Green Synthesis of Silver and Gold Nanoparticles via Sargassum serratifolium Extract for Catalytic Reduction of Organic Dyes

The green synthesis of inorganic nanoparticles (NPs) using bio-materials has attained enormous attention in recent years due to its simple, eco-friendly, low-cost and non-toxic nature. In this work, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized by the marine algae extract, Sargassum serratifolium (SS). The characteristic studies of bio-synthesized SS-AgNPs and SS-AuNPs were carried out by using ultraviolet–visible (UV–Vis) absorption spectroscopy, dynamic light scattering (DLS), high-resolution transmission electron microscope (HR-TEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Phytochemicals in the algae extract, such as meroterpenoids, acted as a capping agent for the NPs’ growth. The synthesized Ag and Au NPs were found to have important catalytic activity for the degradation of organic dyes, including methylene blue, rhodamine B and methyl orange. The reduction of dyes by SS-AgNPs and -AuNPs followed the pseudo-first order kinetics.

Central Administration of Sargahydroquinoic Acid Elevates Peripheral Thermogenic Signaling and Ameliorates High Fat Diet-Induced Obesity

Sargassum serratifolium (C.Agardh) C.Agardh, a marine brown alga, has been consumed as food and traditional medicine in Asia. A previous study showed that the meroterpenoid-rich fraction of an ethanolic extract of Sargassum serratifolium (MES) induced adipose tissue browning and suppressed diet-induced obesity and metabolic syndrome. Sargahydroquinoic acid (SHQA) is a major component in MES. However, it is unclear whether SHQA can regulate energy homeostasis through the central nervous system. To figure it out, SHQA was administrated through the third ventricle of the hypothalamus in high-fat diet-fed C57BL/6 mice and investigated its effects on energy homeostasis. Bath application of SHQA increases the intrinsic neuronal excitability of hypothalamic ARC neurons in acutely prepared brain slices. Thus, we further tested its effect on energy balance. Chronic administration of SHQA into the brain reduced bodyweight without a change in food intake and improved metabolic syndrome-related phenotypes. Cold experiments and biochemical analyses indicate that SHQA elevates thermogenic signaling pathways evidenced by an increase in body temperature and UCP1 signaling in white and brown adipose tissues. As partial mechanisms, SHQA significantly elevated mRNA levels of genes associated with sympathetic outflow and GABA signaling pathways. Our data indicate that hypothalamic injection of SHQA elevates peripheral thermogenic signaling and ameliorates diet-induced obesity.

Effects of Sargaquinoic Acid in Sargassum Serratifolium on Inducing Brown Adipocyte-like Phenotype in Mouse Adipocytes In Vitro

A previous study showed that the meroterpenoid-rich fraction of an ethanolic extract of Sargassum serratifolium (MES) stimulated adipose tissue browning and inhibited diet-induced obesity and metabolic syndrome. Sargaquinoic acid (SQA) is a major component in MES. We investigated the effects of SQA on the differentiation of preadipocytes to the beige adipocytes. SQA was treated in 3T3-L1 adipocytes differentiated under a special condition that has been reported to induce the browning of adipocytes. SQA at 10 µM reduced lipid accumulation by approximately 23%. SQA at 2.5 – 10 µM induced the differentiation of white adipocytes to beige adipocytes partially by increasing the mitochondrial density and the expression of beige/brown adipocyte markers. In addition, SQA activated lipid catabolic pathways, evidenced by the increased expression levels of perilipin, carnitine palmitoyltransferase 1, and acyl-CoA synthetase long-chain family member 1. As a partial mechanism, biochemical and in silico analyses indicate that SQA activated AMP-activated protein kinase signaling in adipocytes.

Sargahydroquinoic Acid in Sargassum Serratifolium Activates Lipid Catabolic Pathways in 3T3-L1 Preadipocytes by Inducing White Adipocyte Browning (P06-108-19)

Objectives Sargassum serratifolium, a marine brown alga consumed in Asian countries, has shown anti-obesity effect by stimulating white adipose tissue browning. Therefore, the purpose of this study was to investigate lipid catabolic effects of sargahydroquinoic acid (SHQA), which is one of the major bioactive compounds of S. serratifolium by white adipocyte browning effect. Methods Isolated and purified SHQA from S. serratifolium was used to treat 3T3-L1 preadipocytes to see the effects of lipid catabolism and white adipocyte browning. Glycerol concentration measurement, Oil Red O lipid staining, and triglyceride quantification were conducted to examine the lipid catabolism by SHQA in the 3T3-L1 cells. In addition, real-time PCR and Western Blot assays were used to examine the expressions of genes related with lipid catabolic pathway, mitochondria biogenesis and white adipocyte browning. Results SHQA significantly upregulated non-shivering thermogenic gene expressions in 3T3-L1 cells including uncoupling protein 1, peroxisome proliferator-activated receptor γ and PR domain containing 16. SHQA also notably reduced cellular lipid accumulation. Interestingly, peroxisome proliferator-activated receptor (PPAR)γ, which is involved in lipid uptake and adipogenesis was upregulated by SHQA treatment. However, Western Blotting and protein-ligand docking simulation revealed that SHQA activates not only PPARγ but also PPARα and AMP-activated protein kinase (AMPK) α, which are lipid-catabolic proteins. In addition, SHQA treatment markedly elevated lipolysis and the amounts of mitochondria in 3T3-L1 cells. Conclusions Our results indicate that SHQA may combat obesity and associated metabolic syndromes through lipid catabolic pathways, mitochondria biogenesis and adipocyte browning by activating PPARγ, PPARα, and AMPKα pathways. Funding Sources This study was a part of the project, “Development of functional food products with natural materials derived from marine resources” funded by the Ministry of Oceans and Fisheries, Republic of Korea.