The present invention refers to tricyclic diterpenes and their derivatives of the formulae I and II, wherein R 1 is hydrogen or C 1-6 -alkyl； R 2 is hydroxy, C 3-5 -acyloxy, hydroxymethyl, 1,3-dihydroxypropyl or C 1-6 -alkyl； R 3 and R 4 independently from each other are hydrogen, hydroxy, hydroxymethyl, C 1-5 -acyloxy or C 1-6 -alkoxy； R 5 is C 1-6 -alkyl, hydroxymethyl, carboxy or methoxycarbonyl； R 9 is hydrogen, hydroxymethyl, methoxy, oxo or C 1-5 -acyloxy； R 10 is hydrogen, or R 5 and R 9 taken together are -CH 2 -O- or -O-CH 2 -； or R 5 and R 10 taken together are -CO-O-, -O-CO-, -CH 2 -O- or -O-CH 2 -； R 6 is hydrogen, or R 5 and R 6 together form a bond； R 7 and R 8 independently from each other are C 1-6 -alkyl, carboxy, x-hydroxy-C x -alkyl (with x being an integer from 1 to 6), or C 1-6 -alkoxycarbonyl with the proviso that at least one of R 7 and R 8 is C 1-6 -alkyl； R 11 and R 12 are both hydrogen or R 11 and R 12 together are oxo, with the further proviso for formula I that if R 2 is hydroxy R 1 is C 1-6 -alkyl, for use as medicaments for the treatment of a disorder connected to impaired neurotransmission, as well as to dietary and pharmaceutical compositions and their uses.
