Yibo Hu

In this study, fresh leaves of the same Camellia sinensis (L.) O. Kuntze cv. Qilan cultivar grown at similar elevations but contrasting latitudes in Wuyishan, Fujian (the 2L-FQ cultivation site), and Baisha, Hainan (the 2L-HQ cultivation site), were systematically compared using environmental characterization, enzyme activity assays, gas chromatography–ion mobility spectrometry (GC–IMS), and untargeted metabolomics. Black teas produced from the two groups of fresh leaves under identical standardized processing conditions were further evaluated using electronic nose and electronic tongue analyses. Correspondingly, 2L-HQ leaves were longer and wider than 2L-FQ leaves, with higher moisture content and water activity. The lower L*, b*, and chroma values of 2L-HQ, together with a ΔE*ab of 6.54, indicated a darker leaf appearance, which was accompanied by higher chlorophyll and carotenoid concentrations. Compared with 2L-FQ, 2L-HQ contained 11.8% more tea polyphenols, 26.4% more soluble polysaccharides, 11.4% more caffeine, and 10.6% more free amino acids. The non-gallated catechins catechin, epicatechin, epigallocatechin, and gallocatechin were significantly enriched in 2L-HQ. DPPH, ABTS, and FRAP antioxidant capacities were also 6.1%, 4.9%, and 2.2% higher in 2L-HQ, respectively. Lipoxygenase, polyphenol oxidase, and peroxidase activities increased by 137.0%, 98.0%, and 93.8%, respectively, whereas β-glucosidase activity remained unchanged. GC–IMS resolved 61 volatile compounds, of which 46 differed significantly between the two origins. 2L-FQ was enriched in several aromatic aldehydes, β-phenyl ethanol, and fruity esters, whereas 2L-HQ contained higher levels of selected alcohols, unsaturated aldehydes, furanic compounds, and lipid-derived esters. Untargeted metabolomics retained 4359 metabolic features, of which 4356 were shared by both groups. After multiple-testing correction, 793 differential metabolic features were identified using VIP > 1, FDR-adjusted p < 0.05, and |log₂FC| > 1, including 420 features with higher abundance and 373 features with lower abundance in 2L-HQ relative to 2L-FQ. These differential features were mainly associated with carbohydrate, amino acid, flavonoid-related, lipid, and cofactor metabolism. Overall, regional cultivation was associated with coordinated differences in leaf morphology, hydration, pigmentation, taste-related composition, antioxidant capacity, oxidative-enzyme potential, volatile fingerprints, and metabolic allocation, providing a data foundation for region-adapted processing of Qilan tea leaves.

To elucidate differences in fresh-leaf quality associated with cultivar and leaf tenderness at harvest, this study investigated three tea samples: Hainan Dayezhong with one bud and one leaf (1L-HN), Hainan Dayezhong with one bud and two leaves (2L-HN), and Yunnan Dayezhong with one bud and one leaf (1L-YN). Basic physicochemical indices, non-targeted metabolomics, and sensory evaluation were integrated for comprehensive analysis. The results showed that 1L-HN exhibited excellent sensory quality and contained abundant polyphenols and amino acids, thereby providing a material basis for its balanced taste profile. Metabolites such as L-tryptophan, 13(S)-HPOT, and linoleic acid were closely associated with the characteristic floral and fruity flavor of Hainan Dayezhong. Metabolomic analysis further indicated that flavonoid biosynthesis and glycerophospholipid metabolism were the major pathways contributing to the observed metabolic differences. This study provides a theoretical basis for understanding the mechanisms underlying flavor formation in different varieties of black tea.

With the drastic changes in lifestyle, nonalcoholic fatty liver disease (NAFLD) has become a widespread health problem. Natural actives such as polyphenols have multi-target, multi-mechanism characteristics, and offer new opportunities for NAFLD treatment. This study established a high-fat diet (HFD)-induced NAFLD model in mice to investigate the molecular mechanism of Pandanus amaryllifolius Roxb. polyphenol extract (PAE) in alleviating NAFLD. The results showed that PAE significantly inhibited HFD-induced obesity, maintained glucose homeostasis, mitigated oxidative damage in liver tissue, and reduced liver steatosis. Moreover, PAE treatment remarkably reversed 16 endogenous DMs, and significantly affected glycerophospholipid metabolism, which increased the levels of phosphatidylcholine and phosphatidylethanolamine, and down-regulated choline and sn-glyceropl-3P. Further validation revealed that PAE was able to prevent NAFLD progression by regulating the AMPK/AKT/mTOR signaling pathway to enhance autophagy levels. Meanwhile, PAE treatment restored the balance of gut microbiota mainly by increasing the relative abundance of Bacteroidetes, decreasing the relative abundance of Firmicutes and the ratio of Firmicutes/Bacteroidetes. Overall, the findings highlight that the mechanism by which PAE alleviates NAFLD may be related to the regulation of the gut microbes and AMPK/AKT/mTOR signaling pathway, enriching the health-promoting effects of PAE on NAFLD.