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BACKGROUND Siphonaxanthin, a xanthophyll present in green algae, has been shown to possess antiangiogenic and apoptosis-inducing activities. OBJECTIVE We evaluated the antiobesity effects of siphonaxanthin by using a 3T3-L1 cell culture system and in diabetic KK-Ay mice. METHODS 3T3-L1 cells were differentiated with or without 5 μmol/L siphonaxanthin, and lipid accumulation and critical gene expressions for adipogenesis were examined. In vivo, 4-wk-old male KK-Ay mice were administered daily oral treatment of 1.3 mg siphonaxanthin for 6 wk and body weight, visceral fat weight, serum variables, and gene expressions involved in lipid metabolism were evaluated. RESULTS Compared with the other carotenoids evaluated, siphonaxanthin potently inhibited adipocyte differentiation. Siphonaxanthin significantly suppressed lipid accumulation at noncytotoxic concentrations of 2.5 and 5 μmol/L by 29% and 43%, respectively. The effects of siphonaxanthin were largely limited to the early stages of adipogenesis. Siphonaxanthin significantly inhibited protein kinase B phosphorylation by 48% and 72% at 90 and 120 min, respectively. The expressions of key adipogenesis genes, including CCAAT/enhancer binding protein α (Cebpa), peroxisome proliferator activated receptor γ (Pparg), fatty acid binding protein 4 (Fabp4), and stearoyl coenzyme A desaturase 1 (Scd1), were elevated by 1.6- to 166-fold during adipogenesis. After 8 d of adipocyte differentiation, siphonaxanthin significantly lowered gene expression of Cebpa, Pparg, Fabp4, and Scd1 by 94%, 83%, 95%, and 90%, respectively. Moreover, oral administration of siphonaxanthin to KK-Ay mice significantly reduced the total weight of white adipose tissue (WAT) by 13%, especially the mesenteric WAT by 28%. Furthermore, siphonaxanthin administration reduced lipogenesis and enhanced fatty acid oxidation in adipose tissue. Siphonaxanthin was observed to highly accumulate in mesenteric WAT, and the accumulation in the mesenteric WAT was almost 2- and 3-fold that in epididymal (P = 0.14) and perirenal (P < 0.05) WAT, respectively. CONCLUSION These results provide evidence that siphonaxanthin may effectively regulate adipogenesis in 3T3-L1 cells and diabetic KK-Ay mice.

Phycoerythrin from the red alga Porphyra yezoensis has been demonstrated to possess antioxidative activity and is expected to have anti-inflammatory activity. In this study, we examined the effects of phycoerythrin and its pigment moiety, phycoerythrobilin, on the degranulation of mast cells. Phycoerythrin (0.01 mg/mL) and phycoerythrobilin (1 μmol/L) significantly inhibited calcium ionophore (A23187) induced release of β-hexosaminidase from rat basophilic leukemia (RBL-2H3) cells (approximately 50% and 40%, respectively). Phycoerythrobilin significantly suppressed IgE-antigen-stimulated degranulation of RBL-2H3 cells, while phycoerythrin had no effect. A23187-induced degranulation of peritoneal exudate cells (PEC) prepared from rats treated orally with phycoerythrin (4 mg/kg) or phycoerythrobilin (1 μmol/kg) was significantly reduced compared to control PEC. These results suggest that phycoerythrin and phycoerythrobilin exhibit anti-inflammatory activities through the suppression of mast cells degranulation in vivo.

In this report, we reviewed recent literature on physiologically active substances from sea cucumbers (SCs) and their activities together with results obtained from our study. Preventive properties against lipid metabolism were reported in rats using a whole SC preparation with no particular constituent specified. Administration of the preparation lowered serum and hepatic cholesterol levels and improved the HDL/LDL ratio. These functions may be attributed to the stimulatory effect of the extract on the secretion of cholesterol in feces. Novel fucosylated chondroitin sulfates (FCSs) from Ludwigothurea grisea significantly induced fibroblast growth factor 2-dependent angiogenesis in human umbilical vein endothelial cells (HU-VECs). The proangiogenetic activity seemed attributable to the action of the sulfated fucose branches on the polysaccharide. SCs contain mycosporine-like amino acids (MAAs) that are capable of absorbing UV. A biogenetic precursor of MAAs was first reported in SCs. The anti-proliferative effects of a branched chain fatty acid from a sea cucumber on prostate cancer cells was reported with the activity of 5-lipoxygenase. Glycosphingolipid constituents in SCs have been systematically analyzed over the past ten years. The results showed that the gangliosides in several SCs differed from those of mammals in that a sialic acid of SC gangliosides directly binded to glucose of cerebroside. Neuritogenic activity of the glycosphingolipids was demonstrated in vitro experiments and may lead to the development of therapeutic products for neurological disorders. Our study also showed that sphingoid bases, the hydrolyzed products of glycosphingolipids from SCs, induced significant apoptosis in several tumor cell lines.