Optically pure (R)-4, 4-diethoxy-2-(hydroxymethyl)butyl acetate (1) was synthesized enantioselectively by lipase-catalyzed transesterification from 4, 4-diethoxy-2-(hydroxymethyl)butanol. Coupling of silylated nucleobases and 2-O-acetyl-5-O-pivaloyl-(3S)-2, 3-dideoxyapiose (2) prepared from 1 was found to proceed smoothly in the presence of a catalytic amount of trimethylsilyl iodide under mild conditions to afford optically active nucleoside analogs.
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Three groups of polysaccharides from the edible mushroom "Maitake, " the cultured fruiting body of Grifola frondosa, were extracted with hot water, 3% NH4-oxalate (100°C), and 5% sodium hydroxide solution (30°C) in this order. The three fractions, FI, FII and Fill, were divided into several sub-fractions using various chromatographic techniques. The fractions with host-mediated antitumor activity were as follows: Water-soluble β-(1→ 3)-o-glucan: FI0-a-β1, [α]D +9° (water), MW 1, 000, 000, N 0%, degree of branching = 3, average chain-length = 5, ID50 (the dose level, mg/kg in mice, inhibiting tumor growth in 50% of animal controls) = 5.8. Water-soluble acidic β-D-glucan: FA-la-β1, [a]D +5° (water), MW 500, 000, component sugars; Glc 82.4% and GlcUA 8.8%, ID50=12.9. Water-insoluble acidic xyloglucan: FII-3, [α]D + 56° (NaOH), MW 50, 000, component sugars; Glc:Xyl=100:82, GlcUA 16.5%, ID50 = 23.8. Acidic hetero-glycan: Fill-la, [α]D +6° (NaOH), MW 100, 000-250, 000, protein content 3.8%, component sugars; Glc:Xyl: Man: Fuc= 100: 58:34:14, GlcUA 20.4%, ID50 = 16.1. Acidic glycoproteins: FIII-2a, FIII-2b and FIII-2c: [a]D +58°, +43°, -11° (NaOH); MW 1, 000, 000, 70, 000- 100, 000, 20, 000- 50, 000; ID50= 38.5, 13.9, 9.3 respectively; component sugars; major = Glc, minor = Fuc, Xyl, Man, and Gal. None of the polysaccharides intraperitoneally active against mouse-implanted Sarcoma 180 had any activity orally.
