1. A compound for promoting the growth of neural cells, represented by a general formula as (I): wherein, R 1 represents —H, —OH, a linear or branched alkyl group with 1 to 3 carbon atoms, or an isoprene group; R 2 , R 3 , R 4 , R 5 , R 6 and R 7 represent —H, —OH, a linear or branched alkyl group with 1 to 3 carbon atoms, an isoprene group or a geranyl group represented by formula (II) or (III), respectively.