Current Medicinal Chemistry - Volume 12, Issue 17, 2005

Several studies showed that after a fatty meal, plasma triglyceride (TG) levels are higher in patients with coronary heart disease. This abnormality may explain why some individuals develop atherosclerotic disease despite normal fasting lipid values. TG-rich lipoproteins are involved in atherosclerosis and thrombosis. TG, remnant-like particle (RLP) cholesterol (RLP-C) and RLP-TG increase after fat load and could contribute to atherothrombosis. Postprandial lipaemia is not a uniform abnormality. Its pathophysiology is not yet entirely clarified; possibly, the response to dietary fat is a polygenic phenomenon. However, a link with insulin resistance is likely; this link as well as that with obesity is discussed. A substantial part of life is spent in the postprandial state. Therefore, several investigators described fat load tests. However, it is still difficult to establish normal postprandial TG ranges since only small numbers of subjects were studied and there is as yet no standardised method. A more simplified fat load test should be established for 'routine' use. In this review, we consider the metabolic features, prevalence and management of postprandial lipaemia. Treatment may involve lifestyle measures as well as the use of lipid lowering (e.g. fibrates or statins), weight reducing and hypoglycaemic drugs.

The plecomacrolides are a large family of natural products typically featured with a 16- or 18- membered macrolactone possessing two conjugated diene units and a hemiacetal side chain. The macrocycle skeleton is connected with the side chain through a three-carbon linker, forming a biologically important intramolecular hydrogen bonding network among the lactone/linker/hemiacetal structural motif. Many members of the plecomacrolides act as selective inhibitors of vacuolar H+-ATPases (V-ATPases) and they are considered to have the potential for treatment of postmenopausal osteoporosis. Significant progress has been achieved in recent years in the area of plecomacrolide total synthesis. These include the total synthesis of bafilomycin A1 by Evans, Toshima, Hanessian, and Roush, of bafilomycin V1 by Marshall, of hygrolidin by Hashimoto and Yonemitsu, of concanamycin F by Paterson and Toshima, and of formamicin by Roush. The synthetic strategies and key transformations used in the total synthesis are discussed.

A number of amine-boranes and related derivatives possess a wide range of biological activities including antineoplastic, antiviral, hypolipidemic, anti-inflammatory activities, anti-osteoporotic and dopamine receptor antagonist activities. The compounds include borane complexes of α-amino acids, aromatic, aliphatic and heterocyclic amines, and nucleosides. The syntheses of amine-borane derivatives are generally carried out by first preparing a tertiary amine- or phosphine-cyano- or carboxyborane to serve as a borane donor for a subsequent Lewis acid exchange reaction. Borane adducts of simple aliphatic amines, heterocyclic amines and nucleic acids demonstrated potent cytotoxic activity in vitro and in vivo against murine and human tumor models. These boron-containing compounds were shown to inhibit DNA synthesis; such inhibition was caused primarily by reducing de novo purine biosynthesis via inhibition of PRPP amidotransferase, IMP dehydrogenase and dihydrofolate reductase activities. Aliphatic, heterocyclic and nucleoside amine-boranes have also been shown to possess hypolipidemic activity in mice and rats. Many boron derivatives from different chemical classes demonstrated both cytotoxic and hypolipidemic activities. They decreased low-density lipoprotein (LDL) cholesterol while increasing high-density lipoprotein (HDL) cholesterol levels. The mode of action of these compounds in the 50-100 μM concentration range appeared to be by increasing lipid excretion from the body and by inhibiting rate-limiting enzyme activities for the de novo synthesis of lipids and cholesterol (e.g., phosphatidylate phosphohydrolase, ATP-dependent citrate lyase, cytoplasmic acetyl coenzyme A [CoA] synthetase, HMG CoA reductase, and acetyl CoA carboxylase). Selected amine-boranes (e.g., trimethylamine-cyanoborane, N-methylmorpholine-cyanoborane, and the base-boronated 2'-deoxynucleosides) have anti-inflammatory, analgesic, anti-arthritic and anti-osteoporotic activities.

All biological phenomena depend on molecular recognition, which is either intermolecular like in ligand binding to a macromolecule or intramolecular like in protein folding. As a result, understanding the relationship between the structure of proteins and the energetics of their stability and binding with others (bio)molecules is a very interesting point in biochemistry and biotechnology. It is essential to the engineering of stable proteins and to the structure-based design of pharmaceutical ligands. The parameter generally used to characterize the stability of a system (the folded and unfolded state of the protein for example) is the equilibrium constant (K) or the free energy (ΔG°), which is the sum of enthalpic (ΔH°) and entropic (ΔS°) terms. These parameters are temperature dependent through the heat capacity change (ΔCp). The thermodynamic parameters ΔH° and ΔCp can be derived from spectroscopic experiments, using the van't Hoff method, or measured directly using calorimetry. Along with isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC) is a powerful method, less described than ITC, for measuring directly the thermodynamic parameters which charaterize biomolecules. In this article, we summarize the principal thermodynamics parameters, describe the DSC approach and review some systems to which it has been applied. DSC is much used for the study of the stability and the folding of biomolecules, but it can also be applied in order to understand biomolecular interactions and can thus be an interesting technique in the process of drug design.

Taurine was discovered more than two hundred years ago from animal sources. It is distributed in both mammals and non-mammals and its content is high in several tissues. For more than a century-and-a-half, taurine was regarded just as an end product of sulfur metabolism. Recently, taurine has been rediscovered and its beneficial effects in processes like epilepsy, hypertension, congestive heart failure and diabetes have been well-documented. It was patented and found some clinical utility, but being an amino acid, therapeutic use confronts limitations like restricted permeability and more. This necessitates the development of pro-drugs (analogues) mainly derivatives of taurine. A large number of taurine derivatives have been reported in the literature with partial to marked activity. Taurine derivatives like taltrimide, acamprosate and tauromustine, are already in the market as anti-convulsant, anti-alcoholic and anti-cancer agents. Many other analogues are effective in experimental models. The in depth analysis of these analogues and their biological actions can provide certain clues for further consideration. In the present review, attempts have been made to provide synopsis, synthesis and symbiosis of chemical and biological actions, which may provide future guidance and facilitate further research in this area. The successful journey of these analogues to clinical utility is a healthy and happy sign and an index of bright future, and we hope that this review will provide enough input to ignite the minds.