PubMed · 9357309
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T Hunt. 1997. Extinction is forever.. https://doi.org/10.1016/s0968-0004(97)01121-3
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Ethanol can be produced from lignocellulosic biomass using steam pretreatment followed by enzymatic hydrolysis and fermentation. The sugar yields, from both hemicellulose and cellulose are critical parameters for an economically-feasible ethanol production process. This study shows that a near-theoretical glucose yield (96-104%) from acid-catalysed steam pretreated corn stover can be obtained if xylanases are used to supplement cellulases during hydrolysis. Xylanases hydrolyse residual hemicellulose, thereby improving the access of enzymes to cellulose. Under these conditions, xylose yields reached 70-74%. When pre-treatment severity was reduced by using autocatalysis instead of acid-catalysed steam pretreatment, xylose yields were increased to 80-86%. Partial delignification of pretreated material was also evaluated as a way to increase the overall sugar yield. The overall glucose yield increased slightly due to delignification but the overall xylose yield decreased due to hemicellulose loss in the delignification step. The data also demonstrate that steam pretreatment is a robust process: corn stover from Europe and North America showed only minor differences in behaviour.
Two novel C29-5beta-sterols, opuntisterol [(24R)-24-ethyl-5beta-cholest-9-ene-6beta,12alpha-diol] (1) and opuntisteroside [(24R)-24-ethyl-6beta-[(beta-d-glucopyranosyl)oxy]-5beta-cholest-9-ene-12alpha-ol] (2), together with nine known compounds, beta-sitosterol (3), taraxerol (4), friedelin (5), methyl linoleate (6), 7-oxositosterol (7), 6beta-hydroxystigmast-4-ene-3-one (8), daucosterol (9), methyl eucomate (10) and eucomic acid (11), were isolated from the stems of Opuntia dillenii collected in Guizhou Province, China. Their structures were elucidated mainly by spectroscopic analysis. The absolute configuration of 1 were deduced from comparative 1H NMR data of the (S)- and (R)-methoxyphenyl acetate derivatives. Compounds 6-8, 10 and 11 were isolated from O. dillenii for the first time.
Chemoselective hydrolysis of a variety of thioglycosides in the presence of a wide range of protecting groups has been achieved by using N-iodosuccinimide and H(2)SO(4) immobilized on silica in good to excellent yields.