Characterization of free oligosaccharides from garden cress seed aqueous exudate using PGC LC-MS/MS and NMR spectroscopy.

Garden cress seeds produces mucilage that has found various food applications, however, there is little information on the free oligosaccharides (FOS) contents in these seeds. Herein, we explored the presence of FOS in cress seed aqueous exudate. PGC-LC MS/MS analysis indicated the presence of mainly hexose containing oligosaccharides such as raffinose, stachyose and verbascose belonging to raffinose family of oligosaccharides (RFOs). In addition, minor fraction of planteose, isomeric tri- and tetrasaccharides were also observed. Further, the structural confirmation of the abundant tri- and tetrasaccharide were obtained through 1D and 2D NMR analysis. Thus, the RFOs presence in cress seeds would enhance its bio-functionalities.

Synthesis, antibacterial and antimutagenic activity of zerumbone-bicarbonyl analogues.

Synthesis of new zerumbone-bicarbonyl analogues by SeO2 oxidation is reported. Selective oxidation of methyl at C-13 to an aldehyde and a ketone with exo-cyclic double bond between C-13 and C-6 in zerumbone has been recognized. Both these compounds have an additional conjugated-carbonyl-functionality. They exhibited significantly higher antimutagenic activity than zerumbone against Salmonella tester strains. They are more active against Gram positive bacteria than Gram negative bacteria; however zerumbone showed highest activity against E. coli, whereas its derivatives were least effective against E. coli.

Synthesis and quorum sensing inhibitory activity of key phenolic compounds of ginger and their derivatives.

Phenolic components of ginger (Zingiber officinale Roscoe) viz. [6]-gingerol, [6]-shogaol and zingerone exhibited quorum sensing inhibitory activity (QSI) against Chromobacterium violaceum and Pseudomonas aeruginosa. The inhibitory activity of all the compounds was studied by zone inhibition, pyocyanin, and violacein assay. All the compounds displayed good inhibition at 500ppm. [6]-Azashogaol, a new derivative of [6]-shogaol has been synthesized by Beckmann rearrangement of its oxime in the presence of ZnCl2. The structure elucidation of this new derivative was carried out by 1D ((1)H NMR and (13)C NMR) and 2D-NMR (COSY, HSQC and NOESY) spectral studies. This compound showed good QSI activity against P. aeruginosa. An isoxazoline derivative of [6]-gingerol was prepared and it exhibited good QSI activity. Present study illustrated that, the phenolic compounds of ginger and their derivatives form a class of compounds with promising QSI activity.

Synthesis of amino acid conjugates of tetrahydrocurcumin and evaluation of their antibacterial and anti-mutagenic properties.

Tetrahydrocurcumin (THC), the hydrogenated and stable form of curcumin, exhibits physiological and pharmacological activities similar to curcumin. A protocol has been developed for the synthesis of novel conjugates of THC with alanine (2a), isoleucine (2b), proline (2c), valine (2d), phenylalanine (2e), glycine (2f) and leucine (2g) in high yields (43-82%). All the derivatives of THC exhibited more potent anti-microbial activity than THC against Bacillus cereus, Staphylococcus aureus, Escherichia coli and Yersinia enterocolitica. The MIC values of the derivatives were 24-37% of those for THC in case of both gram-positive and gram-negative bacteria. Derivatives 2g and 2d exhibited maximum anti-mutagenicity against Salmonella typhimurium TA 98 and TA 1538, respectively at a low concentration of 313 µg/plate, with comparable activity for THC evident only at 3750 µg/plate. These results clearly demonstrated that the conjugation of THC at the phenolic position with amino acids led to significant improvement of its in vitro biological attributes.

Synthesis of quinoline derivatives of tetrahydrocurcumin and zingerone and evaluation of their antioxidant and antibacterial attributes.

Tetrahydrocurcumin (THC, 1) and zingerone (2) are biologically active molecules originating from the important spices turmeric and ginger, respectively. Novel quinoline derivatives of THC and zingerone have been synthesised by an efficient protocol involving their reaction with substituted 2-aminobenzophenones and 2-aminoacetophenone. Radical-scavenging activities (RSA) of THC, zingerone and their quinoline derivatives were evaluated. The amino-substituted quinoline derivative of THC, 1e, showed antioxidant activity superior to those of 1 and 1a. Derivatives 1b, 1c, 1d and 1f exhibited relatively lower RSA at equimolar concentrations (∼50-55 µmol). A similar trend was also seen in zingerone (2) and its derivatives (2a-2e), with 2e displaying the best RSA. Derivatives of THC (1a-1f) showed stronger antimicrobial activity than THC (1) against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Yersinia enterocolitica. Also, derivatives of zingerone (2b-2e) exhibited lower minimum inhibitory concentrations (MIC) values than zingerone (2) and its derivative, 2a for both Gram-positive and Gram-negative bacteria. The molecules may have potential pharmacological applications.

Simple HPLC method for resolution of curcuminoids with antioxidant potential.

Development of methodology for qualitative analysis and quantitative separation of individual curcuminoids in curcumin removed turmeric oleoresin (CRTO) and study of antioxidant activity of individual curcuminoids have been achieved in the present study. A simple HPLC protocol was outlined for optimal resolution of curcuminoids (I), (II), and (III) on an Exil-NH(2) column using isocratic elution with a mixture of isopropanol and water. CRTO is shown to be good source for the compounds II and III, as they are in an enriched form. The optimum resolution of the curcumin and its analogs in the present method developed, affords a facile method for estimation of individual curcuminoids in turmeric samples, which is an improvement over the standard AOAC method which estimates only total curcuminoids. The free radical scavenging capacity of pure curcuminoids I, II, and III, as determined by DPPH method at 100 ppm concentration was 88%, 80%, and 68% with IC(50) values being 56, 62, and 73 ppm, respectively. Their antioxidant potential could render them useful as important nutraceuticals or functional food ingredients.