Isolation and structure of a GD3-Type ganglioside molecular species possessing neuritogenic activity from the starfish Luidia maculata

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Marine Natural Products from the Russian Pacific as Sources of Drugs for Neurodegenerative Diseases

Neurodegenerative diseases are growing to become one of humanity's biggest health problems, given the number of individuals affected by them. They cause enough mortalities and severe economic impact to rival cancers and infections. With the current diversity of pathophysiological mechanisms involved in neurodegenerative diseases, on the one hand, and scarcity of efficient prevention and treatment strategies, on the other, all possible sources for novel drug discovery must be employed. Marine pharmacology represents a relatively uncharted territory to seek promising compounds, despite the enormous chemodiversity it offers. The current work discusses one vast marine region-the Northwestern or Russian Pacific-as the treasure chest for marine-based drug discovery targeting neurodegenerative diseases. We overview the natural products of neurological properties already discovered from its waters and survey the existing molecular and cellular targets for pharmacological modulation of the disease. We further provide a general assessment of the drug discovery potential of the Russian Pacific in case of its systematic development to tackle neurodegenerative diseases.

Sphingolipids of Asteroidea and Holothuroidea: Structures and Biological Activities

Sphingolipids are complex lipids widespread in nature as structural components of biomembranes. Commonly, the sphingolipids of marine organisms differ from those of terrestrial animals and plants. The gangliosides are the most complex sphingolipids characteristic of vertebrates that have been found in only the Echinodermata (echinoderms) phylum of invertebrates. Sphingolipids of the representatives of the Asteroidea and Holothuroidea classes are the most studied among all echinoderms. In this review, we have summarized the data on sphingolipids of these two classes of marine invertebrates over the past two decades. Recently established structures, properties, and peculiarities of biogenesis of ceramides, cerebrosides, and gangliosides from starfishes and holothurians are discussed. The purpose of this review is to provide the most complete information on the chemical structures, structural features, and biological activities of sphingolipids of the Asteroidea and Holothuroidea classes.

Chemical constituents and bioactivities of starfish

Starfish have been the research topic in many chemical and pharmacological laboratories due to their complex secondary metabolites and diverse bioactivities. The aim of this review is to provide an up-to-date review on the chemistry and bioactivity of compounds isolated from all kinds of starfish to illustrate the chemodiversity and biological significance of these constituents, along with their geographical distribution where it is discernible.

[Structure and biological activity of glycosphingolipids from starfish and feather stars]

Glycosphingolipids (GSLs) are contained in a various cell membranes and have recently been implicated in many physiologic functions. They are classified based on their sugar moieties into ceramides, cerebrosides, sulfatides, ceramide-oligohexosides, globosides, and gangliosides. A number of GSLs have been obtained from marine invertebrates such as echinoderms, poriferans, and mollusks and have unique biological activities. During the course of our search for biologically active GSLs from echinoderms, we conducted the isolation and structural elucidation of GSLs from starfish and feather stars and found numerous GSLs, some of which have unique structures. In particular, gangliosides from feather stars were unique in that the sialic acids bind to inositol-phosphoceramide. We also found that the GSLs from starfish and feather stars possess neuritogenic activity toward the rat pheochromocytoma cell line PC12, antihyperglycemic effects against type 2 diabetic BKS. Cg-m+/+Leprdb/J (db/db) mice, and antiosteoporosis effects toward the osteoporosis model mice (OVX mice). These biological activities are thought to be related to dementia, osteoporosis, and diabetes, which are becoming social problems, and are expected to become the seeds of preventive or therapeutic drugs for these illness.

Isolation and structure of four new ceramides from the starfish Luidia maculata

A new sphingosine-type ceramide LMCer-1-1 (1) and three new phytosphingosine-type ceramides, LMCer-2-1 (2), LMCer-2-6 (3), and LMCer-2-7 (4), were isolated from the anti-hyperglycemic active ceramide molecular species LMCer-1 and LMCer-2, obtained from the less polar fraction of the chloroform-methanol extract of the whole bodies of Luidia maculata. The structures of these ceramides were determined on the basis of chemical and spectroscopic evidence as: (2S,3R,4E,2'R)-2-(2-hydroxyhexadecanoylamino)-16-methyl-4-octadecene-1,3-diol (1), (2S,3S,4R,2'R)-2-(2-hydroxyhexadecanoylamino)-16-methyl-octadecane-1,3,4-triol (2), (2S,3S,4R,2'R)-2-(2-hydroxydocosanoylamino)-hexadecane-1,3,4-triol (3), and (2S,3S,4R,2'R)-2-(2-hydroxydocosanoylamino)-14-methyl-hexadecane-1,3,4-triol (4).

Neuritogenic Activity of Gangliosides from Echinoderms and Their Structure-Activity Relationship

The effects of the gangliosides isolated from echinoderms on the neuritogenesis of a rat pheochromocytoma cell line (PC-12 cells) in the presence of nerve growth factor were investigated. The results show that they displayed neuritogenic activity. Based on the observed results, a structure-activity relationship has been established.

Marine natural products

This review covers the literature published in 2004 for marine natural products, with 693 citations (491 for the period January to December 2004) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (716 for 2004), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies (8), and syntheses (80), including those that lead to the revision of structures or stereochemistries, have been included.