However, recent studies have demonstrated that the major source of cis-9, trans-11 CLA in milk fat is endogenous synthesis via Δ9-desaturase, with trans-11 18:1 (vaccenic acid VA) as the precursor ( 5– 7). The cis-9, trans-11 CLA isomer is an intermediate in rumen biohydrogenation of linoleic acid, and it was originally assumed this was its source in ruminants. The major dietary source of CLA is foods derived from ruminants, especially dairy products in this case, cis-9, trans-11 CLA is the predominant CLA isomer ( 3, 4). Beneficial health effects have included reductions in carcinogenesis and atherosclerosis. Numerous health benefits have been identified with conjugated linoleic acid (CLA) 2 isomer mixtures in biomedical studies in animal models ( 1, 2). Thus, VA is also anticarcinogenic, and VA and CLA represent functional food components that are present in ruminant fat.Ĭonjugated linoleic acid, vaccenic acid, milk fat, mammary cancer prevention, functional food The finding confirms that the conversion of VA to CLA is as important for cancer prevention as the dietary supply of CLA. Fatty acid analysis showed that the conversion of dietary VA to CLA resulted in a dose-dependent increase in the accumulation of CLA in the mammary fat pad, which was accompanied by a parallel decrease in tumor formation in the mammary gland. The effect of VA was magnified in this experiment because the dose range of VA tested was much broader than that of CLA. In contrast, there was a distinct and marked inhibitory response to VA that was dose dependent. As expected, small increases in dietary CLA at the low end of the CLA dose-response range did not reduce tumorigenesis. The overall dietary treatment scheme was designed to evaluate the modulation of mammary cancer risk by 1) small increases of CLA in the presence of a low level of VA and 2) more substantial increases of VA against a background of low levels of CLA. A total of 7 diets were formulated with varying levels of CLA and VA.
Specifically, our objective was to determine the relative contribution of dietary VA and CLA to the tissue concentration of CLA and its ability to inhibit the development of mammary carcinomas. The conversion of VA to CLA by Δ9-desaturase was documented previously in several species, including rats and humans. Both fatty acids were provided as a natural component in butter fat. The process is benefitable for expanding the application of CLA for medicinal and nutraceutical purposes.The present study was designed to examine the effects of increasing dietary levels of vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acid (CLA) on chemically induced mammary carcinogenesis in rats. Significance and Impact of the Study: Isomer selective bio-process for the practical production of cis-9, trans-11-CLA was first established.
coronata IFO 8586 was successfully established. The strain produced the cis-9, trans-11 isomer of CLA selectively (98% of total CLA), with a small amount of the trans-9, trans-11 isomer (2% of total CLA), mainly in the form of triacylglycerols (69% of total CLA).Ĭonclusions: A practical bio-process for selective production of cis-9, trans-11 isomer of CLA using filamentous fungus D. coronata IFO 8586 after 7 days of cultivation in the medium containing dextrin (5♰%), tryptone (2♰%) and thiourea (0♸3 μmol ml −1). Under the optimal conditions with 33♳ mg ml −1 of t-VAME as substrate, 10♵ mg ml −1 CLA was produced by D. Efficient CLA production was observed during cultivation in medium supplemented with the methyl ester of t-VA ( t-VAME). Delacroixia coronata IFO 8586 was selected as a potent producer of CLA from t-VA. Methods and Results: A total of 550 strains of fungi and yeasts were screened for CLA production from t-VA through Δ9 desaturation. Aims: Bio-process development for isomer selective and efficient production of cis-9, trans-11-octadecadienoic acid (CLA) from trans-vaccenic acid ( t-VA, trans-11-octadecenoic acid) through microbial fatty acid Δ9-desaturation reaction.