These hydrophobic organic ligands make MMT highly lipophilic. Cell membranes consist of hydrophilic and lipophilic endgroups. Colistin is a polycationic peptide and has both hydrophilic and lipophilic moieties. These hydrophobic organic ligands make MMT highly lipophilic, which may increase bioaccumulation. A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. A bioconcentration factor greater than 1 is indicative of a hydrophobic or lipophilic chemical. Weak bases with lipophilic properties accumulate in acidic intracellular compartments like lysosomes. Unlike the acetate salts, acetate esters are often liquids, lipophilic, and sometimes volatile. In both cases, the salt forms of the amine make these otherwise lipophilic compounds water-soluble. It is therefore sometimes employed to crystallize highly lipophilic compounds. Intravenously-delivered general anesthetics are typically small and highly lipophilic molecules. Etretinate is a highly lipophilic, aromatic retinoid. As an unconjugated steroid, finasteride is a highly lipophilic compound. The four methyl-groups on the quaternary N atoms make it less lipophilic than most aminosteroids. Antimalarials are lipophilic weak bases and easily pass plasma membranes.