Hypohalous acid-mediated halogenation of resveratrol and its role in antioxidant and antimicrobial activities

The reactions of resveratrol with proinflammatory oxidants including hypochlorous and hypobromous acids in phosphate-buffered saline/methanol solution were carried out and eight halogenated resveratrol derivatives differing in the number and position of halogen atoms, and the configuration of double bond were obtained. Halogenation of resveratrol took place only at the aromatic A ring, and interestingly, the halogenation increased antioxidant activity of this parent molecule in the 2,2'-azobis(2-amidinopropane) hydrochloride-induced RBC haemolysis model. Additionally, antimicrobial activity of the derivatives against Gram-positive bacteria, Gram-negative bacteria and fungi were tested, and toward Candida albicans, 2-chloro-resveratrol and 2-bromo-resveratrol were more active than the unmodified form and the reference compound fluconazole.

Finding more active antioxidants and cancer chemoprevention agents by elongating the conjugated links of resveratrol

Resveratrol is the subject of intense research as a natural antioxidant and cancer chemopreventive agent. There has been a great deal of interest and excitement in understanding its action mechanism and developing analogs with antioxidant and cancer chemoprevention activities superior to that of the parent compound in the past decade. This work delineates that elongation of the conjugated links is an important strategy to improve the antioxidant activity of resveratrol analogs, including hydrogen atom- or electron-donating ability in homogeneous solutions and antihemolysis activity in heterogeneous media. More importantly, C3, a triene bearing 4,4'-dihydroxy groups, surfaced as an important lead compound displaying remarkably increased antioxidant, cytotoxic, and apoptosis-inducing activities compared with resveratrol.

Flocculation properties of a bioflocculant produced by Bacillus licheniformis

Studies of the flocculation properties of bioflocculant combined with its structure characterization are helpful to develop more effective bioflocculant. This paper reports findings of our research on the flocculation properties of the bioflocculant ZS-7 in the kaolin suspension based on its structure characterization. With the addition of 2 mg/L ZS-7 and 9 mM CaCl(2), the optimum temperature for flocculation performance of ZS-7 in the kaolin suspension is about 30°C, giving the highest flocculating activity 99.2%. Studies of the flocculation properties revealed that it was stable at 60-100°C and pH 4-10. Moreover, it could flocculate a kaolin suspension over a wide range of pH (2-12) and temperatures (4-95°C) in the presence of CaCl(2).

Triterpenoid glycosides from Adina rubella

From the roots of Adina rubella, four new quinovic acid glycosides, quinovic acid 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-fucopyranoside, quinovic acid 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-fucopyranosyl-(28-->1)-beta-D- glucopyranosyl ester, quinovic acid 3-O-beta-D-glucopyranosyl(1-->4)-alpha-L-rhamnopyranosyl-(28-->1) -beta-D-glucopyranosyl ester and quinovic acid 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl-(28-->1)- beta-D-glucopyranosyl ester, were isolated. Their structures were elucidated on the basis of hydrolytic and spectral methods.