Activities from various plant sources

Table II ALS Activities from Various Plant Sources...

Juvabione is a terpene-derived ketoester that has been isolated from various plant sources. There are two stereoisomers, both of which occur naturally with R-configuration at C(4) of the cyclohexene ring and are referred to as erythro- and f/trao-juvabione. The 7(.S )-cnan(iomcr is sometimes called epijuvabione. Juvabione exhibits juvenile hormone activity in insects that is, it can modify the process of metamorphosis.18... 

Compounds with different structures but with the same therapeutic activity isolated from different plant species act as active moieties for the treatment of particular diseases. Some of these compounds have been abandoned due to toxicity but these compounds apparently do not cause serious adverse effects. Some of these active principles originate from edible plants and their inclusion in the diet would undoubtedly be of some value because of their hypocholesterolemic potential. Several phytoconstituents including inulin, pectin, gugglu lipids, flavonoids, ginkoloids, saponins, tannins, and others obtained from various plant sources have proven hypolipidemic potentials as has been further explained in Tables I and II. The chemical structures of a few potential phytoconstituents with hypolipidemic activity are shown in Figure 2. It is hoped that as new additions are made to the list of these active compounds causing only minimum untoward side effects, these naturally... 

The term opium alkaloids has been used rather loosely to cover all narcotic analgesics, whether they be synthetic compounds, partially synthetic, or extracted from plant material. To be precise, we should really only use the term for those natural compounds which have been extracted from opium—the sticky exudate obtained from the poppy (Papaver somniferum). The term alkaloid refers to a natural product which contains a nitrogen atom and is therefore basic in character. There are, in fact, several thousand alkaloids which have been extracted and identified from various plant sources and examples of some of the better known alkaloids are shown in Fig. 12.1. These compounds provide a vast library of biologically active compounds which can be used as lead compounds into many possible fields of medicinal chemistry. However, we are only interested at present in the alkaloids derived from opium. 

Since the discovery of brassinolide, ten years ago, research on brassinolide and related steroids has attained a remarkable degree of development. So far, twenty-three brassinosteroids [BS] have been isolated and identified from twenty-two plant species. Furthermore, many unknown brassinolide-like active substances have been detected, so that the number of identified ones is likely to increase in the future. The background to successful isolation of new BS from various plant sources is due to the use of a rice-lamina inclination test for screening that is sensitive and specific for brassinosteroids. 

The molecule(s) in litchi, longan, and dried longan responsible for induction of COX-2 expression in the macrophage are not known. Plant lectin may be one of candidates because of its water-soluble nature. Lectins from various plant sources have been shown to bind to macro-phage surface glycoproteins (63,64) and can result in activation of the macrophages (64). 

Juvabione is a terpene-derived ketoester that has been isolated from various plant sources. It exhibits juvenile hormone activity in insects that is, it can modify the process of metamorphosis. 

Sterols and Cholesterol. Natural sterols are crystalline C76 C1(1 steroid alcohols containing an aliphatic side chain at C17. Sterols were first isolated as lionsaponifiable fractions of lipids from various plant and animal sources and have been identified in almost all types of living organisms. By far, the most common sterol in vertebrates is cholesterol (8). Cholesterol serves two principal functions in mammals. First, cholesterol plays a role in the structure and function of biological membranes.. Secondly, cholesterol serves as a central intermediate in the biosynthesis of many biologically active steroids, including bile acids, corticosteroids, and sex hormones. 

Various commercial routes for the production of L-phenyalanine have been developed because of the utilization of this amino acid in the dipeptide sweetener Aspartame. One route that has been actively pursued is the synthesis of L-phenylalanine from trans-cinnamic acid using the enzyme phenylalanine ammonia lyase (105,106). This enzyme catalyzes the reversible, nonoxidative deamination of L-phenylalanine and can be isolated from various plant and microbial sources (107,108). 

The specificity of conduritol B epoxide is such that -glucosidases from widely differing sources have been found to react with loss of enzymic activity from various Aspergillus species, > yeast, snail Helix pomatia) sweet almonds, and mammals. The only exceptions have been the / -glucosidases from garbanzo plants Cicer arietum L.) and from Alocasia macrorrhiza The only other enzymes that have been found to be covalently inhibited are a-glucosidase from yeast Saccharo-myces cerevisiae) and the sucrase-isomaltase complex from rabbit small intestine. ... 

This process starts with the synthesis of novel chemical compounds. Substances with complex structures may be obtained from various sources, e.g., plants (cardiac glycosides), animal tissues (heparin), microbial cultures (penicillin G), or human cells (urokinase), or by means of gene technology (human insu-Un). As more insight is gained into structure-activity relationships, the search for new agents becomes more clearly focused. 

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