Changes in the infrared attenuated total reflectance (ATR) spectra of lignins from alfalfa stem with growth and development

Abstract

Lignin is a poorly characterized polymer and its exact properties vary depending on both the species of the plant and its location within the plant. Three classes of lignins taken from alfalfa stem were examined. The investigation was concentrated on the determination of chemical changes in the lignins during growth and development by the attenuated total reflectance (ATR) infrared (IR) spectrometric technique. The spectrum of permanganate lignin was comparable to that of acid detergent lignin. The main differences were in the different relative absorbance of the peaks. The predominant component of acid detergent lignin and permanganate lignin was guaiacyl-type lignin. The predominant component of Klason lignin was syringyl-type lignin. A comparison between the signals from lignin in different development stages revealed the appearance of new peaks, which are indications of new bonds and changes in the structure of the lignins.

Synergistic anticancer effect of the extracts from Polyalthia evecta caused apoptosis in human hepatoma (HepG2) cells

“…Interestingly, the combination fractions of hexane and water showed the appearance of C-H stretching, C=O, aromatic C=C, C-H bending, C-O-H bending and C-O stretching with a respective relative integral area of 50. 4, 10.1, 15.8, 7.4, 16.3 and 2.52 [20] .…”

Evaluation of Cd(II) Ion Removal from Aqueous Solution by a Low-Cost Adsorbent Prepared from White Yam (Dioscorea rotundata) Waste Using Batch Sorption

“…The bands at 1724 cm −1 and 1640 cm −1 are due to carbonyl-group (C=O) stretching, which are characteristics of aldehydes, ketones, esters, amides, and carboxylic acid in the lignin and extractives components of the adsorbent [109]. These groups could exist as non-conjugated (1724 cm −1 ) in lignin/carboxylic acid ester groups [110] or conjugated (1640 cm −1 ) moieties such as amides linked to other aromatic rings within the lignocellulosic structure of the YTBS adsorbent [105,108,[111][112][113]. The peak at 1640 cm −1 can also be associated with the bending vibrations in amide (N-H) groups in the lignocellulosic structure of the adsorbent [114].…”

Application of lignocellulolytic fungi for bioethanol production from renewable biomass

“…Struktura lignina još uvek nije u potpunosti razjašnjena, ali je utvrđeno da su primarni prekursori njegove sinteze (tj. reakcije sparivanja radikala) tri monolignola: p-kumaril, koniferil i sinapil alkohol (slika 1, A pod 1), 2) i 3), redom) [19], koji nastaju od fenilalanina (Phe) u opštem fenilpropanoidnom i specifičnom monolignolnom putu [20]. Oni se inkorporiraju u lignin u formi fenilpropanoida: p-hidroksifenil (H), guajacil (G) i siringil (S) [19].…”

“…reakcije sparivanja radikala) tri monolignola: p-kumaril, koniferil i sinapil alkohol (slika 1, A pod 1), 2) i 3), redom) [19], koji nastaju od fenilalanina (Phe) u opštem fenilpropanoidnom i specifičnom monolignolnom putu [20]. Oni se inkorporiraju u lignin u formi fenilpropanoida: p-hidroksifenil (H), guajacil (G) i siringil (S) [19]. Pošto nastaje polidisperzni polimer -u kom se ne može uočiti pravilno ponavljanje većih jedinica -razlika u strukturi lignina različitog porekla se predstavlja razlikom u brojnosti fenilpropan jedinica i distribuciji veza unutar jedinica.…”

“…Glavne intrapolimerne veze lignina su etarske veze (70%) i ugljenik-ugljenik veze (30%) [21]. Svi lignini u manjim količinama sadrže i nekompletne ili modifikovane monolignole, pa se mogu uočiti i drugačiji mnomeri [19,22].…”