Search for New Plant Constituents with Antiasthmatic and Antihypertonic Activity

Abstract

The development of target-directed in vitro screening methods (specific enzymes, primary cell cultures and receptors) has considerably stimulated the search for new potential drugs from plants. Inspite of the fact that the results obtained in vitro often have no counterpart in vivo and have to be confirmed in experimental animal studies, this new approach opens up the possibility of designing leading structures for the development of new drugs. This review summarizes results obtained in the author's research laboratory in recent years in an extensive program, which comprises the following areas: allergic asthma and cardiovascular diseases, in particular, high blood pressure. For the screening of isolated compounds and the monitoring of plant extract fractionations key enzymes and primary cell cultures of humans and animals as well as some in vivo models were used. The drugs for screening were selected primarily following ethnopharmacological guidelines. The results of structure-activity relationship studies are discussed with regard to their therapeutic relevance.Antiinflammatory drugs and those for the treatment of cardiovascular diseases rank second and third on the list of new drugs wanted for rational therapy, respectively. Although we possess a great number of powerful synthetic drugs we must confess that we do not have enough causally and rationally applicable drugs. In addition a great number of them have the handicap of causing severe adverse effects and being too toxic. In this context, it might also be worth stressing that from about 2000 registered human diseases and disorders, only about 40% can be cured. Bearing this in mind, it is essential to utilize the almost limitless resources provided by the plethora of potential medicinal plants of traditional medicine for an overall and thorough screening. However, only in a few exceptional cases will a screening program such as this result in a highly effective drug. Most of the new plant constituents found by a bioguided fractionation can be regarded as leading structures only, which may serve as starting templates for synthetic 46

Validation of a colorimetric assay for the in vitro screening of inhibitors of angiotensin-converting enzyme (ACE) from plant extracts

“…Procyanidins and flavonoids are the major classes of natural products presenting in vitro ACE inhibitory activity, isolated from plants selected by ethnopharmacological approach (Wagner et al, 1991;Wagner, 1998;Lacaille-Dubois et al, 2001;Actis-Goretta et al, 2003). Other classes of active compounds include phenylpropanes, xanthones, fatty acids, terpenoids, alkaloids and peptide amino acids (see references reviewed in Braga et al, 2000).…”

Subcritical Water for Recovery of Polyphenols from Comfrey Root and Biological Activities of Extracts

“…31 Early works with S. officinale root extract indicated presence of some phenolic compounds such as rosmarinic acid, chlorogenic acid, caffeic acid, rutin, kaempferol, apigenin, quercetin. 7,8 Some of these compounds such as caffeic acid, 31 rutin, 43 quercetin, 44 apigenin and kaempferol, 45 were evaluated for their potency for ACE inhibition. The screening results of several plant methanolic extracts showed a low ACE inhibition activity of the isolated chlorogenic acid.…”

Characterization of Phytochelatin-Like Complexes From Flax (Linum Usitatissimum) Seed

“…1996). In addition to their metal-binding properties, phytochelatins and metallothionein fragments have been reported to exhibit angiotensin converting enzyme (ACE)-inhibitory activity (Wagner 1998).…”