121340-97-4 4537-78-4 DSPG Distearoyl phosphatidylglycerol Distearoyl ppg Distearoylphosphatidylglycerol Octadecanoic acid, 1-((((2,3-dihydroxypropoxy)hydroxyphosphinyl)oxy)methyl)-1,2-ethanediyl ester