Study on improving drug for hyperchoresterolemia directed by sterol biosynthesis in Morus alba cell cultures

Morus alba cells and suspension cultures produce sterols and isoprenylated phenols in high yield.In the experiment with[2-ii D113锡D1C]acetate，comparison of incorporation of C-13into polyketide moieties of isoprenylated phenols，kuwanons J，Q，R，and V，revealed that increasing of oxidation degrees decreased in corporation of C-13。This fact indicated that foremost biosynthesis of lesser hydroxylated compound，kuwanon V，followed by successive hydroxylation reactions to form kuwanon R and then kuwanon J.It was also suggested that chalco-moracin was biosynthesized from mulberrofuran E in the same way.There are two independent isoprene biosyntheses in M.alba cell cultures，one is sensitive to compactin(ML-236B)，an inhibitor of HMG-CoA reductase，and the other is non-sensitive.In one of the two isoprene biosyntheses，non-sensitive to compactin，incorporated acetate was not intact acetate administered，but reconstructed acetate through tricarboxylic acid cycle(TCA Cycle)。To examine the participation of TCA cycle in the isoprene biosynthesis，fatty acid fraction was investigated。Palmitate was isolated from the callus cultures administered[2-I D113西耶D1C]acetate.The I D113个D 1C-NMR spectrum of the palmitate demonstrated that the specified positions corresponding to the methyl group of the acetate were labeled with C-13。This fact suggested that the acetate from fatty acid throughβ-oxidation was incorporated into the isoprene unit via TCA cycle。This is the first example of contribution of fatty acid to the isoprene biosynthesis。It was thus indicated that fatty acid biosynthesis was also important factor in the development of improving drug for hyperchoresterolemia。

Morus alba cells and suspension cultures produce sterols and isoprenylated phenols in high yield. In the experiment with[2-ィイD113ィエD1C]acetate, comparison of incorporation of C-13 into polyketide moieties of isoprenylated phenols, kuwanons J, Q, R, and V, revealed that increasing of oxidation degrees decreased in corporation of C-13. This fact indicated that foremost biosynthesis of lesser hydroxylated compound, kuwanon V, followed by successive hydroxylation reactions to form kuwanon R and then kuwanon J. It was also suggested that chalco-moracin was biosynthesized from mulberrofuran E in the same way. There are two independent isoprene biosyntheses in M.alba cell cultures, one is sensitive to compactin (ML-236B), an inhibitor of HMG-CoA reductase, and the other is non-sensitive. In one of the two isoprene biosyntheses, non-sensitive to compactin, incorporated acetate was not intact acetate administered, but reconstructed acetate through tricarboxylic acid cycle (TCA cycle). To examine the participation of TCA cycle in the isoprene biosynthesis, fatty acid fraction was investigated. Palmitate was isolated from the callus cultures administered [2-ィイD113ィエD1C]acetate. The ィイD113ィエD1C-NMR spectrum of the palmitate demonstrated that the specified positions corresponding to the methyl group of the acetate were labeled with C-13. This fact suggested that the acetate from fatty acid through β-oxidation was incorporated into the isoprene unit via TCA cycle. This is the first example of contribution of fatty acid to the isoprene biosynthesis. It was thus indicated that fatty acid biosynthesis was also important factor in the development of improving drug for hyperchoresterolemia.