**1. Introduction**

For hundreds of years, herbal therapy has played a major role in maintaining the health and wealth of people around the world. For treatment of various illnesses, herbs are widely used. In most of the developing countries, nowadays, people prefer alternative medicine than conventional medicine indicated by a recent survey. Many publications and books claim the proficiency of herbs for the treatment of various illnesses including cirrhosis, hepatitis, and other deadly diseases. It has been observed widely that the medicinal plants and traditional medicines are used as a normative basis for maintaining good health [1].

In the process of developing many drugs, an increasing demand for the use of medicinal plant-derived products in the industries has been found [2]. For personal health maintenance, herbal remedies have become more popular in treatment of minor ailments. Due to increasing demand, there is a great risk that the existing medicinal plants on earth might disappear. Thus an important component of the health care system in a country like India is medicinal plants.

Chemical compounds obtained from plant source are termed as secondary plant products. Alkaloids and glycosides are the two major compounds present. In 4000 plant species, more than 3000 alkaloids have been identified. The difference between a toxic and medicinal effect of many alkaloids depends upon the dosage. When a sugar molecule gets attached to component which is active, it is called as glycoside which is categorized by the nature of the active component or nonsugar.

Clinical research of the present era has confirmed the ability of many medicinal plants in treating various viral diseases, while many recent scientific research have

discovered the exact mechanism by which many different plants provide their therapeutic advantages. Three such plants are *Boerhavia diffusa*, *Eclipta alba* and *Phyllanthus amarus*.
