The ursane triterpenoids, asiatic acid 1 and madecassic acid 2, are the major pharmacological constituents of Centella asiatica, commonly known as Gotu Kola, which is used traditionally for the treatment of anxiety, and for the improvement of cognition and memory. Using the two electrode voltage clamp technique, these triterpenes, and some semi-synthetic derivatives, were found to exhibit selective negative modulation of different subtypes of the GABAA receptor expressed in Xenopus laevis oocytes. Despite differing by only one hydroxyl group, asiatic acid 1 was found to be a negative modulator of the GABA-induced current at α1 β2 γ2L, α2 β2 γ2L, and α5 β3 γ2L GABAA receptors, while madecassic acid 2 was not. Asiatic acid 1 exhibited the greatest effect at α1 β2 γ2L (IC50 37.05 μM), followed by α5 β3 γ2L (IC50 64.05 μM) then α2 β2 γ2L (IC50 427.2 μM) receptors. Conversion of the carboxylic acid group of asiatic acid 1 to a carboxamide group (2α, 3β, 23-trihydroxy-urs-12-en-28-amide 5) resulted in enhanced inhibition at both the α1 β2 γ2L (IC50 14.07 μM) and α2 β2 γ2L receptor subtypes (IC50 28.41 μM). The results of the current study, and the involvement of α5 -containing GABAA receptors in cognition and memory, suggest that asiatic acid 1 may be a lead compound for the enhancement of cognition and memory. This article is protected by copyright. All rights reserved.