Plants produce a diverse array of secondary metabolites, whose number has been estimated to be over 200,000. In plants, a large portion of those natural products are considered to be synthesized for chemical defense against microbial attack and herbivore predation because of their biological activities. Because some of them exhibit a wide range of pharmacological activities, they have also been studied from the aspect of pharmaceutical sources. Alkaloids are one of the better studied classes of plant natural products due to their pharmacological activities