Isolation, Synthesis, and Structure-Activity Relationship Study on Daphnane and Tigliane Diterpenes as HIV Latency-Reversing Agents.

Three new diterpenes, stellejasmins A (1) and B (2) and 12-O-benzoylphorbol-13-heptanoate (3), were isolated from the roots of Stellera chamaejasme L. The structures of 1-3 were elucidated by extensive NMR and mass spectroscopic analyses. Compounds 1 and 2 are the first derivatives containing a hydroxy group at C-2 in the family of daphnane and tigliane diterpenes. The presence of a chlorine atom in 1 is unique in the plant metabolite. Compound 3 has an odd-number acyl group, which is biosynthetically notable. Human immunodeficiency virus (HIV) LTR-driven transcription activity was tested with 1-3 and 17 known diterpenes isolated from S. chamaejasme L. and Wikstroemia retusa A.Gray. Among these, gnidimacrin (4), stelleralide A (5), and wikstroelide A (20) were highly potent, with EC50 values of 0.14, 0.33, and 0.39 nM, respectively. The structure-activity relationship (SAR) was investigated using 20 natural and eight synthetic diterpenes. This is the first SAR study on natural daphnane and tigliane diterpenes.

Chamaejasmins, cytotoxic guaiane sesquiterpenes from the root of Stellera chamaejasme L.

Four new guaiane-type sesquiterpenes, chamaejasmins A-D (1-4), were isolated from the root of Stellera camaejasme L. collected in Nepal, together with two known terpenes, stelleraguaianone B (5) and 1α,7α,10αH-guaia-4,11-dien-3-one (6). The structures of 1-4 including their absolute configurations were determined by extensive 2D NMR analyses, mass spectroscopy, and TDDFT calculations of their 13C chemical shifts and ECD spectra. Chamaejasmin A (1) showed cytotoxicity against HeLa cells with an IC50 value of 6.3 µM.

Free radical scavenging, α-glucosidase inhibitory and lipase inhibitory activities of eighteen Sudanese medicinal plants.

BACKGROUND: Lifestyle-related diseases such as diabetes are steadily increasing worldwide. In Sudan, there are a variety of plant species used traditionally for the treatment of diabetes, obesity and other symptoms which need to be validated through scientific studies for their claimed traditional uses. Therefore, in the current study, the free radical scavenging activity, α-glucosidase inhibitory and pancreatic lipase inhibitory activities of 70% ethanol and water extracts of eighteen Sudanese medicinal plants were investigated using various in vitro assays. Moreover, the cytotoxicity and genotoxicity were assessed for the bioactive plant extracts. METHODS: Eighteen plants were selected on the basis of their traditional uses and extracted with 70% ethanol and water to obtain thirty-six extracts. The obtained extracts were screened using different in vitro bioassays namely, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, α-glucosidase inhibitory and pancreatic lipase inhibitory assays. Furthermore, the active plant extracts were investigated for their cytotoxicity and genotoxicity on HeLa cell line using HCS DNA Damage Assay. RESULTS: Both 70% ethanol and water extracts of Acacia nilotica, Ziziphus spina-christi, Abrus precatorius, and Geigeria alata along with the 70% ethanol extract of Martynia annua showed potent free radical scavenging activity. Regarding the α-glucosidase inhibition assay, both extracts of Acacia nilotica, Ziziphus spina-christi, Geigeria alata, and Cyperus rotundus showed potent activity. In general, 70% ethanol extracts were more potent compared to water extracts with exception of Cordia sinensis and Cymbopogon proximus, for which water extracts also showed potent enzyme inhibitory activity. Similarly, water extracts of Acacia nilotica and Ziziphus spina-christi showed potent inhibitory activity against pancreatic lipase enzyme. Some of the extracts also showed significant genotoxicity and cytotoxicity at the concentration range used for bioactivities. CONCLUSION: The extracts of Acacia nilotica, Ziziphus spina-christi, Geigeria alata, Martynia annua and Abrus precatorius exhibited an appreciable range of activity on antioxidant and enzyme inhibitory assays.

Transcriptomic analysis indicates putative metabolic changes caused by manipulation of phosphorus availability in rice leaves.

Plants have developed several strategies for coping with phosphorus (P) deficiency. However, the details of the regulation of gene expression of adaptations to low P are still unclear. Using a cDNA microarray, transcriptomic analyses were carried out of the rice genes regulated by P deficiency and P re-supply to P-deficient plants. The OsPI1 gene, which was isolated as the most significant up-regulated gene under -P conditions, was also the most significant down-regulated gene following P re-supply. Many starch metabolism-related genes, as well as several genes for P(i)-liberating enzymes, were up-regulated by -P treatment, suggesting a homeostatic contribution to the P(i) concentration in leaf tissues. mRNAs for glucanases were also induced by P re-supply: these are suspected to play a role in loosening the cell wall compounds. Most of the genes up-regulated by -P treatment were down-regulated by P re-supply, suggesting that their responses were specific to -P conditions. Conversely, the number of genes up-regulated by P re-supply was also larger following P re-supply than in the -P condition. It is proposed that the genes up-regulated by P re-supply play an important role in P acquisition by P-deficient plants.

Novel gene encoding a Ca2+-binding protein and under hexokinase-dependent sugar regulation.

A cDNA encoding a predicted 15-kDa protein was earlier isolated from sugar-induced genes in rice embryos (Oryza sativa L.) by cDNA microarray analysis. Here we report that this cDNA encodes a novel Ca2+-binding protein, named OsSUR1 (for Oryza sativa sugar-up-regulated-1). The recombinant OsSUR1 protein expressed in Escherichia coli had 45Ca2+-binding activity. Northern analysis showed that the OsSUR1 gene was expressed mainly in the internodes of mature plants and in embryos at an early stage of germination. Expression of the OsSUR1 gene was induced by sugars that could serve as substrates of hexokinase, but expression was not repressed by Ca2+ signaling inhibitors, calmodulin antagonists and inhibitors of protein kinase or protein phosphatase. These results suggested that Os-SUR1 gene expression was stimulated by a hexokinase-dependent pathway not mediated by Ca2+.

cDNA microarray analysis of gene expression during Fe-deficiency stress in barley suggests that polar transport of vesicles is implicated in phytosiderophore secretion in Fe-deficient barley roots.

To acquire Fe from soil, graminaceous plants secrete mugineic acid family phytosiderophores (MAs) from their roots. The secretion of MAs increases in response to Fe deficiency, and shows a distinct diurnal rhythm. We used a microarray that included 8987 cDNAs of rice EST clones to examine gene expression profiles in barley roots during Fe-deficiency stress. Approximately 200 clones were identified as Fe-deficiency-inducible genes, of which seven had been identified previously. In order to meet the increased demand for methionine to produce MAs, Fe-deficiency enhances the expression of genes that participate in methionine synthesis, as well as recycling methionine through the Yang cycle. Of these 200 genes, approximately 50 exhibited different transcription levels in Fe-deficient roots at noon and at night. Northern blot analysis of time course experiments confirmed that five of these genes exhibited a diurnal change in their level of expression. The diurnal changes in the expression of these genes suggest that polar vesicle transport is involved in the diurnal secretion of MAs.