Hye Won Kang

Background/Objective: An obesogenic diet triggers intestinal inflammation and oxidative stress, leading to epithelial barrier dysfunction and increased risk of metabolic disorders. This study investigated the mechanisms by which quercetin protects intestinal integrity in high-fat diet (HFD)–fed mice. Methods: Mice were fed an HFD or a low-fat diet (LFD) with or without 1% quercetin, intestinal gene and protein expression, microRNA levels, permeability, and circulating intestinal biomarkers were assessed. Results: Mice fed an HFD with quercetin (HFDQ) showed a 17% improvement in intestinal barrier integrity with increased expression of tight junction and mucin genes and proteins. The nuclear translocation of the nuclear factor-κB (NF-κB) p65 subunit in the ileum decreased by 34%, whereas its acetylation was reduced by 50–57% throughout the intestine, with downregulation of NF-κB-regulated pro-inflammatory genes and proteins. Quercetin increased the nuclear factor erythroid 2-related factor 2 (NRF2) by ~ 25% across intestinal segments and upregulated antioxidant enzyme genes. It suppressed toll-like receptor 4 (TLR4) by 50% and restored AMP-activated protein kinase (AMPK) and sirtuin 1 to levels comparable to those in LFD mice. Altered microRNAs (miRNA-16, 200b, 122, 34a, and 21) supported these molecular changes. Quercetin also restored short-chain fatty acid receptors and serotonin transporters that were affected by HFD. Plasma lipopolysaccharide (LPS), cluster of differentiation 14, LPS-binding protein, and myeloperoxidase activity decreased by 36, 31, 42, and 37%, while glucagon-like peptide-1 increased by 23%. Conclusions: Quercetin protects epithelial barrier integrity against HFD-induced intestinal inflammation and oxidative stress via the AMPK-mediated NF-κB and NRF2 signaling pathways.

Onion peel extract (OPE) is rich in polyphenolic compounds with antimicrobial potential. Salmonella Enteritidis (SE) infection in young broiler chicks causes morbidity, reduced growth, and contributes to human gastroenteritis through contaminated poultry products. The spleen is a key secondary lymphoid organ coordinating systemic responses to pathogens in chicken. This study evaluated how dietary OPE influences spleen metabolic profiles during SE infection. Day-old Ross 708 male chicks (n = 128) were assigned to four treatments: CON, CON-SE, OPE (6 g/kg), and OPE-SE. Chicks in CON and OPE received sterile broth, whereas CON-SE and OPE-SE received 2.25 × 10⁸ CFU/mL SE at 2 d of age. At 5 and 12 dpi, spleens from six chicks per treatment were collected for untargeted HPLC-MS metabolomics. A total of 857 metabolites were identified and analyzed using MetaboAnalyst 6.0 (p < 0.05; fold change ≥ 2.0; VIP score > 1.0). In CON-SE chicks, energy generating metabolites (6-phosphogluconic acid, methylmalonic acid, propionic acid) increased, while 13,14-dihydro-15-keto-prostaglandin D2 and kynurenic acid decreased. Dietary OPE elevated several dipeptides (L-Val-Gly, L-Leu-Gly, Gly-Gly-Leu, L-Val-L-Met) and reduced ATP linked metabolites (3,6-di-O-methyl-beta-D-glucose and 3-O-beta-D-galactosyl-sn-glycerol). Enrichment analysis showed that SE infection altered valine, leucine, and isoleucine degradation and aromatic amino acid biosynthesis, whereas OPE enriched galactose and biotin metabolism in uninfected chicks, but enriched tryptophan, taurine and hypotaurine metabolism in SE-infected chicks. Overall, dietary OPE optimized response of metabolic pathways associated with immune activation, unlike corresponding pathways in CON-SE birds.

Enteric greenhouse gas (GHG) emissions represent a major challenge in livestock production, contributing significantly to global methane output. Various strategies have been explored to mitigate these emissions, including dietary modifications, feed additives, and genetic improvements. In the present study, the focus was on onion peel (OP), a byproduct of the onion processing industry that has shown promise as a natural feed supplement with potential methane-reducing properties. We evaluated the effect of different inclusion levels of OP at 2.5% (OP2.5), 5% (OP5), 7.5% (OP7.5), and 10% (OP10) on the in vitro fermentation of two diets: a total mixed ration referred to as high concentrate (HC), and corn silage referred to as high forage (HF). A 48 h batch culture experiment using a 2 × 3 × 5 factorial arrangement was conducted to assess total gas production (GP), methane (CH₄), carbon dioxide (CO₂), ammonia (NH₃), and hydrogen sulfide (H₂S) concentrations, and nutrient degradability. Measurements were taken at 6 h, 24 h, and 48 h of incubation. Significant additive × diet interactions were observed for most of the parameters. The HC diet produced more gas but less CH₄, CO₂, NH₃, and H₂S compared to the HF diet (p < 0.05). At 24 h of incubation, the OP at all levels increased CH₄, CO₂, NH₃, and H₂S concentrations in the HF diet (p < 0.05). The OP2.5 treatment had the lowest (quadratic effect, p < 0.05) degradable dry matter (dDM) in the HC diet, while the OP linearly (p < 0.001) increased degradable acid detergent fiber (dADF) in both diets. The lowest total volatile fatty acids (VFA) and acetate (quadratic effect, p = 0.027) were observed with the OP5 treatment in the HC diet, while OP5, OP7.5, and OP10 had lower total VFA concentration in the HC diet. At 48 h of incubation, the OP7.5 treatment increased (p < 0.05) GP and CH₄ and CO₂ production in the HC diet. However, the OP5 treatment had the lowest CH₄ production (quadratic effect, p = 0.027) in the HF diet. The highest dDM was observed with OP7.5 treatment (quadratic effect, p = 0.038) in the HC diet with lower values noted at different inclusion levels in the HF diet. Inclusion of OP had no effect on total VFA, and individual VFA in both diets. In conclusion, OP supplementation is more suitable for HF diets than HC diets. A 5% inclusion level is recommended to decrease ruminal CH₄production and improve nutrient degradability.

The current study evaluated the effect of combining mannan oligosaccharide (MOS) and onion peel (OP) on ruminal in vitro total gas (GP), greenhouse gas emissions, dry matter and fiber fraction digestibility, partitioning factor (PF₂₄; mg degradable DM per mL gas), microbial mass, and volatile fatty acids using two dietary substrates: high forage (HF) and high concentrate (HC) diets. The study was arranged as a 2 × 2 × 6 factorial design with two dietary substrates, two time points (6 and 24 h), and six treatments. The treatments included a control group with no MOS or OP administration and groups administered with 2% of a mixture containing MOS and OP in the following ratios: 1:0 (MOS), 0:1 (OP), 1:1 (MOS:OP), 1:2 (MOS:2OP), and 1:3 (MOS:3OP). No significant diet × treatment interactions were observed for any of the measured parameters. However, treatments decreased (p < 0.05) the undegraded portion of HC, and treatment × substrate interactions were significant (p < 0.05) for PF₂₄ and microbial mass. The treatments in the HC diet produced higher GP (p < 0.001) at 6 h compared to the treatments in the HF diet. Administration of MOS:2OP to the HC diet increased GP at 24 h of incubation, while the lowest GP was observed with the OP in the HF diet. The administration of MOS, OP, and MOS:2OP to the HC diet decreased methane production at 24 h of incubation. Additionally, MOS:2OP and MOS:3OP increased (p < 0.001) degradable acid detergent fiber (dADF) in the HC diet at 6 h of incubation. Both OP and MOS:3OP decreased the degradability of acid detergent lignin in the HC diet (p < 0.001). The OP also resulted in the lowest DM disappearance (p < 0.001) at 24 h of incubation in the HF diet, while the MOS:3OP had the highest dADF. At the end of incubation, the highest productions of total volatile fatty acids and acetate were observed (p = 0.002) with the MOS:OP administration in the HC diet, whereas the lowest values were observed with MOS and OP administration to the HF diet. The inclusion of mannan oligosaccharide and onion peel combinations as additives improved substrate (HC and HF) fermentation, leading to higher GP and volatile fatty production, and modulated fiber degradability by improving the breakdown of acid detergent fiber and acid detergent lignin.

Background: Obesogenic diets cause intestinal inflammation and dysfunction. Polyphenols have shown a positive impact on reducing inflammation in in vitro studies. However, their bioactivity may not be the same in the in vivo system due to structural alteration by the gastrointestinal digestive process. The purpose of this study was to investigate the anti-inflammatory effect of onion peel and its major bioactive compound, quercetin, in the intestine and further examine the impact of intestinal digestion on this effect. Methods: Onion peel extract (OPE) and quercetin (Q) were digested using gastrointestinal digestive enzymes in vitro and then treated into lipopolysaccharide (LPS)-stimulated Caco-2/HT-29 cells. Genes and proteins related to tight junction, inflammation, and epithelial integrity were measured. Results: OPE and digested OPE (DOPE) had a higher protective effect on LPS-induced tight junction and inflammatory genes and paracellular permeability than Q and digested Q (DQ). DOPE was more effective than OPE, while digestion did not change the activity of Q. The anti-inflammatory effect of OPE and Q with or without digestion was achieved by inhibiting nuclear factor kappa B through AMP-activated protein kinase-activated silent mating-type information regulation 2 homolog 1. Conclusions: It was the first to find that a crude extract, after undergoing gastrointestinal digestion, demonstrated a notably superior anti-inflammatory effect in the cell study, suggesting the consumption of onion peels could potentially yield similar benefits in the human intestine. This discovery underscores the potential of onion peel polyphenols in combating intestinal inflammation, making them a compelling area of research for future therapeutic applications using food byproducts.

Due to increasing concerns about the contamination of animal food products with antibiotic-resistant bacteria and their byproducts, phytogenic feed additives in animal diets have been explored as antibiotic alternatives. In this study, we investigated the effect of ginger root extract (GRE), green tea extract (GTEC caffeinated and GTED decaffeinated), and onion peel combined (OPEC) on the activity of C. perfringens toxin genes and Eimeria tenella sporozoites. To this end, two Clostridium perfringens strains, CP19 and CP240 (Rollins Diagnostic Lab, Raleigh, NC, USA), were cultured (three replicates per treatment) as follows: without additives (Control), with Bacitracin Methylene Disalicylate (BMD), with GRE, with GTEC, with GTED, and, finally, with OPEC for 0, 2, 4, 6, 8, and 24 h. RNA was extracted to determine the expression of tpeL, alpha toxin (α-toxin), and NetB and we measured the protein concentration of NetB-positive C. perfringens toxin. Also, we evaluated the cytotoxic effect of green tea and ginger extracts on E. tenella sporozoites. Results show that phytogenic extracts, GRE, GTEC, and GTED, significantly reduced (p < 0.05) the level of expression of α-toxin gene compared to control; however, BMD treatment showed much less effect. Furthermore, NetB and tpeL encoding gene expression was significantly (p < 0.05) reduced by GRE and GTED, as well as BMD treatment, compared to the control. In contrast, GTEC treatment did not change the expression levels of these genes and was similar to control. With the CP240 strain, all the selected phytogenic extracts significantly reduced (p < 0.05) the expression of selected genes, except for OPEC, which was similar to control. GRE, GTEC, and GTED all reduced the viability of concentration of E. tenella sporozoites. Overall, our data show that these selected phytogenic extracts reduced the level of expression of toxin encoding genes associated with necrotic enteritis and decreased the viability of sporozoites which cause coccidiosis in broiler chicken.

연구목적: 관용어는 학령기에 빈번하게 사용하는 비유 언어 중 하나로 어휘의 단면만으로는 의미를 정확히 알 수 없어 여러 정보를 통합하여 이해하는 능력이 필요하다. 이에 본 연구는 ADHD 아동과 일반 아동의 문맥 유무에 따른 관용어 이해 특성에 대해 알아보았다. 연구방법: 서울 및 경기에 거주하는 만 10-11세 초등학생 ADHD 아동 12명과 일반 아동 12명, 총 24명이 연구에 참여하였다. 연구 과제는 문맥의 효과를 확인하고자 친숙하지 않고 낮은 투명도를 보이는 관용어를 문맥이 있는 조건과 문맥이 없는 조건으로 나누어 제작하였다. 응답은 관용적 해석의 정답, 문자적 오답, 관련 없는 오답의 보기 중 답을 선택하는 방식으로 진행하였다. 연구결과: ADHD 아동 집단과 일반 아동 집단은 관용어 이해 과제에서 통계적으로 유의한 차이를 나타내며 ADHD 아동은 일반 아동에 비해 관용어 의미를 이해하는 것에 어려움을 보였다. 두 집단 모두 문맥 없는 조건보다 문맥 있는 조건에서 더 높은 수행을 나타냈으며, ADHD 아동은 문맥이 있을 때 일반 아동과 비슷한 수준의 관용어 이해 수행을 보였다. 집단 간 오류 양상으로는 ADHD 아동은 문자적 오류에서, 일반 아동은 관련 없는 오류에서 높은 빈도를 보였다. 결론: ADHD 아동은 특수한 의미를 지닌 관용어를 이해하는데 어려움이 있으나 문맥 단서가 관용적 의미를 유추하는데 도움이 되는 것을 확인하였고, ADHD 아동은 관용어를 주로 문자적인 해석으로 접근한다는 것을 알 수 있었다. 본 연구의 결과 ADHD 아동의 관용어 이해를 돕기 위해서 문맥 효과를 활용할 수 있음을 시사하였다.

Watermelon produces many byproducts (watermelon rind and skin) even though those components contain various bioactive compounds, including citrulline. This study evaluated the citrulline concentration, total phenolic content, and antioxidant activity (DPPH and FRAP assays) of different parts of watermelon and investigated the bioavailability of citrulline from different parts of watermelon using an in vitro human intestinal epithelial Caco-2 cell monolayer model. Solid-phase extracted watermelon flesh, rind, and skin samples were treated on a Caco-2 cell monolayer for 1, 2, and 4 h. The collected basolateral solution at each time point was analyzed for the percentage of citrulline transport. Watermelon flesh had the highest citrulline content, but the watermelon skin had the highest total phenolic content and antioxidant activity compared to other watermelon parts. The citrulline bioavailability showed greater % transport in watermelon skin than in watermelon flesh, rind, and L-citrulline standard. It may be due to the different food matrices of watermelon parts. This suggests that the utilization of watermelon by-products such as skin would help develop value-added products with better bioavailability of citrulline. However, since this study was conducted with an in vitro cell model, more extensive research with in vivo studies will be needed.

Hindering the absorption of glucose through inhibition of intestinal carbohydrate-hydrolyzing enzymes is an efficient strategy for reducing hyperglycemia. The purpose of this study was to examine the effect of watermelon flesh extracts (WFE), rind extract (WRE), skin extract (WSE), and citrulline on intestinal carbohydrate-hydrolyzing enzymes and to identify their bioactive compounds. WSE showed higher bioactive compounds and total phenolic content than WFE and WRE. WFE, WRE, and WSE demonstrated dose-dependent inhibition against carbohydrate-hydrolyzing enzymes. WFE, WRE, and WSE inhibited α-glucosidase by 40~45% at a concentration of 60 mg/mL whereas 80 mg/mL citrulline showed a similar inhibitory effect. WRE and citrulline showed IC₅₀ values of 0.02 and 0.01 mg/mL for maltase and sucrase, respectively. Citrulline at 20 mg/mL exhibited higher glucoamylase and pancreatic α-amylase inhibition than WFE, WRE, and WSE at the same concentration. Citrulline and WRE showed similar IC₅₀ values for glucoamylase and α-amylase compared to 1 mg/mL acarbose. This study suggests that watermelon, including its byproduct parts possibly due to citrulline, has the potential for carbohydrate-hydrolyzing enzyme inhibition that is beneficial to reducing postprandial hyperglycemia.