Abstract
Since ancient times, medicinal plants have been utilized to cure and prevent a wide range of animal and human illnesses. Nowadays, the use of therapeutic herbs is increasing in utilization of medicinal plants. The growing resistance of bacteria to antibiotics has made humans more worried about finding other ways to cure infections. Phytoconstituents have the potential to act as antimicrobial drugs against sensitive and resistant pathogens by various modes of action. Phytobiotics are naturally occurring bioactive compounds derived from plants that are secondary metabolites such as essential oils, phenolics, flavonoids, tannins, alkaloids, organosulfur, and saponins. These compounds are produced by herbal plants and have antimicrobial and growth-promoting properties that can help treat a variety of animal diseases. Plant extracts possess several advantages over synthetic drugs as most of them have no residual effects, due to its applicability in human medicine so they could be added to animals’ food to prevent and treat various animal health disorders in addition to their possible nutritional characteristics. However, additional investigation is necessary to have a greater awareness of the phytochemicals’ mechanisms of action. In this regard, this review summarizes several effects of some biologically active plants and their phytoconstituents on some infectious microbial diseases in animal. It also summarizes the efficiency, modes of action, and some applications of medicinal plants active phytochemicals to solve the antibiotic resistance problem. Regarding these facts, it could be concluded that medicinal plants resemble a furious source of active constituents that possess antimicrobial potential.

Key words: Phytoconstituents, phenolics, flavonoids, tannins, terpenes, alkaloids, essential oils, polypeptides