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Theonella swinhoei is a fairly common inhabitant of reefs throughout the Indian and Pacific Oceans. Metabolomic analyses of samples of T. swinhoei collected in different depths in the Gulf of Aqaba revealed two chemotypes differing in the profiles of the theonellamides they produce, some of which seem to be unknown. Driven by this finding, we examined a sample of T. swinhoei collected more than 40 years ago in the southern part of the Gulf of Aqaba. Large-scale extract of this sample yielded four theonellamides, the known theopalauamide (4), as the major component, and three new metabolites, theonellamide J (1), 5-cis-Apoa-theopalauamide (2), and theonellamide K (3), as the minor components. The planar structure of these complex cyclic glycopeptides was elucidated by combination of 1D and 2D NMR techniques and HRESIMS. The absolute configuration of the amino acids was established by Marfey’s and advanced Marfey’s methods, and the absolute configuration of its galactose unit using “Tanaka’s method” for monosaccharides. The biological activity of the pure compounds was tested for antibacterial activity and for cytotoxicity to HTC-116 cell line. The compounds presented significant cytotoxicity against the HTC-116 cell line, illuminating the importance of the Apoa subunit for the activity. 相似文献
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Jeong Kyu Bang Jun Hyuck Lee Ravichandran N. Murugan Sung Gu Lee Hackwon Do Hye Yeon Koh Hye-Eun Shim Hyun-Cheol Kim Hak Jun Kim 《Marine drugs》2013,11(6):2013-2041
Antifreeze proteins (AFPs) and glycoproteins (AFGPs), collectively called AF(G)Ps, constitute a diverse class of proteins found in various Arctic and Antarctic fish, as well as in amphibians, plants, and insects. These compounds possess the ability to inhibit the formation of ice and are therefore essential to the survival of many marine teleost fishes that routinely encounter sub-zero temperatures. Owing to this property, AF(G)Ps have potential applications in many areas such as storage of cells or tissues at low temperature, ice slurries for refrigeration systems, and food storage. In contrast to AFGPs, which are composed of repeated tripeptide units (Ala-Ala-Thr)n with minor sequence variations, AFPs possess very different primary, secondary, and tertiary structures. The isolation and purification of AFGPs is laborious, costly, and often results in mixtures, making characterization difficult. Recent structural investigations into the mechanism by which linear and cyclic AFGPs inhibit ice crystallization have led to significant progress toward the synthesis and assessment of several synthetic mimics of AFGPs. This review article will summarize synthetic AFGP mimics as well as current challenges in designing compounds capable of mimicking AFGPs. It will also cover our recent efforts in exploring whether peptoid mimics can serve as structural and functional mimics of native AFGPs. 相似文献
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Gerrit J. Gerwig Henry G. Hocking Reto St?cklin Johannis P. Kamerling Rolf Boelens 《Marine drugs》2013,11(3):623-642
Conotoxins are small peptides present in the venom of cone snails. The snail uses this venom to paralyze and capture prey. The constituent conopeptides display a high level of chemical diversity and are of particular interest for scientists as tools employed in neurological studies and for drug development, because they target with exquisite specificity membrane receptors, transporters, and various ion channels in the nervous system. However, these peptides are known to contain a high frequency and variability of post-translational modifications—including sometimes O-glycosylation—which are of importance for biological activity. The potential application of specific conotoxins as neuropharmalogical agents and chemical probes requires a full characterization of the relevant peptides, including the structure of the carbohydrate part. In this review, the currently existing knowledge of O-glycosylation of conotoxins is described. 相似文献
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Light and election microscopy were used to document the degree of renal corpuscle development in boreal telcost fishes that produce peptide or glycopeptide antifreeze compounds on a seasonal or permanent basis. Emphasis was placed on gadids, cottids and pleuronectids from both the North Atlantic and North Pacific Oceans. Based on the classification of Marshall and Smith (1930), corpuscle development ranged from fully glomerular (Type 1) to pauciglomerular (Type III). Unlike the situation in Antarctic notothenioid fishes, there were no aglomerular species among the boreal fishes. Corpuscles were small in diameter in gadids whereas in cottids they ranged from small to large with considerable intraspecific variation. Eight of eleven species with antifreeze had intermediate (Type II–III) or pauciglomerular kidneys with relatively few dense corpuscles (dia. 36–82m). In some of these species an extensive mesangium and a substantial capillary endothelium contributed to a glomerular filtration barrier that was four to five times thicker than that in Type I kidneys. The corpuscles of other pauciglomerular species were unremarkable and appeared functional at the ultrastructural level. The boreal fish fauna is taxonomically diverse and, compared to the unrelated Antarctic fauna, of relatively recent evolutionary origin. Furthermore, antifreeze is present only during the winter in some species. Hence it is not surprising that the urinary conservation of antifreeze is accomplished by mechanisms other than the evolutionary loss of renal corpuscles. 相似文献
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Diaa T. A. Youssef Lamiaa A. Shaala Gamal A. Mohamed Jihan M. Badr Faida H. Bamanie Sabrin R. M. Ibrahim 《Marine drugs》2014,12(4):1911-1923
In our search for bioactive metabolites from marine organisms, we have investigated the polar fraction of the organic extract of the Red Sea sponge Theonella swinhoei. Successive chromatographic separations and final HPLC purification of the potent antifungal fraction afforded a new bicyclic glycopeptide, theonellamide G (1). The structure of the peptide was determined using extensive 1D and 2D NMR and high-resolution mass spectral determinations. The absolute configuration of theonellamide G was determined by chemical degradation and 2D NMR spectroscopy. Theonellamide G showed potent antifungal activity towards wild and amphotericin B-resistant strains of Candida albicans with IC50 of 4.49 and 2.0 μM, respectively. Additionally, it displayed cytotoxic activity against the human colon adenocarcinoma cell line (HCT-16) with IC50 of 6.0 μM. These findings provide further insight into the chemical diversity and biological activities of this class of compounds. 相似文献
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