Ultrasound-Assisted Extraction of Water-Soluble Polysaccharides from the Fruit of Acanthopanaxbrachypus: Physicochemical, Structural and Functional Properties.

The ultrasound-assisted extraction (UAE) parameters of total water-soluble polysaccharides (TABPs) from Acanthopanaxbrachypus fruit were optimized by Box-Behnken design (BBD) and response surface methodology (RSM). Physicochemical, structural, and functional properties of TABPs were investigated by chemical analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), high performance liquid chromatography (HPLC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), water-holding capacity (WHC), oil-holding capacity (OHC), emulsion capacity (EC), emulsion stability (ES), as well as DPPH. and ABTS.+ scavenging assays. The results showed that the maximal UAE-yield of TABPs was 3.81±0.18 % under the optimal conditions (ultrasonic power 325 W, extraction temperature 47 °C, extraction time 22 min). TABPs was rich in some beneficial element (Mg, K, Fe, Zn and Na) but little in harmful elements (Hg, Cd, As and Pb), and displayed rough surface with flake-like features and large dents, contained 93.89±0.08 % of total carbohydrate with more different monosaccharides including glucose, galactose, rhamnose, arabinose, mannose, xylose, and uronic acid in a molar ratio of 8.83 : 7.90 : 4.74 : 4.55 : 2.80 : 2.39 : 1.00, respectively. TABPs exhibited broad weight distribution (11.2-133.5 kDa), excellent thermal stability (>280 °C), WHC (0.61±0.08 g water/g sample) and OHC (4.53±0.12 g oil/g sample), as well as higher EC (43.75±1.23 %) and ES (38.32±1.50 %). Furthermore, TABPs also displayed remarkable scavenging activities on DPPH. and ABTS.+ in vitro. These findings provide a scientific basis for the applications of TABPs in functional additives for food, medicine, and cosmetics.

Chemical modification and antioxidant activity of the polysaccharide from Acanthopanax leucorrhizus.

A water-soluble polysaccharide (ALP) from Acanthopanax leucorrhizus was chemically modified to obtain two sulfated derivatives (S-ALP1 and S-ALP2), two phosphorylated derivatives (P-ALP1 and P-ALP2) and two acetylated derivatives (A-ALP1 and A-ALP2) with different degree of substitution (DS). Their structures were characterized by chemical and spectral (IR, 13C NMR and 31P NMR) analysis, and in vitro antioxidant activity were evaluated by reducing power assay, DPPH• and HO• scavenging assay. The results obtained showed that the modifications were successful, although the molecular weight (Mw) of the ALP derivatives decreased due to slight degradation during the reaction. Physicochemical and antioxidant properties of ALP changed by the chemical modifications, and the type of the substitution group and DS played a decisive role in the antioxidant activity of the derivatives. P-ALP and S-ALP with higher DS displayed stronger antioxidant abilities on scavenging DPPH• and HO•, ferric-reducing power compared with ALP, and exhibited a certain dose-effect relationship, whereas A-ALP were less effective. These results provide a scientific basis for the further studies and utilization of A. leucorrhizus polysaccharides.

Isolation, modification and cytotoxic evaluation of stilbenoids from Acanthopanax leucorrhizus.

Twenty natural stilbenoids (1-20), including seven new stilbenoids (2, 4-7, 19, 20) and thirteen known stilbenoids (1, 3, 8-18), were isolated from the stem barks of Acanthopanax leucorrhizus, and six modified stilbenoid derivatives (1a, 2a, 4a, 4b, 7a and 17a) were obtained via methylation, demethylation and isopentenylation of the corresponding isolates (1, 2, 4, 7 and 17). These stilbenoids were structurally characterized by comprehensive analysis of their spectroscopic data and comparison with literature information, and evaluated for their cytotoxic activities against three human tumor cell lines (leukemia HL-60, hepatoma SMMC-7721 and breast carcinoma MCF-7) in vitro by MTT assay. The results showed that compounds 1a, 4a and 4b showed potent selective cytotoxicity against SMMC-7721 (IC50=10.16±1.95µM and 9.76±1.32µM) and MCF-7 (IC50=10.72±2.78µM) cell lines. The cytotoxic evaluation of these structurally modified stilbenoid derivatives have led to the establishment of a structure-activity relationship.

Structural Modification of Stilbenoids from Acanthopanax leucorrhizus and Their Cytotoxic Activity.

A new cis-stilbenoid, 1,9-dihydroxy-10-methoxy-6H-dibenzo[b,f]oxocin-6-one (2) was isolated from the AcOEt extract of the stem barks of Acanthopanax leucorrhizus, along with three known stilbenoids, 9-hydroxy-10-methoxy-6H-dibenzo[b,f]oxocin-6-one (1), 5-O-methyl-(E)-resveratrol 3-O-ß-d-glucopyranoside (3), and (E)-resveratrol 3-O-ß-d-xylopyranoside (4). Two derivatives (2a and 2b) were synthesized by the structural modification of compound 2, which exhibited certain cytotoxic activities against HT-29 and HeLa cell lines in vitro. All compounds were structurally characterized by comprehensive analysis of their spectroscopic data and comparison with literature information, and evaluated for their cytotoxic activities against three human tumor cell lines (HL-60, HT-29, and HeLa) by the standard MTT assay in vitro. The results showed that derivatives 2a and 2b exhibited strong activities than compounds 2 against HT-29 and HeLa cell lines.