The aerial parts of Halfordia kendack (Rutaceae) have yielded the known alkaloid trans-erioaustralasine ({rel}-1-acetoxymethyl-4.8'epoxy-3-(1'beta ,2'beta -epoxy-3'beta ,4'alpha -para-menthyl-3'-yl)quinofin-2-one) together with four new alkaloids. The latter were characterised by spectroscopic methods as trans-deacetoxyerioaustralasine ({rel}-1-methyl-4.8'-epoxy-3-(1'beta ,2'beta -epoxy-3'beta ,4'alpha -para-menthyl-3'-yl)quinolin-2-one), trans-deacetoxyerioaustralasine hydrate ({rel}-1-methyl-4.8'-epoxy-3-(1'alpha ,2'alpha -dihydroxy-3'beta ,4'alpha -para-;menthyl-3'-yl)quinolin-2-one), trans-erioaustralasine hydrate ({rel}-1-acetoxymethyl-4.8'-epoxy-3-(1'alpha ,2'alpha -dihydroxy-3'beta ,4'alpha -para-menthyl-3'-yl) quinolin-2-one) and trans-l-epi-deacetoxyerioaustralasine hydrate ({rel}-1-acetoxymethyl-4.8'-epoxy-3-(1'beta ,2'alpha'-dihydroxy-3'beta ,4'alpha -para-menthyl-3'-yl)quinolin-2-one). (C) 2001 Elsevier Science Ltd. All rights reserved.