Structural modifications of bryostatin 2

Continuation of a structure/activity relationship study of the bryostatins was focused on bryostatin 2. Stepwise catalytic hydrogenation of bryostatin 2 gave the following results. Reduction of the side-chain diene system to saturated ester 2a (P388 cell line ED50 8.5 x 10(-3) micrograms/ml) did not significantly affect the murine P388 cell line inhibition by bryostatin 2. Further hydrogenation to hexahydro derivative 2b gave a reduced P388 ED50 of 5.1 x 10(-2) micrograms/ml. Conversion to the octahydrobryostatin 2c caused a further reduction of P388 cell line activity to ED50 2.9 x 10(-1) micrograms/ml. Other structural modifications of bryostatin 2 in respect to esterification at the C-7 position significantly affected the P388 lymphocytic leukemia cell line response. Each of the bryostatin 2 derivatives was also evaluated with respect to protein kinase C binding.