M. W. Whitehouse

Studies on the interaction of gold(I) phosphines with 2-thiouracil. Related studies with silver(I) phosphines

Abstract The crystal structure of Et3PAu(2-TU) shows that the gold atom is linearly coordinated by a P atom (2.248(2) A) and a S atom (2.310(2) A) derived from a 2-TU anion which functions as a thiolate ligand. Monoclinic crystals of the complex have space group P21/c with unit cell dimensions a=9.161(1), b=11.233(1), c=14.049(2) A, β=95.39(1)°; final R=0.044 for 2181 reflections. The anti-arthritic activity of R3PAu(2-TU), R  Et and Ph, is reported. The attempted reaction between the bis chelated diphosphine complex [Au(dppe)2]Cl and the 2-TU anion yielded a complex of stoichiometry [Au(dppe)2][(2-TU)(2-TUH)] in which there is no interaction between the nucleobase and the Au atom. The lattice comprises discrete tetrahedral cations and 2-TU anions; the latter being associated with the neutral 2-TUH molecule via a hydrogen bond. Crystals are triclinic, P 1 , a=15.407(2), b=17.251(2), c=11.526(2) A, α=109.50(1), β=97.81(1), γ=85.11(1)°; final R=0.046 for 6323 reflections. Related reactions employing silver phosphine salts and three nucleobases are also reported briefly. In no instances were mixed silver phosphine/nucleobase complexes obtained. In general, silver phosphine complexes remained intact after reaction with a nucleobase and, in all but one instance, when starting with an authentic silver nucleobase complex the phosphine ligand replaced the coordinated nucleobase yielding binary silver phosphine compounds.

Is aspirin a prodrug for antioxidant and cytokine-modulating oxymetabolites* ?

Aspirin and salicylate are transformed by stimulated human polymorphonuclear leucocytes (PMN), likely to be found at inflammatory sites, into both 2,3- and 2,5-dihydroxybenzoates (DHB). These DHB inhibit both the production of hydrogen peroxide by stimulated human PMN and prostaglandin (PG) E2 by activated rat macrophages. In contrast, DHB stimulated production of interleukin (IL)-1 and tumour necrosis factor (TNF) but inhibited IL-6 production by rat macrophages. These effects were probably a consequence of PGE2 inhibition. Gentisate (2,5-DHB) and homogentisate (a tyrosine metabolite) inhibited the lymphoproliferative action of IL-1. Some related phenols, e.g. 5-aminosalicylate, inhibited H2O2 production but had little effect on PGE2 production.These findings suggest that the local synthesis of DHB may contribute to the overall anti-inflammatory activity of salicylate, which (unlike aspirin) has little direct effect on PG production.

Zinc monoglycerolate: A slow-release source of zinc with anti-arthritic activity in rats

Zinc repletion by parental administration of zinc monoglycerolate (ZMG) or certain other lipophilic zinc complexes, suppressed the development of adjuvant-induced polyarthritis in rats.While ZMG was effective when given parenterally over various limited time schedules (immunosuppressant, therapeutic, singledose), it was not effective given orally. The complex showed no acute anti-inflammatory activity in the carrageenan paw oedema assay and little gastric-intestinal or other organ toxicity. When injected s.c. it caused very much less local irritation than most zinc salts.Being lubrous, ZMG could be applied as the dry powder for rubbing into the skin and by this route was found to have anti-arthritic activity.65Zn was shown to be absorbed and excreted in the faeces (biliary exretion) after applying65Zn-ZMG dermally to shaved dorsal skin of rats.ZMG showed consistent anti-arthritic activity in rats under conditions in which 2 gold drugs (aurothiomalate, Auranofin) exhibited variable effects, depending on the strain of rat. The role of zinc and its availability in chronic inflammation are discussed on the basis of these studies.

Ammonium 4-chloro-7-sulfobenzofurazan: A new fluorigenic thiol-specific reagent

Abstract This paper describes the synthesis and study of a new fluorigenic, thiol-specific reagent, ammonium 4-chloro-7-sulfobenzofurazan, which is readily prepared by sulfonation of 4-chlorobenzofurazan. Evaluation of ammonium 4-chloro-7-sulfobenzofurazan was undertaken using glutathione as a model thiol peptide and bovine serum albumin and jackbean urease as thiol-containing proteins. Thiol specificity of this reagent was established using various amino acids and peptides including l -cysteine, l -lysine, l -histidine, l -tyrosine, glutathione, and oxidized glutathione. Nitrogen and sulfur derivatives of ethanediol and acetic acid were also investigated. Optimum conditions for the thiol labeling reaction have been investigated using the parameters of pH, buffer type, time, temperature, and relative concentrations. Under appropriate conditions the fluorescence produced by the reaction of ammonium 4-chloro-7-sulfobenzofurazan is linearly related to thiol concentration. The fluorescence intensity of 7-sulfobenzofurazan thiol derivatives are considerably greater than the corresponding 7-nitrobenzofurazan derivatives in both aqueous and aprotic solvents, rendering this reagent highly sensitive. Our preliminary experiments with proteins labeled with ammonium 4-chloro-7-sulfobenzofurazan have shown the probe to be removable by thiolysis with excess 2-mercaptoethanol.

Anti-inflammatory activity of the isoquinoline alkaloid, tetrandrine, against established adjuvant arthritis in rats

Two isoquinoline plant alkaloids, tetrandrine (1) and berbamine (2), have been evaluated for anti-inflammatory activity in an acute paw oedema assay and in adjuvant-induced arthritis in rats.1 but not2 suppressed the chronic inflammation in the arthritis model but neither compound was active in the acute inflammation assay. In the adjuvant-induced polyarthritis,1 was not effective when given at the time of inoculation (Day 0), nor just before (Day 7–10) signs of arthritis were evident. However, when given on a therapeutic dose schedule (Days 10–13) or continually (Day −1 to +14) on a prophylactic schedule, signs of arthritis including weight loss due to cachexia were significantly reduced. Given orally,1 was considerably more potent than aspirin but not gastro-irritant and may be a promising lead for the development of a safe and effective treatment of chronic inflammatory diseases.

Zinc monoglycerolate--a slow-release source of therapeutic zinc: solubilization by endogenous ligands.

A combination of65Zn-tracer determinations, oxidative analyses for glycerol, and a bioassay for uncomplexed Zn2+ have shown that: (i) zinc monoglycerolate (ZMG) dissolves in aqueous salt dissolutions/physiological media by dissociation into zinc ions and glycerol, but the rate and extent of ZMG dissolution depend upon pH, and/or concentration and complexing efficiency of zinc-ligands; (ii) under physiological conditions certain ligands present in skin and blood (e.g. citrate, lactate, albumin, histidine, glutathione and other thiols and, to a lesser extent, amino acids) accelerate ZMG dissolution; and (iii) there is a general correlation between the conditional stability constants (pH 7.3, 25°C) of zinc-ligand complexes and the ability of given ligands to (a) solubilize ZMGin vitro and (b) mask the irritancy of Zn2+in vivo. These observations indicate a mechanism for the transformation of ZMG applied transdermally or subcutaneously, to bioactive zinc (anti-arthritic nutritional supplement, etc.).

Biodistribution of 64Cu in inflamed rats following administration of two anti-inflammatory copper complexes.

Abstract64Cu was administered in two anti-inflammatory formulations to normal rats and to rats with 2 forms of local inflammation, namely (a) an acute paw oedema (elicited with carrageenan) or (b) a chronic granulomatous response to an implanted irritant (Mycobacterium tuberculosis in a polyurethane sponge). The copper formulations used were (i) a slow release one consisting of Cu(II) salicylate applied dermally with ethanol/DMSO and (ii) short acting hydrophilic complex (Cu(I)Cu(II)-penicillamine)5− given subcutaneously.Three types of changes in copper biodistribution with these forms of inflammation were discerned based on determination of64Cu and copper content in the following organs: inflammatory locus (foot or sponge implant), kidney, liver, spleen, adrenals, brain, blood, thymus, heart, and skin (site of application). The most evident changes were in the kidneys, liver, spleen, adrenals, thymus and serum from animals with chronic granulomatous inflammation. In contrast, a short term acute inflammatory stress (carrageenan paw oedema) had little effect.While copperd-penicillamine (applied subcutaneously) appeared to move as a bolus through the animals, the results with the percutaneous copper salicylate formulation are consistent with it providing a slow release source of copper(II). Exogenous64Cu from both formulations was sequestered at inflammatory sites (relative to serum). This may partly explain how applied copper complexes can be anti-inflammatory.

Anti–Inflammatory activity of a holothurian (sea cucumber) food supplement in rats

Whitehouse MW, Fairlie DP. Anti-inflammatory activity of a holothurian (sea cucumber) food supplement in rats. Inflammopharmacology. 1994;2:411-417.A human food supplement (SeaCare ) composed of dried extracts from specific varieties of holothurians (sea cucumbers) and a sea plant has been found to have anti-inflammatory activity in both sexes of two strains of rats. It is slightly less active than aspirin (w/w) against the acute carrageenan-induced paw inflammation, but without the gastrotoxicity of aspirin. It is also active against adjuvant-induced polyarthritis in rats on a daily dose schedule.

Effects of prostaglandin E1 analogue, misoprostol, on the development of adjuvant arthritis in rats

Prostaglandins (PG) E , E and the PGE analogue, misoprostol, have been shown to inhibit T-cell functions and the production by activated monocytes or macrophages of interleukin-1, indicating that these PGs may have potential anti-arthritic activity by suppressing T-cell and monocyte activity. In view of this the potential anti-arthritic effects of the long half-life PG, misoprostol (MPL), were examined in adjuvant arthritic rats under prophylactic and therapeutic treatment regimes. Transcutaneous or subcutaneous MPL given at 200 Μg/kg/day but not at 50 or 5 Μg/kg/day when given 0 to +5 or 0 to + 14 days post-induction inhibited the development of the disease whereas the orally administered drug was without effects. MPL given transcutaneously with oral indomethacin (1 or 2 mg/kg/day) on days +17 to + 30 post-induction produced greater anti-inflammatory effects than with this NSAID alone. MPL given orally in combination with this NSAID did not enhance the anti-inflammatory effects of the latter. MPL 200 Μg/kg given transcutaneously exhibited anti-ulcer activity against indomethacin (30 mg/kg p.o.), naproxen (10 mg/kg i.p.) or piroxicam (5 mg/kg i.p.) induced gastric damage in arthritic rats and this was comparable with that from 100 Μg/kg MPL given orally. These results show that MPL has both unique anti-arthritic effects only when given transcutaneously or parenterally as well as anti-ulcer activity.

Conditional pharmacology: II. Ambivalent effects of aurocyanide, a putative active metabolite of anti-arthritic gold drugs, on human and rat PMN leucocytes

Aurocyanide, and to a lesser extent, aurothiomalate and aurothiosulphate, showed diverse antioxidant/pro-oxidant effects on PMN leucocytes when stimulated ex-vivo to generate hydrogen peroxide. In normal human cells, aurocyanide inhibited peroxide production (ID50 for aurocyanideca. 5 μmol/L) and reduced average cell size more potently than the thiomalate and thiosulphate (ID50 of 200 μmol/L for both). Factors influencing the results included the type of fluorochrome for detecting peroxide and intrinsic variability between human donors. In the presence of azide (1 mmol/L), peroxide production was stimulated but cell size was still reduced. Some PMN stimulants such as fMLP and complement component C5a with aurocyanide only stimulated peroxide production in the presence of azide and had no effect in its absence. In both normal and arthritic rat neutrophils, aurocyanide only stimulated peroxide production but still reduced cell size. These observations show that mechanisms of action of these gold drugs may be related to the effects of aurocyanide but there are differences between rat and human cells in vitro. A single dose of aurocyanide (10 mg/kg) co-administered with two arthritogenic adjuvants effectively prevented arthritis development in rats. Much higher doses, bordering on toxic, were required for two gold-thiolates to exhibit similar activity.