Determination of phenolic acids and flavonoids of apple and pear by high-performance liquid chromatography

Phytochemicals, antioxidant activity and hepatoprotective effect of ginger (Zingiber officinale) on diethylnitrosamine toxicity in rats

Context: Chronic liver damage has serious medical consequences. Objective: To investigate the hepatoprotective effect of dry Zingiber officinale (ginger) and its essential (volatile) oil against diethylnitrosamine (DEN) toxicity in rats. Materials and methods: Phenols and flavonoids components were characterized in dry ginger using HPLC-UV instrument while ginger essential oil (E.O.) was investigated via GC-MS technique. Antioxidant activity was determined in vitro. In rat model, ginger was administrated for 2 months. Lipid profile, antioxidant biomarkers, liver functions and histopathology were assessed. Results: Chlorogenic acid (63.85 ppm) and hesperidin (156.91 ppm) are among the major phenolic and flavonoid constituents in dry ginger. Curcumene (15.21%) and linalool (13.47%) represent the main E.O. constituents. In rats treated with ginger E.O., a significant elevation in serum HDL (31.14%) was accompanied by a decrease in LDL (55.14%). A significant decrease in serum ALT and ALP was reported (56.85% and 53.84%, respectively). Serum GSH-Px activity has significantly increased 75.06%. Meanwhile, E.O. showed anticancer potential against HepG2 cell line (IC50 = 40 µg/mL). Liver histopathological examinations confirmed the protective effect against abnormalities. Conclusion: Ginger was able to reduce the severity of DEN-cytotoxicity in rats, which suggests a novel antioxidant role originating from this medicinal plant.

Comparative Phytochemical Analysis and Antioxidant Activities of Tamalakyadi Decoction with Its Modified Dosage Forms

Background and Objective

Tamalakyadi decoction (TD) is a classical formulation mentioned in authentic traditional medicine text Sarasankshepaya under nasal diseases and used as a remedy for allergic rhinitis. It consists of 12 plant ingredients. Decoction preparations are widely used in Sri Lankan traditional system and considered effective and safe for treating many disorders. However, decoctions have to be used only in fresh state due to shorter shelf life and loss of stability. This decoction preparation method leads to decreasing the patient compliance and is also time consuming. Hence, the objective of the present study was to convert TD to consumer friendly novel dosage form, namely, freeze dried, spray dried, and traditional ganasara forms.

Methodology

Therefore, we compared the phytochemical constituents and antioxidant activities of TD with its modified dosage forms. The chemical comparison of four dosage forms comprises phytochemical screening, TLC and HPTLC fingerprint profiles and the antioxidant activities by DPPH free radical scavenging activity, Ferric reducing antioxidant power (FRAP), total polyphenol content (TPC), and total flavonoid content (TFC).

Results

Phytochemical screening revealed the presence of alkaloids, saponins, tannins, steroids, flavonoids, phenols, and terpenoids in all dosage forms. However, the saponins, alkaloids, flavonoids, terpenoids, and steroids were more prominent in TD and freeze dried preparation than the other two preparations. HPTLC fingerprint pattern of freeze dried dosage was more similar with HPTLC fingerprint pattern of TD in terms of number of peaks and their intensity compared to that of spray dried and ganasara dosage forms. Antioxidant activities such as DPPH, FRAP, TPC, and TFC were higher in decoction and freeze dried preparation than in spray dried and ganasara preparation.

Conclusion

Freeze dried TD is the most suitable ready to use preparation having similar chemical properties and antioxidant activities to TD.

Effects of heat treatment on the phenolic compounds and antioxidant capacity of quince fruit and its tisane's sensory properties

The quince fruit can be an alternative for producing healthy tea because it is a rich source of bioactive compounds. This study was conducted to evaluate the effects of heating (for 20, 40 and 60 min) on the bioactive compounds of quince and quality attributes its tisanes. To this aim, phenolic content of the treated sample (for 40 min according to sensory analysis) was evaluated by HPLC and antioxidant activity was measured using DPPH method. The analysis of sensory evaluation data demonstrated that the heating process significantly improved the color and taste of the quince tisanes. Thermal treatment (180 °C) for 40 min had maximum acceptability. Although, results confirmed negative effects of the heating process on phenolic content, it showed an increase in antioxidant activity. The HPLC data displayed significant reduction in total amount of five identified phenolic compounds from 460.51 to 25.49 mg/25 g extract by heat treatment. In contrast the roasted sample exhibited lower IC50 (663.88 µg/ml) than the unprocessed sample (1098.66 µg/ml). Considering the elevated antioxidant activity achieved through the heating process, the quince tisane can be considered as a healthy beverage.

Biocompatibility and Bioimaging Potential of Fruit-Based Carbon Dots

Photo-luminescent carbon dots (CD) have become promising nanomaterials and their synthesis from natural products has attracted attention by the possibility of making the most of affordable, sustainable and, readily-available carbon sources. Here, we report on the synthesis, characterization and bioimaging potential of CDs produced from diverse extensively produced fruits: kiwi, avocado and pear. The in vitro cytotoxicity and anticancer potential of those CDs were assessed by comparing human epithelial cells from normal adult kidney and colorectal adenocarcinoma cells. In vivo toxicity was evaluated using zebrafish embryos given their peculiar embryogenesis, with transparent embryos developing ex-utero, allowing a real-time analysis. In vitro and in vivo experiments revealed that the synthesized CD presented toxicity only at concentrations of ≥1.5 mg mL-1. Kiwi CD exhibited the highest toxicity to both cells lines and zebrafish embryos, presenting lower LD50 values. Interestingly, despite inducing lower cytotoxicity in normal cells than the other CDs, black pepper CDs resulted in higher toxicity in vivo. The bio-distribution of CD in zebrafish embryos upon uptake was investigated using fluorescence microscopy. We observed a higher accumulation of CD in the eye and yolk sac, avocado CD being the ones more retained, indicating their potential usefulness in bio-imaging applications. This study shows the action of fruit-based CDs from kiwi, avocado and pear. However the compounds present in these fruit-based CDs and their mechanism of action as a bioimaging agent need to be further explored.

Determination of Flavonoids and Carotenoids and Their Contributions to Various Colors of Rose Cultivars (Rosa spp.)

Rose is one of the most valuable ornamental crops worldwide. In this study, the composition of hydrophilic and lipophilic pigments in petals of six rose cultivars at seven developing stages was investigated using high performance liquid chromatography and mass spectrometry. Four anthocyanins, 20 flavonols, and 10 carotenoids were detected in petals of tested cultivars. Major individual anthocyanin, flavonol, and carotenoid were cyanidin/pelargonidin 3,5-diglucoside, kaempferol 3-O-rhamnoside, and (9Z)-violaxanthin, respectively. Significant differences were observed in pigments content in petals of different rose cultivars. The yellow petals of YI and GC exhibited no to very small amounts of anthocyanins, moderate amount of total flavonols, and highest content of total carotenoids. Similarly, pink petals of PF, WQ, and YX showed average concentration of total anthocyanins, highest concentration of total flavonols, and small amount of carotenoids. Further, orange petals of CH showed highest content of total anthocyanins, lowest content of total flavonols, and average content of total carotenoids. Correlation analysis demonstrated that there were many pigments influencing petal colors. Moreover, multiple linear regression indicated that pelargonidin 3,5-diglucoside, total anthocyanins and (9Z)-violaxanthin were the major factors. In addition, this study showed that orange cultivar CH, pink cultivar PF and yellow cultivar YI can have great potential as a natural source for the extraction of pelargonidin 3-O-glucoside, kaempferol 3-O-rhamnoside, and (9Z)-violaxanthin, respectively. These investigations would contribute toward understanding the mechanism on the development of flower colors and provide a theoretical basis for the breeding of rose with specific color.

High Antimicrobial Efficacy, Antioxidant Activity, and a Novel Approach to Phytochemical Analysis of Bioactive Polyphenols in Extracts from Leaves of Pyrus communis and Pyrus pyrifolia Collected During One Vegetative Season

Dried leaf samples of Pyrus communis L. var. 'Conference' and Pyrus pyrifolia Burm. f. (Nakai) var. 'Shinseiki' were subjected to the successful extraction procedures using various solvents, followed by filtering and/or drying liquid plant preparations under reduced pressure. As a result of this, for each Pyrus leaf sample examined, four dried residues were obtained, including methanolic (EA), ethyl acetate (EC), water (EB), and the residue obtained from aqueous solution (ED). Antiradical activity of these preparations was measured using the ABTS^+• assay, and antimicrobial activity was examined using various strains of bacteria and yeasts. The highest antiradical activity was observed for EC from leaves of P. communis var. 'Conference' collected in May, but the highest average antibacterial activity was noted for EC residues from P. pyrifolia var. 'Shinseiki' collected in May. Antibacterial activity positively correlated with concentration of hydroquinone in extracts. No antifungal activity was observed for any extract. In addition, qualitative and quantitative analyses of active polyphenolic components in extracts from Pyrus were performed. Hydroquinone and hydroxycinnamic acid derivatives were analyzed using a new optimized method comprising reversed-phase high-performance liquid chromatography (RP-LC) coupled with simultaneous photodiode-array and fluorescence detection.

Enrichment of Apple Slices with Bioactive Compounds from Pomegranate Cryoconcentrated Juice as an Osmodehydration Agent

Pomegranate juice is an important source of bioactive compounds, and cryoconcentrated juice is an interesting osmodehydration agent to enrich a vegetal matrix. This investigation aimed to incorporate bioactive compounds from pomegranate cryoconcentrated juice into apple slices using osmodehydration (OD) assisted by pulse vacuum (PV) and ohmic heating (OH). The apple slices (3 × 4 × 0.5 cm) were osmodehydrated using a 47 °Brix pomegranate cryoconcentrated juice at 30, 40, or 50°C for 180 min with an electric field of 6.66 V/cm (50 V) and a 5 min pulsed vacuum. Over the time, all of the treatments applied to the apple slices increased the soluble solids and bioactive compounds compared with the fresh sample. PVOD/OH at 50°C had the highest content of total anthocyanin during processing, and the best results for the total flavonoids were obtained with OD/OH at 50°C and 40°C. The osmodehydration assisted by pulse vacuum and ohmic heating using a cryoconcentrated juice is a useful combined technique to acquire enriched vegetal samples with bioactive compounds.

Targeted Metabolic Profiling Indicates Apple Rootstock Genotype-Specific Differences in Primary and Secondary Metabolite Production and Validate Quantitative Contribution From Vegetative Growth

Previous reports regarding rhizodeposits from apple roots are limited, and complicated by microbes, which readily colonize root systems and contribute to modify rhizodeposit metabolite composition. This study delineates methods for collection of apple rhizodeposits under axenic conditions, indicates rootstock genotype-specific differences and validates the contributions of vegetative activity to rhizodeposit quantity. Primary and phenolic rhizodeposit metabolites collected from two apple rootstock genotypes, G935 and M26, were delineated 2 months after root initiation by utilizing gas chromatography/liquid chromatography-mass spectrometry (GC/LC-MS), respectively. Twenty-one identified phenolic compounds and 29 sugars, organic acids, and amino acids, as well as compounds tentatively identified as triterpenoids were present in the rhizodeposits. When adjusted for whole plant mass, hexose, erythrose, galactose, phloridzin, kaempferol-3-glucoside, as well as glycerol, and glyceric acid differed between the genotypes. Phloridzin, phloretin, epicatechin, 4-hydroxybenzoic acid, and chlorogenic acid were among the phenolic compounds found in higher relative concentration in rhizodeposits, as assessed by LC-MS. Among primary metabolites assessed by GC-MS, amino acids, organic acids, and sugar alcohols found in relatively higher concentration in the rhizodeposits included L-asparagine, L-cysteine, malic acid, succinic acid, and sorbitol. In addition, putative ursane triterprenoids, identified based on accurate mass comparison to previously reported triterpenoids from apple peel, were present in rhizodeposits in high abundance relative to phenolic compounds assessed via the same extraction/instrumental method. Validation of metabolite production to tree vegetative activity was conducted using a separate set of micropropagated trees (genotype MM106) which were treated with a toxic volatile compound (butyrolactone) to inhibit activity/kill leaves and vegetative growth. This treatment resulted in a reduction of total collected rhizodeposits relative to an untreated control, indicating active vegetative growth contributes to rhizodeposit metabolites. Culture-based assays indicated an absence of bacterial or fungal endophytes in roots of micropropagated G935 and M26 plants. However, the use of fungi-specific primers in qPCR indicated the presence of fungal DNA in 30% of the samples, thus the contribution of endophytes to rhizodeposits cannot be fully eliminated. This study provides fundamental information for continued research and application of rhizosphere ecology driven by apple rootstock genotype specific rhizodeposition.

Anti-Melanogenic Effect of Chestnut Spike Extract through Downregulation of Tyrosinase-Related Proteins and Activation of ERK 1/2

Melanin has been reported to be the key factor for skin homeostasis. Besides defining an important human phenotypic trait, melanin overproduction may cause various disorders such as vitiligo, Addison's disease, Cushing's syndrome, and melasma. In this study, we aimed to investigate the anti-melanogenic potential of dried spike extract of chestnut. The extract inhibited tyrosinase (TYR) activity in a dose-dependent manner. Cellular melanin content decreased markedly after treatment with the extract. The spike extract inhibited microphthalmia-associated transcription factor (MITF) expression and downregulated TYR, TYRP-1, and TYRP-2 protein expression by increasing the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 signalling pathway in melan-a cells. In addition, treatment with U0126, a specific inhibitor of ERK, restored melanin content. Collectively, these results suggest that the chestnut spike extract attenuated melanogenesis by inhibiting MITF expression and downregulating TYR, TYRP-1, and TYRP-2 protein expressions via activation of ERK1/2 pathway.

Determination of major phenolic compounds in apples: Part I-Optimization of high-performance liquid chromatography separation with diode array detection

The separation of seven phenolic compounds including gallic acid, chlorogenic acid, epicatechin, quercitrin, rutin, phloridzin, and phloretin present in apple peel and pulp and differing in elution properties has been optimized using high-performance liquid chromatography with diode array detection. Several stationary phases were tested to achieve the efficient separation of phenolic compounds in fruit extracts and C18 was found to be the most efficient. Core-shell and fully porous C18 packings were assessed with respect to the complex composition of the fruit extracts. The developed high-performance liquid chromatography method comprised gradient elution in which mobile phase A was water at pH 2.8 adjusted with acetic acid and B was acetonitrile. The gradient shape was the following: 0 min 95% A/5% B, 2.5 min 85% A/15% B, 12 min 50% A/50% B, 15 min 95% A/5% B. The flow rate was 1 mL/min, injection volume 10 μL, and UV detection at 255, 280, 320, and 365 nm was applied. Our method was validated for both C18 core-shell and fully porous packings. The resolution 6.2-14.8, symmetry 0.99-1.34, peak capacity 18-60, peak area repeatability 0.45-1.00% relative standard deviation, calibration range 0.125-5 mg/mL (0.25-10 mg/mL for chlorogenic acid and rutin), correlation coefficients of calibration curve 0.9976-0.9997, and accuracy evaluated as recovery 95.56-107.54% were determined for the core-shell column.

The performance of cathodically pretreated boron-doped diamond electrode in cationic surfactant media for enhancing the adsorptive stripping voltammetric determination of catechol-containing flavonoid quercetin in apple juice

In the present paper, an electroanalytical methodology was developed for the determination of an important catechol-containing flavonoid derivative, quercetin using adsorptive stripping voltammetry at a cathodically pretreated boron-doped diamond electrode. In cyclic voltammetry, the compound showed a couple of oxidation/reduction peak at low positive potentials, and additional two oxidation peaks at more positive potentials. The sensitivity of the stripping voltammetric measurements was significantly improved when the cationic surfactant, cetyltrimethylammonium bromide (CTAB) was present in the electrolyte solution. Using square-wave stripping mode, a highly linear analytical curve was obtained for quercetin determination in 0.1 M acetate buffer solution (pH 4.7) containing 3 × 10^-4 M CTAB at + 0.37 V (vs. Ag/AgCl) (after 30 s accumulation at open-circuit condition) in the range of 0.5-200 ng mL^-1 (1.7 × 10^-9-3.3 × 10^-7 M), with a detection limit of 0.132 ng mL^-1 (4.4 × 10^-10 M). As an example, the practical applicability of proposed method was successfully tested with the measurement of quercetin concentration in commercial apple juice samples.

Diversity of bioactive compounds and antioxidant activity in Delicious group of apple in Western Himalaya

Apple contributes significantly to the livelihood and health of the people living in Himalayan regions. Among others, the Delicious group of apple is known for their health promoting and income generating attributes. However, the systematic investigation on morphological and phytochemical attributes of the apple growing in Indian Himalayan region is poorly known. An altitude-dependent variation in the fruit quality traits and phytochemical diversity was observed. The Royal Delicious was found rich in total tannin, flavonoids, flavonols, antioxidant activity [2,2-azinobis (3-ethylbenzothiazoline-6-sulphonic acid), 2,2-Diphenyl-1-picryhydrazyl, Ferric reducing antioxidant power], procyanidin B₂, phloridzin and gallic acid; Red Delicious for total phenol and epicatechin and Golden Delicious for chlorogenic acid. The cultivar and altitude-dependent variation of phenolic profile in peel and pulp portion emphasizes genotype-specific biosynthesis of phenolic compounds in regulatory mechanisms. It is suggested that selection of suitable altitude and cultivars is required for harnessing the maximum phytochemical and antioxidant activity for benefits to human consumption.

Flavonoid-Rich Apple Improves Endothelial Function in Individuals at Risk for Cardiovascular Disease: A Randomized Controlled Clinical Trial

SCOPE

The cardioprotective effects of apples are primarily attributed to flavonoids, found predominantly in the skin. This study aimed to determine if acute and/or chronic (4 weeks) ingestion of flavonoid-rich apples improves endothelial function, blood pressure (BP), and arterial stiffness in individuals at risk for cardiovascular diseases (CVD).

METHODS AND RESULTS

In this randomized, controlled cross-over trial, acute and 4 week intake of apple with skin (high flavonoid apple, HFA) is compared to intake of apple flesh only (low flavonoid apple, LFA) in 30 participants. The primary outcome is endothelial function assessed using flow-mediated dilation (FMD) of the brachial artery, while main secondary outcomes are 24 h ambulatory BP and arterial stiffness. Other outcomes include fasting serum glucose and lipoprotein profile, plasma heme oxygenase-1 (Hmox-1), F₂ -isoprostanes, flavonoid metabolites, and plasma and salivary nitrate (NO₃^- ) and nitrite (NO₂^- ) concentrations. Compared to LFA control, the HFA results in a significant increase in FMD acutely (0.8%, p < 0.001) and after 4 weeks chronic intake (0.5%, p < 0.001), and in plasma flavonoid metabolites (p < 0.0001). Other outcomes are not altered significantly.

CONCLUSION

A lower risk of CVD with higher apple consumption could be mediated by the beneficial effect of apple skin on endothelial function, both acutely and chronically.

Photoprotective effects of cranberry juice and its various fractions against blue light-induced impairment in human retinal pigment epithelial cells

CONTEXT

Cranberry has numerous biological activities, including antioxidation, anticancer, cardioprotection, as well as treatment of urinary tract infection (UTI), attributed to abundant phenolic contents.

OBJECTIVE

The current study focused on the effect of cranberry juice (CJ) on blue light exposed human retinal pigment epithelial (ARPE-19) cells which mimic age-related macular degeneration (AMD).

MATERIALS AND METHODS

Preliminary phytochemical and HPLC analysis, as well as total antioxidant capacity and scavenging activity of cranberry ethyl acetate extract and different CJ fractions (condensed tannins containing fraction), were evaluated. In cell line model, ARPE-19 were irradiated with blue light at 450 nm wavelength for 10 h (mimic AMD) and treated with different fractions of CJ extract at different doses (5-50 μg/mL) by assessing the cell viability or proliferation rate using MTT assay (repairing efficacy).

RESULTS

Phytochemical and HPLC analysis reveals the presence of several phenolic compounds (flavonoids, proanthocyanidin, quercetin) in ethyl acetate extract and different fractions of CJ. However, the condensed tannin containing fraction of ethyl acetate extract of CJ displayed the greater (p < 0.05) scavenging activity especially at the dose of 1 mg/mL. Similarly, the condensed tannin containing fraction at 50 μg/mL presented better (p < 0.05) repairing ability (increased cell viability). Furthermore, the oligomeric condensed tannin containing fraction display the best (p < 0.05) repairing efficiency at 50 μg/mL.

DISCUSSION AND CONCLUSION

In conclusion, this study distinctly proved that condensed tannin containing fraction of CJ probably exhibits better free radicals scavenging activity and thereby effectively protected the ARPE-19 cells and thus, hampers the progress of AMD.

Polyphenolic content, in vitro antioxidant activity and chemical composition of extract from Nephelium lappaceum L. (Mexican rambutan) husk

OBJECTIVE

To determinate the recovery of total polyphenolic compounds content, in vitro antioxidant activity and HPLC/ESI/MS characterization of extract from Nephelium lappaceum L. (Mexican rambutan).

METHODS

The rambutan husk extract was obtained by aqueous extraction and a polyphenolic fraction was recovered using Amberlite XAD-16. The total polyphenolic compounds content was determined by the Folin Ciocalteu and butanol-HCI methods. In vitro antioxidant activity was performed using ABTS and ferric reducing antioxidant power methods.

RESULTS

Mexican rambutan husk showed a total polyphenolic content of 582 mg/g and an evident antioxidant activity by ABTS and ferric reducing antioxidant power analysis. The HPLC/ESI/MS assay allowed the identification of 13 compounds, most of which belong to ellagitannins. Geraniin, corilagin and ellagic acid were present in the sample; the mineral composition was also evaluated.

CONCLUSIONS

Rambutan husk cultivated in Mexico is a promising source for the recovery of added value bioactive compounds with antioxidant activity, which have potential applications as bioactive antioxidant agents for the treatment of diseases.

Cytotoxic activities of Telectadium dongnaiense and its constituents by inhibition of the Wnt/β-catenin signaling pathway

BACKGROUND

Wnt/β-catenin signaling pathway is a potential target for the treatment of human colon cancer. Thus, the inhibitory effects of various plant extracts on cell proliferation and Wnt signal transduction were evaluated to discover a Wnt signaling inhibitor.

PURPOSE

The present study aimed to investigate the cytotoxicity involved in Wnt pathway of the MeOH extract from Telectadium dongnaiense bark (TDB) and to identify its bioactive constituents by bioassay-guided fractionation.

METHODS

The sulforhodamine B-based proliferation assay and the β-catenin/TCF-responsive reporter gene assay were employed as screening systems. The isolation and identification of compounds were elucidated on the basis of spectroscopic methods. Inhibitory effects on the expression levels of Wnt target genes were determined by real-time PCR and western blotting.

RESULTS

The extract of TDB most strongly inhibited cell proliferation and TOPflash activity (IC₅₀ = 1.5 and 2.0 µg/ml), which was correlated with its inhibitory effects on the expression of Wnt target genes. Three major compounds were isolated from bioactive fractions and were identified as 1,4-dicaffeoylquinic acid (1), quercetin 3-rutinoside (2), and periplocin (3). Only compound 3 showed anti-proliferative activity (IC₅₀ = 0.06 µM) and exhibited Wnt signaling inhibitory effects in HCT116 colon cancer cells.

CONCLUSIONS

This study contributes to understanding the cytotoxic properties of TDB extract and its constituents and provides a potent strategy for its further application.

Structure of Pigment Metabolic Pathways and Their Contributions to White Tepal Color Formation of Chinese Narcissus tazetta var. chinensis cv Jinzhanyintai

Chinese narcissus (Narcissus tazetta var. chinensis) is one of the ten traditional flowers in China and a famous bulb flower in the world flower market. However, only white color tepals are formed in mature flowers of the cultivated varieties, which constrains their applicable occasions. Unfortunately, for lack of genome information of narcissus species, the explanation of tepal color formation of Chinese narcissus is still not clear. Concerning no genome information, the application of transcriptome profile to dissect biological phenomena in plants was reported to be effective. As known, pigments are metabolites of related metabolic pathways, which dominantly decide flower color. In this study, transcriptome profile and pigment metabolite analysis methods were used in the most widely cultivated Chinese narcissus “Jinzhanyintai” to discover the structure of pigment metabolic pathways and their contributions to white tepal color formation during flower development and pigmentation processes. By using comparative KEGG pathway enrichment analysis, three pathways related to flavonoid, carotenoid and chlorophyll pigment metabolism showed significant variations. The structure of flavonoids metabolic pathway was depicted, but, due to the lack of F3ʹ5ʹH gene; the decreased expression of C4H, CHS and ANS genes; and the high expression of FLS gene, the effect of this pathway to synthesize functional anthocyanins in tepals was weak. Similarly, the expression of DXS, MCT and PSY genes in carotenoids synthesis sub-pathway was decreased, while CCD1/CCD4 genes in carotenoids degradation sub-pathway was increased; therefore, the effect of carotenoids metabolic pathway to synthesize adequate color pigments in tepals is restricted. Interestingly, genes in chlorophyll synthesis sub-pathway displayed uniform down-regulated expression, while genes in heme formation and chlorophyll breakdown sub-pathways displayed up-regulated expression, which also indicates negative regulation of chlorophyll formation. Further, content change trends of various color metabolites detected by HPLC in tepals are consistent with the additive gene expression patterns in each pathway. Therefore, all three pathways exhibit negative control of color pigments synthesis in tepals, finally resulting in the formation of white tepals. Interestingly, the content of chlorophyll was more than 10-fold higher than flavonoids and carotenoids metabolites, which indicates that chlorophyll metabolic pathway may play the major role in deciding tepal color formation of Chinese narcissus.

The influence of plant protection by effective microorganisms on the content of bioactive phytochemicals in apples

BACKGROUND

The phytochemicals of two apple cultivars (Yellow Transparent and Early Geneva) protected in two ways, conventionally with chemical pesticides or by effective microorganisms (EM), were compared. Two types of components were determined: lipids synthesised constitutively and generated via inducible pathways polyphenols along with antioxidant activity and profiles.

RESULTS

The antioxidant activities assessed with ABTS, DPPH and Folin-Ciocalteu reagents were about two-fold higher in the case of microbiologically protected apples. The qualitative composition of phenolics determined by LC-DAD-MS varied between cultivars and the part of apples studied, while the method of protection caused mainly differences in concentration of some groups of polyphenols (hydroxycinnamates, flavanols, dihydrochalcones, flavonols, anthocyanins). The apples from biological cultivation contained about 34-54% more phenolics than these from a conventional orchard. In contrast, lipid composition did not differ significantly between apples originating from conventional and bio-crops.

CONCLUSION

The results indicate that the advantage of using the EM technology in agriculture may not only be the reduction of consumption of chemical fertilisers and synthetic pesticides, but also, at least in the case of apples, may lead to the production of crops with improved health quality due to the higher content of bioactive phytochemicals. © 2017 Society of Chemical Industry.

Structural identification of compounds for use in the detection of juice-to-juice debasing between apple and pear juices

The ability to detect the undeclared addition of a juice of lesser economic value to one of higher value (juice-to-juice debasing) is a particular concern between apple and pear juices due to similarities in their major carbohydrate/polyol profiles. Fingerprint compounds for the detection of this type of adulteration were identified in both commercial apple and pear juices by HPLC-PDA, were isolated chromatographically, and structurally identified by LC-MS/MS. The apple juice fingerprint was identified as 4-O-p-coumarylquinic acid and two pear compounds as isorhamnetin-3-O-rutinoside and abscisic acid. Additionally, the HPLC-PDA profile of pear juices in combination with pear fingerprint compounds including arbutin could be used to identify samples originating from China versus those from other geographical locations.

A Metabolomics-Guided Exploration of the Phytochemical Constituents of Vernonia fastigiata with the Aid of Pressurized Hot Water Extraction and Liquid Chromatography-Mass Spectrometry

Vernonia fastigiata is a multi-purpose nutraceutical plant with interesting biological properties. However, very little is known about its phytochemical composition and, thus the need for its phytochemical characterization. In the current study, an environmentally friendly method, pressurized hot water extraction (PHWE), was used to extract metabolites from the leaves of V. fastigiata at various temperatures (50 °C, 100 °C, 150 °C and 200 °C). Ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-qTOF-MS) analysis in combination with chemometric methods, particularly principal component analysis (PCA) and liquid/gas chromatography mass spectrometry (XCMS) cloud plots, were used to descriptively visualize the data and identify significant metabolites extracted at various temperatures. A total of 25 different metabolites, including hydroxycinnamic acid derivatives, clovamide, deoxy-clovamide and flavonoids, were noted for the first time in this plant. Overall, an increase in extraction temperature resulted in an increase in metabolite extraction during PHWE. This study is the first scientific report on the phytochemical composition of V. fastigiata, providing insight into the components of the chemo-diversity of this important plant.

Antidiabetic Properties of an Apple/Kale Extract In Vitro, In Situ, and in Mice Fed a Western-Type Diet

Type 2 diabetes mellitus (T2DM) is a common and increasingly prevalent metabolic disorder, and effective preventive strategies against this disease are needed. The aim of the present study was to evaluate the potential antidiabetic properties of a dietary apple/kale extract (AKE), which was rich in phlorizin and flavonoids, in laboratory mice. Mice were fed a control diet, a Western-type high-sugar, high-fat diet (WTD), or a WTD plus AKE for 10 weeks. Body weight, food and energy intake, body composition, and blood glucose level were recorded in addition to the postprandial rise in blood glucose concentration after a single administration of glucose (oral glucose tolerance test, OGTT). Furthermore, changes in glucose-induced short-circuit current (I_SC) in response to AKE and phlorizin administration were evaluated in situ in intestinal tissues with Ussing chambers. In addition, the in vitro inhibition of α-glucosidase by AKE was determined. The present data suggest that supplementation of an AKE to a WTD significantly improved both blood glucose levels and OGTT in mice. Furthermore, in situ uptake of glucose was significantly inhibited by AKE. Finally, we showed that AKE significantly inhibits α-glucosidase activity in vitro. We conclude that AKE exhibits antidiabetic properties by a dual mechanism, including the inhibition of α-glucosidase and sodium-dependent glucose transporter 1 (SGLT1). Thus, AKE has the potential to serve as a natural plant bioactive compound for dietary prevention strategies against T2DM.

A Study about Regioisomeric Hydroquinones with Multiple Intramolecular Hydrogen Bonding

A theoretical exploration about hydrogen bonding in a series of synthetic regioisomeric antitumor tricyclic hydroquinones is presented. The stabilization energy for the intramolecular hydrogen bond (IHB) formation in four structurally different situations were evaluated: (a) IHB between the proton of a phenolic hydroxyl group and an ortho-carbonyl group (forming a six-membered ring); (b) between the oxygen atom of a phenolic hydroxyl group and the proton of an hydroxyalkyl group (seven membered ring); (c) between the proton of a phenolic hydroxyl group with the oxygen atom of the hydroxyl group of a hydroxyalkyl moiety (seven-membered ring); and (d) between the proton of a phenolic hydroxyl group and an oxygen atom directly bonded to the aromatic ring in ortho position (five-membered ring). A conformational analysis for the rotation around the hydroxyalkyl substituent is also performed. It is observed that there is a correspondence between the conformational energies and the IHB. The strongest intramolecular hydrogen bonds are those involving a phenolic proton and a carbonyl oxygen atom, forming a six-membered ring, and the weakest are those involving a phenolic proton with the oxygen atom of the chromenone, forming five-membered rings. Additionally, the synthesis and structural assignment of two pairs of regioisomeric hydroquinones, by 2D-NMR experiments, are reported. These results can be useful in the design of biologically-active molecules.

Characterization and quantification of fruit phenolic compounds of European and Tunisian pear cultivars

The flesh and peel of 19 pear cultivars (8 Tunisian dessert cultivars, 8 European dessert cultivars and 3 French perry pear cultivars) were studied for their phenolic composition. Phenolic compounds were identified by HPLC/ESI-MS² and individually quantified by HPLC-DAD. Five classes of polyphenols were present: flavan-3-ols, phenolic acids, flavonols, anthocyanins and simple phenolics (hydroquinones). The total phenolic content ranged between 0.1g/kg Fresh Weight (FW) ('Conference' cultivar) and 8.6g/kg FW ('Plant De Blanc' cultivar) in the flesh and between 1.6g/kg FW ('William vert' cultivar) and 40.4g/kg FW ('Arbi Chiheb' cultivar) in the peel. Procyanidins, analyzed after thioacidolysis, were the main phenolic compounds in all pear cultivars either in the pulp or the peel, their constitutive units being essentially (-)-epicatechin. Tunisian dessert pears and French perry pears are richer in procyanidins with very high degree of polymerization (>100) for Tunisian pears. Peel procyanidins were less polymerized (from 4 to 20). Pear peel phenolic profile was more complex especially for Tunisian cultivars, with flavonols and in some cultivars anthocyanins.

Analytical method for metabolites involved in biosynthesis of plant volatile compounds

The progress in the successful techniques used for studying metabolites involved in the metabolic routes of plant volatiles is summarized.

Determination of the Phenolic Composition and Antioxidant Activity of Pear Extracts

The specific HPLC analytical procedure was developed and validated for the determination of phenolic compounds in pear samples of different popular cultivars “Conference,” “Concordia,” “Grabova,” and “Patten.” HPLC mobile phase consisted of 0.05% (v/v) trifluoroacetic acid in water and 100% (v/v) acetonitrile. The HPLC method was used to identify and confirm the specificity of 8 analytes: chlorogenic acid, rutin, hyperoside, isoquercitrin, isorhamnetin rutinoside, quercitrin, quercitrin malonyl glucoside, and isorhamnetin glucoside. Repeatability % RSD did not exceed 3.87%, and intermediate precision did not exceed 4.63%. The total content of phenolic compounds varied from0.51±0.001 mg/g (cv. “Concordia”) to1.11±0.013 mg/g (cv. “Patten”). Chlorogenic acid was the major component in all the tested pear cultivars. The highest amount of chlorogenic acid (0.69±0.033 mg/g) was found in pear samples of the cultivar “Grabova,” and the highest amount of flavonol compounds (1.11±0.013 mg/g) was found in pear samples of the cultivar “Concordia.”

Volatile Composition and Enantioselective Analysis of Chiral Terpenoids of Nine Fruit and Vegetable Fibres Resulting from Juice Industry By-Products

Fruit and vegetable fibres resulting as by-products of the fruit juice industry have won popularity because they can be valorised as food ingredients. In this regard, bioactive compounds have already been studied but little attention has been paid to their remaining volatiles. Considering all the samples, 57 volatiles were identified. Composition greatly differed between citrus and noncitrus fibres. The former presented over 90% of terpenoids, with limonene being the most abundant and ranging from 52.7% in lemon to 94.0% in tangerine flesh. Noncitrus fibres showed more variable compositions, with the predominant classes being aldehydes in apple (57.5%) and peach (69.7%), esters (54.0%) in pear, and terpenoids (35.3%) in carrot fibres. In addition, enantioselective analysis of some of the chiral terpenoids present in the fibre revealed that the enantiomeric ratio for selected compounds was similar to the corresponding volatile composition of raw fruits and vegetables and some derivatives, with the exception of terpinen-4-ol andα-terpineol, which showed variation, probably due to the drying process. The processing to which fruit residues were submitted produced fibres with low volatile content for noncitrus products. Otherwise, citrus fibres analysed still presented a high volatile composition when compared with noncitrus ones.

Characterization of phenolic and other polar compounds in peel and flesh of pink guava (Psidium guajava L. cv. 'Criolla') by ultra-high performance liquid chromatography with diode array and mass spectrometric detection

Pink guava (Psidium guajava L.) is a highly consumed fruit in tropical countries. Despite of interesting research on health effects of this fruit, investigations into the profile of secondary plant metabolites are scarce. In this study, the phenolic compounds in the peel and flesh of pink guava were characterized by ultra-high performance liquid chromatography with diode array and mass spectrometric detection. Sixty phenolic compounds were characterized by MS² and classified as ellagitannins, flavones, flavonols, flavanols, proanthocyanidins, dihydrochalcones, and anthocyanidins, and non-flavonoids such as phenolic acid derivatives, stilbenes, acetophenones, and benzophenones. Forty-two polyphenols are reported for the first time in both peel and flesh, and twenty-four compounds were detected for the first time in P. guajava, e.g., phlorizin, nothofagin, astringin, chrysin-C-glucoside, valoneic acid bilactone, cinnamoyl-glucoside, and two dimethoxycinnamoyl-hexosides.

The Growth of SGC-7901 Tumor Xenografts Was Suppressed by Chinese Bayberry Anthocyanin Extract through Upregulating KLF6 Gene Expression

To investigate the antitumor effect of anthocyanins extracted from Chinese bayberry fruit (Myrica rubra Sieb. et Zucc.), a nude mouse tumor xenograft model was established. Treatments with C3G (cyanidin-3-glucoside, an anthocyanin) significantly suppressed the growth of SGC-7901 tumor xenografts in a dose-dependent manner. Immunohistochemical staining showed a significant increase in p21 expression, indicating that the cell cycle of tumor xenografts was inhibited. qPCR screening showed that C3G treatment up-regulated the expression of the KLF6 gene, which is an important tumor suppressor gene inactivated in many human cancers. Western blot showed that C3G treatments markedly increased KLF6 and p21 protein levels, inhibited CDK4 and Cyclin D1 expression, but did not notably change the expression of p53. These results indicated that KLF6 up-regulates p21 in a p53-independent manner and significantly reduces tumor proliferation. This study provides important information for the possible mechanism of C3G-induced antitumor activity against gastric adenocarcinoma in vivo.