Microbial transformations of natural antitumor agents. 23. conversion of withaferin-A to 12β- and 15β-hydroxy derivatives of withaferin-A.

Microbial transformation experiments were conducted with the antitumor lactone withaferin-A. $\text{Cunninghamella elegans}$ NRRL 1393 transformed withaferin-A ($\text{1a}$) to 15β-hydroxywithaferin-A ($\text{2a}$) and 12β-hydroxywithaferin-A ($\text{3a}$). The hydroxylated metabolites were isolated by solvent extraction and were purified by column and thin-layer chromatography. Structures of the hydroxylated metabolites were determined by protonand carbon-13 NMR, IR and mass spectral analyses, and by the preparation of acylated derivatives. Compounds $\text{2a}$ and $\text{3a}$ inhibited the growth and biochemical functions of $\text{in vitro}$ grown P-388 lymphocytic leukemic cells.     

Synthesis of 7-(β-D-Glucopyranosyl)-6-Thiotheophylline and 7-(α-D-Arabinopyranosyl)-6-Thiotheopwlline. Conformational Study of the Peracetyl Derivatives.

Abstract

The synthesis of two 7-glycosyl-6-thiotheophylline nucleosides where the sugar moieties are β-D-glucose (1b) and α-D-arabinose (2b) is reported. The syn-anti equilibrium of the peracetyl derivatives was studied by the line-shape and the ¹H-NMR nOe methods, and molecular mechanics analysis.     

Partial Protection of Carbohydrate Derivatives. Part 19. Highly Regioselective 5′-O-Aroylation of 2′-Deoxyribonucleosides in Terms of Dilution - Drop-by-Drop - Addition Procedure

Abstract

Treatment of a 2′-deoxyribonucleoside in pyridine with an aroyl chloride, which was added dropwise as a dilute solution in pyridine, gave the corresponding 5′-O-aroyl-2′-deoxyribonucleoside in 84 - 93% yields.     

Sequential synthesis and 13C-N.m.r. spectra of methyl β-glycosides of (1→4)-β-d-xylo-oligosaccharides

The reaction of 2,3-di-O-acetyl-4-O-benzyl-α,β-d-xylopyranosyl bromide (2) with methyl 2,3-di-O-acetyl-β-d-xylopyranoside gave methyl O-(2,3-di-O-acetyl-4-O-benzyl-β-d-xylopyranosyl)-(1→4)-2,3-di-O-acetyl-β-d-xylopyranoside (22). Catalytic hydrogenolysis of 22 exposed HO-4′ which was then condensed with 2. This sequence of reactions was repeated three more times to afford, after complete removal of protecting groups, a homologous series of methyl β-glycosides of (1→4)-β-d-xylo-oligosaccharides. ¹³C-N.m.r. spectra of the synthetic methyl β-glycosides (di- to hexa-saccharide) are presented together with data for six other, variously substituted, homologous series of (1→4)-d-xylo-oligosaccharides.     

CONTENTS of Vol. 13(1-6), 2003

NO。lMINIREVIEWNew insights into the immunology and evolution of HIVJustin STEBBING,Steve PAI,TERSON,Frances GOTCH(l)RE、IEWHyPertroPhie eardiomyoPathy:from gene defeet to elinical diseaseMan一W亡1 CHUNG,Tatiana TSOUTSMAN,ChristoPher SEMSARIAN(9)REGULAR ARTICLESRegulation of swelling一activated ehloride ehannels in embryonie ehiek heart eellsHua WEI,Yan Ai MEI,Jia Ting SUN,Han Qing ZHOU,Zhi Hong ZHANG(21)Ohmefentanyl stereoisomers induee ehanges o…