Plant-Based Antiamoebic Natural Products: Literature Review and Recent Developments

Amoebiasis, caused by Entamoeba histolytica (E. histolytica), is the third leading cause of health problems in developing countries and affects more than 10% of the world’s population. If left untreated, amoebiasis causes severe complications including hepatic and intestinal tissue destruction. According to World Health Organization (WHO), approximately 80% of the people in less-developed countries still rely on traditional medicine for their healthcare needs. In different parts of the world, plant extracts obtained from numerous plants have been used in the indigenous system of medicine for the treatment of dysentery. To apply these remedies to the rational scientific use of herbal medicines, studies on antiamoebic drugs mainly focused on natural products associated with folklore medicine. Plant extracts have been tested, and several natural products have been isolated from the active fractions, leading to the characterization and extensive biological studies of the isolated compounds. This book chapter reviews the noticeable crude extracts from medicinal plants tested for antiamoebic activities and isolated natural products that have been evaluated for antiamoebic activities in the last five decades. Most of these compounds with known structures belong to alkaloids, terpenoids, quassinoids, flavonoids, iridoids, and other phenolic compounds obtained from higher plants. These natural products showed activity against E. histolytica and other protozoa in vitro, and some of the natural products have been tested in vivo. Only a very few of them have been tested clinically. Herein, we report the traditional user’s knowledge, pharmacological activity, mechanism of action, toxicity, and other properties of antiamoebic natural products.

Keywords: Amoebiasis, Antiamoebic, Alkaloids, E. histolytica, Flavonoids, Iridoids, Natural products, Quassinoids, Terpenoids.