Agelasphin-9b, (2S,3S,4R)-1-O-(alpha-D-galactopyranosyl)-16-methyl-2- [N-((R)-2- hydroxytetracosanoyl)-amino]- 1,3,4-heptadecanetriol, is a potent antitumor agent isolated from the marine sponge Agelas mauritianus. Various analogues of agelasphin-9b (a lead compound) were synthesized, and the relationship between their structures and biological activities was examined using several assay systems. From the results, KRN7000, (2S,3S,4R)-1-O-(alpha-D- galactopyranosyl)-2-(N-hexacosanoylamino)-1,3,4-octadecanetriol , was selected as a candidate for clinical application.

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The first, enantiospecific total syntheses of pyranonaphthoquinone antibiotics, nanaomycins D and A, and their enantiomers, kalafungin and 4-deoxykalafunginic acid are described by an “enantiodivergent” strategy from a common optically active intermediate, (1S,3RS,4S)-3,4-dihydro-5,9,10-trimethoxy-1-methyl-1H-naphtho[2,3-c]pyran-3,4-diol, which has been derived from l-rhamnose via condensation of 4-methoxy-3(phenylsulfonyl)-1(3H)-isobenzofuranone and methyl 3,4,6-trideoxy-α-l-glycero-hex-3-enopyranosid-2-ulose.

Ten kinds of monoglycosylceramides (MonoCers), having the same ceramide portion and different sugar moieties, were synthesized and their immunostimulatory and antitumor activities were examined. The manner of combination between sugar and ceramide has been demonstrated to affect the manifestation of immunostimulatory and resultant antitumor activities of MonoCers, and in the case of D-MonoCers having the D-sugar, alpha-D-MonoCers (sugar combined to ceramide in an alpha-configuration) show stronger activities than beta-D-MonoCers. Furthermore, the form of sugar, not the furanose-form but the pyranose-form, and the 2"- and 4"-hydroxyl groups of the pyranose-form of sugar, seemed to play an important role in the manifestation of the activities of alpha-D-MonoCers.

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