Comparative Analysis of Proanthocyanidin Metabolism and Genes Regulatory Network in Fresh Leaves of Two Different Ecotypes of Tetrastigma hemsleyanum

Tetrastigma hemsleyanum Diels et Gilg is a rare and wild medicinal resource. Metabolites, especially secondary metabolites, have an important influence on T. hemsleyanum adaptability and its medicinal quality. The metabolite proanthocyanidin (PA) is a polyphenol compound widely distributed in land plants, which can be used as antioxidants and anticancer agents. Here, we discovered that three types of PA accumulated in large amounts in purple leaves (PL), but not in green leaves (RG), based on widely non-targeted metabolomics. In addition, we further found that catechins and their derivatives, which are the structural units of PA, are also enriched in PL. Afterwards, we screened and obtained five key genes, DNR1/2, ANS, ANR and LAR closely related to PA biosynthesis through transcriptome analysis and found they were all highly expressed in PL compared to RG. Therefore, observed the regulatory relationship between the main compounds and genes network, and the PA metabolism regulatory pathway was complicated, which may be different to other species.

Antioxidant Activity In Vitro Guided Screening and Identification of Flavonoids Antioxidants in the Extract from Tetrastigma hemsleyanum Diels et Gilg

This study aimed to investigate the extract with high antioxidant activity of Tetrastigma hemsleyanum Diels et Gilg and identify the antioxidant components in vitro. α, α-Diphenyl-β-picrylhydrazyl (DPPH) radical assay, Trolox equivalent antioxidant capacity (TEAC) assay, ferric reducing antioxidant power (FRAP), and hydroxyl radical scavenging method were used to screen the extract with high antioxidant activity. The antioxidant capacity of the extracts was evaluated by the free radical scavenging ability of DPPH. The ability of extracts to scavenge 2, 2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical was evaluated by TEAC assay. The FRAP method was used to evaluate the ability of extracts to reduce Fe3+. The ability to scavenge hydroxyl radicals produced by the interaction of hydrogen peroxide and Fe2+ was measured by monitoring the change in the absorbance of the reaction mixture at 536 nm. Then, high-performance liquid chromatography-DPPH (HPLC-DPPH) and HPLC-hydroxyl radical scavenging methods were used to screen the antioxidant components in the extract. The molecular weight of the above antioxidant components was investigated using the qualitative analytical method of high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (HPLC-Q-TOF LC/MS). Based on the concentrations of the samples (0.2–4 mg/mL), the DPPH free radical scavenging ability, ABTS+ free radical scavenging ability, hydroxyl free radical scavenging ability, and Fe3+ reducing ability of the ethyl acetate extract (EAE) were stronger than that of the crude extract (CE), petroleum ether extract (PEE), and n-butanol extract (BE). The EAE has higher antioxidant activity than CE, PEE, and BE. Six antioxidant components, rutin, quercetin, isoquercetin, astragalin, kaempferol, and kaempferol-3-o-rutoside, were identified in the EAE.

Multi-omics Analyses Revealed Key Factors Involved in Fluorescent Carbon-Dots-Regulated Secondary Metabolism in Tetrastigma Hemsleyanum

Background: Luminescent nanomaterials (LNMs), especially newly-exploited fluorescent carbon-dots (CDs), have demonstrated promising candidates for sunlight harvesting and enhanced photosynthesis efficiency of crops. However, most of the studies focus on the design and synthesis of LNMs and primary metabolism in biomass acceleration, secondary metabolism that closely associated with the quality ingredients of plants is rarely mentioned. Results: UV-absorptive and water-soluble NIR-CDs were harvested via a facile microwave-assisted carbonization method. The effect and regulatory mechanism of NIR-CDs on the secondary metabolism and bioactive ingredients accumulation in Tetrastigma hemsleyanum were explored. A total of 191 differential secondary metabolites and 6874 differentially expressed genes were identified when the NIR-CDs were adopted for enhancing growth of T. hemsleyanum. The phenolic acids were generally improved, but the flavonoids were more likely to decrease. The pivotal differentially expressed genes were involved in biosynthesis of secondary metabolites, flavonoid biosynthesis, porphyrin and chlorophyll metabolism, etc. The gene-metabolite association was constructed and 44 hub genes highly related to quality ingredients accumulation and growth were identified, among which and the top 5 genes of the PPI network might be the key regulators.Conclusion: This research provided key regulatory genes and differentially accumulating quality ingredients under NIR-CDs-treatment, which could provide a theoretical basis for expanding the applications of nanomaterial in industrial crop agriculture.

Tetrastigma hemsleyanum flavones exert anti-hepatic carcinoma property both in vitro and in vivo

Tetrastigma hemsleyanum has been regarded as an anticancer food in China. However, its corresponding mechanisms remains unclear. Thus, in this study, the antitumor activity of flavones-rich fraction of root of Tetrastigma hemsleyanum (FRTH) was investigated in vitro and in vivo. The results indicated that FRTH could inhibit the proliferation and migration of HepG2 cells in vitro by PI3K/AKT pathway. FRTH could increase the ROS level and change the mitochondrial membrane potential (MMP) in HepG2 cells. In addition, FRTH treatment (300, 600 mg/kg BW) significantly suppressed tumor growth on HepG2 tumor-bearing nude mice. Besides, immunohistochemistry assays and western blotting revealed that FRTH enhanced the expression level of Bax/Bcl-2, cytochrome C, Caspase-3, caspase-9, Cleaved-caspase-3, and downregulated the expression level of CD31, ki67 and VEGF in HepG2 tumor-bearing mice. Our study suggests Tetrastigma hemsleyanum as a promising candidate medicine for liver cancer treatment.

Metabolism of Phenolics of Tetrastigma hemsleyanum Roots under In Vitro Digestion and Colonic Fermentation as Well as Their In Vivo Antioxidant Activity in Rats

Tetrastigma hemsleyanum Diels et Gilg is a herbaceous perennial species distributed mainly in southern China. The Tetrastigma hemsleyanum root (THR) has been prevalently consumed as a functional tea or dietary supplement. In vitro digestion models, including colonic fermentation, were built to evaluate the release and stability of THR phenolics with the method of HPLC-QqQ-MS/MS and UPLC-Qtof-MS/MS. From the oral cavity, the contents of total phenolic and flavonoid began to degrade. Quercetin-3-rutinoside, quercetin-3-glucoside, kaempferol-3-rutinoside, and kaempferol-3-glucoside were metabolized as major components and they were absorbed in the form of glycosides for hepatic metabolism. On the other hand, the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activity, and glutathione (GSH) content were significantly increased, while malondialdehyde (MDA) content was decreased in plasma and tissues of rats treated with THR extract in the oxidative stress model. These results indicated that the THR extract is a good antioxidant substance and has good bioavailability, which can effectively prevent some chronic diseases caused by oxidative stress. It also provides a basis for the effectiveness of THR as a traditional functional food.