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Page 427<br />

These aromatic diamidines inhibit IL-1 production and also block IL-6 and TNF. Imidazoline blocks IL-<br />

1 and TNF and is less toxic to the cell with an in vitro LD 50 >>10 -4. Examples of these compounds are<br />

1,5-bis(4-amidophenoxy) pentane (pentamidine), in the form of pentamidine isothionate, and an<br />

imidazoline in the form of 1,5-di(4-imidazolinophenoxy)pentane. Tricycli- cylidene-acetic acid [92] and<br />

its 2-chloro derivative [93] were found to be inhibitors of IL-1 release, claiming clinical improvement in<br />

patients with psoriasis, periodontal disease, and Alzheimer's disease. In vitro this compound blocks the<br />

synthesis of prostaglandins and inhibits the release of IL-1α and IL-1β from human monocytes and<br />

murine macrophages.<br />

Probucol, a hypocholesterolemic drug that possesses antioxidant activity, inhibits the ex vivo release of<br />

IL-1 from LPS-stimulated macrophages of mice pretreated orally with 100 mg/kg/day of this compound<br />

[94,95]. This compound has been shown to inhibit LPS-induced zinc-lowering effect, is cited as direct<br />

evidence for the inhibition of IL-1 release, and may be useful candidate for the treatment of<br />

atherosclerosis [95,96]. An amino-dithiol-one derivative (RP 54745) blocked the proliferative action of<br />

IL-1β on murine thymocytes in vitro and also inhibited the production of IL-1 in mouse peritoneal<br />

macrophages in vitro and in vivo. The compound RP 54745 selectively inhibited the expression of IL-<br />

1α and IL-1β mRNA while TNFα mRNA was unaffected [97, 98].<br />

Administration of a cocktail containing eicosapentenoic acid and docosahexenoic acid to volunteers for<br />

up to 6 weeks, resulted in a significant depression in IL-1β (61%), IL-1α (39%), and TNF (40%)<br />

synthesis. These levels returned to normal after a few weeks [99]. In vitro studies indicate that<br />

Pentoxifylline can block the effects of IL-1 and TNF on neutrophils [100]. It is a phosphodiesterase<br />

(PDE) inhibitor that causes increased capillary blood flow <strong>by</strong> decreasing blood viscocity and is used<br />

clinically in chronic occlusive arterial disease of the limbs with intermittent claudication. Denbufylline,<br />

a closely related xanthine, has been patented as a functional inhibitor of cytokines and exhibits a similar<br />

profile to Pentoxifylline [101]. Romazarit (Ro-31-3948) derived from oxazole and isoxazole propionic<br />

acids has been shown to block IL- 1-induced activation of human fibroblasts in vitro and in animal<br />

models reduces inflammation [102,103,104]. By using a spontaneous autoimmune MRL/lpr mouse<br />

model, a significant efficacy was shown [105]. Two-dimensional structures of some of these molecules<br />

are shown in Figure 14.<br />

Even though the above mentioned small molecules exhibit IL-1 inhibition none of them were discovered<br />

<strong>based</strong> on defined functional or structural aspects. An understanding of the three-dimensional structure of<br />

IL-1s and their receptors, <strong>by</strong> themselves or in complexes, will form a very strong foundation for<br />

structure-<strong>based</strong> design of more specific and potent IL-1-<strong>based</strong> immunomodulators.<br />

http://legacy.netlibrary.com/nlreader/nlReader.dll?bookid=12640&filename=Page_427.html [4/5/2004 5:50:49 PM]

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