Olive pomace oil (‘orujo’ oil) is an olive oil product suitable for human consumption that is traditionally produced in Spain(Reference Perona, Aracemis, Ruiz-Gutierrez and Catalá¹). The non-acylglycerol component of this oil is a good source of interesting minor components, e.g. triterpenes(Reference Perez Camino and Cert²), or fatty alcohols, derived from waxy materials. Tetracosanol (C₂₄OH; 30%), hexacosanol (C₂₆OH; 37%) and octacosanol (C₂₈OH; 15%) are the major constituents of the long-chain fatty alcohol (LCFA) fraction isolated from orujo olive oil(Reference Marquez³). A similar mixture of long-chain alcohols, termed ‘policosanol’ and purified from waxy materials of different sources such as sugar cane, bees wax, rice bran or spinach, have shown many beneficial physiological activities(Reference Taylor, Rapport and Lockwood^4, Reference Singh, Li and Porter⁵). The present study focused on the effect of LCFA isolated from orujo olive oil on NO, PGE₂ and TNFα release by a lipopolysaccharide (LPS)-stimulated murine macrophage cell line (RAW-264.7) as well as the effect on thromboxane B₂ (TXB₂) generation by A-23187-stimulated rat peritoneal neutrophils (PMN). Nitrite (as an index of NO generation) levels were determined by a fluorometric method. PGE₂, TNFα and TXB₂ production were quantified by sandwich immunoassay.

LCFA significantly and dose-dependently decreased the NO production in LPS-stimulated RAW-264.7 cell line macrophages (Fig. 1). Western-blot analysis for inducible NO synthase (iNOS) showed that NO reduction was a consequence of the 100% inhibition of iNOS expression at a dose of 100 μg/ml (Fig. 2). By contrast, LCFA scarcely affected PGE₂ levels (Fig. 1). TNFα production was also significantly decreased by LCFA at the highest dose assayed (100 μg/ml; Fig. 1). LCFA significantly reduced TXA₂ production in rat PMN stimulated with A-23187 (Fig. 3).

Fig. 1. Effect of LCFA on NO, PGE₂ and TNFα produced by LPS (10 μg/ml)-stimulated RAW-264.7 murine macrophages (1×106 cells/ml). Mean values were significantly different from those for LPS control group: **P<0.01, ***P<0.001.

Fig. 2. Effect of LCFA subfraction on iNOS expression and densitometric analysis in RAW 264.7 cells. DEX, dexamethasone; OD, optical density.

Fig. 3. Effect of LCFA on TXB₂ produced by A-23187-stimulated rat PMN. Mean values were significantly different from the control value: *P<0.05, ***P<0.001.

These results showed that LCFA isolated from ‘orujo’ oil has a protective effect on some mediators implicated in the development of inflammatory damage in these experimental models and suggest its potential value as a functional component of the olive pomace oil.