1. Field of the Invention
The present invention relates to a new use of bismuth subgallate in the inhibition of the production of nitric acid synthase.
2. Description of the Prior Art
Nitric oxide (NO) is an unstable free radical that mediates both homeostatic and pathophysiologic processes within the cardiopulmonary, nervous, and immune systems. The list of potential disease associations for NO is increasing dramatically (Cochran et al., Medicinal Research Reviews, 1996, 16(6):547-563). Thus, agents that modulate the activity of NO may be of considerable therapeutic value. In particular, those that reduce the formation of NO may be beneficial in pathophysiological states in which excessive production of NO is a contributory factor. These include diseases such as septic shock, neurodegenerative disorders, and inflammation. NO is formed endogenously by a family of enzymes known as nitric oxide synthases (NOS) (Hobbs et al., Annu. Rev. Pharmacol. Toxicol, 1999, 39:191-220).
It is known that three distinct isoforms of NOS have been identified: an inducible form (iNOS) and two constitutive forms referred to neuronal NOS (nNOS) and endothelial NOS (eNOS). The NOS, particularly iNOS, are associated with the conditions including platelet aggregation, homeostatic processes, tissue injury, inflammatory conditions, shock states, immune disorders, disorders of gastrointestinal motility and diseases of the central nervous system (Epstein, The New England Journal of Medicine, 1993, 329(27): 2002-2011; Hobbs. et al, Annu. Rev. Pharmacol. Toxicol., 1999, 39: 191-220; Pfeilschfter et al., Cell Biology International, 1996, 20(1): 51-58). The NOS are also associated with the conditions caused by nitric oxide, such as tissue injury, cerebral ischemia, epilepsy, immunity and inflammation (Mulligan et al., Proc. Natl. Acad. Sci. USA, 1991, 88:6338-6342).
Given the above, it is expected that the compounds or agents capable of decreasing the amount or activity of NOS are useful as therapeutic agents. For example, U.S. Pat. No. 6,030,985 discloses the amidine derivatives useful for treating and preventing conditions in which inhibition of nitric oxide synthase is beneficial, such as stroke, schizophrenia, anxiety, and pain. U.S. Pat. No. 6,071,906 provides a pharmaceutical compositions containing an amidino derivative useful as an inhibitor of nitric oxide synthase. U.S. Pat. No. 6,133,306 features treating a neurodegenerative disease by administration of an effective amount of a nitroindazole, which is an inhibitor of neuronal nitric oxide synthase. U.S. Pat. No. 6,235,747 relates to certain 6-phenyl-pyridin-2-ylamine derivatives that exhibit activity as nitric oxide synthase (NOS) inhibitors, to pharmaceutical compositions containing them and to their use in the treatment and prevention of central nervous system disorders.
Bismuth subgallate is the product of the reaction among gallic acid, glacial acetic acid and bismuth nitrate which is represented by a molecular formula of C7H5BiO6. It is known as an oral anti-diarrhea agent effective in treating acute or chronic diarrhea by virtue that it can react with H2S, which is present in large quantities in the intestinal tract due to abnormal fermentation, and thereby alleviate diarrhea and pains caused by gas irritation to the intestinal tract. Bismuth subgallate can also be used as a disinfectant in view of its nature as a benzene derivative.
A pharmaceutical composition for wound healing comprising bismuth subgallate and borneol is disclosed in U.S. Pat. No. 6,232,341. However, none of the prior art teaches or suggests the new use of bismuth subgallate in the inhibition of NO synthase.
It is surprisingly found that bismuth subgallate is useful in the inhibition of the production of nitric oxide synthase (NOS).
Accordingly, the invention provides the new use of bismuth subgallate in the inhibition of the production of NOS.
An object is to provide a method of inhibiting the production of nitric oxide synthases (NOS) in a subject, comprising administering to said subject in need thereof an effective amount of bismuth subgallate; wherein said bismuth subgallate is administered in an amount effective to inhibit the production of NOS. According to the preferred embodiment of the invention, the method comprises administering to said subject in need thereof an effective amount of bismuth subgallate in combination with borneol, wherein said bismuth subgallate in combination with borneol are administered in an amount synergistically effective to inhibit the production of NOS.
Another objective of the invention is to provide a pharmaceutical composition for inhibiting the production of nitric oxide synthases comprising an effective amount of bismuth subgallate sufficient to inhibit the production of NOS and a pharmaceutical acceptable carrier. According to a preferred embodiment of the invention, the pharmaceutical composition of the invention further comprises borneol to provide a synergistic effect in the inhibition of the production of NOS.