Protective Effects of an Octapeptide Identified from Riceberry™ (Oryza sativa) Protein Hydrolysate on Oxidative and Endoplasmic Reticulum (ER) Stress in L929 Cells

Reactive oxygen species (ROS) play a critical role in oxidative stress and cellular damage, underscoring the importance of identifying potent antioxidants. This research focuses on the antioxidant capabilities of Riceberry™-derived peptides and their protective effects against oxidative and endoplasmic reticulum (ER) stress in L929 cells. By simulating human digestion, Riceberry™ protein hydrolysate was generated, from which antioxidant peptides were isolated using OFFGEL electrophoresis and LC-MS/MS. Notably, an octapeptide (VPAGVAHW) from the hydrolysate demonstrated significant antioxidant activity, particularly against oxidative stress induced by iodoacetic acid (IAA) or hydrogen peroxide (H2O2) and ER stress caused by tunicamycin (TM) in L929 cells. This peptide's effectiveness was evident in its dose-dependent ability to enhance cell viability and mitigate stress effects, although its efficiency varied with the stress inducer. Our study suggests that Riceberry™-derived peptides could serve as a promising natural antioxidant with potential benefits for health promotion and applications in the food industry, offering an environmentally friendly alternative to synthetic antioxidants.

Natural products from Camellia oleifera fruit and its comprehensive utilisation

Camellia oleifera (C. oleifera) is a woody oil plant with a good reputation of 'Oriental Olive Oil' in China. The national understanding of the health-care benefits of Camellia oil are already widespread, but the production of C. oleifera fruit has not been achieved large-scale industrialisation. In this review, we focus on the properties and commercial value of its natural products, and processing technology, performance characterisation, and novel modification strategies of its processed products. In addition, we briefly summarised the research progress of breeding and put forward the comprehensive utilisation of C. oleifera fruit based on the tandem of extraction and processing. This review might attract more researchers to make profound study regarding it as an alternative of olive oil.

Tea (Camellia sinensis (L.) Kuntze) as an emerging source of protein and bioactive peptides: A narrative review

Tea residues represent one of the major agricultural wastes that are generated after the processing of tea. They account for 21-28% of crude protein and are often discarded without the extraction of valuable proteins. Due to various bioactivity and functional properties, tea proteins are an excellent alternative to other plant-based proteins for usage as food supplements at a higher dosage. Moreover, their good gelation capacity is ideal for the manufacturing of dairy products, jellies, condensation protein, gelatin gel, bread, etc. The current study is the first to comprehend various tea protein extraction methods and their amino acid profile. The preparation of tea protein bioactive peptides and hydrolysates are summarized. Several functional properties (solubility, foaming capacity, emulsification, water/oil absorption capacity) and bioactivities (antioxidant, antihypertensive, antidiabetic) of tea proteins are emphasized.

Proteomics and Molecular Docking Analyses Reveal the Bio-Chemical and Molecular Mechanism Underlying the Hypolipidemic Activity of Nano-Liposomal Bioactive Peptides in 3T3-L1 Adipocytes

Obesity is a global health concern. Physical activities and eating nutrient-rich functional foods can prevent obesity. In this study, nano-liposomal encapsulated bioactive peptides (BPs) were developed to reduce cellular lipids. The peptide sequence NH₂-PCGVPMLTVAEQAQ-CO₂H was chemically synthesized. The limited membrane permeability of the BPs was improved by encapsulating the BPs with a nano-liposomal carrier, which was produced by thin-layer formation. The nano-liposomal BPs had a diameter of ~157 nm and were monodispersed in solution. The encapsulation capacity was 61.2 ± 3.2%. The nano-liposomal BPs had no significant cytotoxicity on the tested cells, keratinocytes, fibroblasts, and adipocytes. The in vitro hypolipidemic activity significantly promoted the breakdown of triglycerides (TGs). Lipid droplet staining was correlated with TG content. Proteomics analysis identified 2418 differentially expressed proteins. The nano-liposomal BPs affected various biochemical pathways beyond lipolysis. The nano-liposomal BP treatment decreased the fatty acid synthase expression by 17.41 ± 1.17%. HDOCK revealed that the BPs inhibited fatty acid synthase (FAS) at the thioesterase domain. The HDOCK score of the BPs was lower than that of orlistat, a known obesity drug, indicating stronger binding. Proteomics and molecular docking analyses confirmed that the nano-liposomal BPs were suitable for use in functional foods to prevent obesity.

Identification of a Novel ACE Inhibitory Hexapeptide from Camellia Seed Cake and Evaluation of Its Stability

The camellia seed cake proteins (CP) used in this study were individually hydrolyzed with neutral protease, alkaline protease, papain, and trypsin. The results showed that the hydrolysate had the highest ACE inhibitory activity at 67.36 ± 0.80% after four hours of neutral protease hydrolysis. Val-Val-Val-Pro-Gln-Asn (VVVPQN) was then obtained through ultrafiltration, Sephadex G-25 gel chromatography separation, LC-MS/MS analysis, and in silico screening. VVVPQN had ACE inhibitory activity with an IC₅₀ value of 0.13 mg/mL (198.66 μmol/L), and it inhibited ACE in a non-competitive manner. The molecular docking indicated that VVVPQN can combine with ACE to form eight hydrogen bonds. The results of the stability study showed that VVVPQN maintained high ACE-inhibitory activity in weakly acidic and neutral environments and that heat treatment (20-80 °C) and Na⁺, Mg²⁺, as well as Fe³⁺ metal ions had little effect on the activity of VVVPQN. Moreover, it remained relatively stable after in vitro simulated gastrointestinal digestion. These results revealed that VVVPQN identified in camellia seed cake has the potential to be applied in functional food or antihypertensive drugs.

Discovery of a Multifunctional Octapeptide from Lingzhi with Antioxidant and Tyrosinase Inhibitory Activity

Ganoderma lucidum or Lingzhi is a fungus species widely known as a traditional medicine. Exploring the beneficial peptides by hydrolysis using pepsin and trypsin has been extensively performed to identify new bioactive natural products. A multifunctional peptide that expresses potential scavenging activity and tyrosinase inhibition is valuable in therapeutic and cosmetic applications. This study aimed to identify and investigate the effects of a novel multifunctional peptide from Lingzhi on the melanogenic enzymes in melanoma cells by a targeted-proteomics approach. The multifunctional peptide was de novo sequenced by LC-MS/MS to be NH₂-PVRSSNCA-CO₂H (octapeptide). This sequence was chemically synthesized by solid-phase peptide synthesis (SPPS). The antioxidant ability of the synthesized octapeptide was measured by the DPPH, ABTS, and FRAP assays. The results showed that the peptide exhibited an antioxidant activity equal to 0.121 ± 0.01 mg equivalent to ascorbic acid, 0.173 ± 0.03 mg equivalent to gallic acid, and 2.21 ± 0.23 mM equivalent to FeSO₄, respectively, which is comparable to these well-known antioxidants. The proteomics approach identified a total of 5804 proteins and several pathways involved in the effects of the octapeptide in melanoma cells. Targeted proteomics revealed three specific proteins associated with pigmentation including Rab29, Dct, and Tyrp1. The Rab29 and Dct were upregulated whereas Tyrp1 was downregulated in the octapeptide treatment group. These findings could be used in the understanding of the molecular functions of the multifunctional octapeptide on melanogenic enzymes, supporting its potential as a therapeutic and cosmetic ingredient.