Plant sources, stimulators from

Virus Replication Inhibitors and Stimulators from Plant Sources... 

The major bases found in nucleic acids are adenine and guanine (purines) and uracil, cytosine, and thymine (pyrimidines). Thymine is found primarily in DNA, uracil in RNA, and the others in both DNA and RNA. Their structures, along with their chemical parent compounds, purine and pyrimidine, are shown in Figure 10.1, which also indicates other biologically important purines that are not components of nucleic acids. Hypoxanthine, orotic acid, and xanthine are biosynthetic and/or degradation intermediates of purine and pyrimidine bases, whereas xanthine derivatives—caffeine, theophylline, and theobromine—are alkaloids from plant sources. Caffeine is a component of coffee beans and tea, and its effects on metabolism are mentioned in Chapter 16. Theophylline is found in tea and is used therapeutically in asthma, because it is a smooth muscle relaxant. Theobromine is found in chocolate. It is a diuretic, heart stimulant, and vasodilator. 

Caffeine is a bitter-tasting compound found in coffee, tea, cola beverages, and chocolate. Caffeine is a mild stimulant, usually imparting a feeling of alertness after consumption. It also increases heart rate, dilates airways, and stimulates the secretion of stomach acid. Caffeine is an alkaloid, a naturally occurring amine derived from a plant source. In Chapter 25 we learn about the properties and reactions of amines. 

Ephedrine is labeled for sale as a bronchodilator. Caffeine is marketed as a minor stimulant to produce greater alertness or reduce drowsiness. Synephrine is available from plant sources as an herbal weight loss supplement. 

The reported stimulation of fungal spore germination by volatile compounds identified from plant sources (8) and the... 

In short, such scientific oriented investigations though may not help in the establishment of potent remedies from plant sources, yet the expository information of the various components along with the physical and chemical characteristics profusely stimulate ingenous ventures. 

The bronchodilatory activity of khellin, a chromone obtained from a plant source Ammi visnaga) used by ancient Egyptians for spasmolytic activity, stimulated the search for related compounds with similar pharmaoological properties (14). From a study of many bischromones, cromolyn sodium was developed and marketed (Fig. 37.5). Although it prevents bronchospasm, it does not reverse antigen-induced bronchiolar constriction. Thus, it and other agents like it that followed prevent the release of histamine and do not block the effects of histamine at its reoeptors. 

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