Two new C-glycosylflavones from the leaves of Iris lactea var. chinensis

Two new acylated C-glycosylflavones were isolated from the leaves of Iris lactea var. chinensis, and their structures were elucidated on the basis of extensive NMR experiments and mass spectrometry methods and were assigned as 5-hydroxy-4＇- methoxyflavone-7-O-（β-D-2＇＇＇＇4＇＇＇＇-diacetylrhamnopyranosyl）-6-C-[ O-（α-L-6＇＇＇-acetyl-glucpyranosyl）-1→2-β-D-glucopyrano- side] （irislactin A） and 5-hydroxy-4＇,7-dimethoxyflavone-6-C-[O-（α-L-2＇＇＇,3＇＇＇-diacetylrhanmo-pyranosyl）-1→ 2-β-D-glucopyranoside] （irislactin B）.

Integration of full-length transcriptomics and targeted metabolomics to identify benzylisoquinoline alkaloid biosynthetic genes in Corydalis yanhusuo

Corydalis yanhusuo W.T.Wang is a classic herb that is frequently used in traditional Chinese medicine and is efficacious in promoting blood circulation,enhancing energy,and relieving pain.Benzylisoquinoline alkaloids(BIAs)are the main bioactive ingredients in Corydalis yanhusuo.However,few studies have investigated the BIA biosynthetic pathway in C.yanhusuo,and the biosynthetic pathway of species-specific chemicals such as tetrahydropalmatine remains unclear.We performed full-length transcriptomic and metabolomic analyses to identify candidate genes that might be involved in BIA biosynthesis and identified a total of 101 full-length transcripts and 19 metabolites involved in the BIA biosynthetic pathway.Moreover,the contents of 19 representative BIAs in C.yanhusuo were quantified by classical targeted metabolomic approaches.Their accumulation in the tuber was consistent with the expression patterns of identified BIA biosynthetic genes in tubers and leaves,which reinforces the validity and reliability of the analyses.Full-length genes with similar expression or enrichment patterns were identified,and a complete BIA biosynthesis pathway in C.yanhusuo was constructed according to these findings.Phylogenetic analysis revealed a total of ten enzymes that may possess columbamine-O-methyltransferase activity,which is the final step for tetrahydropalmatine synthesis.Our results span the whole BIA biosynthetic pathway in C.yanhusuo.Our full-length transcriptomic data will enable further molecular cloning of enzymes and activity validation studies.

Two types of coumarins-specific enzymes complete the last missing steps in pyran- and furanocoumarins biosynthesis

Pyran-and furanocoumarins are key representatives of tetrahydropyrans and tetrahydrofurans,respectively,exhibiting diverse physiological and medical bioactivities.However,the biosynthetic mechanisms for their core structures remain poorly understood.Here we combined multiomics analyses of biosynthetic enzymes in Peucedanum praeruptorum and in vitro functional verification and identified two types of key enzymes critical for pyran and furan ring biosynthesis in plants.These included three distinct P.praeruptorum prenyltransferases(PpPT1e3)responsible for the prenylation of the simple coumarin skeleton 7 into linear or angular precursors,and two novel CYP450 cyclases(PpDC and PpOC)crucial for the cyclization of the linear/angular precursors into either tetrahydropyran or tetrahydrofuran scaffolds.Biochemical analyses of cyclases indicated that acid/base-assisted epoxide ring opening contributed to the enzyme-catalyzed tetrahydropyran and tetrahydrofuran ring refactoring.The possible acid/base-assisted catalytic mechanisms of the identified cyclases were theoretically investigated and assessed using site-specific mutagenesis.We identified two possible acidic amino acids Glu303 in PpDC and Asp301 in PpOC as vital in the catalytic process.This study provides new enzymatic tools in the epoxide formation/epoxide-opening mediated cascade reaction and exemplifies how plants become chemically diverse in terms of enzyme function and catalytic process.

Effects of ethanol extract of Bombax ceiba leaves and its main constituent mangiferin on diabetic nephropathy in mice

The present study was designed to explore the mechanism by which ethanol extract of Bombax ceiba leaves(BCE) and its main constituent mangiferin(MGF) affect diabetic nephropathy by combating oxidative stress. Oral administration of BCE and MGF to normal and streptozotocin(STZ)-induced diabetic mice were carried out. Fasting blood glucose, 24-h urinary albumin, serum creatinine, and blood urea nitrogen were tested, histopathology, and immunohistochemical analysis of kidney tissues were performed. Moreover, mesangial cells were treated with BCE and MGF for 48 h with or without 25 mmol·L^(-1) of glucose. Immunofluorescence, Western blot and apoptosis analyses were used to investigate their regulation of oxidative stress and mitochondrial function. BCE and MGF ameliorated biochemical parameters and restored STZ-induced renal injury in the model mice. In vitro study showed that high glucose stimulation increased oxidative stress and cell apoptosis in mesangial cells. BCE and MGF limited mitochondrial membrane potential(Δψm) collapse by inhibiting Nox4, mitochondrially bound hexokinase II dissociation, and subsequent ROS production, which effectively reduced oxidative stress, cleaved caspase-3 expression and cell apoptosis. Our work indicated that BCE and MGF had protective effects on diabetic caused kidney injury and prevented oxidative stress in mesangial cells by regulation of hexokinase II binding and Nox4 oxidase signaling.

Antihyperglycemic,antihyperlipidemic and antioxidant effects of standard ethanol extract of Bombax ceiba leaves in high-fat-diet-and streptozotocin-induced Type 2 diabetic rats

The present study aimed at exploring the therapeutic potential of standard extract of Bombax ceiba L.leaves(BCE) in type 2 diabetic mellitus(T2DM).Oral administration of BCE at doses of 70,140,and 280 mg·kg^(-1),to the normal rats and the high-fat-diet-and streptozotocin-induced T2 DM rats were carried out.Effects of BCE on blood glucose,body weight,and a range of serum biochemical parameters were tested,and histopathological observation of pancreatic tissues was also performed.HPLC-ESI-Q/TOF-MS/MS analysis indicated that the chemical composition of BCE mainly contained mangiferin,isoorientin,vitexin,isomangiferin,isovitexin,quercetin hexoside,2'-trans-O-cumaroyl mangiferin,and nigricanside.BCE caused a significant decrease in the concentrations of fasting blood glucose,glycosylated hemoglobin,total cholesterol,triglyceride,low density lipoprotein-cholesterol,serum insulin,and malondialdehyde,and increases in oral glucose tolerance,high density lipoprotein-cholesterol,and superoxide dismutase in the T2 DM model rats.Moreover,considerable pancreatic β-cells protection effect and stimulation of insulin secretion from the remaining pancreatic β-cells could be observed after BCE treatment.The results indicated that BCE exhibited an excellent hypoglycemic activity,and alleviated dyslipidemia which is associated with T2 DM.Antioxidant activity and protecting pancreatic β-cells are the possible mechanisms involved in anti-diabetic activity of BCE.

Molecular diversity analysis of Tetradium ruticarpum(Wu Zhu Yu) in China based on inter-primer binding site(iPBS) markers and inter-simple sequence repeat(ISSR) markers

"Wu zhu yu", which is obtained from the dried unripe fruits of Tetradium ruticarpum(A. Jussieu) T. G. Hartley, has been used as a traditional Chinese medicine for treatment of headaches, abdominal colic, and hypertension for thousands of years. The present study was designed to assess the molecular genetic diversity among 25 collected accessions of T. ruticarpum(Wu zhu yu in Chinese) from different areas of China, based on inter-primer binding site(i PBS) markers and inter-simple sequence repeat(ISSR) markers. Thirteen ISSR primers generated 151 amplification bands, of which 130 were polymorphic. Out of 165 bands that were amplified using 10 iPBS primers, 152 were polymorphic. The iPBS markers displayed a higher proportion of polymorphic loci(PPL = 92.5%) than the ISSR markers(PPL = 84.9%). The results showed that T. ruticarpum possessed high loci polymorphism and genetic differentiation occurred in this plant. The combined data of iPBS and ISSR markers scored on 25 accessions produced five clusters that approximately matched the geographic distribution of the species. The results indicated that both iPBS and ISSR markers were reliable and effective tools for analyzing the genetic diversity in T. ruticarpum.

Cause and control of Radix Ophiopogonis browning during storage

In the storage of Radix Ophiopogonis, browning often happens to cause potential risk with regard to safety. Previously few reports investigate the browning of Radix Ophiopogonis. In this research, the causes and mechanisms of the browning of Radix Ophiopogonis were preliminarily elucidated. Content determination by high-performance liquid chromatography(HPLC) and spectrophotometry, enzyme activity determination by colorimetry, and morphological observation by electron microscopy were performed in the present study. Uniform design and three-dimensional response surfaces were applied to investigate the relationship between browning and storage factors. The cortex cell wall of browned Radix Ophiopogonis was ruptured. Compared with the normal Radix Ophiopogonis, cellulase and polyphenol oxidase enzymes were activated, the levels of 5-hydroxymethylfurfural(5-HMF), total sugars, and reducing sugars were increased, while the levels of polysaccharides and methylophiopogonanone A were decreased in browned Radix Ophiopogonis. The relationship between the storage factors and degree of browning(Y) could be described by following correlation equation: Y =- 0.625 4 + 0.020 84 × X3 + 0.001 514 × X1× X2 – 0.000 964 4 × X2× X3. Accompanied with browning under storage conditions, the chemical composition of Radix Ophiopogonis was altered. Following the activation of cellulase, the rupture of the cortex cell wall and the outflow of cell substances flowed out, which caused the Radix Ophiopogonis tissue to become soft and sticky. The main causes of the browning were the production of 5-HMF, the activation of polyphenol oxidase, Maillard reactions and enzymatic browning. Browning could be effectively prevented when the air relative humidity(HR), temperature, and moisture content were under 25% RH, 12°C and 18%, respectively.

C-glycosylflavones from the leaves of Iris tectorum Maxim.

A new C-glycosylflavone,5-hydroxyl-4′,7-dimethoxyflavone-6-C-[0-(α-L-3″-acetylrhamno-pyranosy)-1→2-β-D-glucopyranoside](1),along with five known C-glycosylflavones,5-hydroxy-4′,7-dimethoxyfavone-6-C-[0-(α-L-2′″-acetylrhamnopyranosy1)-1→2-β-D-glucopyranoside](2),embinin(3),embigenin(4),swertisin(5)and swertiajaponin(6)were isolated from the leaves of Iris tectorum Maxim.Their structures were elucidated on the basis of extensive NM R experiments and spectral methods and their cytotoxic activities against A 549(lung cancer)human cell lines were determined.