Genome-enabled discovery of anthraquinone biosynthesis in Senna tora.

Senna tora is a widely used medicinal plant. Its health benefits have been attributed to the large quantity of anthraquinones, but how they are made in plants remains a mystery. To identify the genes responsible for plant anthraquinone biosynthesis, we reveal the genome sequence of S. tora at the chromosome level with 526 Mb (96%) assembled into 13 chromosomes. Comparison among related plant species shows that a chalcone synthase-like (CHS-L) gene family has lineage-specifically and rapidly expanded in S. tora. Combining genomics, transcriptomics, metabolomics, and biochemistry, we identify a CHS-L gene contributing to the biosynthesis of anthraquinones. The S. tora reference genome will accelerate the discovery of biologically active anthraquinone biosynthesis pathways in medicinal plants.

Quercetin 3-O-xyloside ameliorates acute pancreatitis in vitro via the reduction of ER stress and enhancement of apoptosis.

BACKGROUND AND PURPOSE: Glycosylation of phenolic compounds has been reported to increase water-solubility, reduce toxicity, and sometimes give improved or novel pharmacological activities. Present study was aimed to evaluate and compare the beneficial effects of quercetin aglycone (Quer) and its glycosylated derivative, quercetin 3-O-xyloside (Quer-Xyl), against acute pancreatitis (AP). METHODS: The cellular acute pancreatitis model was established by treating the rat pancreatic acinar cells (AR42J) with lipopolysaccharide (10 µg/ml) and cerulein (10-7 M). The cytotoxicity of Quer or Quer-Xyl on AR42J cells was assessed by MTT assay. Calcium and ROS levels were fluorometrically determined. The ER stress levels (PERK, GRP78), expression levels of amylase and lipase, and apoptotic markers (caspase-3 and -9) were measured by RT-PCR, western blotting, or fluorometric assay. RESULTS: While Quer increased the mRNA expressions of AP marker enzymes, amylase and lipase, Quer-Xyl dose-dependently reversed their expressions. Quer-Xyl suppressed intracellular ROS production and both mRNA and protein levels of GRP78 and PERK, which were significantly elevated in cerulein and LPS-treated AR42J cells. Further, RT-PCR and fluorescence assay revealed that Quer-Xyl dose-dependently augmented the mRNA expressions and activities of caspase-3 and -9. CONCLUSION: These results showed that Quer-Xyl, but not Quer, has a significant anti-pancreatitis activity through attenuating intracellular ROS production and ER stress response and enhancing apoptotic cell death, suggesting that it might be useful as a potent functional ingredient in health-beneficial foods or as a therapeutic agent to prevent or treat AP.

Glycosylation and subsequent malonylation of isoflavonoids in E. coli: strain development, production and insights into future metabolic perspectives.

Genistin and daidzein exhibit a protective effect on DNA damage and inhibit cell proliferation. Glycosylation and malonylation of the compounds increase water solubility and stability. Constructed pET15b-GmIF7GT and pET28a-GmIF7MAT were used for the transformation of Escherichia coli and bioconversion of genistein and daidzein. To increase the availability of malonyl-CoA, a critical precursor of GmIF7MAT, genes for the acyl-CoA carboxylase α and ß subunits (nfa9890 and nfa9940), biotin ligase (nfa9950), and acetyl-CoA synthetase (nfa3550) from Nocardia farcinia were also introduced. Thus, the isoflavonoids were glycosylated at position 7 by 7-O-glycosyltranferase and were further malonylated at position 6(″) of glucose by malonyl-CoA: isoflavone 7-O-glucoside-6(″)-O-malonyltransferase both from Glycine max. Engineered E. coli produced 175.7 µM (75.90 mg/L) of genistin and 14.2 µM (7.37 mg/L) genistin 6''-O-malonate. Similar conditions produced 162.2 µM (67.65 mg/L) daidzin and 12.4 µM (6.23 mg/L) daidzin 6''-O-malonate when 200 µM of each substrate was supplemented in the culture. Based on our findings, we speculate that isoflavonoids and their glycosides may prove useful as anticancer drugs with added advantage of increased solubility, stability and bioavailability.