Plants are a source of large amount of drugs comprising to different groups such as antispasmodics, emetics, anti-cancer, antimicrobials etc. A large number of the plants are claimed to possess the antibiotic properties in the traditional system and are also used extensively by the tribal people worldwide. It is now believed that nature has given the cure of every disease in one way or another. Plants have been known to relieve various diseases in Ayurveda.
Therefore, the researchers today are emphasizing on evaluation Prashant Tiwari*, Bimlesh Kumar, Mandeep Kaur, Gurpreet Kaur, Harleen Kaur Department of Pharmaceutical Sciences, Lovely School of Pharmaceutical Sciences, Phagwara, Punjab and characterization of various plants and plant constituents against a number of diseases based on their traditional claims of the plants given in Ayurveda. Extraction of the bioactive plant constituents has always been a challenging task for the researchers. In this present review, an attempt has been made to give an overview of certain extractants and extraction processes with their advantages and disadvantages.
extracts. Such preparations have been popularly called Plant-derived substances have recently become of galenicals, named after Galen, the second century great interest owing to their versatile applications. Greek physician . Medicinal plants are the richest bio-resource of drugs Extraction methods used pharmaceutically involves of the separation of medicinally active portions of plant traditional systems of modern folk tissues from the inactive/inert components by using medicines, pharmaceutical intermediates and chemical selective solvents. During extraction, solvents diffuse entities for synthetic drugs .
Into the solid plant material and solubilize compounds Extraction (as the term is pharmaceutically used) is the with similar polarity . separation of medicinally active portions of plant (and The purpose of standardized extraction procedures for animal) tissues using selective solvents through crude drugs (medicinal plant parts) is to attain the standard procedures. The products so obtained from therapeutically desired portions and to eliminate plants are relatively complex mixtures of metabolites, unwanted material by treatment with a selective in liquid or semisolid state or (after removing the solvent known as menstrum.
The extract thus solvent) in dry powder form, and are intended for oral obtained, after standardization, may be used as or external use. These include classes of preparations medicinal agent as such in the form of tinctures or known extracts, fluid extracts or further processed to be incorporated tinctures, pilular (semisolid) extracts or powdered in any dosage form such as tablets and capsules.
These as decoctions, food medicine, supplements, infusions, fluid products contains complex mixture of many medicinal plant metabolites, such as alkaloids, glycosides, terpenoids, flavonoids and lignans . The general techniques of medicinal plant extraction include maceration, infusion, percolation, digestion, Internationale Pharmaceutica Sciencia Jan-Mar 2011 Vol 1 Issue 1
Prashant Tiwari, et al: Phytochemical screening and Extraction: A Review decoction, (Soxhlet), part of the plant like bark, leaves, flowers, roots, fruits, aqueous-alcoholic extraction by fermentation, counter- seeds, etc i.e. any part of the plant may contain active current extraction, microwave-assisted extraction, components. The systematic screening of plant species ultrasound extraction (sonication), supercritical fluid with the purpose of discovering new bioactive
extraction, (with compounds is a routine activity in many laboratories. hydrofluorocarbon solvents). For aromatic plants, Scientific analysis of plant components follows a hydrodistillation techniques (water distillation, steam logical pathway. Plants are collected either randomly distillation, water and steam distillation), hydrolytic or by following leads supplied by local healers in maceration followed by distillation, expression and geographical areas where the plants are found . enfl eurage (cold fat extraction) may be employed. Fresh or dried plant materials can be used as a source Some of the latest extraction methods for aromatic for the extraction of secondary plant components. plants include headspace trapping, solid phase micro- Many authors had reported about plant extract extraction, protoplast extraction, microdistillation, preparation from the fresh plant tissues.
The logic thermomicrodistillation and molecular distillation . behind this came from the ethno medicinal use of fresh The basic parameters influencing the quality of an plant materials among the traditional and tribal extract are : people.