Solvent-free lipase-catalyzed preparation of diacylglycerols.

Various methods have been applied for the enzymatic preparation of diacylglycerols that are used as dietary oils for weight reduction in obesity and related disorders. Interesterification of rapeseed oil triacylglycerols with commercial preparations of monoacylglycerols, such as Monomuls 90-O18, Mulgaprime 90, and Nutrisoft 55, catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) in vacuo at 60 degrees C led to extensive (from 60 to 75%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with Nutrisoft, catalyzed by Lipozyme RM in vacuo at 60 degrees C, also led to extensive (from 60 to 70%) formation of diacylglycerols. Esterification of rapeseed oil fatty acids with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme RM and lipases from Thermomyces lanuginosus (Lipozyme TL IM) and Candida antarctica (lipase B, Novozym 435), also provided diacylglycerols, however, to a lower extent (40-45%). Glycerolysis of rapeseed oil triacylglycerols with glycerol in vacuo at 60 degrees C, catalyzed by Lipozyme TL and Novozym 435, led to diacylglycerols to the extent of

Stereospecific incorporation of palmitoyl, oleoyl and linoleoyl moieties into adipose tissue triacylglycerols of rats results in constant sn-1:sn-2:sn-3 in rats fed rapeseed, olive, conventional or high oleic sunflower oils, but not in those fed coriander oil.

We report the stereospecific (sn-1, sn-2, sn-3) distribution of fatty acids in subcutaneous adipose tissue triacylglycerols of male weaned Wistar rats fed either a standard diet or diets containing, in addition to 20 g corn oil/kg feed, 120 g/kg feed, each, of canola-type rapeseed oil, olive oil, conventional or high oleic sunflower oil or high petroselinic coriander oil for 10 wk. The regiospecific distribution of the major acyl moieties in the sn-1 (3) vs. sn-2 positions of the adipose tissue triacylglycerols broadly reflected that of the dietary oils. The saturated palmitoyl and stearoyl moieties were more abundant in the sn-1 and sn-3 positions compared with the sn-2 position of the adipose tissue triacylglycerols, and both occurred at a higher proportion in the sn-1 than in the sn-3 position. Oleoyl moieties were abundant in all the three positions of the adipose tissue triacylglycerols, whereas petroselinoyl moieties were more abundant in the sn-1 and sn-3 positions compared with the sn-2 position. Linoleoyl moieties occurred predominantly in the sn-2 position compared with the sn-1 and sn-3 positions of the adipose tissue triacylglycerols; however, they were more abundant in the sn-3 than in the sn-1 position. Despite widely varying proportions of the palmitoyl, oleoyl and linoleoyl moieties at the three positions of the dietary triacylglycerols, the ratios of each of these acyl moieties at the sn-1, sn-2, and sn-3 positions in adipose tissue triacylglycerols were essentially constant for all groups, with the exception of the group fed coriander oil, indicating a rigid stereospecific incorporation.

The composition of the major molecular species of adipose tissue triacylglycerols of rats reflects those of dietary rapeseed, olive and sunflower oils.

We report the composition of constituent fatty acids and molecular species of adipose tissue triacylglycerols of male weaned Wistar rats fed diets containing, in addition to 20 g corn oil/kg feed, 120 g per kg feed canola-type rapeseed oil, olive oil or conventional sunflower oil for 10 wk. The composition of fatty acids and molecular species of the triacylglycerols of subcutaneous, epididymal and perirenal adipose tissues did not differ among groups (P > 0.01), broadly reflecting the corresponding compositions of the dietary oils. The major molecular species of dietary triacylglycerols, especially trioleoylglycerol (OOO) and linoleoyl-dioleoylglycerols (LOO) in the rapeseed oil and olive oil diets, dioleoyl-palmitoylglycerols (OOP) in the olive oil diet, dilinoleoyl-oleoylglycerols (LLO) in the rapeseed oil and sunflower oil diets, and dilinoleoyl-palmitoylglycerols (LLP), linoleoyl-oleoyl-palmitoylglycerols (LOP) as well as trilinoleoylglycerol (LLL) in the sunflower oil diet were also prominent constituents of the corresponding adipose tissue triacylglycerols. On the other hand, predominant molecular species containing alpha-linolenoyl (Ln) moieties, e.g., alpha-linolenoyl-linoleoyl-oleoylglycerols (LnLO) and alpha -linolenoyl-dioleoylglycerols (LnOO) from the rapeseed oil diet were not prominent constituents of rat adipose tissue triacylglycerols, whereas LOP from rapeseed oil and olive oil diets and OOP from rapeseed oil and sunflower oil diets were distinctly enriched in the corresponding adipose tissues. Most of the minor molecular species of the dietary triacylglycerols from all the three diets were distinctly present in the corresponding adipose tissues. Thus, despite numerous biochemical processes involved in the metabolism of dietary triacylglycerols, a substantial proportion of the molecular species of adipose tissue triacylglycerols containing linoleoyl (L), oleoyl (O) and palmitoyl (P) moieties resemble those of dietary triacylglycerols.