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Ilex rotunda Thunb., has been used to treat common cold, tonsillitis, and eczema. It is also a source of antioxidants. However, information regarding its antioxidative phytochemical composition is still incomplete and limited. In this present study, we initially determined DPPH radical scavenging activity of the extracts of I. rotunda fruits, twigs, and leaves. Among them, the twig extract exhibited a potential of antioxidant capacity. Based on antioxidant effect guided experiments, extraction condition using 80% EtOH was then optimized. DPPH and ABTS radical scavenging assays were also performed for fractions. The n-butanol fraction showed the highest antioxidant effect. Using chromatographic methods, eight marker compounds (1–8) were further isolated. Their structures were determined by spectroscopic and mass data. Method validation was employed to quantitate contents of these eight marker compounds. Subsequently, the HPLC-DPPH method was used to evaluate the contribution of certain compounds to total antioxidant activity of the extract. Lastly, parallel artificial membrane permeability assay for blood–brain barrier (PAMPA-BBB) was applied to investigate brain-penetrable antioxidants from I. rotunda extract. As a result, compound 7 (4,5-dicaffeoylquinic acid) showed significant antioxidant activity and penetration across the BBB via transcellular passive diffusion. Our findings suggested that compound 7 can be used as a therapeutic potential candidate in natural product-based central nervous system (CNS) drug discovery. [ABSTRACT FROM AUTHOR]

Ilex rotunda Thunb., has been used to treat common cold, tonsillitis, and eczema. It is also a source of antioxidants. However, information regarding its antioxidative phytochemical composition is still incomplete and limited. In this present study, we initially determined DPPH radical scavenging activity of the extracts of I. rotunda fruits, twigs, and leaves. Among them, the twig extract exhibited a potential of antioxidant capacity. Based on antioxidant effect guided experiments, extraction condition using 80% EtOH was then optimized. DPPH and ABTS radical scavenging assays were also performed for fractions. The n-butanol fraction showed the highest antioxidant effect. Using chromatographic methods, eight marker compounds (1–8) were further isolated. Their structures were determined by spectroscopic and mass data. Method validation was employed to quantitate contents of these eight marker compounds. Subsequently, the HPLC-DPPH method was used to evaluate the contribution of certain compounds to total antioxidant activity of the extract. Lastly, parallel artificial membrane permeability assay for blood–brain barrier (PAMPA-BBB) was applied to investigate brain-penetrable antioxidants from I. rotunda extract. As a result, compound 7 (4,5-dicaffeoylquinic acid) showed significant antioxidant activity and penetration across the BBB via transcellular passive diffusion. Our findings suggested that compound 7 can be used as a therapeutic potential candidate in natural product-based central nervous system (CNS) drug discovery.

Abstract Lancea tibetica is an important traditional Tibetan medicinal plant that grows on the Qinghai-Tibet Plateau with great development potential in pharmaceutical industry. In this study, a combinative method using HPLC-DPPH and two-dimensional liquid chromatography has been developed to identify and separate antioxidants from Lancea tibetica. Under the target-guidance of HPLC-DPPH experiment, three antioxidant fractions from Lancea tibetica were recognized. Then, separation of the three fractions using two-dimensional semi-preparation liquid chromatography led to seven phenylpropanoids: (+)-pinoresinol-β-D-glucoside (1), isoacteoside (2), acteoside (3), tibeticoside (4),epipinoresinol (5), anthelminthicol (6) and phillygenol (7). As a result, seven major antioxidants in Lancea tibetica were isolated with more than 96% purity. Furthermore, in vitro bioassay against DPPH revealed compounds 1 – 7 with IC 50 values ranging from 6.16 ± 0.08 to 25.09 ± 0.11 (μM) and compounds 1 , 2 and 3 showed activities stronger than the two reference antioxidants (vitamin C, rutin), with IC 50 values of 6.16 ± 0.08, 8.93 ± 0.06 and 7.98 ± 0.05 (μM), respectively. Results of the present study indicated that the method was an efficient technique to systematically screen and isolate antioxidants from medicine crops. Graphical abstract Unlabelled Image Highlights • A novel screen and separation method for purification of antioxidants directly. • Seven antioxidants isolated from Lancea tibetica bioactivity-guided. • Isolated antioxidants with IC 50 values from 6.16 ± 0.08 to 25.09 ± 0.11 (μM). • The first report on antioxidant capacity of the compounds from Lancea tibetica. [ABSTRACT FROM AUTHOR]

The goal of this study was to explore the potential of carob extracts to act as lipid inhibitors in model food systems. First, the extraction efficacy of fourteen solvents on the phenolic and flavonoid contents as well as on the antioxidant activity was assessed. Results showed that the phenolic composition and antioxidant activity of the extracts were strongly affected by solvents. Subsequently, the antioxidant potential of the most promising extracts (water, methanol, acidic acetone, and acetone−water) against four model food systems were evaluated. The acidic acetone extract had the highest antioxidant activity (70.3 ± 5.3%) in the β-carotene-linoleic acid system, followed by the acetone−water extract (62.1 ± 4.9%). Both extracts significantly prevented the lipid oxidation in sunflower oil and cooked comminuted pork; the inhibition activity at the end of storage period was 36.7−50.5% and 17.4−24.8%, respectively. A reduction of 49.5−54.8% in the formation of dienes in the oil-in-water emulsion was also found. The inhibitory effect of methanolic and aqueous extracts was significantly lower. Qualitative and quantitative variations in extracts are responsible for this antioxidant behavior in food systems. Gallic acid, myrecetin, rutin, and catechin are the main components of the extracts while myricetin and quercetin play an essential role in the antioxidant activity, according to the biochromatograms.

Quantitative phytochemical characterisation of the chief flavonoid aglycones in the hydrolysed Lysimachia extracts revealed the dominance of kaempferol, quercetin and myricetin in L. vulgaris, L. nummularia, L. punctata, L. christinae, L. ciliata and L. clethroides, respectively. Due to the significant radical scavenging capacity of the samples, the contribution of the individual aglycones to the total antioxidant activity became of interest. Therefore, a HPLC method coupled to pre-column DPPH scavenging assay was developed. Differences in the six Lysimachia species' phenolic composition regarding their participation to the antioxidant activity were revealed. The participation of the three investigated flavonoids to the radical quenching activity was the highest (91.2%) in the L. vulgaris sample, the lowest in L. christinae sample with 29.6%. In L. vulgaris sample, the 76.3% contribution of quercetin to the scavenger capacity was the highest peak area decrement ratio among the investigated samples. [ABSTRACT FROM AUTHOR]

Semen Oroxyli, derived from the seed of Oroxylum indicum L., is a commonly used Traditional Chinese Medicine with beneficial effects against several respiratory disorders. Antioxidative flavonoids may be partly responsible for its medicinal functions. The aim of this study was to rapidly determine the antioxidants in Semen Oroxyli based on a HPLC-DPPH method. Four major flavonoids, baicalein-7-O-gentiobioside, baicalein-7-O-glucoside, baicalein, and baicalin, were identified as the active components against DPPH free radicals, which is in accord with the results of our former traditional activity-guided phytochemical study. The oxidative products of the four antioxidant flavonoids were studied in the DPPH spiking HPLC assay, it was suggested that the three active flavonoid glycosides were converted into 5,6-dihydroxy-7-methoxyflavone, which implied that an additional hydroxyl at C-6 in 5,7-dihydroxyflavones plays an important role in the DPPH assay.

Mountain tea is an easily available, low cost herb consumed on a daily basis, and is believed to contain bioactive phytochemicals. The evaluation of functional properties and bioactive composition of the decoction is essential for its exploitation as a health-promoting beverage. The antimicrobial properties of Sideritis syriaca decoction were demonstrated a considerable antimicrobial activity against Staphylococcus aureus. In addition, its antioxidant activity was indicated from different in vitro assays. HPLC–SPE–NMR technique was then optimized to analyze its phytochemical content. The major phytochemicals were found to be hypoelatin and isoscutellarein diglucosides, while the phenylpropanoids such as verbascoside, martynoside, lavandulifolioside, and chlorogenic acid were also identified by combining NMR, UV and MS data. Finally, the on-line HPLC–DPPH demonstrated that the antioxidant activity of the decoction was mainly due to its flavonoid content. Overall, mountain tea decoction can be considered as a health-promoting beverage with functional properties that deserve further exploitation.

Brazilian green propolis is known as an appreciable natural antioxidant with abundant polyphenolic compounds. For quality control, a fingerprint-efficacy study of Brazilian green propolis was carried out in this work. Chemical fingerprints of Brazilian green propolis from 22 different sources were determined by HPLC and investigated by similarity analysis. The fingerprint-efficacy relationships between chemical fingerprint and DPPH radical-scavenging activity were established. The results showed that 14 characteristic common peaks were identified, and 9 compounds were discovered with free radical-scavenging activities. Caffeoylquinic acids and artepillin C might be the major effective components for quality control of Brazilian green propolis due to their specificity and strong antioxidant activity. This study provides new markers for the quality assessment of Brazilian green propolis and its derived products. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mountain tea decoction was analyzed in terms of antioxidant and antimicrobial activity. [•] Phytochemical composition of mountain tea decoction was monitored using HPLC–SPE–NMR. [•] HPLC–DPPH showed the significant contribution of flavonoids to its antioxidant activity. [•] Mountain tea decoction showed potent antimicrobial activity against Staphylococcus aureus. [•] Mountain tea decoction is a valuable source of bioactive compounds in foods such as beverages. [Copyright &y& Elsevier]

Objectives To use an online assay to identify key antioxidants in Sonchus oleraceus leaf extracts and to investigate the effect of leaf position and extraction conditions on antioxidant concentration and activity. Methods Separation of phytochemicals and simultaneous assessment of antioxidant activity were performed online using HPLC and post-column reaction with a free-radical reagent (2, 2-diphenylpicrylhydrazyl, DPPH). Active compounds were identified using nuclear magnetic resonance spectroscopy and mass spectrometry. We applied the online HPLC-DPPH radical assay to evaluate antioxidants in leaves from different positions on the plant and to assess the effect of pre-treatment of leaves with liquid N2 before grinding, extraction time, extraction temperature and method of concentrating extracts. Key findings Key antioxidants identified in S. oleraceus leaf extracts were caftaric acid, chlorogenic acid and chicoric acid. Middle leaves contained the highest total amount of the three key antioxidant compounds, consisting mainly of chicoric acid. Pre-treatment with liquid N2, increasing the extraction temperature and time and freeze-drying the extract did not enhance the yield of the key antioxidants. Conclusion The online HPLC-DPPH radical assay was validated as a useful screening tool for investigating individual antioxidants in leaf extracts. Optimized extraction conditions were middle leaves pre-treated with liquid N2, extraction at 25° C for 0.5 h and solvent removal by rotary evaporation. [ABSTRACT FROM AUTHOR]

Abstract: Teucrium polium is a popular medicinal plant that is used in the daily diet and the in vitro and in vivo antioxidant potency of its extracts has been widely investigated. In the present work, polar extracts from T. polium were analyzed in terms of its composition and radical-scavenging activity with the employment of the state-of-the-art HPLC-SPE-NMR and HPLC-DPPH techniques in the search of new antioxidant agents for food industry. NMR and MS data revealed the presence of phenylpropanoid glycosides verbascoside and poliumoside, the flavones apigenin and its derivatives and two methoxyflavones. The on-line DPPH experiments showed that poliumoside is the most active component of the extracts and the antioxidant potential of T. polium polar extracts is mainly attributed to phenylpropanoid glycosides (66–80%). Our results suggested that T. polium extracts could be a promising source of natural antioxidants. This holistic approach also revealed that poliumoside or polar extracts of T. polium can be used in food industry as antioxidant agents with natural origin. The HPLC-SPE-NMR and HPLC-DPPH analysis of the extracts was performed for first time in the same device without any modification of the instrumentation, avoiding the need for isolation of the individual components. [Copyright &y& Elsevier]

The goal of this study was to explore the potential of carob extracts to act as lipid inhibitors in model food systems. First, the extraction efficacy of fourteen solvents on the phenolic and flavonoid contents as well as on the antioxidant activity was assessed. Results showed that the phenolic composition and antioxidant activity of the extracts were strongly affected by solvents. Subsequently, the antioxidant potential of the most promising extracts (water, methanol, acidic acetone, and acetone–water) against four model food systems were evaluated. The acidic acetone extract had the highest antioxidant activity (70.3 ± 5.3%) in the β-carotene-linoleic acid system, followed by the acetone–water extract (62.1 ± 4.9%). Both extracts significantly prevented the lipid oxidation in sunflower oil and cooked comminuted pork; the inhibition activity at the end of storage period was 36.7–50.5% and 17.4–24.8%, respectively. A reduction of 49.5–54.8% in the formation of dienes in the oil-in-water emulsion was also found. The inhibitory effect of methanolic and aqueous extracts was significantly lower. Qualitative and quantitative variations in extracts are responsible for this antioxidant behavior in food systems. Gallic acid, myrecetin, rutin, and catechin are the main components of the extracts while myricetin and quercetin play an essential role in the antioxidant activity, according to the biochromatograms. [ABSTRACT FROM AUTHOR]

The goal of this study was to explore the potential of carob extracts to act as lipid inhibitors in model food systems. First, the extraction efficacy of fourteen solvents on the phenolic and flavonoid contents as well as on the antioxidant activity was assessed. Results showed that the phenolic composition and antioxidant activity of the extracts were strongly affected by solvents. Subsequently, the antioxidant potential of the most promising extracts (water, methanol, acidic acetone, and acetone-water) against four model food systems were evaluated. The acidic acetone extract had the highest antioxidant activity (70.3 ± 5.3%) in the β-carotene-linoleic acid system, followed by the acetone-water extract (62.1 ± 4.9%). Both extracts significantly prevented the lipid oxidation in sunflower oil and cooked comminuted pork; the inhibition activity at the end of storage period was 36.7-50.5% and 17.4-24.8%, respectively. A reduction of 49.5-54.8% in the formation of dienes in the oil-in-water emulsion was also found. The inhibitory effect of methanolic and aqueous extracts was significantly lower. Qualitative and quantitative variations in extracts are responsible for this antioxidant behavior in food systems. Gallic acid, myrecetin, rutin, and catechin are the main components of the extracts while myricetin and quercetin play an essential role in the antioxidant activity, according to the biochromatograms.