Identification of a novel oligopeptide from defatted walnut meal hydrolysate as a potential neuroprotective agent.

Free radical damage and oxidative stress are thought to play a crucial role in the development of neurodegenerative diseases. Walnut peptides, especially walnut oligopeptides, have been shown to protect nerve cells from oxidative stress and inflammatory damage, as well as improve memory function. In this study, walnut peptides were obtained from walnut meal through enzymatic hydrolysis, ultrafiltration, and gel filtration chromatography. A novel oligopeptide called AQ was successfully isolated and its chemical structure was identified as AASCDQ using ESI-MS/MS. AQ demonstrated remarkable scavenging activity against O2- free radicals (81.00%), DPPH free radicals (79.40%), and ABTS free radicals (67.09%) at a concentration of 1 mg mL-1. Furthermore, AQ exhibited strong neuroprotective effects against hydrogen peroxide-induced damage in SH-SY5Y cells, reducing cell injury and apoptosis. AQ also effectively inhibited the secretion of pro-inflammatory factors NO (IC50 = 46.03 ± 0.32 µM) and suppressed the expression of IL-6 and TNF-α in RAW264.7 cells stimulated by LPS. In vivo experiments demonstrated that AQ promoted angiogenesis in the quail chick chorioallantoic membrane assay and reduced ROS accumulation in Caenorhabditis elegans, thereby extending its lifespan. The anti-inflammatory mechanism of AQ was further confirmed by western blotting. In summary, the novel oligopeptide AQ possesses potential neuroprotective effects, including antioxidant, anti-inflammatory, angiogenic, and anti-aging properties, making it a promising candidate for the development of functional foods and pharmaceutical products.

Anti-tumor effects of novel alkannin derivatives with potent selectivity on comprehensive analysis.

BACKGROUND: Therapeutic approaches based on glycolysis and energy metabolism of tumor cells are new promising strategies for the treatment of cancer. Currently, researches on the inhibition of pyruvate kinase M2, a key rate limiting enzyme in glycolysis, have been corroborated as an effective cancer therapy. Alkannin is a potent pyruvate kinase M2 inhibitor. However, its non-selective cytotoxicity has affected its subsequent clinical application. Thus, it needs to be structurally modified to develop novel derivatives with high selectivity. PURPOSE: Our study aimed to ameliorate the toxicity of alkannin through structural modification and elucidate the mechanism of the superior derivative 23 in lung cancer therapy. METHODS: On the basis of the principle of collocation, different amino acids and oxygen-containing heterocycles were introduced into the hydroxyl group of the alkannin side chain. We examined the cell viability of all derivatives on three tumor cells (HepG2, A549 and HCT116) and two normal cells (L02 and MDCK) by MTT assay. Besides, the effect of derivative 23 on the morphology of A549 cells as observed by Giemsa and DAPI staining, respectively. Flow cytometry was performed to assess the effects of derivative 23 on apoptosis and cell cycle arrest. To further assess the effect of derivative 23 on the Pyruvate kinase M2 in glycolysis, an enzyme activity assay and western blot assay were performed. Finally, in vivo the antitumor activity and safety of the derivative 23 were evaluated by using Lewis mouse lung cancer xenograft model. RESULTS: Twenty-three novel alkannin derivatives were designed and synthesized to improve the cytotoxicity selectivity. Among these derivatives, derivative 23 showed the highest cytotoxicity selectivity between cancer and normal cells. The anti-proliferative activity of derivative 23 on A549 cells (IC50 = 1.67 ± 0.34 µM) was 10-fold higher than L02 cells (IC50 = 16.77 ± 1.44 µM) and 5-fold higher than MDCK cells (IC50 = 9.23 ± 0.29 µM) respectively. Subsequently, fluorescent staining and flow cytometric analysis showed that derivative 23 was able to induce apoptosis of A549 cells and arrest the cell cycle in the G0/G1 phase. In addition, the mechanistic studies suggested derivative 23 was an inhibitor of pyruvate kinase; it could regulate glycolysis by inhibiting the activation of the phosphorylation of PKM2/STAT3 signaling pathway. Furthermore, studies in vivo demonstrated derivative 23 significantly inhibited the growth of xenograft tumor. CONCLUSION: In this study, alkannin selectivity is reported to be significantly improved following structural modification, and derivative 23 is first shown to be able to inhibit lung cancer growth via the PKM2/STAT3 phosphorylation signaling pathway in vitro, indicating the potential value of derivative 23 in treating lung cancer.