Walnut phenolic extracts reduce telomere length and telomerase activity in a colon cancer stem cell model

Regulation of Intestinal Inflammation by Walnut-Derived Bioactive Compounds

Walnuts (Juglans regia L.) have shown promising effects in terms of ameliorating inflammatory bowel disease (IBD), attributed to their abundant bioactive compounds. This review comprehensively illustrates the key mechanisms underlying the therapeutic potential of walnuts in IBD management, including the modulation of intestinal mucosa permeability, the regulation of inflammatory pathways (such as NF-kB, COX/COX2, MAPCK/MAPK, and iNOS/NOS), relieving oxidative stress, and the modulation of gut microbiota. Furthermore, we highlight walnut-derived anti-inflammatory compounds, such as polyunsaturated fatty acids (PUFA; e.g., ω-3 PUFA), tocopherols, phytosterols, sphingolipids, phospholipids, phenolic compounds, flavonoids, and tannins. We also discuss unique anti-inflammatory compounds such as peptides and polysaccharides, including their extraction and preparation methods. Our review provides a theoretical foundation for dietary walnut supplementation in IBD management and provides guidance for academia and industry. In future, research should focus on the targeted isolation and purification of walnut-derived anti-inflammatory compounds or optimizing extraction methods to enhance their yields, thereby helping the food industry to develop dietary supplements or walnut-derived functional foods tailored for IBD patients.

Manuka honey's anti-metastatic impact on colon cancer stem-like cells: unveiling its effects on epithelial-mesenchymal transition, angiogenesis and telomere length

Colorectal cancer often leads to metastasis, with cancer stem cells (CSCs) playing a pivotal role in this process. Two closely linked mechanisms, epithelial-mesenchymal transition and angiogenesis, contribute to metastasis and recent research has also highlighted the impact of telomere replication on this harmful tumor progression. Standard chemotherapy alone can inadvertently promote drug-resistant CSCs, posing a challenge. Combining chemotherapy with other compounds, including natural ones, shows promise in enhancing effectiveness while minimizing side effects. This study investigated the anti-metastatic potential of Manuka honey, both alone and in combination with 5-fluorouracil, using a 3D model of colonospheres enriched with CSC-like cells. In summary, it was observed that the treatment reduced migration ability by downregulating the transcription factors Slug, Snail, and Twist, which are key players in epithelial-mesenchymal transition. Additionally, Manuka honey downregulated pro-angiogenic factors and shortened CSC telomeres by downregulating c-Myc - demonstrating an effective anti-metastatic potential. This study suggests new research opportunities for studying the impact of natural compounds when combined with pharmaceuticals, with the potential to enhance effectiveness and reduce side effects.

Dietary Walnuts Prevented Indomethacin-Induced Gastric Damage via AP-1 Transcribed 15-PGDH, Nrf2-Mediated HO-1, and n-3 PUFA-Derived Resolvin E1

Non-steroidal anti-inflammatory drugs (NSAIDs), the most highly prescribed drugs in the world for the treatment of pain, inflammation, and fever, cause gastric mucosal damage, including ulcers, directly or indirectly, by which the development of GI-safer (-sparing) NSAIDs relates to unmet medical needs. This study aimed to document the preventive effects of walnut polyphenol extracts (WPEs) against NSAID-induced gastric damage along with the molecular mechanisms. RGM-1 gastric mucosal cells were administered with indomethacin, and the expressions of the inflammatory mediators between indomethacin alone or a combination with WPEs were compared. The expressions of the inflammatory mediators, including COX-1 and COX-2, prostaglandin E2, 15-hydroxyprostaglandin dehydrogenase (15-PGDH), and antioxidant capacity, were analyzed by Western blot analysis, RT-PCR, and ELISA, respectively. HO-1, Nrf-2, and keap1 were investigated. The in vivo animal models were followed with in vitro investigations. The NSAIDs increased the expression of COX-2 and decreased COX-1 and 15-PGDH, but the WPEs significantly attenuated the NSAID-induced COX-2 expression. Interestingly, the WPEs induced the expression of 15-PGDH. By using the deletion constructs of the 15-PGDH promoter, we found that c-Jun is the most essential determinant of the WPE-induced up-regulation of 15-PGDH expression. We confirmed that the knockdown of c-Jun abolished the ability of the WPEs to up-regulate the 15-PGDH expression. In addition, the WPEs significantly increased the HO-1 expression. The WPEs increased the nuclear translocation of Nrf2 by Keap-1 degradation, and silencing Nrf2 markedly reduced the WPE-induced HO-1 expression. We found that the WPE-induced HO-1 up-regulation was attenuated in the cells harboring the mutant Keap1, in which the cysteine 151 residue was replaced by serine. These in vitro findings were exactly validated in indomethacin-induced gastric rat models. Daily walnut intake can be a promising nutritional supplement providing potent anti-inflammatory, antioxidative, and mucosa-protective effects against NSAID-induced GI damage.

The Role of Nut and Seed Consumption in Colorectal Cancer: A Narrative Review

Given the increased incidence of colorectal cancer worldwide, especially in developed and developing countries, is comes as no surprise that researchers are concentrating on methods to combat this public health issue, through investigating both lifestyle interventions and treatment options. Although treatment options are being constantly discovered and developed, researchers have also begun investigating the influence that nutrition and lifestyle have on CRC. Among the food categories, nuts and seeds boast numerous beneficial effects for cardiovascular health and metabolic balance and they contain a plethora of phytochemicals and antioxidants. The present narrative review aims to offer a broad perspective to date on the known effects of this consumption on colorectal cancer. For this purpose, articles were identified by conducting a search in the PubMed and Google Scholar databases, using search phrases such as ″nut intake and colorectal cancer″ and ″seed consumption and colorectal cancer”, narrowing the search pool to those articles published between 2019 and 2022. The search returned eight relevant papers, all of which were validated by a second author. While the existing research is divided between those studies which have found no significant link between nut consumption and colorectal cancer protection and those which have, there is a consensus regarding the necessity for further research on this subject, as well as the possible mechanisms which might be involved in the protective effect observed by some researchers.

Polyphenols Extracted from Chinese Hickory (Carya cathayensis) Promote Apoptosis and Inhibit Proliferation through the p53-Dependent Intrinsic and HIF-1α-VEGF Pathways in Ovarian Cancer Cells

Ovarian cancer is the second most common gynecologic cancer with an estimated 13,940 mortalities across the United States in 2020. Natural polyphenols have been shown to double the survival time of some cancer patients due to their anticancer properties. Therefore, the effect of polyphenols extracted from Chinese hickory seed skin Carya cathayensis (CHSP) on ovarian cancer was investigated in the present study. Cell viability results showed that CHSP is more effective in inhibiting ovarian cancer cells than normal ovarian cells, with the IC50 value for inhibition of cell proliferation of Ovarian cancer cells (OVCAR-3) being 10.33 ± 0.166 μg/mL for a 24 h treatment. Flow cytometry results showed that the apoptosis rate was significantly increased to 44.21% after 24 h treatment with 20 μg/mL of CHSP. Western blot analysis showed that CHSP induced apoptosis of ovarian cancer cells through a p53-dependent intrinsic pathway. Compared with control values, levels of VEGF excreted by OVCAR-3 cancer cells were reduced to 7.87% with a 40 μg/mL CHSP treatment. Consistent with our previous reports, CHSP inhibits vascular endothelial growth factor (VEGF) secretion by regulating the HIF-1α-VEGF pathway. In addition, we also found that the inhibitory effect of CHSP on ovarian cancer is related to the up-regulation of Phosphatase and tension homolog (PTEN) and down-regulation of nuclear factor kappa-B (NF-kappa B). These findings provide some evidence of the anti-ovarian cancer properties of CHSP and support the polyphenols as potential candidates for ovarian cancer adjuvant therapy.

Dietary intake of walnut prevented Helicobacter pylori-associated gastric cancer through rejuvenation of chronic atrophic gastritis

The fact that Fat-1 transgenic mice producing n-3 polyunsaturated fatty acids via overexpressed 3-desaturase significantly mitigated Helicobacter pylori (H. pylori)-associated gastric tumorigenesis through rejuvenation of chronic atrophic gastritis (CAG) led us to study whether dietary intake of walnut plentiful of n-3 PUFAs can be nutritional intervention to prevent H. pylori-associated gastric cancer. In our model that H. pylori-initiated, high salt diet-promoted gastric carcinogenesis, pellet diet containing 100 mg/kg and 200 mg/kg walnut was administered up to 36 weeks. As results, control mice (24 weeks) developed significant chronic CAG, in which dietary walnuts significantly ameliorated chronic atrophic gastritis. Expressions of COX-2/PGE₂/NF-κB/c-Jun, elevated in 24 weeks control group, were all significantly decreased with walnut (p<0.01). Tumor suppressive enzyme, 15-PGDH, was significantly preserved with walnut. Control mice (36 weeks) all developed significant tumors accompanied with severe CAG. However, significantly decreased tumorigenesis was noted in group treated with walnuts, in which expressions of COX-2/PGE₂/NF-κB/IL-6/STAT3, all elevated in 36 weeks control group, were significantly decreased with walnut. Defensive proteins including HO-1, Nrf2, and SOCS-1 were significantly increased in walnut group. Proliferative index as marked with Ki-67 and PCNA was significantly regulated with walnut relevant to 15-PGDH preservation. Conclusively, walnut can be an anticipating nutritional intervention against H. pylori.

Walnut polyphenol extracts inhibit Helicobacter pylori-induced STAT3Tyr705 phosphorylation through activation of PPAR-γ and SOCS1 induction

The health beneficial effects of walnut plentiful of n-3 polyunsaturated fatty acid had been attributed to its anti-inflammatory and anti-oxidative properties against various clinical diseases. Since we have published Fat-1 transgenic mice overexpressing 3-desaturase significantly mitigated Helicobacter pylori (H. pylori)-associated gastric pathologies including rejuvenation of chronic atrophic gastritis and prevention of gastric cancer, in this study, we have explored the underlying molecular mechanisms of walnut against H. pylori infection. Fresh walnut polyphenol extracts (WPE) were found to suppress the phosphorylation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3) induced by H. pylori infection in RGM-1 gastric mucosal cells. Notably, H. pylori infection significantly decreased suppressor of cytokine signaling 1 (SOCS1), but WPE induced expression of SOCS1, by which the suppressive effect of walnut extracts on STAT3^Tyr705 phosphorylation was not seen in SOCS1 KO cells. WPE induced significantly increased nuclear translocation nuclear translocation of PPAR-γ in RGM1 cells, by which PPAR-γ KO inhibited transcription of SOCS1 and suppressive effect of WPE on p-STAT3^Tyr705 was not seen. WPE inhibited the expression of c-Myc and IL-6/IL-6R signaling, which was attenuated in the RGM1 cells harboring SOCS1 specific siRNA. Conclusively, WPE inhibits H. pylori-induced STAT3 phosphorylation in a PPAR-γ and SOCS1-dependent manner.

Evaluation and Exploitation of Bioactive Compounds of Walnut, Juglans regia

In the last few years, great importance has been given to natural materials (such as walnuts, peanuts, chestnuts) due to their medicinal and pharmaceutical uses induced by the presence of natural agents, including polyphenols. Juglans regia is a traditional plant that has been used since ancient times in traditional medicine for the treatment of various diseases like microbial infections, stomach ache, thyroid dysfunctions, cancer, heart diseases and sinusitis. Recently, scientific attention for the phytochemical profile of walnut by-products is increasing due to their valuable active constituents. Natural polyphenols are important compounds present in walnut with valuable properties that have been studied for the treatment of inflammation, cancer or anti-ageing effect. The use of nanocarriers as a drug delivery system is now a promising strategy to get more stable products and is easier to apply in a medical, therapeutic and pharmaceutical environment. The aim of this work was to review the latest information provided by scientific investigators regarding the nutritional value, bioactive compounds, antioxidant and antitumor activity of walnut by-product extracts. Moreover, this review provides comprehensive information on the nanoencapsulation of bioactive constituents for application in clinical medicine, particularly in cancer research.