negative regulation of cellular biosynthetic process negative regulation of lipid biosynthetic process negative regulation of nitrogen compound metabolic process regulation of sphingolipid biosynthetic process negative regulation of sphingolipid biosynthetic process 2009-12-08T03:33:39Z Any process that decreases the rate, frequency or extent of sphingolipid biosynthesis. Sphingolipid biosynthesis is the chemical reactions and pathways resulting in the formation of sphingolipids, any of a class of lipids containing the long-chain amine diol sphingosine or a closely related base (a sphingoid). GO:0090155 biological_process tanyaberardini