Inhibition of 12-O-tetradecanoylphorbol-13-acetate promoted mouse skin papilloma by digalactosyl diacylglycerols from the fresh water cyanobacterium Phormidium tenue

Glyceroglycolipids in marine algae: A review of their pharmacological activity

Glyceroglycolipids are major metabolites of marine algae and have a wide range of applications in medicine, cosmetics, and chemistry research fields. They are located on the cell surface membranes. Together with glycoproteins and glycosaminoglycans, known as the glycocalyx, they play critical roles in multiple cellular functions and signal transduction and have several biological properties such as anti-oxidant and anti-inflammatory properties, anti-viral activity, and anti-tumor immunity. This article focused on the sources and pharmacological effects of glyceroglycolipids, which are naturally present in various marine algae, including planktonic algae and benthic algae, with the aim to highlight the promising potential of glyceroglycolipids in clinical treatment.

Galactosyldiacylglycerols: From a Photosynthesis-Associated Apparatus to Structure-Defined In Vitro Assembling

Being ubiquitously present in plants, microalgae, and cyanobacteria and as the major constituents of thylakoid membranes, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) make up approximately 52 and 26%, respectively, of chloroplast lipids. Thylakoid membranes harbor the photosynthetic complexes and numerous essential biochemical pathways where MGDG and DGDG play a central role in facilitating photosynthesis light reaction, maintaining chloroplast morphology, and responding to abiotic stresses. Furthermore, these galactolipids are also bioactive compounds with antitumor, antimicrobial, antiviral, immunosuppressive, and anti-inflammatory activities and important nutritional value. These characteristics are strictly dependent upon their fatty acyl chain length, olefinic nature, and stereoconfiguration. However, their application potentials are practically untapped, largely as a result of the fact that their availability in large quantity and high purity (structured galactolipids) is challenging. In addition to laborious extraction from natural sources, in vitro assembling of these molecules could be a promising alternative. Thus, this review updates the latest advances in elucidating biosynthesis paths of MGDG and DGDG and related enzyme systems, which present invaluable inspiration to design approaches for a retrosynthesis of galactolipids. More critically, this work summarizes recent developments in the biological and enzymatic syntheses of galactolipids, especially the strategic scenarios for the construction of in vitro enzymatic and/or chemoenzymatic synthesis routes. Protein engineering of enzymes involved in the synthesis of MGDG and DGDG to improve their properties is highlighted, and the applications of galactolipids in foods and medicine are also discussed.

Glycolipids synthesis: improved hydrazinolysis conditions for preparation of 1,2-polyunsaturated fatty acyl-β-monogalactosyl-glycerols

The investigation is related to the development of a general strategy for the synthesis of glycolipids including analogs bearing polyunsaturated fatty acids. In particular, here we report exceptionally mild and selective conditions to remove acetate protecting groups from glyceroglycolipids by hydrazinolysis. Synthetic 1,2-O-di-arachidonoyl-3-O-β-galactosyl-glycerol was used as representative of polyunsaturated β-galactosyl-di-acyl-glycerols due to its reactivity under the conditions usually employed in literature.

Marine bacterial sources of bioactive compounds

Thousands of novel compounds have been isolated from various marine bacteria and tested for pharmacological properties, many of which are commercially available. Many more are being tested as potential bioactive compound at the preclinical and clinical stages. The growing interest in marine-derived antiviral compounds, along with the development of new technology in marine cultures and extraction, will significantly expedite the current exploration of the marine environment for compounds with significant pharmacological applications, which will continue to be a promising strategy and new trend for modern medicine. Marine actinomycetes and cyanobacteria are a prolific but underexploited source for the discovery of novel secondary metabolites.

Novel galactolipids from the leaves of Ipomoea batatas L.: characterization by liquid chromatography coupled with electrospray ionization-quadrupole time-of-flight tandem mass spectrometry

Sixteen novel and ten known galactolipids have been isolated and characterized from the leaves of Ipomoea batatas L. (sweet potato) using an analytical method based on high-performance liquid chromatography coupled with electrospray ionization-quadrupole time-of-flight tandem mass spectrometry. Using this technique, the structures and regiochemistries of the fatty acyl groups and the positions of the double bonds on the acyl chains were determined. Sugar moieties were identified by analysis of one- and two-dimensional nuclear magnetic resonance spectra. The positions of the double bonds of polyunsaturated fatty acids were confirmed, and in some cases their geometries determined, by gas chromatography-mass spectrometry. This is the first report of galactolipids in the leaves of sweet potato.

Bioactive compounds from cyanobacteria and microalgae: an overview

Cyanobacteria (blue-green algae) are photosynthetic prokaryotes used as food by humans. They have also been recognized as an excellent source of vitamins and proteins and as such are found in health food stores throughout the world. They are also reported to be a source of fine chemicals, renewable fuel and bioactive compounds. This potential is being realized as data from research in the areas of the physiology and chemistry of these organisms are gathered and the knowledge of cyanobacterial genetics and genetic engineering increased. Their role as antiviral, anti-tumour, antibacterial, anti-HIV and a food additive have been well established. The production of cyanobacteria in artificial and natural environments has been fully exploited. In this review the use of cyanobacteria and microalgae, production processes and biosynthesis of pigments, colorants and certain bioactive compounds are discussed in detail. The genetic manipulation of cyanobacteria and microalgae to improve their quality are also described at length.

Selective in vivo anti-inflammatory action of the galactolipid monogalactosyldiacylglycerol

The thermophilic blue-green alga ETS-05 colonises the therapeutic thermal muds of Abano and Montegrotto, Italy. Following the isolation, purification and identification of monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulphoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol from ETS-05, we here examine their in vivo anti-inflammatory activities. MGDG, DGDG and SQDG inhibit croton-oil-induced ear oedema in the mouse in a dose-dependent manner. Inhibition by MGDG is greater than that of the reference drug, betamethasone 17,21-dipropionate, and is largely abrogated following acyl group saturation. SQDG is the least potent of these glycoglycerolipids, and shows an early transient effect. In the in vivo carrageenan-induced paw oedema model in the mouse, the inhibitory effects are again dose dependent, with an enhanced efficacy of MGDG over DGDG, SQDG and the reference drug, indomethacin. These compounds are all less toxic than indomethacin. The selective and enhanced inhibitory effects of MGDG over DGDG indicate the mechanisms behind these in vivo anti-inflammatory actions.

Toxic potential of five freshwater Phormidium species (Cyanoprokaryota)

Among the Cyanoprokaryota (blue-green algae), the genus Phormidium has thus far rarely been studied with respect to toxin production and potentially resulting human and environmental health effects. We here show that five previously unexplored freshwater species of this genus (Ph. bijugatum, Ph. molle, Ph. papyraceum, Ph. uncinatum, Ph. autumnale) are indeed capable of producing bioactive compounds. Phormidium extracts caused weight loss as well as neuro/hepatotoxic symptoms in mice, and in the case of Ph. bijugatum even death. Very low levels of saxitoxins and microcystins, as confirmed by ELISA, were insufficient to explain this toxicity and the differing toxic potencies of the Phormidium species. Qualitative HPLC analyses confirmed different substance patterns and in the future could aid in the separation of fractions for more detailed substance characterisation. The results in vivo were confirmed in vitro using cells of human, mouse and fish. The fish cells responded least sensitive but proved useful in studying the temperature dependence of the toxicity by the Phormidium samples. Further, the human cells were more sensitive than the mouse cells thus suggesting that the former may be a more appropriate choice for studying the impact of Phormidium to man. Among the human cells, two cancer cell lines were more responsive to one of the samples than a normal cell line, thereby indicating a potential anti-tumour activity. Thus, the five freshwater Phormidium species should be considered in environmental risk assessment but as well, as a source of therapeutic agents.

GROWTH INHIBITION AND INDUCTION OF DIFFERENTIATION AND APOPTOSIS MEDIATED BY SODIUM BUTYRATE IN CACO-2 CELLS WITH ALGAL GLYCOLIPIDS

Glycolipids should have potential effects as antitumor agents. However, very few studies have examined this property of digalactosyl diacylglycerol (DGDG) and sulfoquinovosyl diacylglycerol (SQDG) on colon cancer cells. Cell viability was determined every 24 h with sodium 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2, 4-disulfophenyl)-2H-tetrazolium dye reduction assay up to 72 h. Alkaline phosphatase activity was measured for assessing cell differentiation. Apoptosis was tested with enzyme-linked immunosorbent assay analysis. Growth of Caco-2 cells was inhibited apparently at 48 h after addition of SQDG and at 72 h with DGDG. Alkaline phosphatase activity of Caco-2 cells obviously increased in combination with DGDG or SQDG and sodium butyrate (NaBT) at 72 h, indicating that DGDG and SQDG enhanced cell differentiation induced with NaBT. An increased enrichment factor was found when the cell was treated in combination with DGDG or SQDG and NaBT. These results strongly suggest that DGDG and SQDG should be considered as the leading compounds of potentially useful colon cancer chemotherapy agents when NaBT is combined.