A spectrophotometric method was developed for the determination of saponin in Yucca extract or its preparation for food additive use. A saponin fraction of Yucca extract was prepared by column chromatography with porous polymer, and hydrolyzed with a 2 mol/L mixture of hydrochloric acid–ethanol (1 + 1) to generate sapogenin. Sapogenin amounts were determined by measuring absorbance at 430 nm, based on the color reactions with anisaldehyde, sulfuric acid, and ethyl acetate. Recoveries from Yucca extracts were 91.5–95.1%, and the detection limit was 10 mg/kg. Commercial Yucca extracts for food additive use were composed of 5.6–6.4% (w/w) saponin, making it a minor component.

Amounts of isothiocyanates and related compounds in a mustard extract and a horseradish extract for food additive use were determined by GC, after confirmation of the identity of GC peaks by GC/MS. Amounts of allyl isothiocyanate, which included that of allyl thiocyanate, because most of the allyl thiocyanate detected in the sample was assumed to have been formed from allyl isothiocyanate during GC analysis, were 97.6 and 85.4, in the mustard extract and the horseradish extract, respectively. Total amounts of the identified isothiocyanates in the mustard extract and the horseradish extract were 98.5 and 95.4, respectively. Allyl cyanide, a degradation product of allyl isothiocyanate, was found in the mustard extract and the horseradish extract at the levels of 0.57 and 1.73, respectively. b-Phenylethyl cyanide, a possible degradation product of b-phenylethyl isothiocyanate, and allyl sulfides were found in the horseradish extract, at the levels of 0.13 and 0.46, respectively. Allylamine, which is another degradation product of allyl isothiocyanate, was determined after acetylation, and was found in the mustard extract and the horseradish extract at the levels of 8 mg/g and 67 mg/g, respectively.

The first total synthesis of the peptidyl nucleoside antibiotic, blasticidin S (1), has been achieved by the coupling reaction of cytosinine (3) and blastidic acid (2). A key step in the synthesis of cytosinine (3) is the sigmatropic rearrangement of allyl cyanate 24; this reaction provided efficient and stereoselective access to 2,3-dideoxy-4-amino-D-hex-2-enopyranose (26 a). Further elaboration of 26 a gave methyl hex-2-enopyranouronate 29, and cytosine N-glycosylation of 31 using the Vorbrüggen conditions for the silyl Hilbert-Johnson reaction furnished the differentially protected cytosinine (32) in 11 steps from 2-acetoxy-D-glucal (14) (4.0 % overall yield). Synthesis of the Boc-protected blastidic acid 47 in nine steps starting from chiral carboxylic acid 35 (23 % overall yield) utilized Weinreb's protocol for the preparation of benzyl amide 38 and Fukuyama's protocol for the synthesis of the secondary amine 40. Assembly of the protected cytosinine (32) and blastidic acid (47) by the BOP method in the presence of HOBt, and finally elaboration to 1 by deprotection of the fully protected 54 established the total synthesis of blasticidin S (1).

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