Andrographolide: the Active Principle of Kalmegh

The paper gives a critical review of the chemistry of andrographolide, the active principle of Andrographis paniculata Nees, the common bitter popularly known as Kalmegh. It was isolated in 1911 and although the gross chemical nature as a trihydroxy diterpene lactone was known much earlier, it took more than fifty years for its complete elucidation.