Biological activity antiulcerative

Source Croton sublyratus. Molecular formula C20 H34 O2. Molecular weight 306.49. Biological activity Antiulcer. 

Nutritionally, the main physiological function of the carotenoids is their capacity as precursors of vitamin A, so that they are said to have provitamin A value. This important quality has led some authors to propose their classification according to nutritional activity (depending on their provitamin A character) and their biological activity (antiulcer, anticancer, immunological regulators, antenna photosynthetic pigments, etc.). ... 

The spectrum of biological activity displayed by tetramic acid-containing natural products is remarkable in its diversity it includes potent antibiotic, antiviral and antiulcerative properties, cytotoxicity and mycotoxicity, the inhibition of tumors (in mice and humans) as well as fungicidal action." Other members of this class are responsible for the pigmentation of certain molds and sponges. 

A wide variety of organosulfur compounds show useful biological activity examples include the sulfonamide antibacterials and diuretics, penicillin and cephalosporin antibiotics, the antiulcer drug ranitidine, and agrochemicals such as the thiophosphoryl (P=S) insecticides like malathion, herbicides like chlorsulfuron, many fungicides like the dithiocarbamates (see Chapter 9, p. 148) and captan (see Chapter 9, p. 151), and sulfone acaricides like tetradifon (see Chapter 7, p. 104). 

On occasions, the useful biological activity may only be a minor property or a side-effect of a compound. The aim then would be to enhance the side-effect and eliminate the major biological activity. The story of the antiulcer agent cimetidine (Fig. 7.29) is a case in point. The desired biological property was selective antagonism of histamine receptors in the stomach. The lead compound was a histamine agonist with a very weak antagonism for the receptors of interest. 

Imidazo[l,2-a]pyridines have emerged as versatile biologically active compounds spanning applications in anti-inflammatory and antibacterial agents, as inhibitors of gastric acids secretion, as calcium channel blockers, and in antiulcer-based therapies. 

It is well known that pyrimidine systems as purine analogues exhibit a wide range of biological activities. Among them, the furo[2,3-d]pyrimidine derivatives act as sedatives, antihistamines, diuretics, muscle relaxants, and antiulcer agents. 

The xenocoumacins are naturally occurring methylbutylamino-3,4-dihydroisocoumarin derivatives recently isolated by the authors and co-workers from the culture broth of bacteria of the genus Xenorhabdus (ref.l). They were isolated as antimicrobial compounds but were subsequently found to exhibit potent antiulcer activity as well as other biological activities. 

Quassinoids have attracted much attention due to the wide spectrum of biological activities that they display, viz., antimalarial, antifeedant, anti-inflanunatory, antiulcer, antipyretic, antifertility, antileukemic, cytotoxic activities, and induction of murine stem cell differentiation which have been widely reported [54-59]. We have demonstrated that quassin is a potent immunomodulatory tool that efficiently controls the estabhshment of leishmanial parasite within the host macrophages [60]. Our contention was that quassin could be used as a potential inununomodulator to generate the required immunity not only for the treatment of leishmaniasis but also for the treatment of other chronic infectious diseases. Subsequently, we had shown that both quassin and neoquassin can be used along with artesunate (a derivative of artemisinin) as combinatorial therapy against malaria [61]. 

Flavonoids are a group of about 4000 naturally occurring compounds with a wide range of biological effects, including antiulcer activity. They are important constituents of the human diet (a daily diet contains approximately 1 g of flavonoids per day) and are also found in several medicinal plants used in folk medicine around the world. Several mechanisms have been proposed to explain the gastroprotective effect of flavonoids ... 

Attempts to quantitatively relate chemical structure to biological action were first initiated in the 19th century, but it was not until the 1960s that Hansch and Fujita devised a method that successfully incorporated quantitative measurements into SAR determinations (see section 4.4). The technique is referred to as QSAR (quantitative structure-activity relationships). One of its most successful uses has been in the development in the 1970s of the antiulcer agents cimetidine and ranitidine. Both SARs and QSARs are important parts of the foundations of medicinal chemistry. 

The benzimidazole scaffold is a useful structural motif for the development of molecules of pharmaceutical or biological interest. Appropriately substituted benzimidazole derivatives have foimd diverse therapeutic apphcations such as in antiulcers, antihypertensives, antivirals, antifungals, anticancers, and antihistaminics [3]. The optimization of benzimidazole-based structures has resulted in various drugs that are currently on the market, such as omeprazole 1 (proton pump inhibitor), pimobendan 2 (ionodilator), and mebendazole 3 (anthelmintic) (Fig. 1). The spectrum of pharmacological activity exhibited by benzimidazoles has been reviewed by several authors [3-6]. 

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