An alkaloid is a naturally occurring chemical compound that primarily contains basic nitrogen atoms. There are also some synthetic compounds that are classified as alkaloids. These compounds are generally classified as neutral or mildly acidic and are quite bitter to the taste. Alkaloids are produced by a large number of naturally occurring organisms such as bacteria, fungi, plants, and animals. Naturally occurring alkaloids are processed and purified by acid-base extraction. They have a great number of medicinal and pharmacological purposes including antimalarials, anti-asthmas, anticancer, vasodilatories, and cholinometrics. Some are also used as psychotropics and as stimulants. Alkaloids are also used by traditional cultures as an entheogenic substance (a chemical substance that is used in a religious, shamanic, or spiritual context) and sometimes as recreational drugs.