Abstract
To find possible therapeutic applications involving the Central Nervous System (CNS) for herbals is a major challenge during functional food and drug discovery and development programmes. Despite the availability of numerous in vitro and in vivo tests, there is no single agreed screening procedure for pharmacological testing of herbal extracts with anticipated CNS activity. Experience gained from more than 25 years of testing has shown that two models give reasonably reliable orientation for future CNS applications: construction of an electropharmacogram based on wireless recording of field potentials from the depth of the brain of freely moving rats (Tele-Stereo-EEG) and recording of the population spike produced by pyramidal cells from hippocampal slices in vitro. A combination of these two methods has now been used to characterize the pharmacological profile of extracts from Rhodiola rosea root, Oenothera paradoxa seeds and Paullinia cupana seeds. Spectral analysis of field potentials revealed attenuation of alpha2 and beta1 waves was common for all extracts. According to previous studies, this is interpreted as activation of the dopaminergic and glutamatergic transmission. In addition, Oenothera and Rhodiola extracts attenuated delta and theta power, probably related to interference with the cholinergic and norepinephrinergic transmission, respectively. Using discriminant analysis for comparison with reference pharmaceutical and botanical drugs, Rhodiola projected near the position of Ginkgo extract, whereas Oenothera extract was projected near the position of Tramadol, an analgesic drug. Physical motion was increased only in the presence of Paullinia extract and caffeine. Increases of long-term potentiation were observed in the presence of Rhodiola extract, Paullinia extract and caffeine. The combined information predicts stimulant and cognitive function-enhancing activities in humans for the Rhodiola extract, which could also be used as a possible caffeine-replacement, and antidepressant and analgesic activity for the Oenothera extract.
Highlights
Therapeutic use of plants dates back thousands of years
Since the communication structure in the brain is based on electro-chemical processes, electric activity contains information on underlying chemical changes induced for example by drugs. This reasoning has led to the development of a rat model allowing for continuous recording of focal field potentials from four brain regions and wireless transmission of the data for quantitative analysis by means of Fast Fourier Transformation
By keeping the discriminant functions fixed with regard to reference drugs in order to obtain a matrix of known pharmacological effects, it becomes feasible to classify the Central Nervous System (CNS) activity of herbal extracts and extrapolate their possible therapeutic indication [2]
Summary
Therapeutic use of plants dates back thousands of years. knowledge on their use for specific indications is mostly based on uses in folk medicine. In order to allow for better quantitative testing and to get reproducible results, extracts are prepared from whole plants or plant parts in the hope that key pharmacologically active molecules survive this procedure in effective amounts. Since the communication structure in the brain is based on electro-chemical processes, electric activity contains information on underlying chemical changes induced for example by drugs. This reasoning has led to the development of a rat model allowing for continuous recording of focal field potentials from four brain regions and wireless transmission of the data for quantitative analysis by means of Fast Fourier Transformation. By keeping the discriminant functions fixed with regard to reference drugs in order to obtain a matrix of known pharmacological effects, it becomes feasible to classify the CNS activity of herbal extracts and extrapolate their possible therapeutic indication [2]
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