The Constituents of Medicinal Plants An introduction to the chemistry and therapeutics of herbal medicine Andrew Pengelly. Download cover. Green, London Metropolitan University, UK This unique book explains in simple terms the commonly occurring chemical constituents of medicinal plants. The major classes of plant constituents such as phenols, terpenes and polysaccharides, are described both in terms of their chemical structures and their pharmacological activities.
Identifying specific chemical compounds provides insights into traditional and clinical use of these herbs, as well as potential for adverse reactions. They can. They also occur in the garden nasturtium, Tropaeolum majus Tropaeolaceae and cress Lepidium sativum , in the form of glucotropaeolin, which is hydrolysed to the antibiotic compound benzyl isothiocyanate.
Therapeutic actions The main use for the Brassicas in general is culinary. In commerce black mustard has largely been replaced by brown mustard Brassica juncea in recent times, since the latter species is better adapted to mechanical harvesting Tucker and DeBaggio Apart from providing a rich source of nutrients, black and brown mustard seeds act to stimulate appetite and digestion.
Mustard seeds are rich in mucilage and essential fatty acids as well as glucosinolates. Seed oils act as rubefacients or irritants when applied topically, causing local vasodilation. Mustard poultices have been used historically to break up congestion in the lungs and.
Table 4. Brassica nigra, B. Taken internally the glucosinolate herbs are effective decongestants for sinus and bronchial conditions e. Large doses may induce emesis. As with many sulfur compounds glucosinolates exhibit antibiotic effects. Benzyl isothiocyanate, obtained by hydrolysis of glucosinolates in Tropaeolum majus, is cytotoxic and active against several human tumour cell lines Pintao et al. Nasturtium is traditionally used for acute bronchitis and in dermatology for skin rashes, mild burns and dandruff Bruneton Glucobrassicin, widely distributed among the edible Brassicas, produces a number of metabolites known as indoles.
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Indoles are. Brassica indoles have been shown to induce tumourinhibiting enzymes in vivo Brinker Toxicology Volatile oil of black mustard seed consists purely of glucosinolates, and should never be used internally or externally. The oil is classified as severely toxic and irritant to skin and mucous membranes, and the oral LD50 is a very low 0. Inhalation of the oil induces severe irritation of the eyes and nasal membranes. Essential oil derived from horseradish root Cochlearia armoracia is equally toxic.
Powdered black mustard seed is the form in which foments and other topical medications are traditionally prepared.
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The Botanical Safety Handbook notes that ingestion of large quantities can produce irritant poisoning; however, it can be used safely at appropriate doses. The handbook further advises that external use should not be sustained for longer than two weeks, and is contra-indicated in children under six years of age. Severe burning can occur after minutes application of the pure powder, but the potency can be reduced by mixing with a carrier such as cornstarch McGuffin et al.
Fundamentals of Pharmacognosy and Phytotherapy
Hypothyroid individuals should avoid oral consumption of glucosinolate herbs and foods except in low quantities. Iridoid glycosides Iridoids are synthesised through the mevalonic acid pathway and are technically known as cyclopentan-[c]-pyran monoterpenoids. They occur mainly as glycosides although non-glycosidic iridoids also occurthese are covered in Chapter 5. The name iridoid is derived from the common Australian meat ant Iridomyrex detectus, from which it was first detected in Sticher Iridoid glycosides are derived from plants belonging to many families, most notably the Rubiaceae, Lamiaceae, Scrophulariaceae and Gentianaceae.
Harpagoside, an anti-inflammatory compound found in devils claw, Harpagophytum procumbens Pedaliaceae , and figwort, Scrophularia nodosa Scrophulariaceae , combines a phenylpropanoid structure with a typical iridoid glycoside. The first iridoid glycoside to be identified was asperuloside from woodruffAsperula odorata Rubiaceae. Other compounds of therapeutic significance include aucubin from plantain, Plantago spp. Plantaganaceae , procumbin from devils claw and loganin from bogbean, Menyanthes spp.
Secoiridoids These glycosides are formed by the opening of the five-carbon ring of the iridoid loganin. They include amarogentin, gentiopicroside from gentian, Gentiana spp. Gentianaceae , picroliv from Picrorhiza kurroa Scrophulariaceae and oleuropein from olive leaves, Olea europea Oleaceae. Therapeutic actions Iridoids are the most bitter of all plant compounds, often responsible for the so-called bitter principle.
On a scale for bitter value devised by Wagner and Vaserian described in Sticher , amarogentin and related secoiridoids were the most bitter of all compounds tested. The taste is perceptible at a dilution of 1 part in 50 Bitters are. Bitters improve appetite and assist pancreatic function.
Fundamentals of Pharmacognosy and Phytotherapy - 2nd Edition
They are regarded as cooling remedies, useful for fevers and inflammations. Various iridoids have been identified as antimicrobial, laxative, choleretic and hepatoprotectiveespecially picroliv Sticher ; Visen et al. While anti-inflammatory activity has been identified in aucubin and others, in most cases it is relatively weak. In the case of harpagoside this may depend on the degree of hydrolysis that occurs in the gut since the aglycone harpagogenin was found to be less active than the glycoside itself Recio et al.
Recently much research has been devoted to olive leaf and the secoiridoid oleuropein.
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Apart from antimicrobial properties, the traditional hypotensive use for the herb has been verified through demonstration of coronary vasodilatory activity Zarzuelo et al. Investigations by Hansen et al. Subsequently oleacein was identified as a potent angiotensin converting enzyme ACE inhibitor, offering further evidence for hypotensive action. It appears the combination of iridoid glycosides with phenolic derivatives in medicinal herbs may produce synergistic effects that we are only beginning to understand Cometa et al. Brinker, F. Cometa, F. Facino, R.
Hansen, K. Herbert, J. Konoshima, T. Macleod, A. Vaughan, A. Macleod and B. McGuffin, M. Panossian, A. Host Pyrus caucasica Fed. Earlier and more recent aspects and concepts on their mode of action, Phytomedicine 6: Pieretti, S. Pintao, A.
europeschool.com.ua/profiles/gehowyzyb/dazy-web-de-citas.php Recio, M. Sasaki, H. Sticher, O. Wagner and P. Tisserand, R. Vaughan, J. Visen, P. Zarzuelo, A. S Introduction Terpenoids, or terpenes, comprise one of the most important groups of active compounds in plants with over 20 known structures. All terpenoid structures may be divided into isoprene five-carbon units containing two unsaturated bonds.
They are synthesised from acetate via the mevalonic acid pathway. During the formation of the terpenes, the isoprene units are linked in a head to tail fashion. Essential oils, e. Monoterpenes These are the major class of chemical compounds found in essential oils.