Three new triterpenoid saponins from Albizia julibrissin.

Three new triterpenoid saponins, julibrosides A5-A7 (1-3), together with five known saponins (4-8), were isolated from the stem bark of Albizia julibrissin. Their structures were elucidated on the basis of extensive spectroscopic data analysis of MS, 1D and 2D NMR, and chemical methods. Compounds 7 and 8 were isolated from the genus Albizia for the first time. The new compounds showed no cytotoxicity and anti-inflammatory activity.

[Transcriptome profiling of high oleic peanut under low temperatureduring germination].

High oleic (HO) peanut (Arachishypogaea L.) oils benefit human health and industrial production due to its superior nutritional composition and thermo-oxidative stability. However, HO peanut is sensitive to cold stress especially during germination, which limits its distribution in low temperature areas. To understand the molecular mechanism of cold responses in HO peanuts at germination stage, four HO peanut varieties with different cold tolerance were selected in field experiments to analyze their genome-wide gene regulation under low temperatures. High-throughput sequencing and transcriptome analysis revealed a total of 139 429 unigenes. Among these, 3520 common differentially expressed genes (DEG) were detected between two groups of cold-tolerant and cold-sensitive peanuts, and the number of up-regulated genes was greater than that of down-regulated genes in the cold-tolerant peanuts. Gene ontology analysis indicates that the number of DEGs involved in cell membrane metabolism and integrity as well as proteins located in the cell periphery were significantly higher in the cold-tolerant peanuts. KEGG pathway analysis suggests that plant-pathogen interaction and plant hormone signal transduction pathway play important roles in cold tolerance. Four cold-induced genes, TIC(TIME FOR COFFEE), ATX3(histone-lysine N-methyltransferase ATX3-like), AGO4(argonaute 4-like), FER(FERONIA-like receptor protein kinase), and three transcription factor genes, bHLH(bHLH49-like transcription factor), MYB(MYB-related protein 3R-1-like)and EREB(Ethylene-responsive element binding factor 6)were selected to verify the expression profile via real-time quantitative PCR detection. The expression of TIC, ATX3, AGO4, bHLH, MYB and EREB significantly increased within 3 hours after low temperature stress, while the expression of FER significantlyincreased after 12 hours, suggesting that these genes responded to low temperature stress during peanut germination. This work not only sheds light on the transcriptional regulation of HO peanut under low-temperature stress during germination but also provides data resources for screening candidate genes in improving peanuts stress resistance.

[Isolation of the promoter region of HAK gene from Aeluropus littoralis and functional analysis in rice].

The AlHAK1 gene encoding a high-affinity K+ transporter was isolated from Aeluropus littoralis (Gouan) Parl, a graminaceous halophyte, and plays a crucial role in nutrition and ion homeostasis in plant cell. To investigate the regulation role of AlHAK1 on the transcriptional level, an about 1.3 kb 5'-flanking region of the AlHAK1 gene containing a putative promoter was cloned by genome walking method. Cis-regulatory elements analysis showed AlHAK1-promoter region contained typical TATA and CAAT boxes, and some growth and development relative motifs, as well as environmental re-sponsive elements. To reveal the function and regulating role, the AlHAK1 promoter was fused to the ß-glucuronidase (GUS) reporter gene in the pCAMBIA1301 vector and introduced into rice via Agrobacterium-mediated transformation. Histo-chemical staining indicated that the GUS expression directed by AlHAK1 promoter was observed in leaves, stems, roots, anther, lemma, and palea. GUS quantitative fluorometric analysis indicated that GUS activity directed by AlHAK1 promoter was lower than CaMV35S and Ubiquitin constitutive promoters; however, in the roots and stems the GUS activity was rela-tively high and displayed a tissue-specific expression pattern. Under ABA, high temperature or drought stress, the GUS activity directed by AlHAK1 promoter was inducible in the roots and stems, suggesting the elements of HSE (-682 bp) and MybBS (-1 268 bp) might play a role in the inducible regulation.

Total saponins of Albiziae Cortex show anti-hepatoma carcinoma effects by inducing S phase arrest and mitochondrial apoptosis pathway activation.

ETHNOPHARMACOLOGICAL RELEVANCE: Albiziae Cortex (AC) is a widely used traditional medicine in China. It is possess various properties to treat insomnia, traumatic injuries, diuresis, sthenia, and confusion. Total saponins of Albiziae Cortex (TSAC) are the most abundant bioactive components of AC, which were reported to show significant anti-tumor effects in vivo and in vitro. But the underlying mechanism of TSAC remained to be revealed. AIM OF STUDY: In this study, we investigated the anti-hepatoma carcinoma effects and the potential mechanism of TSAC in vivo and in vitro. MATERIALS AND METHODS: We first purified TSAC from crude extracts and characterized the major bioactive compounds by high performance liquid chromatography (HPLC). Effects of TSAC on viability of various hepatoma carcinoma cell lines were measured by MTT. Inhibition on cell proliferation was analysed using colony formation assay. Cell cycle distribution was revealed by flow cytometry. The apoptotic cells were observed by Hoechst 33258 staining and acridine orange (AO)/ethidium bromide (EB) double staining. Microstructures of apoptotic cells were examined by Transmission electron microscopy (TEM). The mitochondrial membrane potential were determined by JC-1 staining. Western blot was used to investigate the effects of TSAC on apoptosis-related proteins, B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax), and S-phase related protein cyclin A, cyclin E and cyclin-dependent kinases 2 (CDK2). Effects on tumor growth was assessed by H22-bearing ICR mice. RESULTS: TSAC significantly decreased the hepatoma carcinoma cell viability and inhibited HepG2 cell colony formation in a concentration-dependent manner. We also found that TSAC inhibited HepG2 cell growth via induction of S phase arrest. Further study showed that TSAC significantly down-regulated the expressions of cyclin A, cyclin E and CDK2 in HepG2 cells. Meanwhile, TSAC could effectively induce mitochondria-dependent caspase apoptosis pathway activation. Furthermore, TSAC increased the expression of pro-apoptotic protein Bax and decreased the expression of anti-apoptotic protein Bcl-2. In vivo assay showed that the anti-tumor effects of TSAC were significantly augmented without increasing toxicity in H22-bearing ICR mice. CONCLUSION: TSAC could inhibit cell proliferation through inducing S phase arrest and activate cell apoptosis via mitochondria-dependent apoptosis pathway. Therefore, TSAC could be a promising agent in clinical trials for anti-hepatoma carcinoma treatment.