To investigate the effects of processing with different types of tea infusions on the phenolic components in herbal medicines, this study utilized the Zhuang medicine Tylophora ovata as a model to evaluate the content variations of its characteristic constituents, p-hydroxyacetophenone and paeonol, and to elucidate the underlying mechanisms. High-performance liquid chromatography (HPLC) was employed for quantitative analysis. Ultraviolet (UV) spectroscopy combined with molecular docking was utilized to exclude detection interference from the physical complexation of alkaloids, specifically caffeine and tylophorine. Furthermore, a simulated processing system was established to evaluate the impact of tea polyphenols on the retention rates of these phenolic compounds. Quantitative results indicate that, compared with the raw sample group, the content of p-hydroxyacetophenone significantly increased in the green tea-, white tea-, and dark tea-processed groups, but significantly decreased in the black tea- and yellow tea-processed groups. Meanwhile, paeonol levels declined across all tea infusion-processed groups, with reduction rates ranging from 4.0% to 11.4%. Mechanistic studies confirm that the binding affinities between the two phenolic compounds and the primary alkaloids were exceedingly weak, ensuring their physicochemical independence. The universal depletion of paeonol was primarily governed by high-temperature physical volatilization, upon which tea polyphenols exerted limited influence. In contrast, the variation in p-hydroxyacetophenone content was dictated by a dynamic competition between “thermal dissolution-induced release” and “oxidative degradation-induced consumption”, wherein tea polyphenols provided substantial antioxidant protection. This study clarified the chemical mechanisms by which different tea infusions modulate the retention of phenolic compounds, providing a scientific basis for the rational selection of specific tea types as processing excipients for toxic ethnomedicines.
Regulating the cold resistance of tea plants is of great significance to the overwintering cultivation, stable yield and quality improvement of the tea industry. To explore the effect of plant growth regulators on the low temperature tolerance in tea plants, a tea cultivar ‘Baojing Huangjincha 1' was used as the experimental material in this study. Under the condition of natural low temperature, the leaves were sprayed with indole butyric acid·S-abscisic acid compound at concentration of 1 000 times (active ingredient 0.01 mg·L-1, C1), 500 times (active ingredient 0.02 mg·L-1, C2) and 250 times dilution (active ingredient 0.04 mg·L-1, C3), with water sprayed onto the leaves as the control. The agronomic traits, photosynthetic parameters, relative chlorophyll content (SPAD value), main quality components (tea polyphenols and free amino acids) and stress-resistant physiological indexes (peroxidase activity and malondialdehyde content) of tea plants were systematically determined to comprehensively evaluate the physiological regulation effect of the compound on the cold tolerance of tea plants. RNA-seq analysis was further used for exploring its mechanism at a molecular level. The results show that spraying the compound agent improved leaf growth (length, width and thickness), significantly improved photosynthetic performance such as net photosynthetic rate and stomatal conductance (P<0.05), increased SPAD value, tea polyphenol and free amino acid contents, significantly enhanced POD activity and reduced MDA accumulation (P<0.05), and effectively alleviated membrane lipid peroxidation damage caused by low temperature. Principal component analysis shows that the best treatment was C2 (active ingredient 0.02 mg·L-1). Transcriptome analysis shows that there were 1 150 differentially expressed genes in the C2 treatment compared with the control, of which 674 were up-regulated and 476 were down-regulated. KEGG enrichment analysis shows that the differential genes were mainly enriched in monoterpene biosynthesis, glutathione metabolism, linoleic acid metabolism, flavonoid biosynthesis, zeatin synthesis, carbon metabolism, riboflavin metabolism and secondary metabolite biosynthesis. This study reveals the mechanism of indolebutyric acid·S-abscisic acid to enhance the low temperature adaptability of tea plants by synergistically regulating photosynthetic characteristics, antioxidant system and secondary metabolic network at physiological and molecular levels, which provided a theoretical basis for the cultivation and management of cold-resistant tea plants and the breeding of cold-resistant cultivars.
Tea plant is an important economic crop in China, and its growth is easily affected by temperature. Low-temperature stress severely limits its yield and quality. Flavonols, as secondary metabolites of plants, have been proven to be involved in abiotic stress responses. The metabolism of flavonols is regulated by a network of multiple genes. Our research team previously screened transcriptome sequencing data and identified a significantly differentially expressed gene, CsCYP75B1 (CSS0048905), in the flavonol biosynthesis pathway under low temperature. CsCYP75B1 belongs to the cytochrome P450 family and encodes a F3'H enzyme, which is a key enzyme in the flavonoid biosynthesis. The function of CsCYP75B1 in tea plant response to low temperature is unclear. To explore the molecular mechanism of CsCYP75B1 in regulating flavonol metabolism in tea plants under low temperature, this experiment analyzed the cloned CsCYP75B1 using bioinformatics methods and verified its function through heterologous transformation of Arabidopsis thaliana and transient silencing experiments in tea plants. The results show that the promoter region of the CsCYP75B1 gene contains a low temperature response element (LTR), and the expression of CsCYP75B1 was upregulated under low temperature, thereby promoting flavonol accumulation. Overexpressing CsCYP75B1 in Arabidopsis thaliana significantly enhanced plant cold tolerance, increased antioxidant enzyme activity, reduced membrane lipid peroxidation, and positively regulated the expression of key genes in the ICE-CBF-COR pathway. Transient silencing of the CsCYP75B1 gene in tea plants resulted in reduced flavonol synthesis in leaves and decreased antioxidant capacity. This study reveals the molecular mechanism by which the CsCYP75B1 gene in tea plants positively regulates flavonol synthesis and the low temperature signaling pathway under low-temperature stress, thereby enhancing their cold tolerance. It provided candidate genes for breeding stress-resistant tea cultivars and relevant evidence for the formation of stress-resistant quality in tea plants.
Tea polyphenols are rich in phenolic hydroxyl groups, and possess excellent antioxidant and antibacterial activities, making them suitable for use as natural active additives in the fabrication of biodegradable composite films. In this paper, the physicochemical properties of tea polyphenols, mainstream preparation techniques of composite films (solution casting, electrospinning, layer-by-layer self-assembly, etc.) and their application advances in fruit preservation as well as the storage of meat and aquatic products were reviewed. It was demonstrated that the lipid oxidation and protein deterioration of fresh foods could be effectively inhibited by tea polyphenol composite films, and the shelf life was markedly prolonged. However, several drawbacks were found in such films: uneven release of active components, easy structural failure under high humidity, weak interlayer bonding force and relatively high preparation cost. It was suggested that future studies could integrate arti ficial intelligence calculation, molecular simulation and machine learning and that a formula database of tea polyphenol composite films could be created to enable targeted and precise design of the films and promote iterative upgrading of packaging materials for fresh food preservation.
Polyphenols possess abundant active structures that can form a stable network with matrix materials through multiple molecular interactions, making them suitable for the preparation of multifunctional composite materials with properties such as adhesion, self-healing, antibacterial, antioxidant, chromogenic response, and conductive sensing. In this work, the effects of polyphenol structures on material performances were reviewed. Dominant fabrication strategies including blending, electrospinning and layer-by-layer self-assembly for wearable polyphenol-based sensing materials, together with their technical characteristics, were summarized. Research advances of the as-prepared sensing materials in human motion monitoring and wound healing surveillance were also concluded. It was pointed out that continuous film-forming, multimodal signal integration, intelligent recognition and low-cost green manufacturing technologies were regarded as key research directions in future studies. Industrial applications of wearable polyphenol-based sensing materials were further promoted through the exploration of the above technologies.
