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Thaumatin-like proteins (TLP), existing in various fruits, have allergenic and pro-inflammatory activities. The current research attempts to reduce the pro-inflammatory activity of litchi TLP (LcTLP) through high hydrostatic pressure (HHP). This study demonstrated that HHP (250-500 MPa, 5-10 min) was a potential technique to reduce the pro-inflammatory activity of LcTLP, which was attributed to the irreversible destruction of the active domain, ie., V-cleft. SDS-PAGE showed no change in the protein profile. Continuous HHP treatment promoted LcTLP unfolding and then reassembling (400 MPa was the transition pressure), and the content of β-sheets decreased from 35.4% to 31.1%. HHP treatment could mitigate inflammatory responses of LcTLP, as confirmed by ELISA and western blot. Molecular dynamics simulations showed significant changes in the residue network under HHP, thereby affecting the V-cleft. These findings provide a theoretical explanation and structural insights into the HHP-induced reduction of pro-inflammatory activity of LcTLP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The following are the supplementary data related to this article. Supplementary data to this article can be found online at https://doi.org/10.1016/j.foodchem.2024.140858., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Gamma-aminobutyric acid (GABA) is the predominant amino acid in litchi pulp, known for its neuroregulatory effects and anti-inflammatory properties. Although previous research has highlighted the pro-inflammatory characteristics of litchi thaumatin-like protein (LcTLP), interplay between GABA and LcTLP in relation to inflammation remains unclear. This study aims to explore the hepatoprotective effects of the litchi pulp-derived GABA extract (LGE) against LcTLP-induced liver inflammation in mice and LO2 cells. In vivo experiments demonstrated that LGE significantly reduced the levels of aspartate transaminase and alanine transaminase, and protected the liver against infiltration of CD4 + and CD8 + T cells and histological injury induced by LcTLP. Pro-inflammatory cytokines including interleukin-6, interleukin-1β, and tumor necrosis factor-α were also diminished by LGE. The LGE appeared to modulate the mitogen-activated protein kinase (MAPK) signaling pathway to exert its anti-inflammatory effects, as evidenced by a reduction of 47%, 35%, and 31% in phosphorylated p38, JNK, and ERK expressions, respectively, in the liver of the high-dose LGE group. Additionally, LGE effectively improved the translocation of gut microbiota by modulating its microbiological composition and abundance. In vitro studies have shown that LGE effectively counteracts the increase in reactive oxygen species, calcium ions, and pro-inflammatory cytokines induced by LcTLP. These findings may offer new perspectives on the health benefits and safety of litchi consumption.

Gamma-aminobutyric acid (GABA) dietary intervention is considered to have therapeutic potential against obesity. Microbial enrichment is an effective strategy to naturally and safely enhance GABA production in food. As litchi is "the king of GABA" in fruits, the retention or enrichment of its content during processing has been a key issue in the litchi industry. This study aimed to investigate the potential of GABA and fermented litchi juice enriched with GABA (FLJ) to protect against obesity in a high-fat diet (HFD) mouse model. Supplementation of GABA and FLJ displayed an anti-obesogenic effect by attenuating body weight gain, fat accumulation, and oxidative damage, and improving the serum lipid profile and hepatic function. Sequencing (16S rRNA) of fecal samples indicated that GABA and FLJ intervention displayed different regulatory effects on HFD-induced gut microbiota dysbiosis at different taxonomic levels. The microbial diversity, the relative abundance of Firmicutes and Bacteroidetes as well as the F/B ratio of GABA and FLJ groups were reversed compared to those of the HFD-induced mice. Our finding broadens the potential mechanisms by which GABA regulates gut flora in the amelioration of obesity and provides guidance for developing FLJ as a functional food to prevent obesity.

The pro-inflammation activity of litchi thaumatin-like protein (LcTLP) led to be responsible for the occurrence of adverse reactions after excessive consumption of litchi. This study aimed to characterize the changes in the structure and inflammatory activity of LcTLP induced by ultrasound treatment. Significant molecular structure of LcTLP changes occured at 15 min ultrasound treatment, and then tended to recover with subsequent treatment. Secondary structure (α-helices decreased from 17.3% to 6.3%), tertiary structure (the maximum endogenous fluorescence intensity decreased), and microstructure (mean hydrodynamic diameter reduced from 4 μm to 50 nm) of the LcTLP treated for 15 min (LT15) were significantly affected, which led to the inflammatory epitope of LcTLP (domain II and V-cleft) unfolded. In vitro, LT15 had a significant anti-inflammatory response, which inhibited NO production and had the best effect at 50 ng/mL in RAW264.7 macrophages (73.24%). Moreover, proinflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) secretion and mRNA expression levels were also significantly lower compared with untreated LcTLP (p < 0.05). Western blot further confirmed that the expressions of IκB-α, p65, p38, ERK and JNK reduced markedly (p < 0.05), which indicated LT15 inhibited the inflammatory response through NF-κB and MAPK transduction pathways. Overall, it can be hypothesized that LT15 exposed to low frequency ultrasonic fields have a direct effect on the protein surface structure and thus on the entry of LT15 into cells, making 15-minute ultrasound treatment potentially useful in reducing the pro-inflammatory properties of litchi or related liquid products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Characterization and bioactivity of A-type procyanidins was investigated in litchi fruitlet (LF) at different stages and mature pericarp (MP) of 5 litchi cultivars. The content of total phenols in LFs was higher than that of MP and showed good antioxidant activity. Eleven procyanidins were identified in samples, including procyanidin A 2 , procyanidin A 4 , and 1 dimer, 2 trimers, and 1 tetramer of A-type procyanidin. Also, A-type procyanidin could stably exist in LFs stage, but declined substantially after maturity, which was about 1.45 - 3.56 times than mature pericarp. In addition, the second stage of LFs showed strong anti-inflammatory and anti-proliferative activities, in which monomer and A-type procyanidin trimers in LFs were significantly correlated with antioxidant (r > 0.72; p < 0.01) and anti-inflammatory (r = 0.53; p < 0.05) activities, respectively. Therefore, litchi in LF stage could be a good source of A-type oligomer procyanidins which had good application value., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Pomace is frequently underestimated as a complex by-product. High pressure homogenisation (HPH), enzymatic hydrolysis (EH) and high hydrostatic pressure (HHP) modifications are applied to improve the functional properties of litchi pomace insoluble dietary fibre (LPDF). The relationships between physicochemical properties and structural alterations and digestibility of LPDF are studied. The results showed that HPH, EH and HHP changed the LPDF's microstructure, causing it to develop more porous structures. Meanwhile, HPH modification exhibited a remarkable effect on LPDF's water holding (15.6 g/g), water swelling (26.1 mL/g) and oil retention (5.4 g/g) capabilities, resulting in the change of the complexity of the neutral sugar side chain. Notably, the highest total phenol content (3.4 GAE mg/g) and antioxidant activities (DPPH 153.6, ABTS 188.9, FRAP 195.1 μmol Trolox/g) were also observed in LPDF modified with HPH. Moreover, the diversity of structural features and high affinity of modified LPDFs are conducive to its functional properties, i.e., inhibition of starch digestion. The remarkable potential of LPDF modified with HPH was attributed to the beneficial effects of dietary fibre on human health. As a result, litchi pomace could be a useful and effective source of functional fibres. The incorporation of litchi pomace into the human diet is still underexplored but is a promising alternative. • LPDF treated with the complex enzyme of cellulase and laccase notably increased the content of soluble dietary fibre. • The water holding capacity of LPDF could increase by 53% after HPH treatment. • H-LPDF showed an apparent inhibition effect on the digestion of maize starch. • The higher side chain branching complexity of LPDF favors the digestion inhibition properties. • Litchi pomace could be an efficient source of functional fibres. [ABSTRACT FROM AUTHOR]