Plants and the health of mankind

The use of various herbal mixtures and infusions for curing all manner of illnesses has been practised from time immemorial. Drugs capable of causing death or curing diseases were held in considerable awe by the layman and this, together with the sometimes elaborate rituals which accompanied their dispensation, must often have rendered simple herbal remedies much more efficacious through the psychological effect upon the sick person. 1 bumper issue of the New York Times consumes roughly 400 hectares (1 000 acres) of coniferous forest like this—110 wonder that amino timber is a major industry. More obvious uses for timber are for buildings, boats, tools, furniture, anil weapons, anil its byproducts life hark, resin and latex have further uses. Some of the herbal remedies used really were effective because they contained specific substances which had physiological activity. In many cases studies of these herbs has enabled the active principle to be identified and has occasionally led to the production of whole new ranges of compounds.

In addition to the use of pharmacologically active herbal preparations, many plants contribute to the general health of man by virtue of their vitamin content. Whole books have been written on the nutritional value of foods from this standpoint and it is worth noting that a large proportion of our daily vitamin requirements is very often derived from plant sources. Painkillers

One of the earliest and most famous (or infamous) of the painkillers was the root of mandrake (Maudragora officinarum). The fleshy root of this plant is very often forked and sometimes bears a rough resemblance to a human figure, hence in mediaeval times an air of mystery and legend surrounded its use. Steeping or boiling the root in wine produced a concoction which when taken in the proper dose induced sleep and insensibility to pain. Too much however could cause paralysis, madness or death (the preparation came to be known as ‘death wine’ or morion). The active principle in mandrake has been shown to be the alkaloid hyoscine which also occurs in other plants such as the corkwood of Australia (Duboisia utyo-poroides) and the Indian thorn apple.

Hyoscine is still used in modern medical practice, sometimes as an anaesthetic in combination with morphine, which is obtained from the opium poppy (Papaver somniferum). The opium poppy is cultivated in many parts of the world, especially India, China and in the Near East and Mediterranean area. Opium is the dried milky juice or latex obtained from the poppy seed capsules which are cut some two weeks after the petals have dropped. The latex exudes from the cuts and in hot dry weather congeals into lumps which are subsequently processed for their morphine content (the latex can contain up to 15 percent of morphine together with 1 percent of codeine and various other alkaloids). Morphine is widely used as a painkiller although the abuse of the parent opium and related heroin (acetylated morphine) as narcotic drugs is one of the great social problems of today.

Another well-known anaesthetic is cocaine, the active principle of the coca plant (Erythro-xylon coca). The coca plant is a small tree or shrub with ovate leaves from which the cocaine can be extracted. Although synthetic substitutes are used for cocaine (for example, novo-caine and procaine) the coca plant has become famous as the stimulant used by Peruvian natives when undertaking long arduous journeys, it being said that they can work tor days with little or no food if they chew the leaves of the plant.

Narcotics and drugs

There are many narcotics and drugs obtainable from a wide variety of plants. One of the most remarkable is quinine which is obtained from various species of Cinchona trees. Cinchona is native to the jungles of Peru and following the discovery of the antimalarial properties of the powdered bark, plantations were eventually established (not without various degrees of intrigue), in India and Java. Four alkaloids are found in Cinchona bark, all of which have antimalarial activity. These are cinchonine, cin-chonidine, quinine and quinidinc, with some species of tree yielding a total of 17 percent of them in their bark.

Many more drugs come from the tropical forests of South America. Perhaps the most well-known of these (or most notorious) is curare, a complex resinous mixture prepared by boiling together an assortment of bark and herbs and finally evaporating the extract until a thick black residue remains. The poisonous mixture is used for tipping blowgun darts and arrows to kill animals and birds. Many plants usually go into a brew and maybe no two potions are exactly identical. Chondrodendron tomentosum is very often an ingredient together with plants of the Strychnos species. C. tomentosum provides the active principle of the curare which has been shown to be an alkaloid named d-tubocurarine. The toxic properties of Strychnos species are due to their contents of two alkaloids, strychnine and bruane. When used in the proper dosage these alkaloids can relieve paralysis and stimulate the central nervous system, but in excess have the opposite effect and in large doses cause death.

Not all drugs are obtained from tropical or subtropical plants. One very useful drug is digitalin obtained from the foxglove, Digitalis purpurea, a common European wildflower and grown as a garden plant all over the world. Digitalin containing extracts are prepared from the dried pulverized leaves of the plants, yields of up to 300kg (660lb) per acre being possible. The most important medical uses of digitalin are as a heart stimulant and diuretic.

The search for useful drugs from plants is still continuing and is likely to continue for many years to come. Recent research has shown that an alkaloid extracted from the flowers and developing fruit of Camptotheca acuminata (camptothecin) has anti-tumour activity in tests using laboratory animals. Maybe this plant or a similar one will provide man with the long-sought-after cure for cancer, but even if this is not so there is no doubt that plants from all over the world will still be employed and investigated as possible sources of drugs beneficial to man. Hallucinogens No account of drugs would be complete with- out mentioning the hallucinogenic or psychedelic drugs so familiar to us in the twentieth century. Mescaline, from the cactus Lopho-phora williamsii, panthcrine from the fungus Amanita muscaria and psilocybin from another fungus, Psilocybe mexicana have been used for centuries by primitive peoples. The two best known hallucinogens today are LSD (lysergic acid diethylamide) and marijuana (tetrahydrocannabinol). LSD is easily synthesized but was originally found in plants of the Con-volvulaceae, particularly lpotnoea violacea. Apart from the social problems arising from its use, it does have some promise as a tool in the treatment of schizophrenia. Marijuana is an ancient drug, described as early as 2737 BC, and is obtained from the hemp plant Cannabis saliva. Its use has led to considerable discussion and argument concerning the social problems and possible addictive properties of such drugs, with currently little agreement between the various authorities. Insecticides

There are innumerable plant products which can have intense physiological effects upon man. It is not surprising therefore that there are some plant products which can affect the physiology of pests such as insects even to the extent of destroying them. For the most part synthetic insecticides overshadow the use of natural products but in certain situations the use of the latter is preferred. The best known natural insecticides are rotenone, obtained from Derris species and Lonclwcarpus species, and pyrethrum, obtained from the daisylike flowers of certain species of Chrysanthemum.

Sorry, comments are closed for this post.