR, which was associated with synchronous inhibition of STAT3 and AKT, while promoting JNK expression. CONCLUSION: TAT-KIR mimetic of SOCS3 could be a promising approach for brain repair via regulating the biological behaviors of exogenous NSCs.