Jeong Hoon Pan

Lecithin-Based Nano-emulsification Improves the Bioavailability of Conjugated Linoleic Acid

In this study, we investigated the effects of lecithin-based nano-emulsification on the heat stability and bioavailability of conjugated linoleic acid (CLA) in different free fatty acid (FFA) and triglyceride (TG) forms. CLA nano-emulsion in TG form exhibited a small droplet size (70-120 nm) compared to CLA nano-emulsion in FFA form (230-260 nm). Nano-emulsification protected CLA isomers in TG form, but not in free form, against thermal decomposition during the heat treatment. The in vitro bioavailability test using monolayers of Caco-2 human intestinal cells showed that nano-emulsification increased the cellular uptake of CLA in both FFA and TG forms. More importantly, a rat feeding study showed that CLA content in small intestinal tissues or plasma was higher when CLA was emulsified, indicating an enhanced oral bioavailability of CLA by nano-emulsification. These results provide important information for development of nano-emulsion-based delivery systems that improve thermal stability and bioavailability of CLA.

Preparation of S-Allylcysteine-Enriched Black Garlic Juice and Its Antidiabetic Effects in Streptozotocin-Induced Insulin-Deficient Mice

S-Allylcysteine (SAC), produced in large amounts during the aging process of garlic via enzymatic hydrolysis, is known as a key compound responsible for the multiple pharmacological activities of aged black garlic. This study investigated the effects of enzyme- and high hydrostatic pressure (HHP)-assisted extraction on the content of the bioactive compounds, including SAC, in black garlic juice (BGJ) and evaluated the antidiabetic effects of SAC-enriched BGJ in streptozotocin (STZ)-treated mice. The aging process increased the contents of SAC, total polyphenols, and total flavonoids in garlic juice. More importantly, pretreatment of pectinase cocktail with HHP resulted in a greater increase in those compounds during aging. Enzyme-treated BGJ reduced hyperglycemia and improved islet architecture and β-cell function in STZ-treated mice. Moreover, these effects were more potent than those of BGJ prepared by the conventional aging process. These findings provide useful information for the production of black garlic with improved bioactivities.

Functional comparison of esterified and free forms of conjugated linoleic acid in high-fat-diet-induced obese C57BL/6J mice.

This study investigated the effects of dietary conjugated linoleic acid (CLA), in the form of free fatty acid (FFA-CLA) or triacylglycerol (TG-CLA), on serum and liver lipid composition and gene expression associated with lipogenesis and β-oxidation in high-fat-diet (HFD)-induced obese C57BL/6J mice. Animals were fed a control diet, HFD, HFD supplemented with 2% FFA-CLA, or HFD supplemented with 2% TG-CLA for 8 weeks. Supplementation with both forms of CLA significantly reduced the weights of whole body and adipose tissue and was positively associated with significant liver enlargement. Both forms of CLA significantly decreased serum TG concentration, but had no effect on total cholesterol levels, which were increased in mice fed HFD. There was a prominent increase in serum alanine aminotransferase (ALT) levels in mice that received either form of CLA. TG accumulation and lipogenic gene expression, including the expression of genes for fatty acid synthase (FAS), acetyl-coenzyme A carboxylase (ACC), and malic enzyme, were significantly lower in the livers of mice that received TG-CLA as compared to FFA-CLA. The gene expressions of sterol regulatory element binding protein-1c (SREBP-1c) in both liver and adipose tissue were suppressed in mice that were fed either form of CLA as compared to the mice fed HFD alone, whereas there were no increases in the levels of expression of β-oxidation-related genes. These findings demonstrated that free and esterified forms of CLA have differing effects on liver and adipose tissue lipogenesis.

Black Ginseng Extract Counteracts Streptozotocin-Induced Diabetes in Mice

Black ginseng, a new type of processed ginseng that has a unique ginsenoside profile, has been shown to display potent pharmacological activities in in vitro and in vivo models. Although red ginseng is considered beneficial for the prevention of diabetes, the relationship between black ginseng and diabetes is unknown. Therefore, this study was designed to evaluate the anti-diabetic potential of black ginseng extract (BGE) in streptozotocin (STZ)-induced insulin-deficient diabetic mice, in comparison with red ginseng extract (RGE). HPLC analyses showed that BGE has a different ginsenoside composition to RGE; BGE contains Rg5 and compound k as the major ginsenosides. BGE at 200 mg/kg reduced hyperglycemia, increased the insulin/glucose ratio and improved islet architecture and β-cell function in STZ-treated mice. The inhibition of β-cell apoptosis by BGE was associated with suppression of the cytokine—induced nuclear factor–κB—mediated signaling pathway in the pancreas. Moreover, these anti-diabetic effects of BGE were more potent than those of RGE. Collectively, our data indicate that BGE, in part by suppressing cytokine—induced apoptotic signaling, protects β-cells from oxidative injury and counteracts diabetes in mice.

l-Carnitine enhances exercise endurance capacity by promoting muscle oxidative metabolism in mice

L-Carnitine (LC), the bioactive form of carnitine, has been shown to play a key role in muscle fuel metabolism during exercise, resulting in increased fatty acid oxidation and energy expenditure. However, whether LC contributes to improved endurance exercise performance remains controversial. This study was designed to investigate the effects of LC administration on endurance capacity and energy metabolism in mice during treadmill exercise. Male C57BL/6 mice were divided into two groups (sedentary and exercise) and received daily oral administration of LC (150 mg/kg) or vehicle with a high-fat diet for 3 weeks. During the experimental period, all animals were trained three times a week on a motorized treadmill, and the total running time until exhaustion was used as the index of endurance capacity. LC administration induced a significant increase in maximum running time with a reduction of body fat compared with the control group when mice were subjected to programmed exercise. The serum levels of triglyceride, non-esterified fatty acid, and urea nitrogen were significantly lower in the LC group than the corresponding levels in the control group, while serum ketone body levels were higher in the LC group. Muscle glycogen content of LC administered-mice was higher than that of control mice, concomitant with reduced triglyceride content. Importantly, muscle mRNA and protein expressions revealed enhanced fatty acid uptake and oxidative metabolism and increased mitochondrial biogenesis by LC administration. These results suggest that LC administration promotes fat oxidation and mitochondrial biogenesis while sparing stored glycogen in skeletal muscle during prolonged exercise, resulting in enhanced endurance capacity.

Effects of cellulase from Aspergillus niger and solvent pretreatments on the extractability of organic green tea waste.

As green tea is being consumed in larger amounts, more green tea waste is being produced. Following extraction, several bioactive compounds may exist in the waste including polyphenols and amino acids. It was found that an Aspergillus niger cellulase treatment of green tea waste increased the extractability of various nutritional and functional components after pretreatments with various extraction solvents such as cold water (CW), hot water (HW), sulfuric acid (SA), hydrochloric acid (HA), and methanol (Me). After the residue was treated with cellulase from Aspergillus niger, the amounts of polyphenols, total catechins, and reducing sugars in the HW extract were increased by 64.6, 941.2, and 350.9%, respectively. In particular, levels of epigallocatechin, epicatechin, and gallic acid were significantly enhanced compared to those in the nontreated control. However, protein extraction was not significantly affected, and cellulase treatment was not more efficient for caffeine extraction compared to phenolic extraction. Among the four extraction solvents, HW and SA showed relatively higher extractabilities as compared to the other groups (CW, HA, and Me). These results indicate that cellulase from A. niger can increase the extractability of green tea waste when combined with certain solvent pretreatments. Consequently, the residual functional compounds and essential nutrients from cellulase-treated green tea waste have the potential to be applied in the production of new functional foods.

Cruciferous vegetables and colorectal cancer prevention through microRNA regulation: A review

ABSTRACT Diets rich in fruits and vegetables may lower colorectal cancer risk. In particular, a number of in vitro and in vivo studies demonstrated that cruciferous vegetables and their active compounds elicit chemopreventive potency through multiple mechanisms. However, it is relatively unexplored whether these vegetables modulate the risk of cancer development through epigenetic mechanisms including noncoding RNAs. Therefore, the objective of the present review is to report and discuss existing evidence with regards to modulation of microRNAs (miRNAs), one variety of noncoding RNAs, by cruciferous vegetables and their chemo-preventive effects against colorectal cancers. As results, it seems clear, considering accumulating evidence regarding their interactions with cancer related genes and relevant signaling pathways, that miRNA modulation via cruciferous vegetables is an attractive target for the prevention of colorectal cancer. In addition, miRNAs have been characterized as diagnostic and prognostic biomarkers and utilized in cancer therapeutics. Thus, it is very possible that natural agents (not limited to those in cruciferous vegetables) enhance cancer therapeutic efficacy and elicit chemopreventive effects through modulating key miRNAs.

Saponin-Based Nanoemulsification Improves the Antioxidant Properties of Vitamin A and E in AML-12 Cells

Our work aimed to investigate the protective effects of saponin-based nanoemulsions of vitamin A and E against oxidative stress-induced cellular damage in AML-12 cells. Saponin nanoemulsions of vitamin A (SAN) and vitamin E (SEN) were prepared by high-pressure homogenization and characterized in terms of size, zeta potential, and polydispersity index. SEN and SAN protect AML-12 cells against oxidative stress-induced cellular damage more efficiently via scavenging reactive oxygen species (ROS), and reducing DNA damage, protein carbonylation, and lipid peroxidation. These results provide valuable information for the development of nanoemulsion-based delivery systems that would improve the antioxidant properties of vitamin A and E.

Inhibition of the lipogenesis in liver and adipose tissue of diet-induced obese C57BL/6 mice by feeding oleic acid-rich sesame oil

The effects of sesame oil (SO) on lipogenic gene expression and lipid metabolism were observed. One percent of SO was added into the high-fat diet (HFD) used to feed C57BL/6 male mice for 8 weeks. SO significantly lowered adipose tissue mass than that of the high-fat control group. In addition, serum and hepatic lipid contents were markedly lower than those of the high-fat control group. Especially, the ratio of HDL/LDL was much higher than that of the HFD group. The gene expression of key lipogenic enzymes, Ppar-γ, Srebp-1c, Scd-1, Fas, Acc, Lpl, and malic enzyme, was significantly downregulated in the liver and adipose tissue of mice fed sesame oil. This study suggests that high proportion of oleic acid in SO might be strongly associated with lowering serum and hepatic lipid profile and suppressing lipogenic gene expression.

Naringin Protects Pancreatic β-Cells Against Oxidative Stress-Induced Apoptosis by Inhibiting Both Intrinsic and Extrinsic Pathways in Insulin-Deficient Diabetic Mice

SCOPE Oxidative stress has been suggested to play a central role in the pathogenesis of diabetes, as well as other metabolic disorders. Naringin, a major flavanone glycoside in citrus species, has been shown to display strong antioxidant potential in in vitro and in vivo models of oxidative stress; however, the underlying protective mechanisms in diabetes are unclear. METHODS AND RESULTS To study the protective effects and molecular mechanisms of naringin in preventing islet dysfunction and diabetes, we examined glucose homeostasis, β-cell apoptosis, and inflammatory response in insulin-deficient diabetic mice exposed to acute oxidative stress with streptozotocin (STZ). Naringin dose-dependently ameliorated hyperglycemia and islet dysfunction in insulin-deficient diabetic mice. Naringin counteracted STZ-induced β-cell apoptosis by inhibiting both the intrinsic (mitochondria-mediated) and extrinsic (death receptor-mediated) pathways. Furthermore, these protective effects were associated with suppression of DNA damage response and nuclear factor-kappa B- and mitogen-activated protein kinase-mediated signaling pathways, as well as reduction of reactive oxygen species accumulation and pro-inflammatory cytokine production in the pancreas. CONCLUSION Taken together, our study provides insights into the underlying mechanisms through which naringin protects the pancreatic β-cells against oxidative stress-induced apoptosis.