Preparation of pentacyclic triterpenoid-rich Centella asiatica extract and its pharmacological activities

Centella asiatica is used as a traditional medicine for the treatment of skin diseases and wounds. It has been reported that pentacyclic triterpenes, mainly, asiatic acid, madecassic acid, asiaticoside, and madecassoside are the active constituents that possess various pharmacological activities, including wound healing, anti-ulcer, anti-inflammatory and anticancer. A new method for preparation of pentacyclic triterpenes-rich C. asiatica extract (PRE) was established and its antibacterial and anti-inflammatory activities were evaluated. A simple method for preparation of the PRE, which contained not less than 65% w/w total pentacyclic triterpenes involved a macroporous resin (Diaion® HP-20) column eluted with ethanol, and a decolourisation step with activated charcoal. Antibacterial activities of PRE against Streptococcus spp. were stronger than asiaticoside, and madecassoside, and almost equal to those of madecassic acid, but lower than asiatic acid. PRE showed strong anti-inflammatory activity via inhibition of nitric oxide production by murine macrophage-like RAW264.7 cells assay, with IC₅₀ value of 64.6µg/ml. In addition, the anti-inflammatory activity of PRE was stronger than madecassic acid, asiaticoside, and madecassoside, but lower than asiatic acid.