Current Bioactive Compounds - Volume 3, Issue 2, 2007

Pentagalloylglucopyranose (PGG) is a natural product with widespread occurrence in the plant kingdom. It is present in various tissues of studied plants. PGG is synthesized in plants by covalently linking five galloyl groups to a glucose molecule through ester bonds. Two different linkages between the galloyl group and the anomeric center of the glucose core, carbon 1, are possible (Fig. 1). Both isomers were isolated from natural sources. However, it has been found that β-PGG is much more prevalent than α-PGG. Nevertheless, α-PGG has been identified in some plants [1]. Because of its prevalence, most previous studies were performed with β- PGG, not α-PGG. Unless otherwise specified, the terms “PGG” and “β-PGG” are used interchangeably in this article. PGG was found in some medicinal herbs that were used as agents to treat stomach disorders and other diseases [2]. Because of these interesting bioactivities and medicinal effects, PGG may be used as a model compound for the use of other polyphenolic compounds (tannins) in biomedical research and therapeutic development. This article reviews the progress of research on PGG, including its distribution, bioactivities and therapeutic potentials.

For management of pain, non-steroidal anti-inflammatory drugs (NSAIDs) play a major role. Use of NSAIDs is associated with toxicity, particularly in the gastrointestinal tract and kidney, whereas the use of COX-2 selective NSAIDs is associated with renal failure. Various approaches such as management of COX-1/COX-2 and 5-LOX/COX-2 inhibitors, use of natural products, formulation, drug modification and synthesis of new chemical entities in search of safer anti-inflammatory drugs reported in literature to overcome serious side effects of NSAIDs is summarized in this review. We have also reported recent findings in the area of synthesis of heterocyclic compounds such as pyrimidine, pyridine, thiazole, triazole, imidazole, oxazole, isooxazole, pyrazole , pyrazolidine, pyrole, acridine derivatives and other related heterocyclic compounds and their role as non-selective, COX-2 selective, LOX selective and COX/LOX dual, inhibitors.

The traditional use of Hypericum perforatum L. (St. John's wort, Clusiaceae) in Western medicine was well known even before the 1600s: St. John's extracts were used to relieve various types of nervous disease long before depression was recognized as a well described pathology. Today, random controlled trials clearly confirm the efficacy of this plant extract over placebo in the treatment of mild to moderately severe depression. Of the different classes of H. perforatum secondary metabolites, the prenylated acylphloroglucinol hyperforin has emerged as key player for anti-depressant activity. But as well as Hypericum's anti-depressant property, several other pharmacological actions have now been documented - examples include anti-bacterial, anti-proliferative and anti-inflammatory - many of which may be related to hyperforin. These findings add support to the effectiveness of St. John's wort as a folk remedy in common use for treating skin injuries, burns and neuralgias. This review gives a historical overview of the plant, including its medical uses, plus a look at the chemical structure of the most relevant phyto-constituents. This is followed by a close analysis of recent data regarding the biological effects of hyperforin, focusing on antiinflammatory and anti-tumor activities. The compound's clear and proven actions qualify it as an interesting lead candidate for countering inflammatory disease and cancer.

Amoebiasis, a disease caused by Entamoeba histolytica, remains a major health problem that afflicts several million people worldwide. Moreover, in recent years there has been a rise in the number of reports with amebic brain abscess as well as in developed countries the microorganisms that cause diarrheal diseases are a cause of concern because of their potential to be used as bioterrorist agent. Metronidazole, an antiamoebic agent, is the drug of choice for treating amoebiasis in humans, but it has been shown to be both mutagenic and carcinogenic in bacteria and rodents respectively. The completely safe treatment for this disease does not exist at present and therefore newer and safer agents are required either from synthetic or natural resources. This review covers brief description of the disease, plant secondary metabolites and synthetic compounds that have exhibited moderate to high activity in vitro and in vivo bioassays against E. histolytica. The review also discusses some of the key biochemical targets that are unique and vital for the existence and growth of the parasite which are being further exploited so as to search for therapeutically active antiamoebic agents.

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