Sargassum horneri (SH) and Ulva australis (UA) are marine waste resources that cause environmental and economic problems when entering or multiplying the coastal waters of Jeju Island. We analyzed their anti-diabetic efficacy to assess their reusability as functional additives. The alpha-glucosidase inhibitory activity of SH and UA extracts was confirmed, and the effect of UA extract was higher than that of SH. After the induction of insulin-resistant HepG2 cells, the effects of the two marine extracts on oxidative stress, intracellular glucose uptake, and glycogen content were compared to the positive control, metformin. Treatment of insulin-resistant HepG2 cells with SH and UA resulted in a concentration-dependent decrease in oxidative stress and increased intracellular glucose uptake and glycogen content. Moreover, SH and UA treatment upregulated the expression of IRS-1, AKT, and GLUT4, which are suppressed in insulin resistance, to a similar degree to metformin, and suppressed the expression of FoxO1, PEPCK involved in gluconeogenesis, and GSK-3β involved in glycogen metabolism. The oral administration of these extracts to rats with streptozotocin-induced diabetes led to a higher weight gain than that in the diabetic group. Insulin resistance and oral glucose tolerance are alleviated by the regulation of blood glucose. Thus, the SH and UA extracts may be used in the development of therapeutic agents or supplements to improve insulin resistance.

Current research highlights the use of natural products or phytochemicals as drugs and functional additives to treat obesity with few side effects. Sargassum horneri (SH) and Ulva australis (UA) are marine waste resources on Jeju Island, Republic of Korea. In this study, we analyzed their antioxidant and anti-obesity efficacies to confirm their potential as functional additives. We prepared SH and UA extracts using 80% ethanol and observed that free radical scavenging activity and total phenol content were high in SH extracts, and total flavonoid content was elevated in UA extracts. Additionally, 3T3-L1 cells were treated with SH and UA extracts, and the ability of the extracts to inhibit adipocyte differentiation was examined using Oil Red O staining and analysis of neutral fat content. We confirmed that the mRNA expression of the C/EBPα, PPARγ, and SREBP1c genes that act on adipocyte differentiation, and of FAS, a fatty acid synthase, was suppressed. Experiments in a mouse model of obesity showed that 12-week administration of a high-fat diet with 1% extract added to drinking water resulted in lower weight gain compared to the high-fat diet alone. These results suggest that SH and UA extracts have antioxidant properties and are effective in obesity prevention. Therefore, the two marine waste resources are potential functional additive candidates for preventing obesity.

Young-Hyeon Lee, Min-Ho Yeo, Seon-A Yoon, Ho-Bong Hyun, Young-Min Ham, Yong-Hwan Jung, and Kyung-Soo Chang. Prev Nutr Food Sci 2021;26:307-14. https://doi.org/10.3746/pnf.2021.26.3.307

Young-Hyeon Lee, Min-Ho Yeo, Seon-A Yoon, Ho-Bong Hyun, Young-Min Ham, Yong-Hwan Jung, Hyun Jang, and Kyung-Soo Chang. Prev Nutr Food Sci 2022;27:70-7. https://doi.org/10.3746/pnf.2022.27.1.70

Most (90%) vitamin D synthesis occurs in the skin using sunlight (ultraviolet rays), and 10% is obtained through food. Vitamin D is an essential nutrient for skeletal growth and maintenance, cell proliferation and differentiation, and immune function. This study investigated whether maternal serum vitamin D concentrations induce maternofetal effects. Hematological analysis, serological changes, and precision fetal ultrasound findings were analyzed by maternal vitamin D concentration in gestational weeks 22–25 to ascertain direct effects on fetal growth. Bone density–vitamin D concentration correlation was analyzed. No hematologic or serological effect of maternal vitamin D concentration was detected; however, the sexually transmitted infection and cross-infection rates were inversely proportional to maternal vitamin D concentration. No significant correlation between vitamin D concentration and vertebral and femoral BMD was detected. For fetal growth, biparietal diameter, head circumference, abdominal circumference, femur length, and humerus length were analyzed. Humerus (p < 0.05) and femur (p < 0.001) lengths were higher in the vitamin D-sufficient group than in the vitamin D-deficient group. Vitamin D concentration did not positively affect hematologic changes and bone density; maternal vitamin D concentration essentially affected fetal bone growth. Vitamin D inhibits sexually transmitted infections in mothers and promotes fetal bone growth. Prevention of vitamin D deficiency, supplementation, or outdoor activities is recommended.

Metabolic dysfunction-associated steatohepatitis (MASH), previously referred to as non-alcoholic steatohepatitis (NASH), which is a progressive non-alcoholic fatty liver disease, is accompanied by hepatic steatosis, inflammation, and fibrosis. Despite its increasing prevalence, available treatment options for MASH are limited. Here, we investigated the protective effects of the Distylium racemosum ethyl acetate fraction (DRE) using MASH models and explored its key physiologically active components. Palmitic acid (PA)-induced AML12 hepatocytes and high-fat methionine- and choline-deficient-fed C57BL/6 mice were used as MASH models. Lipid accumulation was evaluated via triglyceride measurement, oil red O staining, and histological analysis. Lipid accumulation, inflammation, and fibrosis-associated gene expression were evaluated via real-time polymerase chain reaction. The physiologically active components of DRE were identified via high-performance liquid chromatography. Lipid accumulation and triglyceride levels were significantly reduced in PA-treated AML12 cells following DRE treatment. Additionally, DRE inhibited the expression of genes involved in lipogenesis (FAS and SREBP1c), inflammation (CD68, IL-6, and MCP-1), and fibrosis (COL1A1, COL1A2, and TIMP1). DRE reduced the liver weight, liver-to-body weight ratio, and hepatic steatosis in MASH model mice. It increased carnitine palmitoyltransferase-1 levels and decreased CD36 and transforming growth factor-β levels in the MASH mouse liver. High-performance liquid chromatography revealed that the extract contained rutin flavonoid family members. Overall, DRE was involved in lipid metabolism, inflammation, and fibrosis regulation, exerting potent hepatoprotective effects partly attributed to rutin and serving as a potential preventive candidate for MASH.