Plant phenolic acids extraction

EXTRACTION OF PLANTS PHENOLIC ACIDS WITH AMBERLITE IR-45 (OH) RESIN... 

A direct injection method was proposed for phenolic acid extracts from plant tissue or soil, based on CZE at pH higher than the pK of the acids. Tetradecyltrimethylammonium bromide was added to reverse the electroosmotic flow. LOD was 1-7 p.M for eight phenolic acids at pH 7.20. ... 

Recently, two-dimensional TLC (2-D TLC) on cellulose plates had been used for the separation of phenolic acids extracted from plants (i.e., leaves, roots, and fruits of Peucedanum vertkillare L. Koch ex DC leaves, inflorescences, and rhizomes of Silphiiim perfoliatumP by eluting with benzene-methanol-acetonitrile-acetic acid (80 10 5 5) in the first direction and sodium formate-formic acid-wate (10 1 200 w/v/v) in the second direction. Table 2 shows the hRf values obtained for phenolic acids from Peucedanum tauricum Bieb foliage by 2-D TLC on cellulose plates. 

Dalton BR, Blum U, Weed SB (1989a) Plant phenolic acids in soils sorption of femlic add by soil and soil components sterihzed by different techniques. Soil Biol Biochem 21 1011-1018 Dalton BR, Blum U, Weed SB (1989b) Differential sorption of exogenously applied feniUc, p-coumaric,p-hydroxybenzoic, and vanillic acids in soil. Soil Sci Soc Am J 53 757-762 Dalton BR, Weed SB, Blum U (1987) Plant phenolic acids in soils a comparison of extraction procedures. Soil Sci Soc Am J 51 1515-1521... 

Types of thin layers. The phenolic acids arising from clinical studies (88) have been examined by TLC on cellulose (88-90) and with cellulose on Silufol (91). TLC was considered superior to paper chromatography. The identification of phenolic acids in varieties of Ribes nigrum has been described (IS), and separation of phenolic acids fix>m plant material or silica gel G and quantitative analysis with spectrophotometry (92). Phenolic acids extracted from plants were best separated on silica gel G with chloroform-ethyl acetate-formic acid (5 4 1) (8). TLC on silica gel combined with scanning spectrophotometry was used to separate nine phenolic acids in wine with hexane-ethyl acetate-formic acid (15 9 2) (93) as the preferred of the 10 solvents examined. Twenty naturally occurring phenolic acids were separated by a combination of one- and two-dimensional TLC and development with three solvents (94) and phenolic acids (and some phenols) related to humic acid examined on alumina with water as solvent (94a). Silica gel F-254 (Silica-Rapid-Platten Woelm in... 

Simple phenols are scarce and, in general, they are found as heterosides in plants. Phenolic acids are grouped into benzoic acid derivatives and cinnamic acid derivatives. The most relevant extracted phenols used in cosmetics are arbutin, vanillin and salicylic alcohol or saligenin. 

Preparation of seedlings for treatments with extract-amended nutrient solution was similar to that described for testing the effects of phenolic acids, except 40 plants were used per treatment and no replacement of the nutrient solution was made during the treatment period. Data collection procedures were modified in that only ab-axial leaf resistance was obtained and water potential was determined from four plants each day. Prior work established that abaxial resistance provided an adequate indicator of stomatal effects. The data were analyzed as described in experiments with pCA and FA. 

Principle Instead of long-lasting extraction with different organic solvents, acids or bases in the Soxhlet apparatus is unsuitable for the extraction of most flavonoids, the Amberlite IR-45 (OH) ion-exchange resin was used for the extraction of plant phenolics. 

EXTRACTION AND DETECTION OF TOTAL PHENOLICS AND PHENOLIC ACIDS IN PLANTS... 

A number of spectrophotometric methods for the quantification of phenolic compounds in plant materials have been developed. Based on different principles, these assays are used to determine various structural groups present in phenolic compounds. Spectrophotometric methods may quantify all extractable phenolics as a group (Marshall and others 2008), or they may determine a specific phenolic substance such as sinapine (Ismail and Eskin 1979) or a given class of phenolics such as phenolic acids (Brune and others 1989). 

The unharvested parts of rice plants are generally mixed with the soil because this has been thought to be beneficial. It has been observed however, that productivity of the second crop of rice in a paddy is less than that of the first crop. Chou and Lin (45) found that aqueous extracts of decomposing rice residues in soil retarded radicle growth of rice seedlings and growth of rice plants. Maximum toxicity occurred in the first month of decomposition and declined thereafter. Some toxicity persisted for four months in the paddies. Five inhibitory phenolic acids were identified from decaying rice residues and several unidentified allelochemicals were isolated. 

Phenolic acids have already been discussed as inhibitory compounds. But inhibition of germination requires a concentration of 10 to 10 M phenolic acids. (j ). Such high concentration may locally be achieved if oat straw is accumulated in the fields (4). This could sometimes be a reason for poor plant growth on fields after harvest of oats without removal of straw. We did not find such concentrations in our husk extracts, however they were 100 - 1000 fold smaller than expected from bioactivity. Phenolic acids are therefore not the active compounds in our inhibitory extracts. 

L.) was also found, and was readily distinguishable by a brittleness of the culm which appeared only after maturity of the plant. This mutant had a lower cellulose content, and this difference was assumed to be related to the brittleness of the culm (24). Significant differences were also found in the extractability of the lignin fractions and associated phenolic acids (25-26), suggesting that lignin formation was also affected. 

Fiamegos, Y.C. et al.. Analytical procedure for the in-vial derivatization-extraction of phenolic acids and flavonoids in methanolic and aqueous plant extracts followed by gas chromatography with mass-selective detection, J. Chromatogr. A, 1041, 11, 2004. 

The vast literature associated with flavanoid chemistry precludes a discussion here but two valuable reviews have been published. The first reviews a number of spectroscopic techniques used for flavonoid analysis, with a strong emphasis on NMR spectroscopy (plus also mass spectrometry, vibrational spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, X-ray crystallography, and circular dichrosim (CD)) . The second review deals with NMR methods that have been successful in the characterization of phenolic acids and flavonoids from plant extracts that have not been separated or isolated as single components. The emphasis of the article is 2-D NMR methodology and a variety of experiments such as total correlated spectroscopy (TOCSY), COSY, nuclear Overhauser enhancement spectroscopy (NOESY) and heteronuclear multiple quantum correlation (HMQC) are discussed . 

Pomponio, R., Gotti, R., Hudaib, M., and Cavrini, V. 2002. Analysis of phenolic acids by micellar electrokinetic chromatography application of Echinacea purpurea plant extracts. J. Chromatogr. A 945, 239-247. 

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