Rapid and green quantification of phloridzin and trilobatin in Lithocarpus litseifolius (Hance) Chun (sweet tea) using an online pressurized liquid extraction high-performance liquid chromatography at equal absorption wavelength method.

Sweet tea is a functional herbal tea with anti-inflammatory, anti-diabetic, and other effects, in which phloridzin and trilobatin are two functional compounds. However, the current methods for their quantification are time-consuming, costly, and environmentally unfriendly. In this paper, we propose a rapid method that integrates online pressurized liquid extraction and high-performance liquid chromatography featuring a superficially porous column for fast separation. Moreover, we employ an equal absorption wavelength method to eliminate using multiple standard solutions and relative calibration factors. Our verification process corroborated the technique's selectivity, accuracy, precision, linearity, and detection limitations. Separately, our methodology demonstrated excellent analytical efficiency, cost-effectiveness, and environmental friendliness. Practical application using six distinct batches of sweet tea samples yielded results in congruence with the external standard method. The analytical rate of this technique is up to over 18 times faster than traditional methods, and organic solvent consumption has been reduced to less than 1.5 mL. Therefore, this method provides a valuable way to achieve quality control and green analysis of sweet tea and other herbal teas.

Comparative metabolomics reveal intraspecies variability in bioactive compounds of different cultivars of pomegranate fruit (Punica granatum L.) and their waste by-products.

BACKGROUND: The different parts of pomegranate fruit are considered a powerful mixture of bioactive compounds yet the peels and pulps of the fruits are usually discarded and considered as industrial waste. In this work, ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-QqQ-MS) was utilized for metabolomics analysis of different parts (peel, pulp, seed and juice) of pomegranate fruit cultivars to verify possible variations among the fruits and their waste products as potential sources of functional constituents. RESULTS: Orthogonal projection to latent structure-discriminant analysis (OPLS-DA) coefficient-plot showed enrichment of phenolic compounds such as punicalagin and ellagic acid derivatives in pulp samples while seeds class was enriched in phlorizin, catechin and quercetin, juice class showed abundance of naringenin and pelargonidin-3-pentoside while peels were enriched in anthocyanins and flavonoids including cyanidin diglycoside, quercetin and luteolin glycosides. Although the juice samples of almost all tested cultivars showed remarkable cytotoxic activity, the pulp samples, particularly the Manfalouti cultivar, exhibited the most potent [half maximal inhibitory concentration (IC50 ) = 2.367 ± 0.14 µg/mL in MCF-7, IC50  = 3.854 ± 0.23 µg/mL in Hep-G2 cell lines]. OPLS models were constructed for determination of cytotoxicity-associated metabolites among where the coefficients plots revealed tannins; granatin A, ellagic acid derivatives, punicalagin α and ß, in addition to anthocyanins and phenolic compounds; cyanidin diglycoside, quercetin, phlorizin, 3-O-caffeoylquinic acid, naringenin and liquiritin were more pertinent with cytotoxicity of the different parts of pomegranate fruit. CONCLUSION: The results obtained allow for the full utilization of the resources of pomegranate fruit and its industrial waste as sources of bioactive compounds. © 2022 Society of Chemical Industry.

Mitigation effects of phlorizin immersion on acrylamide formation in fried potato strips.

BACKGROUND: Several researches reported that natural polyphenols affected acrylamide formation of fried products. However, the effects of different variety of polyphenols on acrylamide formation were distinct. In this study, we isolated and purified phlorizin from apples and identified the influence of phlorizin immersion on acrylamide formation and sensory properties of fried potato strips with regard to the immersion concentration, time and temperature. RESULTS: The acrylamide formation of fried samples decreased as the phlorizin concentration increased from 0 to 0.3 g kg-1 , and 0.14 g kg-1 could be selected as the suitable immersion concentration to dramatically inhibit acrylamide formation with considering the cost of industrial production. Additionally, the acrylamide formation significantly reduced from 8.71 × 10-3 to 2.13 × 10-3 g kg-1 lyophilized weight (LW) with immersion time from 0 to 120 min, and 60 min could be selected to significantly reduce acrylamide formation in consideration of efficiency of the large-scale industrial processing. However, the effect of phlorizin immersion temperature on acrylamide formation of fried samples was not significant. Compared to the fried samples without immersion, the phlorizin immersion improved the color properties and the change of texture parameters was slight. CONCLUSION: The fresh potato strips immersed in the phlorizin solution of 0.14 g kg-1 at 40 °C for 60 min before frying could significantly decrease acrylamide formation of fried samples and retain the majority of fresh sensorial properties. The significant correlations obtained between sensory properties and acrylamide content indicated the sensory properties could be used as the indicator of acrylamide levels during industrial processing. © 2020 Society of Chemical Industry.

The Qualitative and Quantitative Compositions of Phenolic Compounds in Fruits of Lithuanian Heirloom Apple Cultivars.

As the interest in heirloom cultivars of apple trees, their fruit, and processed products is growing worldwide, studies of the qualitative and quantitative composition of biological compounds are important for the evaluation of the quality and nutritional properties of the apples. Studies on the variations in the chemical composition of phenolic compounds characterized by a versatile biological effect are important when researching the genetic heritage of the heirloom cultivars in order to increase the cultivation of such cultivars in orchards. A variation in the qualitative and quantitative composition of phenolic compounds was found in apple samples of cultivars included in the Lithuanian collection of genetic resources. By the high-performance liquid chromatography (HPLC) method flavan-3-ols (procyanidin B1, procyanidin B2, procyanidin C2, (+)-catechin and (-)-epicatechin), flavonols (rutin, hyperoside, quercitrin, isoquercitrin, reynoutrin and avicularin), chlorogenic acids and phloridzin were identified and quantified in fruit samples of heirloom apple cultivars grown in Lithuania. The highest sum of the identified phenolic compounds (3.82 ± 0.53 mg/g) was found in apple fruit samples of the 'Kostele' cultivar.

Phenolic composition of 91 Australian apple varieties: towards understanding their health attributes.

INTRODUCTION: Apples, an important contributor to total dietary phenolic intake, are associated with cardiovascular health benefits. Determining the phenolic composition of apples, their individual variation across varieties, and the phenolic compounds present in plasma after apple consumption is integral to understanding the effects of apple phenolics on cardiovascular health. METHODS: Using liquid chromatography we quantified five important polyphenols and one phenolic acid with potential health benefits: quercetin glycosides, (-)-epicatechin, procyanidin B2, phloridzin, anthocyanins, and chlorogenic acid, in the skin and flesh of 19 apple varieties and 72 breeding selections from the Australian National Apple Breeding program. Furthermore, we measured the phenolic compounds in the plasma of 30 individuals post-consumption of an identified phenolic-rich apple, Cripp's Pink. RESULTS: Considerable variation in concentration of phenolic compounds was found between genotypes: quercetin (mean ± SD: 16.1 ± 5.9, range: 5.8-30.1 mg per 100 g); (-)-epicatechin (mean ± SD: 8.6 ± 5.8, range: 0.2-19.8 mg per 100 g); procyanidin B2 (mean ± SD: 11.5 ± 6.6, range: 0.5-26.5 mg per 100 g); phloridzin (mean ± SD: 1.1 ± 0.6, range: 0.3-4.3 mg per 100 g); anthocyanins (mean ± SD: 1.8 ± 4.4, range: 0-40.8 mg per 100 g); and chlorogenic acid (mean ± SD: 11.3 ± 9.9, range: 0.4-56.0 mg per 100 g). All phenolic compounds except chlorogenic acid were more concentrated in the skin compared with flesh. We observed a significant increase, with wide variation, in 14 phenolic compounds in plasma post-consumption of a phenolic-rich apple. CONCLUSION: This information makes an important contribution to understanding the potential health benefits of apples.

Apple polyphenol-rich drinks dose-dependently decrease early-phase postprandial glucose concentrations following a high-carbohydrate meal: a randomized controlled trial in healthy adults and in vitro studies.

BACKGROUND: Previous research demonstrated that a high dose of phlorizin-rich apple extract (AE) can markedly inhibit early-phase postprandial glycemia, but efficacy of lower doses of the AE is unclear. OBJECTIVE: To determine whether lower AE doses reduce early-phase postprandial glycemia in healthy adults and investigate mechanisms. DESIGN: In a randomized, controlled, double-blinded, cross-over acute trial, drinks containing 1.8 g (HIGH), 1.35 g (MED), 0.9 g (LOW), or 0 g (CON) of a phlorizin-rich AE were consumed before 75 g starch/sucrose meal. Postprandial blood glucose, insulin, C-peptide, glucose-dependent insulinotropic polypeptide (GIP) and polyphenol metabolites concentrations were measured 0-240 min, acetaminophen concentrations to assess gastric emptying rate, and 24 h urinary glucose excretion. Effects of AE on intestinal glucose transport were investigated in Caco-2/TC7 cells. RESULTS: AE significantly reduced plasma glucose iAUC 0-30 min at all doses: mean differences (95% CI) relative to CON were -15.6 (-23.3, -7.9), -11.3 (-19.6, -3.0) and -8.99 (-17.3, -0.7) mmol/L per minute for HIGH, MEDIUM and LOW respectively, delayed Tmax (HIGH, MEDIUM and LOW 45 min vs. CON 30 min), but did not lower Cmax. Similar dose-dependent treatment effects were observed for insulin, C-peptide, and GIP. Gastric emptying rates and urinary glucose excretion did not differ. Serum phloretin, quercetin and epicatechin metabolites were detected postprandially. A HIGH physiological AE dose equivalent decreased total glucose uptake by 48% in Caco-2/TC7 cells. CONCLUSIONS: Phlorizin-rich AE, even at a low dose, can slightly delay early-phase glycemia without affecting peak and total glycemic response.

Simultaneous extraction and separation of bioactive compounds from apple pomace using pressurized liquids coupled on-line with solid-phase extraction.

The objective of this work was the development of an on-line extraction/fractionation method based on the coupling of pressurized liquid extraction and solid-phase extraction for the separation of phenolic compounds from apple pomace. Several variables of the process were evaluated, including the amount of water of the first stage (0-120 mL), temperature (60-80 °C), solid-phase extraction adsorbent (Sepra, Isolute, Strata X and Oasis) and activation/elution solvent (methanol and ethanol). The best results were observed with the adsorbent Sepra. The temperature had a small effect on recovery, but significant differences were observed for phlorizin and a quercetin derivative. Results indicate that ethanol can be used to replace methanol as an activation, extraction/elution solvent. While using mostly green solvents (water, ethanol, and a small amount of methanol that could be reused), the developed method produced higher or similar yields of acids (2.85 ± 0.19 mg/g) and flavonoids (0.97 ± 0.11 mg/g) than conventional methods.

Quantitation of dietary dihydrochalcones in Indian crabapple (Malus sikkimensis) using validated high-performance liquid chromatography.

In the present study, a systematic validated method was developed for the determination of two key dietary dihydrochalcones (DHC) viz. phloridzin (PZ) and phloretin (PT) in the leaves of Sikkim crabapple (Malus sikkimensis) using HPLC-Photo Diode Array (PDA). Chromatographic separation was optimized on a C18 column using a gradient elution of water/acetonitrile with the flow rate of 1.0 mL/min at 25°C at 280 nm. Sample preparation approach is rapid and energy efficient, and it requires no pre-concentration before analysis. Validation showed a good analytical performance in terms of specificity, linearity (r2 > 0.999), precision (% RSD < 1.08), recovery (97-100.4%) and sensitivities (limits of detection: 12.48 and 14.95 ng/mL; limit of quantification: 41.61 and 49.85 ng/mL) of PZ and PT, respectively. Developed approach was employed for targeted phytochemical analysis in the bark and fruits of M. sikkimensis. The PZ content in the bark and leaves was highest (12-13 mg/100 mg), about 90-fold higher than fruits. PT was only present in the leaves (0.57 mg/100 mg). The comparative data on PZ and PT content in various wild apple species/cultivar from different countries have also been discussed. The reliability of the validated method was established by analyzing global and expanded uncertainties in two DHC determinations in wild apple. The present method fulfills the technical requirement of ISO 17025:2017 for quality control of M. sikkimensis.

Chemical Fingerprint and Quantitative Analysis for the Quality Evaluation of Docynia dcne Leaves by High-Performance Liquid Chromatography Coupled with Chemometrics Analysis.

Docynia dcne leaf from the genus of Docynia Dcne (including three species of Docynia delavayi, Docynia indica and Docynia longiunguis.) is an important raw material of local ethnic minority tea, ethnomedicines and food supplements in southwestern areas of China. However, D. dcne leaves from these three species are usually used confusingly, which could influence the therapeutic effect of it. A rapid and effective method for the chemical fingerprint and quantitative analysis to evaluate the quality of D. dcne leaves was established. The chemometric methods, including similarity analysis, hierarchical cluster analysis and partial least-squares discrimination analysis, were applied to distinguish 30 batches of D. dcne leaf samples from these three species. The above results could validate each other and successfully group these samples into three categories which were closely related to the species of D. dcne leaves. Moreover, isoquercitrin and phlorizin were screened as the chemical markers to evaluate the quality of D. dcne leaves from different species. And the contents of isoquercitrin and phlorizin varied remarkably in these samples, with ranges of 6.41-38.84 and 95.73-217.76 mg/g, respectively. All the results indicated that an integration method of chemical fingerprint couple with chemometrics analysis and quantitative assessment was a powerful and beneficial tool for quality control of D. dcne leaves, and could be applied also for differentiation and quality control of other herbal preparations.

Preparation and evaluation of magnetic molecularly imprinted polymers for the specific enrichment of phloridzin.

In present study, magnetic molecularly imprinted polymers (MMIPs) were successfully prepared for specific recognition and selective enrichment of phloridzin from the leaves of Malus doumeri (Bois) A. Chev and rats' plasma. The magnetic Fe3O4 were prepared by the solvothermal reaction method and followed by the modification of TEOS and functionalization with APTES. Using functionalized Fe3O4 particles as the magnetic cores, phloridzin as template, ethylene glycol dimethacrylate (EGDMA) as cross-linker and 2,2-azobisisobutyonnitrile (AIBN) as initiator, the MMIPs were prepared through APTES to associate the template on the surface of the magnetic substrate. The structural features and morphological characterizations of MMIPs were performed by FT-IR, SEM, TEM, XRD, TGA and VSM. The adsorption experiments revealed that the MMIPs presented high selective recognition property to phloridzin. The selectivity experiment indicated that the adsorption capacity and selectivity of polymers to phloridzin was higher than that of baicalin and 2,3,5,4'-ttrahydroxy stilbene-2-O-ß-D-glucoside. Furthermore, the MMIPs were employed as adsorbents for extraction and enrichment of phloridzin from the leaves of M. doumeri and rats' plasma. The recoveries of phloridzin in the leaves of M. doumeri ranged from 81.45% to 90.27%. The maximum concentration (Cmax) of phloridzin in rats' plasma was detected as 12.19 ± 0.84µg/mL at about 15min after oral administration of phloridzin (200mg/kg). These results demonstrate that the prepared MMIPs are suitable for the selective adsorption of phloridzin from complex samples such as natural medical plants and biological samples.

Hepatoprotective effect against CCl4-induced acute liver damage in mice and High-performance liquid chromatography mass spectrometric method for analysis of the constituents of extract of Rubus crataegifolius.

This study is an attempt to evaluate the hepatoprotective activity of Rubus Crataegifolius against carbon tetrachloride-induced liver injury in mice. 70% ethanolic, ethyl acetate and n-BuOH extract of R. crataegifolius were administered daily for 14 days in experimental animals before they were treated with CCl4. The hepatoprotective activity of the extracts in this study was compared with the reference drug silymarin. A high-performance liquid chromatography mass spectrometric (HPLC-EIS-MS/MS) method was developed for the determination of the constituents of the extracts. According to the data of HPLC-EIS-MS/MS, the chemical structures of the largely 14 constituents of R. crataegifolius were identified online without time-consuming isolation. Ethyl acetate extracts of R. crataegifolius showed strong antioxidant activities and significant protective effect against acute hepatotoxicity induced by CCl4. According to the data of HPLC-EIS-MS/MS, Oleanic acid, Phlorizin dehydrate and Quercetin-3-rhamnoside are considered as the main hepatoprotective factor in ethyl acetate extract.

Mitochondrial dysfunction in H9c2 cells during ischemia and amelioration with Tribulus terrestris L.

AIMS: The present study investigates the protective effect of partially characterized Tribulus terrestris L. fruit methanol extract against mitochondrial dysfunction in cell based (H9c2) myocardial ischemia model. MAIN METHODS: To induce ischemia, the cells were maintained in an ischemic buffer (composition in mM -137 NaCl, 12 KCl, 0.5 MgCl2, 0.9 CaCl2, 20 HEPES, 20 2-deoxy-d-glucose, pH-6.2) at 37°C with 0.1% O2, 5% CO2, and 95% N2 in a hypoxia incubator for 1h. Cells were pretreated with various concentrations of T. terrestris L. fruit methanol extract (10 and 25µg/ml) and Cyclosporin A (1µM) for 24h prior to the induction of ischemia. KEY FINDINGS: Different parameters like lactate dehydrogenase release, total antioxidant capacity, glutathione content and antioxidant enzymes were investigated. Studies were conducted on mitochondria by analyzing alterations in mitochondrial membrane potential, integrity, and dynamics (fission and fusion proteins - Mfn1, Mfn2, OPA1, Drp1 and Fis1). Various biochemical processes in mitochondria like activity of electron transport chain (ETC) complexes, oxygen consumption and ATP production was measured. Ischemia for 1h caused a significant (p≤0.05) increase in LDH leakage, decrease in antioxidant activity and caused mitochondrial dysfunction. T. terrestris L. fruit methanol extract pretreatment was found effective in safeguarding mitochondria via its antioxidant potential, mediated through various bioactives. HPLC of T. terrestris L. fruit methanol extract revealed the presence of ferulic acid, phloridzin and diosgenin. SIGNIFICANCE: T. terrestris L. fruit ameliorate ischemic insult in H9c2 cells by safeguarding mitochondrial function. This validates the use of T. terrestris L. against heart disorders.

Inhibitory effects of selected dietary flavonoids on the formation of total heterocyclic amines and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in roast beef patties and in chemical models.

In this study, the inhibitory effects of eight kinds of dietary flavonoids on the formation of heterocyclic amines (HAs) were investigated in roast beef patties. The results showed that most of them exhibited significant inhibition on both total HAs and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), one of the most abundant HAs. Among the studied flavonoids, phlorizin, epigallocatechin gallate (EGCG), and quercetin were found to be the most effective in both the reductions of total HAs (55-70%) and PhIP (60-80%). The reaction activity between the flavonoid and phenylacetaldehyde, a key intermediate in PhIP formation, showed a good correlation with the inhibition of PhIP formation in an aqueous model system (R(2) = 0.8904) and a di(ethylene) glycol reaction system (R(2) = 0.6514). However, no significant correlation was found between the flavonoid antioxidant capacity and PhIP formation (R(2) = 0.2359). The postulated adducts of flavonoids-phenylacetaldehyde were further confirmed by LC-MS analysis in the chemical models. Since phenylacetaldehyde is the chief intermediate in PhIP formation, these results suggest that the inhibitory effects of flavonoids on PhIP formation are mainly dependent on their abilities to trap phenylacetaldehyde as opposed to their antioxidant capacities.

[Simultaneous determination of quercitrin, phloridzin and 3-hydroxyl phloridzin in leaves of Malus halliana by ultrasound-assisted ionic liquid-reversed phase liquid chromatography].

To establish a method for the simultaneous determination of phloridzin, 3-hydroxy phloridzin and quercitrin in leaves of Malus halliana by ultrasonic-assisted ionic liquid coupled with RP-HPLC. An Agilent TC-C18 (4.6 mm×250 mm, 5 µm) column was used, with the mobile phase of acetonitrile and 1% phosphoric acid-water (20∶80) by gradient elution at the detection wavelength of 270 nm. The flow rate was 0.8 mL•min⁻¹, and chromatographic column temperature was controlled at the room temperature. Under the optimized conditions, the linear ranges for phloridzin, 3-hydroxy phloridzin and quercitrin were 0.9-112.5 µg (r = 0.999 6), 0.093 2-11.65 µg (r = 0.999 1) and 0.097 2-12.15 µg (r = 0.999 8), respectively. The average recoveries of the three constituents were 99.35%, 98.80% and 98.19%, respectively. The method was environmental friendly, rapid, accurate and highly reproducible, and so suitable for the quantitative analysis of phloridzin, 3-hydroxy phloridzin and quercitrin in leaves of M. halliana.

UPLC-PDA quantification of chemical constituents of two different varieties (golden and royal) of apple leaves and their antioxidant activity.

BACKGROUND: Malus domestica is the most widely cultivated fruit tree and is well known for its therapeutic value. Apple leaves are known to contain phenolic compounds but the nature of these has not been explored to the same extent as in apple fruit. A simple, rapid and sensitive ultra-performance liquid chromatography-diode array detection (UPLC-DAD) quantification method has been developed. Total polyphenol and flavonoid contents, as well as the antioxidant activity of golden and royal apple leaves were evaluated. RESULTS: Four compounds, namely rutin, 3-hydroxyphloridzin, phloridzin and quercetin-3-O-arabinoside were identified by UPLC. The separation was achieved in less than 7 min. Total polyphenol and flavonoid contents were found to be slightly higher in apple golden variety than royal variety. The IC50 values determined by the DPPH assay were 49.94 µg mL(-1) for golden apple leaves and 43.89 µg mL(-1) for royal apple leaves. IC50 values determined by the ABTS assay were 47.10 and 66.53 µg mL(-1) for golden and royal apple leaves, respectively. Antioxidant activity was determined as 24.45 and 21.15 mg ascorbic acid g(-1) for golden and royal apple leaves, respectively, by using the FRAP assay. CONCLUSION: This study showed that apple leaves (both varieties) contain considerable amounts of polyphenols and flavonoids and are also a promising source of phloridzin.

Acute anti-hyperglycaemic effects of an unripe apple preparation containing phlorizin in healthy volunteers: a preliminary study.

BACKGROUND: The health-promoting properties of apples are directly related to the biologically active compounds that they contain, such as polyphenols. The objective of this study was to prepare a low-sugar, fibre- and phlorizin-enriched powder from unripe apples and to gain insight regarding its anti-hyperglycaemic activity in healthy volunteers. RESULTS: The unripe apples (Malus domestica Borkh.) were collected 30 days after the full bloom day; blanched and pressed to obtain apple pomace which was then processed with a food cutter, oven-dried and milled to prepare apple powder. The concentrations of total sugars, water-soluble pectin and phlorizin in the apple preparation were 153.44 ± 2.46, 27.73 ± 0.51 and 12.61 ± 0.15 g kg(-1), respectively. Acute ingestion of the apple preparation improved glucose metabolism in the oral glucose tolerance test (OGTT) in six healthy volunteers by reducing the postprandial glucose response at 15 to 30 min by approximately two-fold (P < 0.05) and by increasing urinary glucose excretion during the 2- to 4-h interval of the OGTT by five-fold (P < 0.05). CONCLUSION: The results obtained indicate that the dried and powdered pomace of unripe apples can be used as a health-promoting natural product for the reduction of postprandial glycaemia and to improve the health of patients with diabetes.

Biochemical and antimicrobial activity of phloretin and its glycosilated derivatives present in apple and kumquat.

Phloretin and its glycosylated derivatives (phlorizin and phloretin 3',5'-di-C-glucoside) are dihydrochalcones that have many interesting biological properties. The results obtained showed that the dihydrochalcones are able to inhibit growth of Gram positive bacteria, in particular Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 13932 and methicillin-resistant S. aureus clinical strains. Moreover, phloretin is active also against the Gram negative bacteria Salmonella typhimurium ATCC 13311. The determination of the enzymatic activity of key metabolic enzymes allowed us to shed some light on the biochemical mechanism of aglycon cell growth inhibition, showing as it remarkably influences the energetic metabolism of S. aureus. In addition, structure/activity determinations highlighted that the presence of a glycosyl moiety bound to the chalcone structure dramatically decreases the antimicrobial activity of phloretin.

Time of methyl jasmonate application influences the development of 'Cripps Pink' apple fruit colour.

BACKGROUND: The effects of time and numbers of pre-harvest sprays of methyl jasmonate (MJ) on the development of red blush, export-grade fruit, accumulation of flavonoids in fruit skin and quality of 'Cripps Pink' apple were investigated in 2005 and 2006. In the first experiment during 2005, whole trees were sprayed once with 10 mmol L(-1) MJ at weekly intervals from 155 to 183 days after full bloom (DAFB). In second experiment during 2006, different numbers of sprays (0, 1, 2, 3, 4, 5 or 6) of 5 mmol L(-1) MJ were applied from 151 to 179 DAFB. RESULTS: A single spray of MJ (10 mmol L(-1)) at 169 DAFB resulted in the highest increase in the red blush, export-grade fruit, accumulation of anthocyanins, cyanidin 3-galactosides, chlorogenic acid, phloridzin, flavanols and flavonols in fruit skin as compared to all other treatments without affecting fruit quality. A single spray of 5 mmol L(-1) MJ at 186 DAFB was more effective in improving red blush, export-grade fruit and accumulation of anthocyanins in fruit skin as compared to its multiple applications. The exposed sides of fruit developed better colour than the shaded sides, regardless of time and numbers of MJ sprays. Time of a single spray of MJ is more effective than its multiple applications. CONCLUSIONS: A single pre-harvest spray of MJ (10 mmol L(-1)) at 169 DAFB or MJ (5 mmol L(-1)) at 186 DAFB was effective in improving the red blush and export grade fruit through accumulation of flavonoids in fruit skin without adversely affecting quality at harvest.

[Study on the flavon ingredients of Malus hupehensis].

OBJECTIVE: To investigate the flavon ingnedients of Malus hupehensis, Malus toringoides and Malus hupehensis var. pinyiensis. METHODS: TLC was used for the qualitative identification of Malus hupehensis, Malus toringoides and Malus hupehensis var. pinyiensis. The content of total flavonoids was determined by UV spectrophotometry and the content of phlorizin was determined by HPLC. RESULTS: The TLC spots were clear and well separated. The maximum absorption wavelength of phlorizin was 287 nm. The content of total flavonoids of 6 batches of Malus hupehensis ranged from 19.65 mg/g to 20.97 mg/g, Malus toringoides ranged from 10.71 mg/g to 12.13 mg/g and Malus hupehensis var. pinyiensis. ranged from 3.49 mg/g to 3.67 mg/g. The content of phlorizin of Malus hupehensis was 15.51 mg/g, Malus toringoides was 14.66 mg/g and Malus hupehensis var. pinyiensis was 2.05 mg/g. CONCLUSION: Established method is applicable for the study of flavonoid compositione ingredients.

[Determination of the content of phloridzin using reversed-phase high-performance liquid chromatography].

OBJECTIVE: To establish a reversed-phase high-performance liquid chromatographic (RP-HPLC) method for determination of phloridzin content. METHODS: A RP-HPLC method was established for determination of phloridzin using an Inertsil ODS-3 (4.6×150 mm, 5 µm) column with the detection wavelength of 288 nm, flow rate of 1.0 ml/min, and column temperature of 25 degrees celsius;. RESULTS: The result showed that the phloridzin had a good linear relationship when its concentration ranged between 0.5988 and 89.72 µg/ml. The regression equation was Y=46.370 X-0.6728 (r=0.9999, n=3). The average recovery of phloridzin was 99.40% with the relative standard deviations (RSD) of 0.67%. CONCLUSION: This method is simple, quick and accurate for determination of phloridzin content.