Mario Brufani

A long-lasting cholinesterase inhibitor affecting neural and behavioral processes.

A series of analogues of physostigmine were prepared with the aim of investigating their inhibitory effects on acetylcholinesterase in the treatment of Alzheimers disease. One of the isomers prepared was evaluated for its anticholinesterase activity in vivo, acute toxicity, and some behavioral effects. This compound was a competitive inhibitor of the enzyme and was found to antagonize the stimulating effect produced by scopolamine on locomotor activity and to facilitate memory consolidation.

Rifamycins: an insight into biological activity based on structural investigations

Abstract The structures of two compounds of the antibiotic rifamycin series have been studied by X-ray methods: rifamycin B, C 39 H 49 NO 14 , which is active on bacterial RNA polymerase, and rifamycin Y, C 39 H 47 NO 15 , which is devoid of any antibacterial activity. In both cases their p -iodoanilide derivative has been used and the final crystal structure data are now given. A comparative study of the structures of rifamycin B and rifamycin Y, and of the structures of two other ansa -compounds with similar activity on bacterial RNA polymerase, tolypomycin Y and streptovaricin C, together with the analysis of the activity ratios of a series of semisynthetic rifamycins, makes it possible to suggest that the following constitutional and conformational features are common to all the ansa -compounds with anti-bacterial activity: (i) a naphthoquinone or naphthohydroquinone nucleus with free oxygen functions, O(1) and O(2), on C(1) and C(8) respectively: (ii) an amide nitrogen attached to C(2); (iii) a 17-membered chain bridging the chromophoric group; (iv) two free hydroxyl groups attached to atoms C(21) and C(23) of the ansa -bridge and in the same relative positions with respect to each other and with respect to O(1) and O(2). However, the constitution and the conformation of the remaining part of the ansa -bridge can be rather different in different compounds.

New analogs of physostigmine: Alternative drugs for Alzheimer's disease?

The synthesis of a series of physostigmine analogs, in which the methylcarbamyl group has been substituted with monoalkylcarbamyl, dimethyl- and diethylcarbamyl groups, is reported. These compounds were prepared with the aim of investigating their possible therapeutic effects in the treatment of Alzheimers type dementia. The new analogs of physostigmine are inhibitors of acetylcholinesterase from Electroforus electricus, with a value of the reactivation constant, k3 smaller than the one of physostigmine. The percentage of anticholinesterase activity in vitro and in vivo, the acute toxicity and some behavioural effects were also evaluated for selected derivatives. The reactivation constant, in vitro, supports the view that the derivatives described would be more suitable for therapeutic use than physostigmine.

Long chain analogs of physostigmine as potential drugs for Alzheimer's disease: new insights into the mechanism of action in the inhibition of acetylcholinesterase.

Heptylphysostigmine is in advanced clinical trial as a drug for Alzheimers disease. 8-Morpholinooctylphysostigmine and 8-(cis-2,6-dimethylmorpholino)octylphysostigmine are currently undergoing pre-clinical evaluation. The mechanism of action of these compounds in the inhibition of acetylcholinesterase has been investigated. All the examined compounds display non competitive-like kinetics of inhibition. There are no reversible components in the observed inhibition: the whole inhibitory effect is due to the time-dependent pseudo-irreversible carbamylation of the active site. Yet the observed time course of the inhibition does not match a simple second order kinetics. An influence of the quaternary structure of the enzyme on the more complex kinetics of carbamylation is hypothesized. Reactivation experiments on the inhibited enzyme show long lasting inhibitory effects for these compounds. The higher duration of the anticholinesterase effect of the morpholino derivatives compared to heptylphysostigmine should provide the basis for their higher therapeutic potential.

Inflammatory molecule release by β-amyloid-treated T98G astrocytoma cells: role of prostaglandins and modulation by paracetamol

Deposition of beta-amyloid in the brain triggers an inflammatory response which accompanies the neuropathologic events of Alzheimers disease and contributes to the destruction of brain tissue. The present study shows that beta-amyloid can stimulate human astrocytoma cells (T98G) to secrete the proinflammatory factors interleukin-6 and prostaglandins. Furthermore, prostaglandins can stimulate T98G to secrete interleukin-6, which in turn triggers the formation of additional prostaglandins. Prostaglandins are, therefore, a key element in the induction and maintenance of a state of chronic inflammation in the brain which may exacerbate the fundamental pathology in Alzheimer patients. Paracetamol (0.01-1000 microM), an unusual analgesic/antipyretic drug which acts preferentially by reducing prostaglandin production within the central nervous system, and indomethacin (0.001-10 microM) caused a clear dose-dependent reduction of prostaglandin E2 production by stimulated T98G cells whereas interleukin-6 release was not affected. These data provide further evidence of the involvement of non-steroidal anti-inflammatory drugs in the inflammatory processes that can be generated by glial cells in intact brain.

Present state and future development of the therapy of Alzheimer disease.

Senectutis autem nullus est certus terminus, recteque in ea vivitur quoad munus offici exsequi… vivundi est finis optumus cum integra mente certisque sensibus opus ipsa suum eadem quae coagmentavit natura dissolvit. Cicero, “De Senectute”.

Use of metformin in pediatric age

Brufani C, Fintini D, Nobili V, Patera PI, Cappa M, Brufani M. Use of metformin in pediatric age.

Synthesis of a carbocyclic sialic acid analogue for the inhibition of influenza virus neuraminidase.

The influenza virus neuraminidase (NA) is essential for viral infection and offers a potential target for antiviral drug development. We prepared a carbocyclic sialic acid analogue, potentially able to inhibit NA. Its structure is an analogue of the transition-state of the reaction catalysed by NA. As starting material, quinic acid was selected owing to its ready availability and its stereochemical feature suitable for the target structure. The quinic acid was first converted in the shikimic acid; then two of the three hydroxyl functions of this product were selectively functionalised to obtain the target molecule (3R,4S,5R)-4-acetamido-3-guanidino-5-hydroxycyclohex-1-ene-1-carboxylic acid.

A new method of regioselective protection of primary alcoholic function with rare earths salts

Abstract Regioselective acetylation of primary alcoholic functions, in the presence of secondary ones, was performed in very high yield with methyl ortoacetate, by means of catalysis with rare earths salts on silica gel.

Synthesis and structure-activity relationships of new acetylcholinesterase inhibitors: Morpholinoalkylcarbamoyloxyeseroline derivatives

Abstract Several new potent acetylcholinesterase inhibitors have been synthesised as potential drugs for the treatment of Alzheimers disease. Heptylphysostigmine (MF201) is a drug analogue of physostigmine under clinical evaluation. In order to obtain new physostigmine analogues, the methylcarbomoyloxy group was substituted with ω-morpholinoalkylcarbamoyloxy moieties of different chain lengths (C2–C12). Potent in vitro inhibition is seen when the chain length is composed of eight to twelve methylene groups. The inhibitory activity of the C10 and C11 is 7-fold greater with respect to heptylphysostigmine.