REVIEW ON MEDICINAL PLANTS

Medicinal plants have been of existence from time immemorial. Over 250,000 exist and are believed to have different medicinal activities. Moreover, only the activities of about 50,000 plants have been examined. The use of plants for the remedy of diseases is usually termed phytotherapy, complementary and alternative medicine or phytomedicine. These plants have been classified based on part used, habit, habitat, therapeutic value, Ayurvedic formulations in which they are used and Botanical classification. Plant phytochemicals confer medicinal plants their medicinal activities and has been broadly classified into primary constituents which include the common sugars, amino acids, chlorophylls, proteins, purines and pyrimidines of nucleic acids etc. while secondary constituents are the remaining plant chemicals such as alkaloids, terpenes, flavonoids, lignans, plant steroids, curcumines, saponins, phenolics, flavonoids and glucosides. The activity of the phytochemicals depends on their structures. Several methods of extraction of this useful phytochemicals exists depending on the target phytochemical. Medicinal plants have shown promising antimicrobial activities, anti-helminthic, anticancer, antidiarrheal and antiviral activities. Phytotherapy have several advantages over synthetic drugs. Moreover, it also has limitations. The characteristics, advantages, limitations of phytotherapy is been reviewed in this work.