Tianxing Liu

Isolation, identification and antioxidant activity of bound phenolic compounds present in rice bran

The bound phenolic compounds in rice bran were released and extracted with ethyl acetate based on alkaline digestion. An investigation of the chemical constituents of EtOAc extract has led to the isolation of a new compound, para-hydroxy methyl benzoate glucoside (8), together with nine known compounds, cycloeucalenol cis-ferulate (1), cycloeucalenol trans-ferulate (2), trans-ferulic acid (3), trans-ferulic acid methyl ester (4), cis-ferulic acid (5), cis-ferulic acid methyl ester (6), methyl caffeate (7), vanillic aldehyde (9) and para-hydroxy benzaldehyde (10). The structures of these compounds were determined using a combination of spectroscopic methods and chemical analysis. Among the compounds isolated, compound 3, 5 and 7 exhibited strong DPPH and ABTS(+) radical scavenging activities, followed by compounds 4 and 6. Compound 1 and 2 showed potent DPPH and ABTS(+) radical scavenging activities, compound 8 displayed moderate antioxidant activity against ABTS(+) radical, whereas compound 9 and 10 showed weak antioxidant activity.

Pentadecyl ferulate, a potent antioxidant and antiproliferative agent from the halophyte Salicornia herbacea.

An investigation of the chemical constituents of Salicornia herbacea has led to the isolation of one new natural product, pentadecyl ferulate (6), together with 11 known compounds, including phytol (1), stearolic acid (2), γ-linolenic acid (3), (3Z,6Z,9Z)-tricosa-3,6,9-triene (4), linoleic acid (5), stigmasterol (7), ergosterol (8), dioctyl phthalate (9), dibutyl phthalate (10), vanillic aldehyde (11), and scopoletin (12). The chemical structures of these materials were elucidated mainly by spectroscopic analysis. This work represents the first recorded example of the isolation of compounds 1, 2, 3, 4, 9, 10, and 11 from S. herbacea. The antioxidant experiments revealed that compound 6 possessed strong hydroxy radical and superoxide anion scavenging activities and was the principle antioxidant ingredient in the ethyl acetate extract. The antiproliferative results exhibited that compound 1 selectively inhibited HepG2 cells, whereas compounds 3 and 6 showed potent antiproliferative activities against HepG2 and A549 cells.

Two new noroleanane-type triterpene saponins from the methanol extract of Salicornia herbacea

Two new noroleanane-type triterpene saponins, Salbige A (1) and Salbige B (2), have been isolated from the aerial parts of Salicornia herbacea together with five other known compounds, including echinocystic acid (3), gypsogenin (4), pheophorbide a (5), (13(2)S)-hydroxy-pheophorbide a (6) and (13(2)S)-hydro-pheophorbide-lactone a (7). The chemical structures of these compounds were elucidated by extensive spectroscopic analysis and on the basis of their chemical reactivity. This work represents the first recorded example of the isolation of these compounds from S. herbacea. Compounds 1 and 2 exhibited potent antiproliferative activities and high levels of selectivity towards A549 cancer cells, with IC50 values of 52.35 and 79.39 μM, respectively, whereas compound 5 showed high levels of inhibitory activity against A549 and HepG2 cancer cells with IC50 values of 6.15 and 17.56 μM, respectively. None of these compounds exhibited antioxidant activities except for compound 7, which showed weak antioxidant activity.

Isolation and identification of bound compounds from corn bran and their antioxidant and angiotensin I-converting enzyme inhibitory activities

A large amount of bound compounds, especially phenolics, present in corn bran has been underestimated because of difficulties in extracting them directly by organic solvents under mild conditions. Based on alkaline digestion, the bound compounds in corn bran were released and extracted with ethyl acetate. An investigation of the chemical constituents of the ethyl acetate (EtOAc) extract led to the isolation of ten compounds: trans-ferulic acid (1), trans-ferulic acid methyl ester (2), cis-ferulic acid (3), cis-ferulic acid methyl ester (4), vanillin (5), para-hydroxybenzaldehyde (6), 2-(1-oxo-2-hydroxyethyl) furan (7), graminones B (8), β-sitosterol glucoside (9), and sucrose (10). The chemical structures of these compounds were elucidated mainly by nuclear magnetic resonance and electrospray ionization mass spectrometry analysis. Graminones B was identified for the first time and showed potent angiotensin I-converting enzyme inhibitory activity, and compounds 1, 2, 3, and 4 displayed strong DPPH and ABTS+ radical-scavenging activity. This work represents the first recorded example of the isolation of compounds 3, 4, 8, and 9 from corn bran in the bound form.