Current Medicinal Chemistry (v.23, #14)

Meet Our Editorial Board Member by Antonio Lavecchia (1391-1391).

The success rate to achieve clinical approval of drugs developed to treat diseases of the central nervous system (CNS) is the lowest of all disease indications. A large contributor to this poor success rate is failure of small molecules to pass through the blood-brain barrier (BBB), a barrier composed of capillary endothelial cells connected by tight junctions that functions to extrude xenobiotics from the brain. Designing small molecules to be BBB penetrant has been the subject of intensive research and has resulted in a series of guidelines to attain the best possible chances of BBB penetration. This review will analyze the current state of thinking in ranking the importance of various physicochemical properties required to select BBB penetrant molecules, describe model systems to determine BBB penetration, summarize data analysis methods and provide an outlook on further developments in the field.

Enzymology of Pyrimidine Metabolism and Neurodegeneration by Silvia Vincenzetti, Valeria Polzonetti, Daniela Micozzi, Stefania Pucciarelli (1408-1431).
It is well known that disorders of pyrimidine pathways may lead to neurological, hematological, immunological diseases, renal impairments, and association with malignancies. Nucleotide homeostasis depends on the three stages of pyrimidine metabolism: de novo synthesis, catabolism and recycling of these metabolites.
Cytidine and uridine, in addition to be used as substrates for pyrimidine nucleotide salvaging, also act as the precursors of cytidine triphosphate used in the biosynthetic pathway of both brain's phosphatidylcholine and phosphatidylethanolamine via the Kennedy cycle. The synthesis in the brain of phosphatidylcholine and other membrane phosphatides can utilize, in addition to glucose, three compounds present in the blood stream: choline, uridine, and a polyunsaturated fatty acids like docosahexaenoic acid.
Some authors, using rat models, found that oral administration of two phospholipid precursors such as uridine and omega-3 fatty acids, along with choline from the diet, can increase the amount of synaptic membrane generated by surviving striatal neurons in rats with induced Parkinson's disease. Other authors found that in hypertensive rat fed with uridine and choline, cognitive deficit resulted improved. Uridine has also been recently considered as a neuroactive molecule, because of its involvement in important neurological functions by improving memory, sleep disorders, anti-epileptic effects, as well as neuronal plasticity. Cytidine and uridine are uptaken by the brain via specific receptors and successively salvaged to the corresponding nucleotides. The present review is devoted to the enzymology of pyrimidine pathways whose importance has attracted the attention of several researchers investigating on the mechanisms underlying the physiopathology of brain.

Alzheimer disease (AD) is an irreversible neurodegenerative disorder associated with cognitive dysfunction. The disease incidence has growing tendency worldwide with strong impact on healthcare funds. The fact that there is no effective therapy makes the disorder more serious. Currently, AD manifestation can be suppressed by having impact on enzyme acetylcholinesterase: donepezil, rivastigmine, and galantamine or ionotropic glutamate NMDA receptor ( memanitine). Contrary to the drugs effecting symptomatically, vaccination against amyloid plaques or neurofibrillary tangles and their precursors amyloid beta and hyperphosphorylated tau are expected to be more suitable. Huge numbers of works have been done on the issue. Unfortunately, the promising vaccines like the AN 1792 were halted during clinical trials because of adverse effects like meningoencephalitis. Monoclonal antibody specific to amyloid plaques, Bapineuzumab, was closest to the practical performance but the clinical trials were also stopped. The review summarizes facts about AD, opportunities in AD vaccination, and obstacles that limit the vaccination including reasons why the recent trials have fallen.

Multiple sclerosis (MS) is a disease of the central nervous system (CNS) with an unknown etiology. MS complex pathophysiology—characterized by CNS inflammation, demyelination and axonal injury—has made its modeling in experimental systems particularly problematic. Moreover, the evidence that MS does not naturally occur in other species has further complicated MS preclinical studies. Through the years, several MS in vivo models have been developed. Experimental autoimmune encephalomyelitis (EAE) represents the most widely used MS experimental model and relies upon the autoimmune paradigm to explore MS neuropathology. Although EAE has been instrumental in understanding the molecular events which take place upon neuroinflammation, not all MS hallmarks can be efficiently shaped within this conceptual frameshift. Thus, alternative models of CNS demyelination have been characterized, either based on viral infection or neurotoxin administration. However imperfect, these models have greatly improved our knowledge of the immune system's function in health and disease. On the other side, their intrinsic distance from MS has often led to misinterpreting and overestimating the data gleaned from these experimental systems. In this review, each model will be discussed in the light of its potentiality to mimic MS and translate the most promising therapies to patients. In addition, we will address how new genomic technologies can help improve the existing models.

Berberine: New Insights from Pharmacological Aspects to Clinical Evidences in the Management of Metabolic Disorders by Cristiana Caliceti, Placido Franco, Silvia Spinozzi, Aldo Roda, Arrigo F.G. Cicero (1460-1476).
Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids found in such plants as gender Berberis. Berberine is recognised to improve glucose and lipid metabolism disorders and preliminary clinical evidences suggest the ability of berberine to reduce endothelial inflammation improving vascular health, even in patients already affected by cardiovascular diseases, suggesting a possible interesting role of berberine and its metabolites in clinical practice. However, its physicochemical properties, pharmacokinetic, and metabolism are not fully elucidated and contradictory data have been reported.
This review provides a summary regarding the pharmacological and biological features of berberine, with a focus on berberine as well as their pharmacologically active metabolites and the different mechanisms underlying their activities in order to clarify the correct use of berberine supplementation, alone or in association with other nutraceuticals, for the management of metabolic disorders associated to increased cardiovascular disease risk. A particular attention has also been given to the available clinical trials assessing its short- and middle- term use tolerability, safety and efficacy in various conditions, such as dyslipidaemia, impaired fasting glucose, metabolic syndrome and type 2 diabetes.

Bacteriotherapy and nanotechnology have shown remarkable potential in diagnostic and therapeutic applications for various diseases. Individual impacts of these micro-nano systems over different aspects of human health are well studied; however, an integrated system of bacteria-nanoparticle (NP) conjugation is less explored. The untamed potential of bacteria-NP conjugation could be a new tool for diagnosis and treatment of invasive diseases like malaria, tuberculosis and cancer. Mammalian cells exhibit cytosis as their defense mechanism when they encounter foreign elements such as bacteria. In these mammalian cells, during phagocytosis, bacteria are ruptured and lysed by lysozymes. A bacterium carrying the drug-tagged NP would be engulfed in the same manner and ultimately reaches the target cells. Rapid and continuous cell divisions in the cancer tissues lead to defective vessels, underdeveloped cellcell interconnects, development of hypoxic areas and heterogeneous population of tumor cells. This unorganized and poorly developed angiogenesis in tumor cells makes it difficult for conventional chemotherapeutic drugs to localize the tumors selectively. In the present scenario of diagnosis and treatment of cancer/tumor cells, it could be expected that the existing bacteriotherapy with the advanced nanotechnology would be a way further in the targeted drug delivery for cancer therapy. This review emphasizes the potential applications of bacteriotherapy with nanotechnology for the diagnosis and treatment of cancer.