There is a continuous and urgent need to discover new antimicrobial compounds with diverse chemical structures and novel mechanisms of action because there has been an alarming increase in the incidence of new and re-emerging infectious diseases. Another big concern is the development of resistance to the antibiotics in current clinical use.
Higher plants produce hundreds to thousands of diverse chemical compounds with different biological activities (Hamburger and Hostettmann, 1991). It is believed that these compounds have an important ecological role. They can work as pollinator attractants and as chemical defenses against insects, herbivores and microorganisms (Harborne, 1990). These antimicrobial compounds produced by plants are active against plant and human pathogenic microorganisms (Mitscher et al., 1987). There are several reports in the literature regarding the antimicrobial activity of plant crude extracts and the bioassay-guided fractionation of them to yield active principles (Rabe and van Staden, 2000; Palombo and Semple, 2001; Portillo et al., 2001; Srinivasan et al., 2001; El-Seedi et al., 2002; Zgoda-Pols et al., 2002).
From an estimated 250,000 higher plants in the world (Wilson, 1988), only 5–15% have been studied for a potential therapeutic value (Balandrin et al., 1985; Kinghorn, 1992). A large number remains to be investigated.
In Peru, like in other developing countries, medicinal plants still represent the main therapeutic tool in traditional medicine. The Peruvian flora offers great possibilities for the discovery of new compounds with antimicrobial activity. It is estimated that 17,144 flowering plant species occur in Peru of which 5354 (31.3%) are endemic (Brack, 1999).