<italic>Centella asiatica</italic>: phytochemistry and mechanisms of neuroprotection and cognitive enhancement.

This review describes in detail the phytochemistry and neurological effects of the medicinal herb <italic>Centella asiatica</italic> (L.) Urban. <italic>C. asiatica</italic> is a small perennial plant that grows in moist, tropical and sub-tropical regions throughout the world. Phytochemicals identified from <italic>C. asiatica</italic> to date include isoprenoids (sesquiterpenes, plant sterols, pentacyclic triterpenoids and saponins) and phenylpropanoid derivatives (eugenol derivatives, caffeoylquinic acids, and flavonoids). Contemporary methods for fingerprinting and characterization of compounds in <italic>C. asiatica</italic> extracts include liquid chromatography and/or ion mobility spectrometry in conjunction with high-resolution mass spectrometry. Multiple studies in rodent models, and a limited number of human studies, support <italic>C. asiatica</italic>’s traditional reputation as a cognitive enhancer, as well as its anxiolytic and anticonvulsant effects. Neuroprotective effects of <italic>C. asiatica</italic> are seen in several in vitro models, for example against beta amyloid toxicity, and appear to be associated with increased mitochondrial activity, improved antioxidant status, and/or inhibition of the pro-inflammatory enzyme, phospholipase A2. Neurotropic effects of <italic>C. asiatica</italic> include increased dendritic arborization and synaptogenesis, and may be due to modulations of signal transduction pathways such as ERK1/2 and Akt. Many of these neurotropic and neuroprotective properties of <italic>C. asiatica</italic> have been associated with the triterpene compounds asiatic acid, asiaticoside and madecassoside. More recently, caffeoylquinic acids are emerging as a second important group of active compounds in <italic>C. asiatica</italic>, with the potential of enhancing the Nrf2-antioxidant response pathway. The absorption, distribution, metabolism and excretion of the triterpenes, caffeoylquinic acids and flavonoids found in <italic>C. asiatica</italic> have been studied in humans and animal models, and the compounds or their metabolites found in the brain. This review highlights the remarkable potential for <italic>C. asiatica</italic> extracts and derivatives to be used in the treatment of neurological conditions, and considers the further research needed to actualize this possibility. [ABSTRACT FROM AUTHOR]