Natural and Biomimetic Antitumor Pyrazoles, A Perspective.

The present review presents an overview of antitumor pyrazoles of natural or bioinspired origins. Pyrazole compounds are relatively rare in nature, the first ones having been reported in 1966 and being essentially used as somniferous drugs. Cytotoxic pyrazoles of natural sources were first isolated in 1969, and a few others have been reported since then, most of them in the last decade. This paper presents a perspective on the current knowledge on antitumor natural pyrazoles, organized into two sections. The first focuses on the three known families of cytotoxic pyrazoles that were directly isolated from plants, for which the knowledge of the medicinal properties is in its infancy. The second section describes pyrazole derivatives of natural products, discussing their structure-activity relationships.