Search

Propolis is known to possess antioxidant activity. However, there is no information on this activity in emulsions O/W. The protective effect of propolis on the oxidation and rheological properties of emulsions O/W containing wheat germ and almond oils was evaluated. Emulsions O/W were prepared with different concentration of propolis extract, almond oil and wheat germ oil. All emulsions physically stable without phase separation were stored at 37 °C for 9 weeks. Chemical composition of propolis was established by Gas chromatography coupled to mass spectrometry. Rheological characterization of different emulsions was performed evaluating consistency index and flow behavior index. The oxidation was monitored by measuring the lipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS) methods. Flavonoids, phenolic acid esters, and aromatic acids were the main groups of compounds found in propolis. The results showed that popolis was good antioxidant in the concentration of 0.02 and 0.04% when lipid phase was constituted by almond oil. The rheological behavior is typical of a non-Newtonian fluid, being almond oil more adequate for having a higher stable O/W emulsion. Keywords: Emulsion, Flavonoids, Phenolic acid esters, Almond oil, Wheat germ oil, Natural antioxidant

A new ferulic acid ester named 4-methyl-3-trans-hexenylferulate (1), together with eight known phenolic acid esters (2-9), was isolated from the methanolic extract of the roots and rhizomes of Notopterygium incisium. Their structures were elucidated by extensive spectroscopic techniques, including 2D NMR spectroscopy and mass spectrometry. 4-Methoxyphenethyl ferulate (8) NMR data is reported here for the first time. The uptake and transepithelial transport of the isolated compounds 1-9 were investigated in the human intestinal Caco-2 cell monolayer model. Compounds 2 and 6 were assigned for the well-absorbed compounds, compound 8 was assigned for the moderately absorbed compound, and compounds 1, 3, 4, 5, 7, and 9 were assigned for the poorly absorbed compounds. Moreover, all of the isolated compounds were assayed for the inhibitory effects against nitric oxide (NO) production in the lipopolysaccharide-activated RAW264.7 macrophages model and L-N⁶-(1-iminoethyl)-lysine (L-NIL) was used as a positive control. Compounds 1, 5, 8, and 9 exhibited potent inhibitory activity on NO production with the half maximal inhibitory concentration (IC50) values of 1.01, 4.63, 2.47, and 2.73 μM, respectively, which were more effective than L-NIL with IC50 values of 9.37 μM. These findings not only enriched the types of anti-inflammatory compounds in N. incisum but also provided some useful information for predicting their oral bioavailability and their suitability as drug leads or promising anti-inflammatory agents.

Immobilized lipase from Candida antarctica (Novozyme 435) was tested for the synthesis of various phenolic acid esters (ethyl and n-butyl cinnamate, ethyl p-coumarate and n-butyl p-methoxycinnamate). The second-order kinetic model was used to mathematically describe the reaction kinetics and to compare present processes quantitatively. It was found that the model agreed well with the experimental data. Further, the effect of alcohol type on the esterification of cinnamic acid was investigated. The immobilized lipase showed more ability to catalyze the synthesis of butyl cinnamate. Therefore, the process was optimized for the synthesis of butyl cinnamate as a function of solvent polarity (logP) and amount of biocatalyst. The highest ester yield of 60.7 % was obtained for the highest enzyme concentration tested (3 % w/w), but the productivity was for 34 % lower than the corresponding value obtained for the enzyme concentration of 1 % (w/w). The synthesized esters were purified, identified, and screened for antioxidant activities. Both DPPH assay and cyclic voltammetry measurement have shown that cinnamic acid esters have better antioxidant properties than cinnamic acid itself.

The esterification activity of the commercial immobilized lipase CALB towards cinnamic acids and its derivative has been studied. Using cinnamic acid as substrate, the reaction rate constants (1.95 h-1 mM-1 for ethanol and 3.07 h-1 mM-1 for butanol) were more than four and nine times higher compared to those obtained with p-coumaric (0.47 h-1 mM-1) and p-methoxycinnamic acids (0.32 h-1 mM-1), respectively. Thus, esterification of cinnamic acid with ethanol by using C. antarctica lipase has selected as a model reaction for further study. Isooctane is shown to be the best solvent for this reaction even though solubility of cinnamic acid in this a polar solvent is very low. Highest esterification yield of ethyl cinnamate is obtained when initial molar ratio of substrates 1:3 (cinnamic acid is limiting substrate) is used. Esterification of cinnamic acid appeared to result in increasing radical-scavenging ability. The effect of esterification of cinnamic acid was also confirmed by electrochemical method using ethyl cinnamate which appeared to enhance the antioxidant activity. These findings should stimulate the application of such lipase-catalyzed reactions for the preparation of food acceptable esters of cinnamic acid as potential lipophilic antioxidants.

Department of Chemistry, Department of Botany, University of Rajasthan, Jaipur-302 055, Rajasthan, India E-mail : profrjain@rediffmail.com Manuscript received 18 May 2010, accepted 27 August 2010 Chemical investigation of pet. ether and benzene solubles from the ethanolic extract of the stem barkof Callistemon lanceolatus DC. afforded two novel phenolic acid esters : dotriacontanyl ferulate and 32-hydroxy dotriacontanyl ferulate, triterpenoids : euph-7-en-3β-ol, 3-O-acetyl unolic acid, ursolic acid, uvaol-3-acetate, erythrodiol-3-acetate and asiatic acid along with ß-sitosterol and its glucoside. Tills is the first report of the isolation of phenolic acid esters from this genus.

A feruloyl esterase (StFaeC) produced by Sporotrichum thermophile was purified to homogeneity. The native StFaeC was homodimer with a subunit of M-r 23,000 and pI 3. 1. The enzyme activity was optimal at pH 6.0 and 55 degrees C. The esterase displayed remarkable stability at pH 10.0 and retained 50% of its activity after 133 and 55 min at 55 and 60 degrees C, respectively. Determination of k(cat)/K-m revealed that the enzyme had a broad spectrum of activity against the (hydroxyl) cinnamate esters indicating a type C feruloyl esterase. The enzyme was active on substrates containing ferulic acid ester linked to the C-5 and C-2 linkages of arabinofuranose and hydrolysed 4-nitrophenyl-5-O-trans-fer-uloyl-alpha-L-arabinofuranoside three times more efficiently than 4-nitrophenyl-2-O-trans-feruloyl-alpha-L-arabinofuranoside. Ferulic acid was efficiently released from wheat bran when the esterase was incubated together with xylanase from S. thermophile (a maximum of 41% total ferulic acid released after 1 h incubation). StFacC by itself could release FA but at a level almost 10-fold lower than that obtained in the presence of xylanase. The potential of StFaeC for the synthesis of various phenolic acid esters was examined using as a reaction system a ternary water-organic mixture consisting of n-hexane, 1-butanol and water. Also StFaeC catalyzed the transfer of the feruloyl group to L-arabinose in a similar system using t-butanol, with about a 40% conversion of L-arabinose to feruloylated derivative was achieved. This work is the first example of enzymatic feruloylation of a carbohydrate. (c) 2004 Elsevier Inc. All rights reserved. Enzyme and Microbial Technology

An extracellular feruloyl esterase (FoFAE-I) from the culture filtrates of Fusarium oxysporum F3 was purified to homogeneity by ion-exchange, hydrophobic interaction and gel filtration chromatographies. The protein corresponded to molecular mass and pI values of 31 kDa and 9.5, respectively. The enzyme was optimally active at pH 7.0 and 55 degreesC. The purified esterase was fully stable at pH 7.0-9.0 and temperature up to 30 degreesC. Determination of k(cat)/K-m revealed that the enzyme hydrolysed methyl p-coumarate (MpCA) 4.5, 9, and 239 times more efficiently than methyl caffeate (MCA), methyl ferulate (MFA) and methyl sinapinate (MSA), respectively. The enzyme was active on substrates containing ferulic acid ester linked to the C-5 and C-2 linkages of arabinofuranose but showed preference for the ester at position 2. 4-Nitrophenyl-2-O-trans-feruloyl-alpha-L-arabinofuranoside (NPh-5-Fe-Araf) was hydrolysed 100 times more efficiently than 4-nitrophenyl-5-O-trans-feruloyl-alpha-L-arabinofuranoside (NPh-2-Fe-Araf). Ferulic acid (FA) was efficiently released from destarched wheat bran (DSWB) when the esterase was incubated together with xylanase from Sporotrichum thermophile (a maximum of 92% total ferulic acid released after 4 h incubation). FoFAE-I by itself could release FA but at a level almost five-fold lower than that obtained in the presence of xylanase. The potential of FAE-I for the synthesis of various phenolic acid esters was tested using as a reaction system a surfactantless microemulsions formed in ternary mixture consisting of n-hexane, 1-butanol and water. (C) 2003 Elsevier Inc. All rights reserved. Enzyme and Microbial Technology

Aromatic constituents of cell walls limit the feeding value of forages, but information is lacking on the sites and types of these constituents that retard biodegradation. A series of cell types in stems and leaf blades of a normal (N) and a brown midrib (bmr) mutant line of pearl millet (Pennisetum glaucum (L) R Br) were analyzed by UV absorption microspectrophotometry from freeze-dried bulk walls and from 4 µm thick sections. Cell types were evaluated by scanning and transmission electron microscopy for rumen microbial degradation . Generally, N cell walls had a higher absorbance, hypsochromatically shifted λmax' and a higher absorbance ratio (280:320 nm) compared with bmr walls. Spectra suggested that ester-linked phenolic acids were present in lignified and non-lignified walls of both plant lines. Results are consistent with previous information that N cell types have substantially higher concentrations of esterlinked p-coumaric acid and more condensed aromatics than bmr walls. Pronounced variations occurred within regions of some cell types, including the middle lamella region vs. secondary layers of sclerenchyma cells and the outer vs. inner regions of epidermal cells. Biodegradable cell walls, such as stem parenchyma and epidermis and parenchyma bundle sheaths of leaf blades, showed less absorbance than heavily lignified walls. For some walls, UV spectra related well with variations in digestibility, while for other cell walls further work is needed to relate spectra to biodegradation.