Thirty years ago the plant kingdom should have had about 350,000 species. Nowadays this figure is estimated at circa 250,000 species, from which about 18,000 aromatic and about 60,000 medicinal plants. Of course there exists an overlap between aromatic and medicinal plants. The in-use of aromatic plants for flavours and fragrances concerns around 300 species and their isolates have an estimated value of one billion dollars. The application of medicinal plants is estimated at 10,000 species with a value of more than ten billion dollars. The turnover of medicinal plants in some important countries in Western Europe are for instance: Germany with more than 2 billion dollars, France and United Kingdom with about 0.2 billion dollars each.
The most important plant families are the orchids with about 25,000 species and the composites with 15,000 species. Aromatic plants are mainly found in the families of Rutaceae (Citrus species), Lamiaceae (Labiates), Apiaceae (Umbelliferes), Asteraceae (Composites) and Myrtaceae (Eucalyptus species). Some important medicinal plants are ginseng (Panax ginseng), ginkgo (Ginkgo biloba), chamomile (Anthemis nobilis) and taxus (Taxus brevifolia). In a recent report by McAlpine, Thorpe and Warrier (Nature 13/2/1997 and New Scientist 15/2/1997) the dying out of at least 18 important medicinal plants are mentioned.
Aromatic plants are the source for essential oils and other volatile isolates, like extracts. The annual world production of essential oils is estimated at 50,000 tons, from which circa 50% citrus oils (orange, lemon, mandarin, grapefruit) and circa 20% mint oils (peppermint, cornmint, spearmint). Besides about 300,000 tons of turpentine is produced from plantmaterials (Pine) of which one third is used for the production of aroma chemicals.
A lot of research is carried out on aromatic and medicinal plants. Each year hundreds of publications appear in journals like: Phytochemistry, Planta Medica, Flavour and Fragrance Journal, Journal of Essential Oil Research, Journal of Agricultural and Food Chemistry etc. One assumes that about 90,000 secondary plant metabolites exist, which are defined chemical compounds. From these 90,000 compounds are circa 33,000 isoprenoids and circa 17,000 alkaloids. Isoprenoids are formed from C-5 units (mevalonate) and called mono-, sesqui-, di-, tri- and tetraterpenes, including the carotenoids and steroids. Alkaloids are plant-bases containing nitrogen and are often formed from C-9 units (phenylalanine).
So far around 7,000 volatile compounds have been found in foods, drinks and edible essential oils (see VCF database). In essential oils around 3,000 volatile isoprenoids have been characterised (see ESO database). This figure is less than 10% of the total number of identified volatile and non-volatile isoprenoids.
During the last decade more than 1,000 studies have been published about the genetic modification of plant materials. These genetic investigations are for instance carried out to circumvent plant diseases, to make plants resistant against herbicides, fungicides, insecticides etc., and to improve the yield and the quality of plant isolates (seeds, fruits, oils etc.). Some examples of genetic modified plant materials are soy beans, potatoes, tomatoes, and corn. These studies and their applications will increase tremendously in the future.
Reprinted by Leffingwell & Associates, 2006, with Permission