Structure–activity relationship studies on acremomannolipin A, the potent calcium signal modulator with a novel glycolipid structure 2: Role of the alditol side chain stereochemistry

Crystal structure of (S)-1-O-tert-butyl-diphenyl-silylglycerol: eight chiral mol-ecules in a triclinic cell

The asymmetric unit of the title compound {systematic name: 3-[(tert-butyl-diphenyl-sil-yl)-oxy]propane-1,2-diol, C19H26O3Si}, contains eight chiral mol-ecules (Z' = 8). These mol-ecules are connected via a complex system of hydrogen bonds into an infinite assembly along the [100] axis; hydro-phobic tert-butyl and phenyl groups form an external coating of the assembly. These assemblies are packed by weak inter-molecular inter-actions in a peculiar formation resembling a 'header bond' masonry brick wall. Disorder of flexible fragments increases with temperature but the same crystal structure exists from 120 to 220 K (and most probably to the melting point at 334 K).

Structure-activity relationship studies on acremomannolipin A, the potent calcium signal modulator with a novel glycolipid structure 3: role of the length of alditol side chain

Five homologs of a novel glycolipid acremomannolipin A (1a), the potential Ca(2+) signal modulator isolated from Acremonium strictum, bearing alditols of different length (1g-1k) were synthesized by a stereoselective β-mannosylation of appropriately protected mannosyl sulfoxide (2) with five alditols (1g: C2, 1h: C3, 1i: C4, 1j: C5 and 1k: C7 units), and their potential in modulating Ca(2+) signaling were evaluated. Homologs with alditols of more than 4 carbons (1i, 1j and 1k) were equally or more potent than the parent compound (1a) regardless of the length of the alditol chain. Whereas activities of two homologs with shorter chains (1g and 1h) decreased to a considerable extent. The results indicated that the length of the alditol side chain was a crucial determinant for the potent calcium signal modulating activity.