the present invention relates to a compound of the formula : ## str1 ## wherein r 1 is 2 - methyl - 1 - propenyl group or isobutyl group ; r 2 and r 3 are each hydrogen atom , an optionally substituted hydrocarbon residue or an optionally substituted acyl group or r 2 and r 3 may form a ring together with the adjacent nitrogen atom ; and the bonding mark ˜ represents an α - linkage or β - linkage , or a salt thereof . the compound of the present invention has , among others , angiogenesis inhibiting activity , cell - growth inhibiting activity and immune reaction inhibiting activity , thus being useful as medicines , etc .