Tannin

Bamboo pulp was obtained from Sichuan Tianzhu Bamboo Resources Development Co., Ltd., Yibin, China. Tannin (GalloTannin, Mw = 1701.2 g/mol) and chitosan (medium molecular weight) were purchased from Sigma-Aldrich L.L.C., Shanghai, China. N-methyl morpholine-N-oxide, NMMO (AR, purity ≥ 99%) was purchased from Bide Pharmatech Ltd., Shanghai, China. Cu(NO₃)₂ (AR, purity ≥ 99%) and Cd(NO₃)₂ (AR, purity ≥ 99%) were purchased from West Asia Chemical Technology (Shandong) Co., Ltd., Linyi, China. Ultra-pure water was self-made, with resistivity ≥ 18.25 MΩ·cm.

Stryphnodendron adstringens barks were collected in Rubião Junior district (Botucatu, SP, Brazil, 22°52′60′′S and 48°28′60′′W), during the morning period. Voucher specimens were deposited at the Herbarium of the Department of Botany, Institute of Biosciences, UNESP, under the number 026633 BOTU. A crude extract was obtained according to Betoni et al. [11 (link)]. Briefly, S. adstringens barks were dried, ground and extracted with 70% methanol at 4–8 °C and filtered after 48 h. The residual plant material was re-extracted with methanol 70% and filtered after 24 h. The extract was concentrated in a rotary evaporator at 45 °C for elimination of methanol and kept in sterile flask under refrigeration until use. Levels of total tannin in the extract were measured according to Waterhouse [12 ], as follows: 10 mg of the extract were dissolved in 50 mL of distilled water, and a 2 mL aliquot was mixed with 2 mL of Folin–Ciocalteu reagent and homogenized. Three minutes later, 2 mL of 8% sodium carbonate solution were added to this mixture, stirred and kept for 2 h at room temperature. Then, centrifugated at 2000 rpm to measure total levels of tannin. The analytical calibration curve of commercially available tannin (Sigma-Aldrich) was estimated by the absorbance at 725 ηm of 10, 20, 30, 40, 60 and 80 µL/mL.

Methyl alcohol 99.9%, n-hexane 95%, chloroform 99%, n-butanol 99%, dimethyl sulfoxide (DMSO) 99.7%, aluminum chloride 99.9%, sodium acetate >99%, quercetin, acetone >99.5%, picric acid ≥98.0%, dextrose 99.5%, sodium carbonate 99.5%, phosphate buffered saline (pH 7.2 at 25 °C), potassium ferricyanide (III), trichloroacetic acid, α-Cyano-4-hydroxycinnamic acid (for MALDI-TOF MS), acetonitrile ≥99.0%, iron (III) chloride 99%, ascorbic acid ≥99%, sulfuric acid 99.9%, sodium phosphate 96%, ammonium molybdate, potassium persulfate ≥99.0%, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) 97%, Folin–Denis’ reagent, gallic acid, tannin and chemical standards were purchased from Sigma-Aldrich.
EMEM and DMEM incubation media, L-glutamine, essential amino acids mixture, penicillin-streptomycin 100x lyophilized mixture, 0.25% trypsin solution and 0.02% versene solution were purchased from PanEco, Ltd. (Moscow, Russia), fetal bovine serum—from BioWest (Nuaillé, France), and MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide)—from Diaem, Ltd. (Moscow, Russia).