II. Reading. Phytopharmacy is the study of the plants that are used as drugs and the drugs that are isolated from plants

Phytopharmacy

Phytopharmacy is the study of the plants that are used as drugs and the drugs that are isolated from plants. Medicinal plants are im­portant for many reasons: they provide us with natural drugs, active constituents and intermediates for semi-synthetic drugs. Nature pro­duces an astonishing variety of complex phytoconstituents which em­brace all fields of pharmacological action.

Plants are constantly metabolising, both breaking down preformed molecules and building new ones at the same time. Besides their own essential principles, the so-called primary plant products, plants pro­duce other principles, which apparently do not have any definite bio­logical function. These are the so-called secondary products. Their biological function is often discussed but the fact is that many of them have a special importance outside the plant because of their pharma­cological action. Plants that give drugs have both active and inactive substances. The inactive substances include cellular structures and pharmacological inactive compounds.

A plant seldom has only one active principle. Often it produces a series of structurally related compounds having similar pharmacologi­cal properties. In this case it is possible to use either the total princi­ples or the isolated and chemically pure compounds. This situation may be complicated when there are synergistic or antagonistic prin­ciples or substances with other pharmacological effects in the plant at the same time. Also the inactive compounds may interfere with the action of the active ones or they may be their precursors. The inactive principles may alter the activity of the drug by physical means, for example, they may act as co-solvents of the active compounds or de­lay their absorption or diffusion in the organism.

Drugs in general arise from a heterogeneous population of indi­vidual plants living under a variety of conditions. Therefore, it is not surprising that their quality is affected by their variability, which is due to two main causes: intrinsic (endogenous) factors inherent to the genetic constitution and independent of external conditions; and ex­trinsic (exogenous) factors dependent on the ecological and environ­mental conditions in which the plant grows. Sometimes intrinsic fac­tors are latent in the plant and only appear as a response to the ap­propriate external factors.

III. Language development

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