Isolation and characterization of fatty acid derivatives from an actinomycetes and examination of the effects on activities of phospholipase C and protein kinase C

Abstract

In our screening to search inhibitors of phosphoinositide(PI)-specific phospholipase C (PIPLC), two inhibitors, MT965-A and -B were isolated from a culture broth of an actinomycetes. MT965-A and -B were identified as fatty acid derivatives, 14-methylpentadecanoic acid and 16-methyllinoleic acid methyl ester, respectively, based on the spectral data including NMR and MS. Both inhibitors directly inhibited not only in vitro PLCγ1 activity but also the platelet-derived growth factor (PDGF)-induced inositol phosphates (IPt) formation in NIH 3T3γ1 cells overexpressing PLCγ1. However, the inhibitors enhanced in vitro protein kinase C (PKC) activity. On examination of the effects of various fatty acids (FAs) on activities of PLC, PKC, and PDGF-induced IPt formation, the unsaturated FAs (UFAs) showed the same activities like the inhibitors, but the saturated FAs (SFAs) did not show similar activities. It was inferred that the chain length, degree of unsaturation, methyl esterification, branching with a methyl group, and cisconfiguration were important for their activity.