Individual Phenolic Acids Research Articles

Phenolic composition and antioxidant capacity of different heat‐processed forms of sweetpotato cv. ‘Beauregard’

SummarySweetpotato [Ipomoea batatas (L.) Lam.] cv. ‘Beauregard’ roots were cooked using three different heat‐processing techniques (baked in a conventional oven, baked in a microwave oven, and boiled). Total phenolic content, individual phenolic acids, and antioxidant capacity were determined using Folin‐Denis assay, HPLC (high‐performance liquid chromatography), and DPPH (1,1‐diphenyl‐2‐picrylhydazyl) assay, respectively. The skin tissue (raw or processed) contained the highest concentration of total phenolics. All heat‐processing methods resulted in a significant loss in total phenolic content and antioxidant capacity of the skin tissue. However, compared with the other processing methods, conventional oven baking resulted in greater losses in antioxidant capacity of skin tissue. Total phenolic content ranged from a low of 1.58 mg chlorogenic acid equivalent g−1 dry tissue weight in boiled pith tissue to a high of 17.7 mg chlorogenic acid equivalent g−1 dry tissue weight in raw skin tissue. The antioxidant capacity was highest in raw skin tissue (22.9 mg Trolox equivalent g−1 dry tissue weight). Chlorogenic acid was the principal phenolic acid found in all sweetpotato tissues. Caffeic acid and three isomers of dicaffeoylquinic acid (diCQA) were also identified and quantified.

Metabolic analysis of four phenolic acids in rat by liquid chromatography–tandem mass spectrometry

A liquid chromatography-diode array detection-electrospray ionization ion trap mass spectrometry (LC–DAD–ESI-MS n ) method was established for the analysis of danshensu, caffeic acid, ferulic acid and isoferulic acid in rat plasma, bile, urine and feces after oral administration or intravenous injection. Liquid–liquid extraction was employed for the preparation of biosamples, and the chromatographic separation was carried out using an Agilent Zorbax Extend C 18 reversed phase column and acetonitrile-0.1% formic acid as the mobile phase. Totally nineteen metabolites were detected and identified as prototype, methylated, hydroxylated, sulfated and glucuronized conjugates. The metabolism of the individual phenolic acids in biosamples was investigated, and the metabolic pathway was proposed. By comparing the metabolism of different compounds which shared similar structures, we were able to find that methylation was the main pathway of danshensu metabolism, and the double bond on the side chain was critical for the drug excretion via bile and the formation of glucuronized conjugates. The results proved that the established method was simple, sensitive and reliable, which could be used to detect and identify the structures of metabolites and to better understand their in vivo metabolism.

Effect of Style of Cut and Storage on Phenolic Composition and Antioxidant Activity of Fresh-cut Sweetpotatoes

Three different style fresh-cut (shredded, French fry, and sliced) sweetpotatoes [Ipomoea batatas (L.) Lam.] were stored at 0 and 5 °C for 4 and 8 days. At specified storage intervals, the fresh-cut sweetpotatoes were analyzed for total phenolics, individual phenolic acids, and antioxidant activity. Sweetpotato tissue analyzed immediately after cutting was considered the control. Storage at 5 °C resulted in an increase in total phenolics in all types of fresh-cut sweetpotatoes, except in shredded tissue analyzed after 4 days of storage. However, at 0 °C, only sliced tissue accumulated higher total phenolics than the control. In general, antioxidant activity in all fresh-cut sweetpotatoes held at 5 °C was higher than in the control. No significant increase in antioxidant activity was observed in shredded sweetpotatoes stored at 0 °C. Chlorogenic acid followed by 3,5-dicaffeoylquinic acid were the predominant phenolic acids present in fresh-cut sweetpotatoes. The highest content of chlorogenic acid (539.9 μg·g−1 dry weight) in sliced tissue stored for 8 days at 5 °C was ≈6-fold higher than in the control (88.3 μg·g−1 dry weight). No significant development of tissue browning, off-odors, or off-flavors were observed after 8 days of storage and the products were considered to be marketable.

Antioxidant Activity and Phenolic Composition of Wild, Edible, and Medicinal Fennel from Different Mediterranean Countries

Fennel (Foeniculum vulgare Mill.) is a typical aromatic plant of the Mediterranean area, long used as a medicinal and spice herb. Fennel is also well-known for its essential oil, which has been extensively studied for many years owing to its commercial importance. In this work, the antioxidant activity and the total phenolic and flavonoid contents, as well as the quantitative determination of individual flavonoids and phenolic acids of wild, edible, and medicinal fennel from different Mediterranean countries, have been determined. The antioxidant activity was measured as the free radical (DPPH), hydroxyl radical, and superoxide anion scavenging activities. Wild fennel was found to exhibit a radical scavenging activity, as well as a total phenolic and total flavonoid content, higher than those of both medicinal and edible fennels.

수삼의 증숙 횟수에 따른 페놀산 함량 변화와 라디칼 소거활성

본 연구는 증숙 횟수에 따른 인삼의 총페놀 화합물 함량과 페놀산 획분의 DPPH, ABTS 라디칼 소거활성을 시험하고, 개별 페놀산 조성과 함량을 GC로 분석하였다. 총페놀 함량은 0.53-2.89%로 증숙 횟수에 비례하여 증가하였다. 결합 형태에 따른 페놀산 획분의 함량은 결합형 >에스테르형>유리형 순으로 나타났으며, 이들 세 획분의 총량 (1.03-1.41%)은 증숙횟수에 영향을 받지 않았다. 각 획분에서 salicylic, cinnamic, p-hydroxybenzoic, gentisic, vanillic, syingic, caffeic, ferolic acid가 확인되었으며, 이 중 gentisic acid와 ferulic acid 가 주된 페놀산으로 50% 이상을 차지하였다. 각 페놀산 획분은 50% 이상의 DPPH와 ABTS 라디칼 소거활성을 보였으며, 결합형태에 따른 페놀산 획분 간에는 큰 차이가 없었다. 반면 각 획분별로 증숙 횟수에 따라 라디칼 소거활성이 차이를 보였으며, 증숙 횟수가 증가할수록 라디칼 소거활성도 증가하는 경향을 보였다. This study was conducted to investigate the contents of the total phenolic compounds, and DPPH, ABTS radical scavenging activities of phenolic acid fractions of ginseng according to steaming times. Also the individual phenolic acid compositions and contents were analyzed by GC. The contents of the total phenolic compounds proportionally increased from 0.530 to 2.893% according to steaming times. Phenolic acid fractions were separated according to bound types, and the insoluble bound form fraction showed the highest contents followed by ester form fraction and free form fraction. The total contents of these three fractions (1.031-1.416%) were not significantly influenced by steaming times. Salicylic, cinamic, p-hydroxybenzoic, gentisic, vanillic, syringic, caffeic, ferolic acid were found in each fraction, and gentisic and ferolic acid were the major phenolic acid. Each phenolic acid fraction showed over 50% of DPPH and ABTS radical scavenging activities. There were no differences between the phenolic acid fractions according to binding types. Free radical scavenging activities were affected by a number of steaming times and augmented as steaming times increased.

Total and individual carotenoids and phenolic acids content in fresh, refrigerated and processed spinach (Spinacia oleracea L.)

The carotenoid and phenolic acid contents in fresh, stored and processed (blanched, frozen and boiled) spinach were comparatively determined by spectrophotometric and HPLC analyses. The major carotenoids identified after HPLC analysis in saponified samples were lutein (37–53μg/kg), β-carotene (18–31μg/kg), violaxanthin (9–23μg/kg) and neoxanthin (10–22μg/kg). These carotenoids were all affected by storage and/or heating. The content of carotenoids was best preserved after storage for one day at 4°C.The total phenolic content in the fresh spinach was 2088mg GAE/kg FW. After LC–MS analysis three phenolic acids were identified and quantified. These being ortho-coumaric acid (28–60mg/kg FW), ferulic acid (10–35mg/kg) and para-coumaric acid (1–30mg/kg) depending on the sample type. After storage of spinach at different temperatures (4°C or −18°C) the amount of total phenolic compounds decreased by around 20%, while the amount of individual phenolic acids increased by four times on average.

Methodology Optimization for Quantification of Total Phenolics and Individual Phenolic Acids in Sweetpotato (Ipomoea batatas L.) Roots

Phenolic acids are one of the several classes of naturally occurring antioxidant compounds found in sweetpotatoes. Simplified, robust, and rapid methodologies were optimized to quantify total and individual phenolic acids in sweetpotato roots. Total phenolic acid content was quantified spectrophotometrically using both Folin-Denis and Folin-Ciocalteu reagents. The Folin-Ciocalteu reagent gave an overestimation of total phenolic acids due to the absorbance of interfering compounds (that is, reducing sugars and ascorbic acid). Individual phenolic acids were quantified by high-performance liquid chromatography (HPLC) using the latest in column technology. Four reversed-phase C18 analytical columns with different properties (dimensions, particle size, particle shape, pore size, and carbon load) were compared. Three different mobile phases using isocratic conditions were also evaluated. A column (4.6 x 150 mm) packed with 5-microm spherical silica particles of pore size 110 A combined with 14% carbon load provided the best and fast separation of individual phenolic acids (that is, chlorogenic acid, caffeic acid, and 3 isomers of dicaffeoylquinic acid) with a total analysis time of less than 7 min. Among the 3 mobile phases tested, a mobile phase consisting of 1% (v/v) formic acid aqueous solution: acetonitrile: 2-propanol, pH 2.5 (70:22:8, v/v/v) gave adequate separation. Among the solvents tested, aqueous mixtures (80:20, solvent:water) of methanol and ethanol provided higher phenolic acid extraction efficiency than the aqueous mixture of acetone.

Effect of low temperature storage on phenolic composition and antioxidant activity of sweetpotatoes

Low temperature stress-induced phenolic compounds may increase the antioxidant activity and hence the nutraceutical value of sweetpotatoes [ Ipomoea batatas (L.) Lam]. Cured and non-cured roots of ‘Beauregard’ sweetpotatoes were exposed to low temperature storage (5 °C) for up to 4 weeks. A significant increase in total phenolic content in cured and non-cured roots was observed after 2 weeks of low temperature exposure. However, an increase in the antioxidant activity after 3 weeks of storage at 5 °C was noticed only in non-cured roots. After 4 weeks of storage at 5 °C, non-cured roots accumulated higher total phenolics and antioxidant activity than cured roots. Among tissue locations, the highest phenolic content and antioxidant activity were found in the periderm tissue and the lowest in the pith tissue. A 3-day exposure period to ambient temperature (∼22 °C) following low temperature storage resulted in a significant increase in antioxidant activity in periderm tissue. The highest total phenolic content (7.55 g kg −1) and antioxidant activity (8.05 g kg −1), on a fresh weight basis, were found in periderm tissue from roots transferred to ambient temperature after 4 weeks of low temperature storage. The most abundant individual phenolic acid in sweetpotato roots was chlorogenic acid followed by 3,5-dicaffeoylquinic acid. Chilling injury symptoms such as pitting and internal discoloration were apparent after 3 weeks of storage and were noticeably more severe in non-cured roots than cured root tissue.

Extraction, Quantification, and Characterization of Phenolics Extracted with the Aid of Sonication from Rice Bran

ABSTRACTPhenolics are phytochemicals extensively distributed among plants that have been receiving great deal of attention for their functionality. Rice bran is a good source of phenolics, especially hydroxycinnamates. Although chemicals are commonly employed to isolate phenolics, the use of physical treatments such as sonication is still limited. This study was conducted to optimize a procedure to isolate phenolics from rice bran using sonication as a preextraction treatment. Sonication was optimized by varying output, time, and temperature. Extraction was optimized by varying solvent, extraction time, temperature, and sample‐to‐solvent ratio. After an optimum procedure was established, HPLC analyses were conducted to identify and quantify the major individual phenolic acids extracted. The optimum conditions for extracting phenolics from rice bran were sonication with water (1:100 sample‐to‐solvent ratio) for 1 min; output intensity of 10; holding at ambient temperature; and autoclave treatment for 20 min at 121°C. This procedure extracted 8.85 ± 0.18 mg of phenolics/g of dried rice bran. Benzoic, p‐coumaric, and trans‐ferulic acids were the major phenolics identified in the extract. The proposed procedure will be valuable in obtaining phenolics for increasing product functionality such as lipid oxidation inhibitors in food systems.

Phenolic Acid Content and Composition in Leaves and Roots of Common Commercial Sweetpotato (Ipomea batatas L.) Cultivars in the United States

Phenolic acids in commercially important sweet potato cultivars grown in the United States were analyzed using reversed-phase high-performance liquid chromatography (HPLC). Caffeic acid, chlorogenic acid, 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 3,4-di-O-caffeoylquinic acid were well separated with an isocratic elution in less than 25 min compared to about 120 min for analyzing and re-equilibrating the column with a gradient method. The isocratic elution order of these caffeoylquinic acid derivatives was confirmed by LC-MS/MS. Chlorogenic acid was the highest in root tissues, while 3,5-di-O-caffeoylquinic acid and/or 4,5-di-O-caffeoylquinic acid were predominant in the leaves. Steam cooking resulted in statistically nonsignificant increases in the concentration of total phenolics and all the individual phenolic acids identified. Sweetpotato leaves had the highest phenolic acid content followed by the peel, whole root, and flesh tissues. However, there was no significant difference in the total phenolic content and antioxidant activity between purees made from the whole and peeled sweet potatoes.

Influence of cranberry phenolics on glucan synthesis by glucosyltransferases and Streptococcus mutans acidogenicity

To investigate the influence of several phenolic compounds isolated from cranberry fruit (Vaccinium macrocarpon) on some of the virulence properties of Streptococcus mutans associated with glucan synthesis and acidogenicity. Individual phenolic acids, flavonols and proanthocyanidins were isolated by semi-preparative high-performance liquid chromatography from fresh cranberry fruit. Flavonols and proanthocyanidins (at 500 micromol l(-1)) moderately inhibited the activity of surface-adsorbed glucosyltransferases (GTFs) B and C and F-ATPases (15-35% inhibition; P < 0.05), and also disrupted acid production by S. mutans cells without affecting bacterial viability. Phenolic acids displayed minimal biological effects. Quercetin-3-arabinofuranoside, myricetin and procyanidin A2 displayed the most inhibition of S. mutans virulence traits; a combination of these compounds displayed enhanced effects. Specific flavonoids from cranberries exhibit statistically significant but moderate biological activity against S. mutans. The biological activity of cranberry extracts may be a result from the complex mixture of flavonoids rather than a single active compound. This is the first study to identify the bioactive constituents in cranberry against an oral bacterium using highly purified isolated compounds. The combined effects of specific flavonols and proanthocyanidins from cranberry on GTFs activity, acid production and acid tolerance of S. mutans make them attractive compounds to fully explore for their anti-biofilm and cariostatic properties.

Phenolic compounds of Sorghum vulgare in response to Sclerotium rolfsii infection

Identification of individual phenolic acids of Sorghum vulgare Pers. cv. M.P. after interaction with Sclerotium rolfsii Sacc. using high performance liquid chromatograph (HPLC) showed the presence of phenolics namely tannic, gallic, ferulic, chlorogenic and cinnamic acids in varying amounts. After 72 h inoculation with S. rolfsii, a maximum amount of ferulic acid (166.6 µg g−1 fresh wt) was present in the collar of inoculated plants, followed by leaves and roots and its level decreased gradually with time. Similarly, the presence of chlorogenic acid was traced after 48 h, while that of cinnamic acid was traced after 72 h of inoculation. Reddish-brown pigmentation at the collar region of inoculated plants was also observed along with the high content of tannic acid. Among other phenolics, the presence of gallic acid was recorded consistently and maximum accumulation (139.3 µg g−1 fresh wt) was noticed at the zone of interaction (collar region) after 72 h of inoculation. In contrast, maximum lignin deposition was observed at collar region after 96 h of inoculation. Induction of phenolic acids in S. vulgare along with the lignin deposition and red pigmentation at collar region is considered a key biomarker in the non-host-pathogen interaction in the S. valgare–S. rolfsii pathosystem.

Phenolic Compounds of Barley Grain and Their Implication in Food Product Discoloration

Barley grains contain significant amounts of phenolic compounds that may play a major role in the discoloration of food products. Phenolic acid and proanthocyanidin (PA) composition of 11 barley genotypes were determined, using high-performance liquid chromatography and liquid chromatography-mass spectrometry, and their significance on food discoloration was evaluated. Abraded grains contained 146-410 microg/g of phenolic acids (caffeic, p-coumaric, and ferulic) in hulled barley and 182-282 microg/g in hulless barley. Hulled PA-containing and PA-free genotypes had comparable phenolic acid contents. Catechin and six major barley PAs, including dimeric prodelphinidin B3 and procyandin B3, and four trimers were quantified. PAs were quantified as catechin equivalents (CE). The catechin content was higher in hulless (48-71 microg/g) than in hulled (32-37 microg/g) genotypes. The total PA content of abraded barley grains ranged from 169 to 395microg CE/g in PA-containing hulled and hulless genotypes. Major PAs were prodelphinidin B3 (39-109 microg CE/g) and procyanidin B3 (40-99 microg CE/g). The contents of trimeric PAs including procyanidin C2 ranged from 53 to 151 g CE/g. Discoloration of barley flour dough correlated with the catechin content of abraded grains (r = -0.932, P < 0.001), but not with the content of individual phenolic acids and PAs. Discoloration of barley flour dough was, however, intensified when total PA extracts and catechin or dimeric PA fractions were added into PA-free barley flour. The brightness of dough also decreased when the total PA extract or trimeric PA fraction was added into heat-treated PA-free barley flour. Despite its low concentration, catechin appears to exert the largest influence on the discoloration of barley flour dough among phenolic compounds.

Content of total phenolics and phenolic acids in tomato ( Lycopersicon esculentum Mill.) fruits as influenced by cultivar and solar UV radiation

Two cultivars of fresh market tomato [Oregon Spring (OS) and Red Sun (RS)] were each grown in two high tunnels at Beltsville, MD covered with a contrasting material of similar thickness (0.152 mm) and durability (4-year polyethylene). One covering material (Tyco Tufflite IV) transmitted ambient solar UV radiation from 290 to 400 nm (designated+UV) while the other material (Dura-Film Super 4) blocked UV wavelengths below 380 nm (designated−UV). Both films transmitted comparable amounts of photosynthetically active radiation (PAR) from 400 to 700 nm. Ripe tomato fruits comparable in size and development were collected at maturity from plants of the two cultivars grown in each high tunnel under the contrasting covering materials. Four lots of tomatoes of each cultivar and each UV treatment were assayed for total phenolic (TP) content by a colorimetric Folin-Ciocalteu (FC) assay and for content of individual phenolic acids by a high performance liquid chromatography (HPLC)-diode array detection (DAD) procedure. The phenolic acids extracted from the base hydrolyzed fraction were identified as caffeic acid, p-coumaric acid, and ferulic acid. Caffeic acid was the predominant phenolic acid in both tomato cultivars (OS and RS) grown in the two high tunnels. The total concentration of these three phenolic acids measured by HPLC was approximately 20% higher under +UV than under −UV treatment; this was true for both cultivars. A similar trend in quantities of TP yield was also observed when tomato extracts were assayed by a FC method. These results indicate that the phenolic content of tomato fruits is significantly affected by the spectral quality of solar UV radiation. Since phenolic compounds are known to play a key role as antioxidants in human nutrition, subtle differences in phenolic composition between the two high tunnels as a result of differences in the UV transmission properties of these different covering materials may be of considerable importance.

(184) Phenolic Composition and Antioxidant Activity of Sweetpotato Cultivars Marketed in the European Union

Phenolic compounds and antioxidant activity were quantified in the principal sweetpotato cultivars marketed in the European Union. Total phenolic content, individual phenolic acids, and antioxidant activity in each cultivar were determined using Folin-Denis reagent, reversed-phase HPLC, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, respectively. Significant differences in phenolic composition and antioxidant activity were found between cultivars. A Jamaican-grown, white-fleshed cultivar had the highest total phenolic content [4.11 mg·g-1 chlorogenic acid (dry tissue weight)], while the highest antioxidant activity [3.60 mg·g-1 Trolox (dry tissue weight)] was observed in the orange-fleshed California-grown cultivar Diane. Chlorogenic acid and 3,5-dicaffeoylquinic acid were the predominant phenolic acids, while caffeic acid was the least abundant in most cultivars. The highest content of chlorogenic acid (0.42 mg·g-1 dry tissue weight); 3,5-dicaffeoylquinic acid (0.43 mg·g-1 dry tissue weight); and 3,4-dicaffeoylquinic acid (0.25 mg·g-1 dry tissue weight) was present in the white-fleshed Jamaican cultivar. The orange-fleshed cultivars Diane and Beauregard had the highest content of caffeic acid (0.13 mg·g-1 dry tissue weight) and 4,5-dicaffeoylquinic acid (0.32 mg·g-1 dry tissue weight), respectively.

Phenolic Composition and Antioxidant Activity of Minimally Processed Sweetpotatoes

Three different style cuts of minimally processed sweetpotatoes (shredded, French-fry, and sliced) were stored at 0 °C and 5 °C for 4 and 8 days. Total phenolic content, individual phenolic acids, and free radical scavenging activity were determined using Folin-Denis reagent, reversed-phase HPLC, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, respectively. Total phenolic content in sliced cut sweetpotatoes held at 5 °C was higher than in the shredded cut. Both sliced and French-fry cut sweetpotatoes held at 5 °C had significantly higher antioxidant activity than shredded cut sweetpotatoes. All treatments, except shredded sweetpotatoes held at 0 °C, had significantly higher total phenolic content and antioxidant activity after 4 and 8 days of storage. Minimally processed sweetpotatoes held at 5 °C accumulated more phenolic compounds and had a higher antioxidant activity than sweetpotatoes held at 0 °C. Chlorogenic acid followed by 3,5-dicaffeoylquinic acid were the predominant phenolic acids present in sweetpotatoes. The rate of increase in individual phenolic acid content with storage time was higher at 5 °C than at 0 °C. No tissue browning was observed in any of the cuts after 8 days of storage and the products were considered to be marketable.

ANTIOXIDANT ACTIVITY AND PHENOLIC COMPOSITION CHANGES IN SWEETPOTATO ROOT AND LEAF TISSUE DURING DEVELOPMENT

Antioxidant activity and phenolic content of sweetpotato root and leaf tissues were quantified at different developmental stages. 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical method was used to measure antioxidant activity and total phenolic content was quantified by spectrophotometry using Folin-Denis reagent. Individual phenolic acids were quantified using reversed phase high performance liquid chromatography. Antioxidant activity and phenolic content decreased with root development and leaf maturity. Roots at the initial stages of development (about 4.0 g root weight) had a higher antioxidant activity and phenolic content compared to fully developed roots. Phenolic content in fully developed roots was significantly higher in the cortex tissue than internal pith tissue. The highest total phenolic content and antioxidant activity was found in cortex tissue at the initial stage of development (10.3 mg chlorogenic acid eq/g dry tissue weight and 9.7 mg Trolox eq/gdry tissue weight, respectively). Sweetpotato leaves had a significantly higher phenolic content and antioxidant activity than roots. Immature unfolded leaves had the highest total phenolic content (88.5 mg chlorogenic acid eq/g dry tissue weight) and antioxidant activity (99.6 mg Trolox eq/g dry tissue weight). Chlorogenic acid was the major phenolic acid in root and leaf tissues with the exception of young immature leaves in which the predominant phenolic acid was 3,5-dicaffeoylquinic acid.

ANTIOXIDANT ACTIVITY AND PHENOLIC COMPOSITION CHANGES IN SWEETPOTATO ROOT AND LEAF TISSUE DURING DEVELOPMENT

Antioxidant activity and phenolic content in sweetpotato root and leaf tissues were quantified at different developmental stages. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical method was used to measure antioxidant activity and total phenolic content was quantified by spectrophotometry using Folin-Denis reagent. Individual phenolic acids were quantified using reversed phase high performance liquid chromatography. Antioxidant activity and phenolic content decreased with root development and leaf maturity. Roots at the initial stages of development (about 4 g root weight) had a higher antioxidant activity and phenolic content compared to fully developed roots. Phenolic content in fully developed roots was significantly higher in the cortex tissue than internal pith tissue. The highest total phenolic content and antioxidant activity was found in cortex tissue at the initial stage of development (10.3 mg chlorogenic acid eq/g dry tissue weight and 9.7 mg Trolox eq/gdry tissue weight, respectively). Sweetpotato leaves had a significantly higher phenolic content and antioxidant activity than roots. Immature unfolded leaves had the highest total phenolic content (88.5 mg chlorogenic acid eq/g dry tissue weight) and antioxidant activity (99.6 mg Trolox eq/g dry tissue weight). Chlorogenic acid was the major phenolic acid in root and leaf tissues with the exception of young immature leaves in which the predominant phenolic acid was 3,5-dicaffeoylquinic acid.

백삼의 페놀산 조성과 항산화 활성

Phenolic acids of white ginseng were extracted and fractionated into free, esterified, and insoluble-bound forms. The contents of individual phenolic acids in different forms were quantified by gas liquid chromatography. Nine different phenolic acids as free, esterified, and insoluble-bound forms were identified in white ginseng. Total phenolic compounds in different forms of extracts was 0.309% (free form), 0.230% (esterified form) and 0.138% (insoluble-bound form), respectively. Total phenolic acid contents in free, esterified and insoluble-bound form were 889.3, 356.8, 1,176.9 ㎎/100 g fraction, respectively. Ferulic acid was the predominant phenolic acid, representing 63.7% and 50.9% of total phenolic acids in esterified form and insoluble-bound form, respectively. While caffeic acid was only detected in esterified form. At 10 ㎎/㎖ insoluble-bound form quenched 95.9% ABTS free radicals generated from 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH). Also, electron donating ability and lipid peroxidation inhibitory activity of insoluble-bound form were higher than other fraction. All phenolic acid fractions scavenged over 80% of hydroxyl radical at 10 ㎎/㎖.

HPLC determination of phenolic acids and antioxidant activity in concentrated peat extract—a natural immunomodulator

The aim of this study was to devise a method for identification and quantification of phenolic acids in concentrated peat extract samples. The simple reversed-phase HPLC method for simultaneous determination of several phenolic acids was developed. The method was validated and it was suitable for the analysis of phenolic acids in peat extracts. This method allowed identifying eight phenolic acids in peat extracts. Phenolic profiles of two samples of peat extract obtained from different medicinal peats were similar, although variations in amounts of individual phenolic acids were observed. Also, slight variations in total phenolic content were detected. The antioxidant activity of peat extracts was evaluated with spectrophotometric ABTS assay. Differences in antioxidant activity were observed for two samples of peat extract produced from different peat varieties. This differences probably reflected phenolic composition of peat extracts.