Therapeutic Potential of Plants as Anti-microbials for Drug Discovery

Abstract

The uses of traditional medicinal plants for primary health care have steadily increased worldwide in recent years. Scientists are in search of new phytochemicals that could be developed as useful anti-microbials for treatment of infectious diseases. Currently, out of 80% of pharmaceuticals derived from plants, very few are now being used as anti-microbials. Plants are rich in a wide variety of secondary metabolites that have found anti-microbial properties. This review highlights the current status of traditional medicine, its contribution to modern medicine, recent trends in the evaluation of anti-microbials with a special emphasis upon some tribal medicine, in vitro and in vivo experimental design for screening, and therapeutic efficacy in safety and human clinical trails for commercial outlet. Many of these commercially available compounds are crude preparations administered without performing human clinical trials. Recent methods are useful to standardize the extraction for scientific investigation of new phytochemicals and anti-microbials of traditionally used plants. It is concluded that once the local ethnomedical preparations of traditional sources are scientifically evaluated before dispensing they should replace existing drugs commonly used for the therapeutic treatment of infection. This method should be put into practice for future investigations in the field of ethnopharmacology, phytochemistry, ethnobotany and other biological fields for drug discovery.

Figure 1.

Some of the folk medicinal plants and its various parts used as therapeutic potential in Southern Tamil nadu, Western Ghats of India. (a and c) Seed with flower of Andrographics paniculata Wallichi ex Nees (Acanthaceae), (b) fruit of Strychnos nux-vomica L. (Loganiaceae), (d) Euphorbia hirta L. (Euphorbiaceae), (e) whole plant of Ocimum sanctum L. (Lamiaceae) and (f) inflorescence of Ocimum sanctum L.

Figure 2.

Some of the folk medicinal plants and its various parts used as therapeutic potential in Southern Tamil nadu, Western Ghats of India. (a) Cardiospermum halicaccabum L. (Sapindaceae), (b) Aloe vera Mill. (Liliaceae), (c) Vitex negundo L. (Verbenaceae), (d) Phyllanthus amarus (Euphorbiaceae) (e) Cathranthus roseus (L) and (f) Mimosa pudica L. (Mimosaceae).

Figure 3.

Flow chart for the various sequential protocols involved for the purification, characterization and structural derivation of medicinal plants and their bioactive compounds. Various fractions, i.e. HF: hexane fraction; PEF: petroleum ether fraction; DCM: dichrloromethane fraction; ETA: ethyl acetate fraction; MF: methanol fraction; CHL: chloroform fraction; WA: water and ACE: acetone fraction.

Figure 4.

Structure of common anti-microbial compounds from the popularly used traditional medicinal plants.