Plant-based medicines have an important role in the lives of millions of people. The ancient knowledge of the use of plants as medicines has led to the discovery of many important western pharmaceuticals, and the popularity of whole plant preparations for a range of therapeutic applications is growing rapidly. However, there are many challenges in the production of plant-based medicines, many of which put both the consumer and the plant populations at risk. Modern biotechnology can be optimized to massproduce plants of specific chemical composition for use as particular treatments and applications. In this review, we have used one of the most important medicinal plant genera, Scutellaria, as a model to assess the potential of applications of biotechnology for the improvement of medicinal plants.

The genus Scutellaria in the family Lamiaceae has over 350 species, many of which are medicinally active. One species, Scutellaria baicalensis, is one of the most widely prescribed plants in Traditional Chinese Medicine, used for neurological disorders, cancer and inflammatory diseases and has been the subject of detailed scientific study but little is known about the phytochemistry of other Scutellaria. The current study was designed to compare the medicinal phytochemistry of 3 species of Scutellaria used to treat neurological disorders. To accomplish this objective, the specific objectives were (a) to establish an in vitro collection of the South American native; S. racemosa, (b) to botanically characterize S. racemosa and (c) to compare the phytochemistry of S. racemosa with S. baicalensis and S. lateriflora. S. racemosa was established in vitro from wild populations in Florida. Botanically, S. racemosa is diploid with 18 chromosomes, and flow cytometry data indicated that S. baicalensis and S. racemosa have small nuclei with estimated small genomes (377 mbp and 411 mbp respectively). Antioxidant potential studies showed that there were no significant differences in the 3 Scutellaria species. Phytochemical analyses detected and quantified the flavonoids baicalin, baicalein, scutellarin, and wogonin as well as the human neurohormones melatonin and serotonin in leaf and stem tissues from S. baicalensis, S. lateriflora, and S. racemosa. These findings represent the first phytochemical analysis of S. racemosa and establish S. racemosa as a model system for study of medicinal plant secondary metabolism and as a potential source of important phytopharmaceuticals for treatment of human disease.

Cao, J., Cole, I. B. and Murch, S. J. 2006. Neurotransmitters, neuroregulators and neurotoxins in the life of plants. Can. J. Plant Sci. 86: 1183-1188. Recent evidence has shown that neurologically active compounds play an important role in the physiology of higher plants. The human neurotransmitter melatonin (N-acetyl-5-methoxytryptamine) has been found in more than 140 different plant species and is associated with flower and seed development, reproductive capacity and root growth. Hyperforin, once thought to be characteristic of St. John's wort (Hypericum perforatum L.), has now been found in several other plant species and preliminary findings indicate that it may function as a modulator of plant cell polarity and ion flow. The excitotoxin, β-methylamino-L-alanine, has been used to selectively isolate glutamate receptor mutants in Arabidopsis, and these studies are leading to new understandings of plant cell development. The study of these and other plant neurochemicals may lead to a new understanding of plant signal transmission and the mechanisms by which plant cells sense, interpret and respond to environmental cues. Mots clés: Neuromédiateurs, mélatonine, hyperforine, plante médicinale Plant cells produce a wide range of common and uncommon chemical compounds that ensure the survival of the individual and the species. Most frequently, plant responsive compounds are thought of as secondary metabolites, compounds that are not essential for the growth and development of the plant, but that accumulate in response to environmental stressors. However, there is another group of phytochemicals that includes compounds historically classified as primary or secondary metabolites that are essential for the reallocation of resources in plants in response to changing environmental factors. Neurologically active compounds fall into this mixed category and include such diverse examples as indoleacetic acid, caffeine, epinephrine, acetylcholine, opiates, nicotine, levodopa, serotonin, melatonin, hyperforin and many others. In mammalian systems, neurologically active compounds mediate brain function so that external stimuli are translated into immediate responses. The human neurotransmitter melatonin (N-acetyl-5-methoxytryptamine) is a ubiquitous, highly conserved molecule associated with timing of circadian rhythms in many organisms, including higher plants. Other compounds such as hyperforin, now isolated from several plant species, may function as serotonin transport inhibitors or nonspecific cation channel activators in human brains and potentially in higher plants. A different group of neuroregulatory molecules produced by plants overstimulate human neurons, resulting in neuronal cell damage and death. Excitotoxins such as β-methylamino-L-alanine not only affect human health but are also regulatory molecules redirecting plant growth. Plants lack the "flight or flight" response common