History (review from herbals): plants an biochemical factories - radiant energy to not only chemical energy BUT complex molecules that have biological activity - thousands of years of trial and error among early 'hunter-gatherer' populations all over the world - Asia, Africa, The Americas. The early interface with plants included not only foods BUT the ONLY source of medicines (plants). Historic trail the developed into modern western culture started in the near east (Sumeria - 2500 B.C.) and Egypt as evidences by lithic records - tablets - wall carvings and the Ebers papyrus (dated at 1550 B.C.-700 medicinal formulas) of important plants for medicine - MOVE FROM VERBAL TRANSFER TO PHYSICAL RECORDS. Golden Age of Greece - THEOPHRASTUS [CA. 300 BC] - description of medicinals growing in the botanical garden at Athens, 1st account of Opium [FATHER OF BOTANY] - also DIOSCORIDES [born 64 AD] - De materia medica - five volumn description of medicinal plants - copied by monks for centuries to produce HERBALS - lists of useful plants indexed by medical applications - mid 1400s - printing press - mass production of herbals - PARACELSUS [1493-1519] burned books of the 'ancients' and promoted the notion that plants were placed on earth by god for human use. Consequently, God provided signs - plant structures - that indicated ailment that the plant was to be use for - DOCTRINE OF SIGNATURES - walnuts [cotyledons look like a brain] were good for mental problems, plants with cordate leaves [heart-shaped] were good for the heart, etc. - herbals of the 15/1600s reflected these 'mystical' notions. (bloodroot, rhizome)
Modern approach has been to examine chemical composition of plant medicines that are parts of traditional medicine - test actual functionality, then try to synthesize the functional compound for mass production. Thus, primary plant materials are currently a minor component of modern medicine, but they have [and will] provide an essential starting point. All major drug companies and US health agencies conduct screening programs for 'natural products' - currently a major screen for 'anti-tumor' compounds in plants - a major argument for maintenance of biological diversity: Taxol (Taxus brevifolia - Taxaceae) - National Cancer Institute screen (1960s) - function (microtubules) identified in 1979 - clinical trials (1983) - rare plant - other yews (1988 - T. baccata leaves) - systhesis with natural precursor - 1994 full synthesis in lab (overview).
In 1979, of the 100 most prescribed drugs, 37 contained natural extracts, 22 of these from plants - most of these were either steroids or alkaloids.
Steroid = complex compound composed of a 'backbone' of 4 carbon rings - 17 points of attachment for other molecules - thus, great diversity of steriods - attachment of a sugar = steroidal glycosides - like essential oils and laticifers - occur in many branches of the angiosperm tree - no direct physiological functions - thus, 'secondary compounds' ALTHOUGH have pronounced affects on animals, particular vertebrates. Might be for anti-herbivory - Milkweeds (Asclepias - Asclepiadaceae)- Monarch larvae not poisoned by steroidal glycosides - eat leaves and STORE steroids - when they change into butterflys - compounds transferred to bufferfly, mostly in wings.
Alkaloid = diverse group of complex molecules characterized by the presence of nitrogen and an alkaline reaction - once thought to be secondary compounds, but recently shown to enter primary metabolism - breakdown and regeneration - very common, like steriods, in diverse lines of flowering plants, and, like steriods, toxic to animals - complex aspect of traditional 'curing' rituals of the 'medicine man' [usually a female] involved processing to insure a 'safe' [non=lethal] does of these materials.
Malaria - one of the most lethal diseases of human history - Jesuits - mid 17th century - South America - native fever remedy 'quina' [to quinine] - bark of Cinchona officinalis [Rubiaceae] - produced a complex mixture of alkaloids - accepted as a treatment in 1681. The story of quinine is similar to that of Hevea - trees varied [natural genetic variation] - the Dutch secured seed from a particlarly potent tree growing near lake Titicaca in Bolivia - established plantations in Java - had a monopoly of quinine until WW II. US supply lines cut during the war - we looked for other sources [Bolivia] BUT, by 1944, US chemists had produced synthetic quinine alkaloids. BUT, like rubber, need for natural quinine alkaloids still present. The sporozoan [Plasmodium] is also variable - new asian strains resistant to synthetic quinine variants (Chloroquine) BUT not to the natural alkaloids, which show variation. 'Gin and tonic' - big doses required. Also, most recently, Artemisia annua (Artemisinin).
ASPIRIN is now probably the most widely used medicine in the world - what is it?
Salix [Salicaceae] - large genus with ca. 400 species distributed in wet areas throughout northern, temperate portions of the world [1 species locally]. Soaking willow leaves produced a topical [on the body part] pain killer for many cultures, New and Old Worlds [mentioned by Dioscorides] - active ingrediant - SALICIN - isolated in 1827 - could not be taken internally - BUT a derivative ACETYLSALICYLIC ACID - produced in germany in 1899. This is the active ingredient in Aspirin
- has been used as a local anesthetic
- numbs tissue - isolated as a pure alkaloid in 1858 - 1884, asistant
Freud placed a solution on his tougue and notice numbing - later
a local anestietic for eye surgery, dentistry. Difficult to synthesize,
similar compounds PROCAINE [NOVACAINE] have been produced.
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21 Apr 2010