Anti-diabetic effect of Ornithogalum caudatum Jacq. polysaccharides via the PI3K/Akt/GSK-3ß signaling pathway and regulation of gut microbiota.

This study evaluated the anti-diabetic effect of polysaccharides isolated from Ornithogalum caudatum and their underlying mechanisms. To achieve this, a type 2 diabetes mellitus mouse model was established using a combination of a high-fat diet and low-dose streptozotocin injection. The mice were treated with Ornithogalumcaudatum polysaccharides (OCPs) for 4 weeks. OCPs treatment significantly decreased body weight loss, fasting blood glucose levels, and plasma insulin levels in diabetic mice. Additionally, compared with the untreated group, OCPs treatment significantly decreased total cholesterol, triacylglycerol, and low-density lipoprotein-cholesterol levels, but increased those of high-density lipoprotein-cholesterol in diabetic mice. Moreover, antioxidant enzyme activity and histopathology results revealed that OCPs effectively alleviated oxidative stress and streptozotocin-induced lesions by increasing antioxidant enzyme activity. Results from mechanistic studies showed that OCPs treatment significantly increased the expression of p-PI3K, p-Akt, and p-GSK-3ß in the liver. Moreover, OCPs optimized the gut microbiota composition of diabetic mice by significantly decreasing the Firmicutes/Bacteroidetes ratio and increasing the levels of beneficial bacteria (Muribaculaceae_norank, Prevotellaceae_UCG-001 and Alloprevotella). Overall, these findings suggest that OCPs exert anti-diabetic effects by triggering the PI3K/Akt/GSK-3ß signaling pathway and regulating the gut microbiota.

Optimum Reaction Conditions for the Synthesis of Selenized Ornithogalum caudatum Ait. (Liliaceae) Polysaccharides and Measurement of Their Antioxidant Activity In Vivo.

This study determined the optimum reaction conditions for synthesizing selenium-containing polysaccharides. Polysaccharide IIA (with the highest yield) from Ornithogalum caudatum Ait. (Liliaceae) (OCAPIIA) was extracted and purified. Then, three parameters were selected to optimize the synthesis of selenized OCAPIIA (Se-OCAPIIA) using the Box-Behnken design (BBD) and response surface methodology (RSM). The morphology of Se-OCAPIIA was analyzed by scanning electron microscopy (SEM). The characteristic peaks and the monosaccharide composition of Se-OCAPIIA were evaluated by Fourier-transform infrared spectroscopy and gas chromatography. A D-galactose-induced aging mouse model was established, and the in vivo antioxidant activity of Se-OCAPIIA was measured. The optimal conditions for the synthesis of Se-OCAPIIA were as follows: reaction temperature, 72.38 °C; Na2SeO3 to OCAPIIA mass ratio, 0.93 g/g; and reaction time, 8.05 h. The selenium content of Se-OCAPIIA obtained using the optimized process was 3.131 ± 0.090 mg/g, close to the maximum predicted value (3.152 mg/g). Se-OCAPIIA contained D-mannose, D-glucose, and D-galactose at a molar ratio of 1.00:0.34:0.88. SEM showed that Se-OCAPIIA was spherical and flocculated. Compared with OCAPIIA, Se-OCAPIIA exhibited two characteristic peaks at 833 and 610 cm-1 in the infrared spectrum. Se-OCAPIIA increased catalase, glutathione peroxidase, and superoxide dismutase activities and decreased MDA concentrations in the mouse liver. Moreover, Se-OCAPIIA treatment improved liver morphology, decreased the levels of IL-1ß and IL-6, and increased IL-10 concentration. In conclusion, the synthesis of Se-OCAPIIA is effective, simple, and feasible. Se-OCAPIIA demonstrated high antioxidant activity in vivo and is a promising antioxidant and therapeutic agent.

Characterization of two flavonol synthases with iron-independent flavanone 3-hydroxylase activity from Ornithogalum caudatum Jacq.

BACKGROUND: Flavonol synthase (FLS) is the key enzyme responsible for the biosynthesis of flavonols, the most abundant flavonoids, which have diverse pharmaceutical effects. Flavonol synthase has been previously found in other species, but not yet in Ornithogalum caudatum. RESULTS: The transcriptome-wide mining and functional characterisation of a flavonol synthase gene family from O. caudatum were reported. Specifically, a small FLS gene family harbouring two members, OcFLS1 and OcFLS2, was isolated from O. caudatum based on transcriptome-wide mining. Phylogenetic analysis suggested that the two proteins showed the closest relationship with FLS proteins. In vitro enzymatic assays indicated OcFLS1 and OcFLS2 were flavonol synthases, catalysing the conversion of dihydroflavonols to flavonols in an iron-dependent fashion. In addition, the two proteins were found to display flavanone 3ß-hydroxylase (F3H) activity, hydroxylating flavanones to form dihydroflavonols. Unlike single F3H enzymes, the F3H activity of OcFLS1 and OcFLS2 did not absolutely require iron. However, the presence of sufficient Fe2+ was demonstrated to be conducive to successive catalysis of flavanones to flavonols. The qRT-PCR analysis demonstrated that both genes were expressed in the leaves, bulbs, and flowers, with particularly high expression in the leaves. Moreover, their expression was regulated by developmental and environmental conditions. CONCLUSIONS: OcFLS1 and OcFLS2 from O. caudatum were demonstrated to be flavonol synthases with iron-independent flavanone 3-hydroxylase activity.

Toll-like receptor 4-related regulation of Ornithogalum caudatum extract on inflammatory responses in LPS activated macrophages / 中国药理学与毒理学杂志

OBJECTIVE To investigate toll-like receptor 4(TLR4)-related the regulation of Ornithog-alum caudatum extract(OCE)on inflammatory responses in lipopolysaccharide(LPS)activated macro-phages.METHODS Primary peritoneal macrophage,Raw 264.7,and THP-1 were incubated in 96-well plate for 24 h and treated with OCE of the concentration of 0-400 μg/ml for 4h.The viability of cells was measured by MTT assay.Specific concentrations of OCE were added into the medium of primary peri-toneal macrophage, Raw 264.7, and THP-1, respectively, then following with lipopolysaccharides (LPS). Cells were harvested and the total cellular protein and nuclear protein were extracted, and the protein content was determined using BCA protein assay Kit.The expressions of TLR4,inducible nitric oxide synthase(iNOS),cyclooxygenase 2(COX-2),α-inhibitor of NF-κB(IκB-α)and nuclear factor-κB (NF-κB)were assayed by Western blot.The expressions of interleukin-1α(IL-1α),interleukin-1β(IL-1β), interleukin-18(IL-18),and tumor necrosis factor-α(TNF-α)were measured by RT-PCR.RESULTS The results of MTT showed that OCE has no cytotoxicity in Raw 264.7 cells between 1.56 μg/ml and 400 μg/ml. Compared with normal group,the expressions of TLR4,iNOS,COX-2,NF-κB and IL-1α,IL-1β,IL-18, TNF-α,the level of nitric oxide(NO)were significantly increased by LPS stimulation,while OCE pretreat-ment reduced these increase induced by LPS. However, OCE pretreatment reversed the reduction of IκB-α after LPS stimulation.CONCLUSION OCE might suppress TLR4 expression and block the inflamma-tion process of NF-κB and iNOS,further decrease the expression of COX-2 and inhibit the release of inflammatory factors.

cDNA isolation and functional characterization of squalene synthase gene from Ornithogalum caudatum.

As the first step of ongoing efforts to investigate the genes responsible for the biosynthesis of steroidal saponins in the medicinal plant Ornithogalum caudatum, this investigation reported the cDNA isolation, prokaryotic expression and functional characterization of squalene synthase (SQS) gene from O. caudatum for the first time. Specifically, two unigenes showing high sequence identity to SQS were retrieved from RNA-Taq data, and then a full-length OcSQS1 corresponding to the two unigenes was isolated from O. caudatum genome by a nested PCR assay. The open reading frame of OcSQS1 was 1230 bp and encoded a polypeptide of 409 aa. OcSQS1 was predicted to be a membrane-bound protein with at least four conserved motifs associated with binding, regulatory and catalytic activities of OcSQS1 and two transmembrane domains. Next, many attempts to generate soluble OcSQS1 in heterologous Escherichia coli were made, including optimization of expression conditions, application of varied expression plasmids with different tags, secretory peptides and molecular chaperones, and truncated mutation of OcSQS1. Finally, the successful availability of a soluble, truncated OcSQS1 mutant was achieved by combinational use of the utensils from the vast genetic toolbook. Moreover, this truncated OcSQS1 mutant retained the folding capability as well as its catalytic activity, converting FPP to form squalene. Importantly, the present research tentatively verified the involvement of the second transmembrane domain in the proper folding of the recombinant OcSQS1 protein.

cDNA Isolation and Functional Characterization of UDP-d-glucuronic Acid 4-Epimerase Family from Ornithogalum caudatum.

d-Galacturonic acid (GalA) is an important component of GalA-containing polysaccharides in Ornithogalum caudatum. The incorporation of GalA into these polysaccharides from UDP-d-galacturonic acid (UDP-GalA) was reasonably known. However, the cDNAs involved in the biosynthesis of UDP-GalA were still unknown. In the present investigation, one candidate UDP-d-glucuronic acid 4-epimerase (UGlcAE) family with three members was isolated from O. caudatum based on RNA-Seq data. Bioinformatics analyses indicated all of the three isoforms, designated as OcUGlcAE1~3, were members of short-chain dehydrogenases/reductases (SDRs) and shared two conserved motifs. The three full-length cDNAs were then transformed to Pichia pastoris GS115 for heterologous expression. Data revealed both the supernatant and microsomal fractions from the recombinant P. pastoris expressing OcUGlcAE3 can interconvert UDP-GalA and UDP-d-glucuronic acid (UDP-GlcA), while the other two OcUGlcAEs had no activity on UDP-GlcA and UDP-GalA. Furthermore, expression analyses of the three epimerases in varied tissues of O. caudatum were performed by real-time quantitative PCR (RT-qPCR). Results indicated OcUGlcAE3, together with the other two OcUGlcAE-like genes, was root-specific, displaying highest expression in roots. OcUGlcAE3 was UDP-d-glucuronic acid 4-epimerase and thus deemed to be involved in the biosynthesis of root polysaccharides. Moreover, OcUGlcAE3 was proposed to be environmentally induced.

Transcriptome-guided gene isolation and functional characterization of UDP-xylose synthase and UDP-D-apiose/UDP-D-xylose synthase families from Ornithogalum caudatum Ait.

KEY MESSAGE: The present study first identified the involvement of OcUAXS2 and OcUXS1-3 in anticancer polysaccharides biosynthesis in O. caudatum. UDP-xylose synthase (UXS) and UDP-D-apiose/UDP-D-xylose synthase (UAXS), both capable of converting UDP-D-glucuronic acid to UDP-D-xylose, are believed to transfer xylosyl residue to anticancer polysaccharides biosynthesis in Ornithogalum caudatum Ait. However, the cDNA isolation and functional characterization of genes encoding the two enzymes from O. caudatum has never been documented. Previously, the transcriptome sequencing of O. caudatum was performed in our laboratory. In this study, a total of six and two unigenes encoding UXS and UAXS were first retrieved based on RNA-Seq data. The eight putative genes were then successfully isolated from transcriptome of O. caudatum by reverse transcription polymerase chain reaction (RT-PCR). Phylogenetic analysis revealed the six putative UXS isoforms can be classified into three types, one soluble and two distinct putative membrane-bound. Moreover, the two UAXS isoenzymes were predicted to be soluble forms. Subsequently, these candidate cDNAs were characterized to be bona fide genes by functional expression in Escherichia coli individually. Although UXS and UAXS catalyzed the same reaction, their biochemical properties varied significantly. It is worth noting that a ratio switch of UDP-D-xylose/UDP-D-apiose for UAXS was established, which is assumed to be helpful for its biotechnological application. Furthermore, a series of mutants were generated to test the function of NAD+ binding motif GxxGxxG. Most importantly, the present study determined the involvement of OcUAXS2 and OcUXS1-3 in xylose-containing polysaccharides biosynthesis in O. caudatum. These data provide a comprehensive knowledge for UXS and UAXS families in plants.

[Research ontherapeutics effect of extract of Ornithogalum caudatum on liver fibrosis].

Rat models of liver fibrosis were made by carbon tetrachloride, and the serum levels of AST, ALT, γ-GT, MDA, GSH-px, SOD were detected, serum markers of PCⅢ, IV-C, LN, HA were detected by ELISA method. HE and Masson staining were conducted in hepatic tissues to observe pathological variations. Collagen Ⅲ, TGF-ß, α-SMA, E-cadherin were detected by Western blot. The curative effect of the extract of Ornithogalum caudatum on rat liver fibrosis induced by CCl4was observed and the mechanism was discussed. The experiment results showed that the extract of O. caudatum (50, 150, 500 mg•kg⁻¹) obviously decreased the serum levels of AST, ALT, γ-GT, MDA, increased the serum levels of GSH-px, SOD, decreased the expression of serum markers of PCⅢ, IV-C, LN, HA, and improved the liver pathological variations of fibrotic rats. The experiment proved that the extract of O. caudatum could treat the liver fibrogenesis induced by CCl4 in rats. The positive medicine may inhibit accumulation of extracellular and activate hepatic stellate cell and epithelial-mesenchymal transition.

Research ontherapeutics effect of extract of Ornithogalum caudatum on liver fibrosis / 中国中药杂志

Rat models of liver fibrosis were made by carbon tetrachloride, and the serum levels of AST, ALT, γ-GT, MDA, GSH-px, SOD were detected, serum markers of PCⅢ, IV-C, LN, HA were detected by ELISA method. HE and Masson staining were conducted in hepatic tissues to observe pathological variations. Collagen Ⅲ, TGF-β, α-SMA, E-cadherin were detected by Western blot. The curative effect of the extract of Ornithogalum caudatum on rat liver fibrosis induced by CCl4was observed and the mechanism was discussed. The experiment results showed that the extract of O. caudatum (50, 150, 500 mg•kg⁻¹) obviously decreased the serum levels of AST, ALT, γ-GT, MDA, increased the serum levels of GSH-px, SOD, decreased the expression of serum markers of PCⅢ, IV-C, LN, HA, and improved the liver pathological variations of fibrotic rats. The experiment proved that the extract of O. caudatum could treat the liver fibrogenesis induced by CCl4 in rats. The positive medicine may inhibit accumulation of extracellular and activate hepatic stellate cell and epithelial-mesenchymal transition.

Antitumor, analgesic, and anti-inflammatory effects of Ornithogalum caudatum extracts / 中草药

Objective: To investigate the antitumor, analgesic, and anti-inflammatory effects of Ornithogalum caudatum extract (OCE). Methods: The MFC, HepG-2, and S180 tumor-bearing mice models were established, and the tumor inhibitory rate of OCE was calculated; The analgesic effect of OCE was observed by acetic acid writhing test of mice; The anti-inflammatory effect of OCE was observed in xylene-induced ear edema model of mice. Results: OCE (5.0 and 2.5 g/kg) could effectively inhibit the growth of solid tumors in tumor-bearing mice in a dose-dependent manner (P < 0.05, 0.001); Compared with the model group, OCE (5.0 and 2.5 g/kg) could significantly inhibit the writhing response (P < 0.05, 0.001) and xylene-induced ear edama (P < 0.05, 0.01). Conclusion: OCE has certain antitumor, analgesic, and anti-inflammatory effects, suggesting they may be worth further investigation.