in a series of 1-octadecyl-2-acetoacetylglycerophospholipids ( 1a-f ) , an increase in the length of the methylene bridge separating the phosphate and trimethylammonio group in the polar head side chain at position 3 of the glycerol backbone resulted in a progressive decrease in paf agonistic activity and a characteristic change in antitumor activity against human promyelocytic leukemia cells ( hl-60 ) .
C1444754
length
C1521970
characteristic