Mohamed A. Awad

Flavonoid and chlorogenic acid levels in apple fruit: characterisation of variation

Abstract Variations in flavonoid and chlorogenic acid levels within fruit, within tree, between orchards, between cultivars and among mutants were characterised and quantified in ‘Elstar’ and ‘Jonagold’ apples by reversed-phase high performance liquid chromatography (RP-HPLC). The sun-exposed skin of individual fruit had much higher cyanidin 3-galactoside (anthocyanin) and quercetin 3-glycoside levels than the shaded skin, while phloridzin, catechins and chlorogenic acid were similar in the skin of both sides. Individual flavonoid and chlorogenic acid levels were not equally distributed within the fruit. Quercetin 3-glycosides and anthocyanin were almost exclusively found in the skin. Catechins were mostly found in the skin but some were present in the flesh. Phloridzin was most abundant in the seeds, with intermediate levels in both the core area and the skin, and the lowest level in the flesh. Chlorogenic acid was mainly present in the core area and the seeds with an intermediate level in the flesh and a low level in the skin. The levels of anthocyanin, quercetin 3-glycosides and total flavonoids were highest in fruit borne in the top of the tree followed by fruit from the outer tree parts, whereas the lowest levels were found in fruit from the inner tree. Terminal fruit contained the highest levels of these compounds, including catechins, compared to lateral and spur fruit. Phloridzin and chlorogenic acid were not affected by the position of the fruit in the tree nor by the bearing wood type. There were large differences in flavonoid and chlorogenic acid levels in ‘Elstar’ fruit between two normally productive orchards differing mainly in growth vigour. ‘Jonagold’ and its mutants had considerably higher levels of flavonoid and chlorogenic acid than ‘Elstar’ and its mutants. The most blushed mutants of both cultivars had higher levels of anthocyanin but not of flavonoids or chlorogenic acid compared to the standard cultivar and to the less blushed mutants. The most blushed mutants had a higher number of red cells per cell layer and more cell layers containing red cells than the standard cultivar and the less blushed mutants.

Effects of light on flavonoid and chlorogenic acid levels in the skin of ‘Jonagold’ apples

Abstract The objective of our work was to determine how fruit position on the tree affects flavonoid and chlorogenic acid contents. Light was measured at different positions within the canopy of 10-year-old ‘Jonagold’ apple trees on M.9 rootstock raised as slender spindles. Fruit from the top of the canopy contained the highest percentage of blush and the highest levels of cyanidin 3-galactoside (anthocyanin) and quercetin 3-glycosides, followed by fruit from the outside of the canopy, and then those from the canopy interior. There were no significant differences in the levels of catechins, phloridzin and chlorogenic acid among fruit from the different canopy positions. Light level was directly correlated with the levels of cyanidin 3-galactoside and quercetin 3-glycosides and with the percentage of blush in the fruit skin. Light in the interior of the canopy was poorer in UV-A, blue, green and red but richer in far-red light than at all other positions. Consequently, the FR/R ratio was much larger at the interior of the canopy than at all other positions. Both anthocyanin and quercetin 3-glycoside concentrations were clearly related to light level, and there was a critical FR/R ratio of about 1 below which no anthocyanin and only minimal quercetin 3-glycosides were formed.

Flavonoid and chlorogenic acid changes in skin of ‘Elstar’ and ‘Jonagold’ apples during development and ripening

Abstract Apple fruits are important dietary sources of potentially healthy phenolics. In two successive seasons, changes in the concentration and amount of individual flavonoids and chlorogenic acid during development and ripening were investigated by reversed-phase high performance liquid chromatography (RP-HPLC), in ‘Elstar’ and ‘Jonagold’ apples from the outside and the inside of the tree canopy. ‘Jonagold’ had a higher concentration and amount of flavonoids and chlorogenic acid than ‘Elstar’ during fruit development and ripening. In both cultivars, the concentration on a dry weight basis of quercetin glycosides, phloridzin and chlorogenic acid was highest early in the season, but decreased at different rates during fruit development to reach a steady level during maturation and ripening. Catechins (catechin plus epicatechin) concentration showed a similar pattern, but a temporary increase was observed in an early stage of development. The concentration of cyanidin 3-galactoside (anthocyanin) was relatively high early in the season, gradually decreased to a very low steady level during growth, but started to increase near maturation, especially in the outer fruit. On a fruit basis the amount of quercetin glycosides increased during development and was about two times higher in ‘Jonagold’ compared to ‘Elstar’, both in outer and inner fruit. These compounds were the most abundant flavonoids in the skin of both cultivars and their accumulation showed a strong dependency on fruit position on tree. In contrast, the amount of the second most abundant flavonoid type, catechins, increased during development to a maximum and then showed some decrease by mid season which was independent of fruit position on tree. The amount of phloridzin increased only early in the season reaching a steady level during development and ripening, and was independent of fruit position on tree. The amount of chlorogenic acid in both cultivars initially increased, but subsequently decreased to reach a low, steady level and was slightly higher in outer than in inner fruit. Although anthocyanin concentration was relatively high at early stages of development, significant accumulation on a fruit basis only occurred during maturation and ripening. The accumulation of anthocyanin, similar to that of quercetin glycosides, showed a strong dependency on fruit position on tree. Remarkably, the difference in accumulation of anthocyanin and quercetin glycosides in outer and in inner fruits had no effect on the accumulation of catechins, phloridzin and chlorogenic acid in these fruits. The results indicate that, in general, the overall production of total flavonoids and chlorogenic acid in apple skin is completed during fruit development before the onset of maturation.

Relationships between fruit nutrients and concentrations of flavonoids and chlorogenic acid in ‘Elstar’ apple skin

Abstract The relationships between fruit N, P, K, Mg and Ca concentrations during the season and flavonoid and chlorogenic acid concentrations in skin of ‘Elstar’ apples at maturity have been studied during three seasons in a nutrition experiment (with the mutant ‘Elshof’), and in a separate experiment with standard ‘Elstar’ using within-tree variation in nutrient concentration due to fruit position in the tree. Negative correlations were frequently found between the concentration of N and Mg and the N/Ca ratio, and occasionally with that of K, in fruit during growth and at maturity, and anthocyanin and total flavonoids concentration at maturity. Calcium concentration showed occasionally positive correlations with anthocyanin and total flavonoids concentration. Chlorogenic acid concentration showed only in the second experiment a correlation with some of the studied nutrients (positive with P and Ca and negative with N, K, Mg and N/Ca). Regression models accounted for up to 40 and 30% of the variance in anthocyanin and total flavonoids concentration of ‘Elshof’ mutant apples, and up to 70 and 65% of the variance in anthocyanin and total flavonoids concentration of standard ‘Elstar’ apples, respectively. The most important variable in predictive models for the anthocyanin and total flavonoids concentration was N concentration in the fruit. The results suggest that the concentration of flavonoids in fruit skin could be increased by optimising fertilisation, especially that of N.

Formation of flavonoids, especially anthocyanin and chlorogenic acid in ‘Jonagold’ apple skin: influences of growth regulators and fruit maturity

Abstract The influences of ethephon, ( S )- trans -2-amino-4-(2-aminoethoxy)-3-butenoic acid hydrochloride (ABG-3168), gibberellins (GA 4+7 and GA 3 ), alar, cycocel (CCC), prohexadione-Ca, seniphos, shikimic acid, plantacur-E and galactose on the accumulation of flavonoids and chlorogenic acid in ‘Jonagold’ apple skin were investigated, with emphasis on anthocyanin, in order to separate maturity-related from other development-related influences. Fruit maturation/ripening as determined by both Streif and Starch indices was not affected by these chemicals though applied according to standard procedures. Ethephon application greatly increased anthocyanin accumulation but not that of other flavonoid compounds and chlorogenic acid compared to the control. ABG and GA 3 applications significantly retarded anthocyanin accumulation but not that of other flavonoid compounds and chlorogenic acid. ABG delayed the transition to fast anthocyanin accumulation by about 2 weeks compared to the control and other treatments. The application of alar, CCC, prohexadione-Ca, GA 4+7 , plantacur-E, shikimic acid, galactose and seniphos did not significantly influence the formation of anthocyanin, total flavonoids and chlorogenic acid in fruit skin. The percentage of blush increased during maturation and was higher in ethephon-treated fruit and lower in ABG and GA 3 -treated fruit compared with the control. The finding that anthocyanin responds much quicker both to ethylene promoting and ethylene inhibiting treatments than other ripening related phenomena suggests that the dependence of anthocyanin synthesis on ethylene is at least complicated.

Biochemical Changes in Fruit of an Early and a Late Date Palm Cultivar During Development and Ripening

The biochemical changes in fruit of an early ‘Lonet-Mesaed’ and a late ‘Helali’ date palm cultivar during development and ripening including the activities of various degradative enzymes were studied. During the 2009 and 2010 seasons, in both cultivars, fruit growth, based on fruit and flesh weight, followed a smooth sigmoidal curve. The fruit and flesh weight gradually increased during development reaching a maximum at the immature green (Bisir) stage, but slightly decreased thereafter during ripening. Moisture percentage was highest at early stages and then gradually decreased to lower levels during the Bisir and the mature firm full-colored (Rutab) stages in both cultivars, with a further sharp decrease at the raisin-like stage (Tamer) in ‘Helali’. The accumulation of both total and reducing sugars in fruit slightly increased during development with a vast increase during maturation and ripening of both cultivars. The concentration of total proteins was highest at early stages and then gradually decreased during development to lower concentrations during ripening. A steady decrease in the membrane stability index (MSI %), as measured by the leakage of ions, was observed upon the progression of fruit development, especially during the Bisir and the Rutab stages, indicates a gradual loss of the membranes stability due to changes occurring in the biochemical and biophysical properties of cell membranes. During the 2009 season, both cultivars possessed polygalacturonase, cellulase xylanase, and α-amylase activities. Within the same fruit, the slightly softened apical half had activity of about 15 and 2 times for polygalacturonase and cellulase, respectively, higher than that of the firm basal half of the same fruit. Moreover, the activity of both xylanase and α-amylase was only detected in the apical tissues. The activities of these enzymes and fruit ripening were closely associated, suggesting their involvement in the ripening process of dates. The differences between the two cultivars in developmental and ripening patterns in conjunction with enzyme activities are discussed.

Three-dimensional finite element analysis of custom-made ceramic dowel made using CAD/CAM technology.

Purpose: This study compares the stress distribution in the structure of a loaded endodontically treated maxillary extracted canine restored with either custom-made zirconia (Cercon) or cast gold dowel and core. Materials and Methods: Standard treatments were implemented to prepare the gutta-percha-filled root canal and dowel space. The tooth along with the dowel and core fabricated pattern resin were prepared to receive an all-ceramic (Cercon) crown. An impression was made for the tooth preparation with the zirconia milled dowel and core in place to fabricate the Cercon crown using CAD/CAM. The restored canine was scanned, and from the scan two models were constructed with the surrounding ligament and bone. Three-dimensional finite element elastic analysis was then carried out for the stress distribution within the different regions of the two models due to a concentrated force of 100 N applied at the mid-lingual area. Analyses were made for three load angulations, vertical, buccolingual horizontal, and an in-between oblique force at 45o. Each region of the models was assumed isotropic and homogeneous. The two restored canines with zirconia and gold were compared in terms of the resulting maximum tensile, compressive, and Von Mises stresses. Results: Generally, there were no significant differences in the maximum stresses in most regions for both models. Von Mises stresses for zirconia dowel and core was 8.966 MPa and for cast gold dowel and core was 8.752 MPa. The maximum tensile stress for zirconia dowel and core was 9.326 MPa, and for cast gold dowel and core was 8.166 MPa. Conclusions: The present work validates the use of CAD/CAM zirconia material for ceramic dowel and cores. Clinical implications: CAD/CAM Zirconia can be used for a custom-made dowel and core in an esthetically demanding zone as an esthetic replacement for a metal cast dowel and core when restoring endodontically treated teeth.PURPOSE This study compares the stress distribution in the structure of a loaded endodontically treated maxillary extracted canine restored with either custom-made zirconia (Cercon) or cast gold dowel and core. MATERIALS AND METHODS Standard treatments were implemented to prepare the gutta-percha-filled root canal and dowel space. The tooth along with the dowel and core fabricated pattern resin were prepared to receive an all-ceramic (Cercon) crown. An impression was made for the tooth preparation with the zirconia milled dowel and core in place to fabricate the Cercon crown using CAD/CAM. The restored canine was scanned, and from the scan two models were constructed with the surrounding ligament and bone. Three-dimensional finite element elastic analysis was then carried out for the stress distribution within the different regions of the two models due to a concentrated force of 100 N applied at the mid-lingual area. Analyses were made for three load angulations, vertical, buccolingual horizontal, and an in-between oblique force at 45(o) . Each region of the models was assumed isotropic and homogeneous. The two restored canines with zirconia and gold were compared in terms of the resulting maximum tensile, compressive, and Von Mises stresses. RESULTS Generally, there were no significant differences in the maximum stresses in most regions for both models. Von Mises stresses for zirconia dowel and core was 8.966 MPa and for cast gold dowel and core was 8.752 MPa. The maximum tensile stress for zirconia dowel and core was 9.326 MPa, and for cast gold dowel and core was 8.166 MPa. CONCLUSIONS The present work validates the use of CAD/CAM zirconia material for ceramic dowel and cores. CLINICAL IMPLICATIONS CAD/CAM Zirconia can be used for a custom-made dowel and core in an esthetically demanding zone as an esthetic replacement for a metal cast dowel and core when restoring endodontically treated teeth.

Total phenolic and flavonoid contents and antioxidant activities of sixteen commercial date cultivars grown in Saudi Arabia

The total phenolic and flavonoid contents and flavonoids/phenolics% of sixteen commercial Saudi date cultivars at the Tamer stage were measured. The antioxidant activities of dates using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) were investigated. A strong correlation was existed between antioxidant activity and phenolic concentration of the date cultivars. Date cultivars had different phenolic and flavonoid patterns and exhibited also different antioxidant capacities. All of the tested cultivars were growing in the same district (Al-madinah Al-Munawwarah), accordingly the observed variations are mainly due to the genetically factor. The results concluded that flavonoid compounds were more sensitive toward DPPH assay than ABTS assay. The correlation of the IC50 between DPPH and ABTS radical scavenging were evaluated. The ABTS assay was more sensitive toward phenolic compounds than DPPH assay for the most tested date cultivars, except of the phenolic compounds of cv. Agwah and cv. Safawi had the same sensitivity toward DPPH and ABTS assays. The results confirmed the antioxidant potential of the most commercial Saudi date cultivars.

Color Variation Between Matched and Fabricated Shades of Different Ceramics

PURPOSE The aim of this study was to evaluate and compare the total color difference (ΔE) between natural teeth and fabricated crowns from three ceramic systems with different thicknesses. MATERIALS AND METHODS The color of ninety maxillary central incisors was measured from the middle third of the labial surface with a Vita Easyshade spectrophotometer. All-ceramic crown preparations with different thicknesses (0.8, 1.2, 1.5 mm) were done on selected teeth (n = 30). Prepared teeth were randomly divided into three equal groups to fabricate ceramic crowns from three ceramic systems, Duceram LFC (DLFC), In-Ceram SPINELL (ICS), and IPS Empress (IPSE). Colors of cemented crowns were measured and compared with their corresponding measurements before preparations. Data were statistically analyzed using two-way ANOVA at 5% significance level. RESULTS A significant difference of ΔE was detected between natural teeth and different thicknesses of crowns constructed from the all-ceramic materials investigated. Comparing the three materials at 0.8 mm thickness revealed that the lowest ΔE was recorded for DLFC, which was significantly different from the other ceramic systems while IPSE showed the highest ΔE. At higher thicknesses there was no difference between natural tooth shade and crowns constructed from different ceramic materials. CONCLUSIONS Reinforcement of ceramics by alumina for In-Ceram and leucite for Empress decreases color production. Level of acceptance between the different ceramic materials and thicknesses varied. DLFC showed the highest color matching at all thicknesses followed by ICS and IPSE in descending order. In general, increasing the thickness of fabricated crowns enhances color match.

Effect of Porcelain Shade and Application Time on Shade Reproduction: Porcelain Shade, Application Time, and Shade Reproduction

PURPOSE To determine the variability in shade reproduction of metal ceramic restorations fabricated by different laboratory technicians at different fabrication times. MATERIALS AND METHODS One hundred thirty five metal copings for metal ceramic restorations were fabricated with a standardized method and distributed among three dental laboratory technicians (n = 45). Each technician was requested to match three different shade specifications including 2L1.5, 3M2, 4R2.5 shade tabs of 3D Master shade guide following the manufacturers instructions. The technicians were instructed to build up each shade 15 times using the same porcelain at three time periods namely first thing in the morning (T1 ), middle of the work day (T2 ), and at the end of the work day (T3 ) (n = 5). Color difference (∆E) was determined with a spectrophotometer. Each restoration was measured and recorded nine times. Data were tabulated and statistically analyzed using a univariate general linear model with Scheffe post hoc test, and one-way ANOVA at 5% level of significance RESULTS: The color difference (∆E) was significantly different among technicians, time of application, and shade matched. Technician 1 demonstrated good color reproduction for all shades in T1 . That was the same as technician 2 for shades 3M2 and 4R2.5, but the lighter shade (2L1.5) was better in T2 and T3 . Technician 3 had better results at T3 . The lowest mean value of ∆E was calculated with technician 3 while the highest mean value was with technician 2. T2 was associated with higher ∆E values in contrast to the other two times for technicians 1 and 2, while T3 was associated with lower ∆E values for technicians 2 and 3. CONCLUSION Within the limitations of this study, it can be concluded that the shade reproduction is affected by the time of porcelain application. The ability to reproduce the target shade differed among laboratory technicians. No specific time can be considered for all technicians to reproduce the shades with more accuracy.