Modifications of andrographolide to increase some biological activities: a patent review (2006 - 2011).

Andrographis paniculata Nees, Acanthaceae, is a well-recognised medicinal plant in Asia. It has been reported to possess a variety of biological activities. The main constituent of A. paniculata is andrographolide (Androg). Since the plant is known to treat many diseases, Androg was modified for many biological activities to treat and prevent a variety of diseases. This review surveys the patents from 2006 to 15 November 2011 for antibacterials, antivirals, antidiabetic, anticancer, analgesic, antipyretic and anti-inflammatory analogues. SciFinder database was used to search for the patent work using the keywords 'andrographolide', 'andrographolide derivatives', 'andrographolide analogues' and later additional limits, that is, 'patent' and 'years', 'Clinical trial' and 'years' were searched. Espacenet was also searched for 'andrographolide', 'andrographolide derivatives' and 'andrographolide analogues'. Androg is a good pharmacophore for many pharmacological activities. Esterification at either one or more of the three hydroxyls with short/long chains, heterocyclic, aromatic fatty acids was attempted and tested for a variety of activities. Most of the responses were positive. Other modifications were epoxidation at Δ(7(18)) along with esterifications with various carboxylic acids for anticancer activity. 15-Alkylidene analogues were investigated for α-glucosidase inhibition. The improvement of activities have not yet been proven to be due to the increase in the ability of analogues to reach the targets as prodrugs or the new feature structures fitted to the receptors. It seems that substitution with active compounds, such as lipoic acid, is a new trend for modification.