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BACKGROUND: Saponins have been shown to possess many pharmacological properties, including altered fat metabolism. The black sea cucumber, Holothuria leucospilota, is a marine animal that contains a specialized organ called a Cuvierian tubule that produces and secrete the bioactive saponins into the tubules and body wall. Therefore, the aims of this study are to investigate the anti‐obesity effect of saponins extracted from body wall and Cuvierian tubules of H. leucospilota. RESULTS: The butanol extracts of H. leucospilota body wall and Cuvierian tubules containing high amounts of saponins significantly reduced fat deposition and triglyceride levels in Caenorhabditis elegans fed with 50 mmol L−1 glucose. Moreover, the saponin‐enriched extracts of H. leucospilota significantly restored the lifespan of 2% glucose‐fed worms (18.71%). Green fluorescence protein‐labeled sbp‐1 gene expression and nuclear translocation of daf‐16 were also significantly decreased in H. leucospilota treatment. The saponin‐enriched extracts downregulated the messenger RNA expressions of genes involved in fat storage and metabolism, including sbp‐1, cebp, and daf‐16 but upregulated the expression of nhr‐49 gene. CONCLUSION: Our results suggest that H. leucospilota‐derived saponins may mediate the reduction of glucose‐induced fat accumulation through sbp‐1, cebp, daf‐16 and nhr‐9 pathways. Therefore, the H. leucospilota extracts could be used as nutraceuticals for anti‐obesity prevention. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Saponins are secondary metabolites that provide medicinal benefits in controlling body homeostasis and metabolic functions. Sea cucumber has been consumed in many Asian countries due to their health benefits. Active chemicals found in sea cucumber include natural source of saponins which are enriched in their tissues, including the Cuvierian tubules and the body wall. Tissue origin of the saponin biosynthesis and accumulation is limitedly known. The present study is to indicate major compositions and distributions of saponins in the body wall of Holothuria leucospilota. Structurally, their body wall consisted of the pigmented layer of the epidermis, the dermal connective tissues, and inner muscular layers. Interestingly, release of the pigmented granules from the epidermis was related to detection of epidermal saponins. Matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) revealed identical mass spectra in the saponin extracts and compared to the known compounds of holothurians. To investigate the release of epidermal saponins, the epidermis dissolved in either butanol or distilled water were analyzed and presented the saponin masses with two prominent masses of m/z 1,243.3 (holothurin A and scabraside B) and 1,259.3 (holothurin A3). MALDI‐IMS also demonstrated strong signals of the known saponins which were only localized in the epidermis of the body wall. Taken together, this study shows that granule release from epidermal pigmented cells is somehow related to the amount of epidermal saponins released to surrounding seawater. Hence, the future research in the sea cucumber better focuses on epidermal cells that are the enriched site of saponins, although several active compounds require further investigation. ‐ Electron microscopy and MALDI‐IMS revealed the major compositions and the distributions of saponins in H. leucospilota body wall, particularly in the epidermis. ‐ The epidermal saponins, m/z 1,243.3 and 1,259.3 were the most abundant compounds. [ABSTRACT FROM AUTHOR]

Dynamin is a 96-kDa protein that has multiple oligomerization states that influence its GTPase activity. A number of different dynamin effectors, including lipids, actin filaments, and SH3-domain-containing proteins, have been implicated in the regulation of dynamin oligomerization, though their roles in influencing dynamin oligomerization have been studied predominantly in vitro using recombinant proteins. Here, we identify higher order dynamin oligomers such as rings and helices in vitro and in live cells using fluorescence lifetime imaging microscopy (FLIM). FLIM detected GTP- and actin-dependent dynamin oligomerization at distinct cellular sites, including the cell membrane and transition zones where cortical actin transitions into stress fibers. Our study identifies a major role for direct dynamin-actin interactions and dynamin's GTPase activity in the regulation of dynamin oligomerization in cells. [ABSTRACT FROM AUTHOR]