Peel Of Grapefruit Research Articles

CHEMICAL COMPOSITION, ANTIMICROBIAL AND INSECTICIDAL ACTIVITIES OF CITRUS PARADISI PEEL ESSENTIAL OIL FROM ALGERIA

The essential oil obtained by microwave-assisted hydro-distillation (MAHD) and hydrodistillation (HD) techniques from the peel of grapefruit (Citrus paradisi. L) from Algeria was analyzed by gas chromatography–flame ionization detector (GC–FID) and gas chromatography ⁄ mass spectrometry (GC⁄ MS). Twenty-one constituents were identified in essential oils obtained by HD and twenty-eight constituents in essential oils by MAHD, representing respectively 99.11% and 99.74% of the total oil. The main constituents were limonene (85.54%-87.51%) for MAHD and HD, β-myrcene (2.99%-3.24%), nootkatone (1.78%-1.80%). The antimicrobial activity of the essential oils was evaluated by disc diffusion method. The results showed interested inhibition growth against the tested bacteria (Escherichia coli, Pseudomonas aeruginos, and Staphylococcus aureus)and the yeast (Candida albicans),with an inhibition zone ranging from 4 to 20 mm.Both essentials oils showed no effect against Aspergilusniger, Verticillium sp and Thielaviopsis sp. The insecticidal activity was investigated against adults ceratitis capitata. Both essential oils showed a toxic effect against this insect (LD50:9.12μl EO/ml of acetone; LD90: 13.18 μl EO/ml of acetone).

English

The peel of grape fruit is used in traditional medicine for the treatment of several diseases. The objective of this study was to evaluate the antimicrobial, anti-inflammatory and antioxidant activities of peel extract from Citrus paradisi. Qualitative phytochemical screening of peel indicates the presence of alkaloids, flavonoids, sterols, triterpenes, tannins, saponins, coumarins, glycosides, reducing sugars, anthraquinones, lignin and carbohydrates. Extract was assessed for their effectiveness against four bacterial strains including both Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Salmonella typhi) bacteria as well as fungal species (Candida albicans and Aspergillus niger) using disc diffusion method. Antibacterial effects of peel extract showed different degrees of inhibition profiles against tested bacteria with inhibition zone that ranged from 13 to 17 mm. Peel extract showed high antifungal activity against A. niger (24 mm) and C. albicans (22 mm). The C. paradisi peel showed high anti-inflammatory activity with inhibition percentage 77.57%. The antioxidant potential of extract was determined on the basis of their scavenging activity of the 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical stability. The peel extract showed DPPH scavenging activity (55%) and vitamin C content was 23.08 mg/kg by HPLC. The quantitative analysis of chemical composition of the extract was determined by Gas Chromatography–Mass Spectrometry (GC-MS). The results showed high amounts of Naringenin (28.09%). The peel extract of C. paradisi is a natural source of chemical constituents which have medicinal uses in treating many disease. Key words: Citrus paradisi peel, antimicrobial activity, phytochemical screening, vitamin C, Naringenin.

Extraction of Citrus paradisi Volatile Components by Headspace Single-Drop Microextraction and Statistical Modeling.

In present study, headspace single-drop microextraction (HS-SDME) was applied for the extraction and preconcentration of the volatile components of the plant sample into a microdrop surface. The extraction occurred by suspending a microliter drop of the solvent from the tip of a microsyringe to the headspace of a ripe fruit sample (grapefruit Citrus paradisi) in a sealed vial for a preset extraction time. Then the microdrop was retracted back into the microsyringe and injected directly into a gas chromatography injection port. The chemical composition of the SDME extracts was confirmed according to their mass spectra, and quantitative analysis was performed by gas chromatography-flame ionization detector (GC-FID). Response surface methodology along with Box-Behnken design was applied to optimize the extraction condition of four components, d-limonene, β-myrcene, α-pinene and β-pinene, from the peel of grapefruit. Parameters considered for SDME include the kind of the extracting solvent, size of drop, extraction temperature and extraction time. The optimized condition was microdrop volume of 1 µL, extraction time of 2 min and sample temperature of 50°C.

연속수증기증류추출법에 의한 오렌지와 자몽의 휘발성 유기화합물 확인

The volatile flavor components of the fruit pulp and peel of orange (Citrus sinensis) and grapefruit (Citrus paradisi) were extracted by simultaneous distillation-extraction (SDE) using a solvent mixture of n-pentane and diethyl ether (1:1, v/v) and analyzed by gas chromatography-mass spectrometry (GC-MS). The total volatile flavor contents in the pulp and peel of orange were 120.55 and 4,510.81 mg/kg, respectively, while those in the pulp and peel of grapefruit were 195.60 and 4,223.68 mg/kg, respectively. The monoterpene limonene was identified as the major voltile flavor compound in both orange and grapefruit, exhibiting contents of 65.32 and 3,008.10 mg/kg in the pulp and peel of orange, respectively, and 105.00 and 1,870.24 mg/kg in the pulp and peel of grapefruit, respectively. Limonene, sabinene, α-pinene, β-myrcene, linalool, (Z)-limonene oxide, and (E)-limonene oxide were the main volatile flavor components of both orange and grapefruit. The distinctive component of orange was valencene, while grapefruit contained (E)-caryophyllene and nootkatone. δ-3-Carene, α-terpinolene, borneol, citronellyl acetate, piperitone, and β-copaene were detected in orange but not in grapefruit. Conversely, grapefruit contained β-pinene, α-terpinyl acetate, bicyclogermacrene, nootkatol, β-cubebene, and sesquisabinene, while orange did not. Phenylacetaldehyde, camphor, limona ketone and (Z)-caryophyllene were identified in the pulp of both fruits, while α-thujene, citronellal, citronellol, α-sinensal, γ-muurolene and germacrene D were detected in the peel of both fresh fruit samples.

Implication of the antioxidant system in chilling injury tolerance in the red peel of grapefruit

Previous observations have indicated that the red peel areas of grapefruit with high lycopene concentrations were more tolerant to CI than yellow peel areas (Lado et al., 2015a). Because lycopene is a carotene with powerful antioxidant capacity, this study investigated whether the CI tolerance of the lycopene-accumulating rind of grapefruit may be due to an enhancement of the enzymatic and/or non-enzymatic antioxidant systems. Total antioxidant capacity, antioxidant metabolite (GSH and AsA) contents, and antioxidant enzyme (GR [glutathione reductase], ascorbate peroxidase [APX], catalase [CAT] and superoxide dismutase [SOD]) activity and gene expression were measured in the peel of Star Ruby grapefruit with contrasting CI tolerance during storage at 2°C for up to 58d. The peel of CI-tolerant fruit exhibited a lower lipid peroxidation level (MDA content). The hydrogen peroxide concentration was similar after 3 weeks of storage, when the differences in chilling damage between sensitive and tolerant fruit were noticeable, suggesting that the increase in H2O2 is a response of flavedo cells to cold stress that is not necessarily related to the development of CI. Moreover, CI tolerance was not associated with enhancement of either total antioxidant capacity or glutathione and AsA contents, indicating that such antioxidant responses may be cold-mediated and not directly linked to chilling tolerance. Analysis of singlet oxygen scavenging capacity by the SOAC assay revealed considerably higher activity in the lycopene-accumulating peel than in the yellow peel at harvest time and throughout the entire cold storage and shelf-life period. Enzymatic activity and gene expression analyses of GR, APX and SOD did not reveal the involvement of these antioxidant enzymes in the protection against CI. However, high CAT activity was detected in the peel of CI-tolerant fruit, although this difference did not correlate with changes in the expression levels of the CAT1 and CAT2 genes. Therefore, the boost in singlet oxygen scavenging capacity is likely the primary factor responsible for CI tolerance in the lycopene-accumulating peel of grapefruit.

Changes of minerals in fruit peel and pulp of grapefruit(Citrus paradisiMacf.) cv. Star Ruby during fruit development

Concentrations of the macronutrients (N, P, K, Ca and Mg) and micronutrients (Fe, Zn, Mn and Cu) in the fruit peel and pulp from grapefruit cv. Star Ruby fruits were estimated at monthly intervals during fruit development. The general order of abundance of the macronutrients was Ca > K > N > Mg > P in the fruit peel and K > N > Ca > P > Mg in the fruit pulp. Similarly, the abundance of the micronutrients followed the order Fe > Mn > Cu > Zn in the fruit peel and Fe > Zn > Cu > Mn in the fruit pulp. The concentrations of most elements in the fruit peel and pulp decreased during fruit development at 120–210 DAFS. Contents of N and P in the fruit peel decreased from fruit set to fruit maturity. However, both nutrients showed a small rise in concentration towards the end of sampling. Ca content in the fruit pulp decreased up to 180 DAFS and then increased towards maturity. Mn concentrations were relatively constant during fruit development, while there was decrease in concentrations of Zn and Cu in the fruit peel. Overall, the K, Ca, Mg, Fe and Mn level was higher in the fruit peel and the N, P, Zn and Cu level was higher in the fruit pulp. These results provide important data on macronutrient and micronutrient changes during fruit growth and development, emphasizing that grapefruit can be a good source of minerals.

Assessing the biosynthetic capabilities of secretory glands in Citrus peel.

Epithelial cells (ECs) lining the secretory cavities of Citrus peel have been hypothesized to be responsible for the synthesis of essential oil, but direct evidence for such a role is currently sparse. We used laser-capture microdissection and pressure catapulting to isolate ECs and parenchyma cells (as controls not synthesizing oil) from the peel of young grapefruit (Citrus × paradisi 'Duncan'), isolated RNA, and evaluated transcript patterns based on oligonucleotide microarrays. A Gene Ontology analysis of these data sets indicated an enrichment of genes involved in the biosynthesis of volatile terpenoids and nonvolatile phenylpropanoids in ECs (when compared with parenchyma cells), thus indicating a significant metabolic specialization in this cell type. The gene expression patterns in ECs were consistent with the accumulation of the major essential oil constituents (monoterpenes, prenylated coumarins, and polymethoxylated flavonoids). Morphometric analyses demonstrated that secretory cavities are formed early during fruit development, whereas the expansion of cavities, and thus oil accumulation, correlates with later stages of fruit expansion. Our studies have laid the methodological and experimental groundwork for a vastly improved knowledge of the as yet poorly understood processes controlling essential oil biosynthesis in Citrus peel.

Essential oil composition and antibacterial activity of the grapefruit (Citrus Paradisi. L) peel essential oils obtained by solvent‐free microwave extraction: comparison with hydrodistillation

SummaryThe chemical composition of the essential oil (EO) obtained by solvent‐free microwave extraction (SFME) and hydrodistillation (HD) from the peel of grapefruit (Citrus Paradisi. L) was analysed by gas chromatography/mass spectrometry (GC/MS). Totally, twenty‐five components were identified in the EO. Limonene was observed as dominant (91.5–88.6%) for two extraction methods, SFME and HD, respectively. β‐Pinene (0.8–1.2%), linalool (1.1–0.7%), α‐terpinene (0.7–1.0%) and the other minor components were also detected. Disc diffusion method was applied to determine the antibacterial properties of the EO. The results showed that the EO of grapefruit peel had a wide spectrum of antimicrobial activities against Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Salmonella typhimurium, Serratia marcescens and Proteus vulgaris, with their inhibition zones ranging from 11 to 53 mm.

Molecular and functional characterization of a novel chromoplast-specific lycopene β-cyclase from Citrus and its relation to lycopene accumulation

Carotenoids are the main pigments responsible of the colouration of Citrus fruits. The β-cyclization of lycopene, catalysed by the lycopene β-cyclases (β-LCY), seems to be a key regulatory step of the carotenoid pathway. In the present study, two β-LCYs from orange fruits (Citrus sinensis), named Csβ-LCY1 and Csβ-LCY2 have been isolated and the activity of the encoded proteins was demonstrated by functional analysis. Csβ-LCY1 was expressed at low levels and remained relatively constant during fruit ripening while Csβ-LCY2 showed a chromoplast-specific expression and a marked induction in both peel and pulp of orange fruits in parallel with the accumulation of β,β-xanthophylls. The potential involvement of Csβ-LCY2 in the accumulation of lycopene, characteristic of some Citrus species such as red grapefruits, was investigated. Expression of Csβ-LCY2 and another seven carotenoid biosynthetic genes were studied in the peel and pulp of the high lycopene-accumulating grapefruit, Star Ruby, and compared with those of ordinary Navel orange. In Star Ruby, the accumulation of lycopene during fruit maturation was associated with a substantial reduction in the expression of both β-LCY2 and β-CHX genes with respect to Navel orange. Moreover, two different alleles of β-LCY2: β-LCY2a and β-LCY2b were isolated from both genotypes, and functional assays demonstrated that the lycopene β-cyclase activity of the allele b was almost null. Interestingly, Star Ruby grapefruit predominantly expressed the unfunctional β-LCY2b allele during fruit ripening whereas Navel oranges preferably expressed the functional allele. It is suggested that the presence of diverse alleles of the β-LCY2 gene, encoding enzymes with altered activity, with different transcript accumulation may be an additional regulatory mechanism of carotenoid synthesis involved in the accumulation of lycopene in red grapefruits.

A new coumarin fromCitrus paradisiMacf.

Phytochemical examination of the peel of grapefruit resulted in the isolation of five compounds namely friedelin, β -sitosterol, 7(3’,7’,11’,14’-tetramethy)pentadec-2’,6’,10’-trienyloxycoumarin, limonin and cordialin B. These compounds have been characterized on the basis of spectral data, and 7(3’,7’,11’,14’-tetramethy)pentadec-2’,6’,10’-trienyloxycoumarin is a hitherto unreported compound.

Distribution of various peptides in citrus fruits (grapefruit, lemon, and orange).

Tissue- and species-specific peptides of the grapefruit have been investigated by SDS-PAGE and Western blot. Five peptides from the juice and one peptide from the peel were isolated by preparative gel electrophoresis. Polyclonal antibodies were developed against them in mice. It can be established that 82, 63, and 46 kDa peptides occurred exclusively in the samples prepared from the grapefruit and the lemon juice, whereas in the orange juice, only the 82 kDa peptide could be detected. The 31 kDa peptide is characteristic for the peel samples of grapefruit and lemon. The 210 kDa peptide did not show any specificity. A 117 kDa peptide appeared in the juice and peel of grapefruit and in the peel of lemon but not in the orange. From the data of this study, it is supposed that some of the polyclonal antibodies developed against characteristic juice and peel peptides can be used to test commercial grapefruit juice products for adulteration.

Low temperature induction of acid invertase activity in flavedo tissue of late season grapefruit ( Citrus paradisi)

Peel tissue from deacclimated late season grapefruit was examined for the capacity to develop cold induced acid invertase. Experimental fruit were subjected to three prolonged temperature treatments (17 days at 25°C, or 17 days at 4°C ± an additional 24 h at 25°C) and the flavedo examined for acid invertase activity immediately after the respective temperature treatment. Invertase activity was not detected when soluble extracts were assayed directly after desalting. However, after isoelectric separation, invertase activity was detected only in samples from cold treated fruit. Cell-wall pellets were also devoid of invertase activity when measured directly. After washing with high ionic buffer (containing 1 M NaCl), activity was recovered in the same cold treated samples. The data indicate that the peel of late season grapefruit retain the capacity to develop acid invertase in response to cold treatment.

Short-term Heat Conditioning of Grapefruit to Alleviate Irradiation Injury

`Marsh' white grapefruit (Citrus paradisi Macf.) harvested from exterior canopy positions were less tolerant of 0.5 or 1.0 kGy irradiation than were interior fruit. Irradiation at 0.0, 0.5, or 1.0 kGy resulted in 0.0%, 24.3%, and 37.5% surface pitting of fruit, respectively. Pitting was reduced 30% by temperature conditioning with vapor heat at 38 or 42 °C for 2 hours. Exterior canopy fruit had ≈2-fold more pitting, had greater weight loss, and were firmer than interior canopy fruit. Fruit weight loss increased and firmness decreased as conditioning temperature and irradiation dose increased. Total soluble solids, titratable acidity, and flavor decreased with increasing irradiation dose. The peel of exterior canopy grapefruit was damaged more by irradiation than was that of interior fruit, but irradiation damage was reduced by temperature conditioning.

Competitive ELISA of Thiabendazole Residues in Produce Using Indirectly Immobilized Monoclonal Antibodies

An enzyme‐linked immunosorbent assay (ELISA), developed originally for analysis of thiabendazole (2‐[4‐thiazolyl] 1H‐benzimidazole, TBZ) residues in bovine liver, was used to analyze residues of this post‐harvest fungicide in the peel of apple, potato, orange, grapefruit and banana. Residues were extracted by soaking peels overnight in 80% methanol and filtering the decanted supernatants. A 20‐fold dilution eliminated significant matrix effects. The ELISA has a limit of detection of 0.1 ppm in peel samples, corresponding to 10–40 ppb in the whole fruit or tuber. The ELISA employs a monoclonal antibody layer, immobilized indirectly via a rabbit anti‐mouse IgG secondary antibody, and horseradish peroxidase‐conjugated 5‐succinamido‐TBZ. Assay wells coated in this way could be dried and stored for at least 6 months without detectable changes in assay parameters. The method exceeds the required sensitivity for regulatory monitoring of TBZ residues in the US, and offers greater speed and specificity than previously reported methods.

An antifungal compound produced by grapefruit and Valencia orange after wounding of the peel.

Wounding citrus induces the production of the antifungal compound 1, isolated from peel of injured grapefruit, Citrus paradisa, and injured orange, Citrus sinensis. Interpretation of ms, uv, and 1D and 2D nmr spectroscopic data led to the identification of the new compound as 3-[4-hydroxy,3-(3-methyl-2-butenyl)-phenyl]-2-(E)-propenal.

Inducible Chilling Injury of Grapefruit on Trees

Potted Marsh grapefruit [Citrus paradisi (Mad.)] trees with mature fruit were subjected to successive 7-day exposures to 20, 15, 10, and 5C, followed by 7 days at 25C in controlled-environment walk-in rooms. Circular depressions (pits), characteristic visible symptoms of chilling injury, developed in the peel of the fruit. To the best of our knowledge, this is the first report of inducible chilling injury of grapefruit on trees under artificial environments. The ability to induce chilling injury in the peel of grapefruit on trees enhances opportunities to study the mechanism of resistance to chilling injury that can be developed by various preharvest strategies.

Lipids in Peel of Grapefruit and Resistance to Chilling Injury During Cold Storage

Abstract Four-year-old ‘Marsh’ grapefruit (Citrus paradisi Macf.) trees on trifoliate orange [Poncirus trifoliate (L.) Raf.] were subjected to temperature regimes of 25° to 5°C over 11 weeks in controlled environment facilities. Levels of total fatty acids in the flavedo of tree fruit decreased over this period by ≈50%, regardless of temperature. After 5 weeks, the level of linoleic acid in the flavedo of grapefruit that had been kept at progressively cooler temperatures from 25° to 5° was 76% greater than the level in control fruit at 25°. On rewarming and cooling, the differential for linoleic acid in flavedo was 41%. Increases of linoleic acid in the flavedo of fruit on trees that were treated with lower temperatures occurred in six lipids, with the greatest increases in phosphatidyl choline and wax-sterol esters. Chilling injury in harvested fruit during cold storage occurred slightly earlier in fruit from trees exposed to low temperatures, but was most severe in nonacclimated fruit.

Free Proline in Peel of Grapefruit and Resistance to Chilling Injury during Cold Storage1

Abstract Peel samples of ‘Marsh’ grapefruit (Citrus paradisi Macf.) from 2 separate chilling injury (CI) experiments conducted during the 1979–80 season were analyzed for proline. Proline levels were highest in the peel of grapefruit after the seasonal night temperatures reached their minimum and levels declined after night temperatures increased in the spring. The greatest resistance of grapefruit peel to CI during postharvest cold storage coincided with high proline concentrations. Peels of unexposed interior canopy fruit had higher proline contents and were also more resistant to CI than peels of exposed exterior canopy fruit. Proline accumulation may be a consequence of an environmental stress rather than a cause of hardening to the stress or a mechanism of resistance.

Respiration of Grapefruit and Orange Flavedo Tissue in Relation to Chilling and Non-chilling Temperatures and Respiratory Inhibitors1

Abstract One theory on the mechanism of chilling injury of tropical and subtropical fruits is that aerobic respiration is impaired at chilling temperatures and injury occurs from consequent accumulation of fermentation products. Therefore, O2 uptake and CO2 evolution by the flavedo (colored portion of peel) of chill-sensitive grapefruit (Citrus paradisi Macf.) and chill-resistant orange (Citrus sinensis (L.) Osbeck) tissue were measured by a manometric Warburg technique over a range of chilling and non-chilling temperatures to see if there were differences in respiratory activities of the 2 tissues. A break in the Arrhenius plot of CO2 evolution and O2 uptake by grapefruit tissues occurred at 12°C but no break was apparent in similar plots for orange tissue. Respiratory quotients for both orange and grapefruit were lower at chilling than non-chilling temperatures. When O2 uptake was determined in the presence of maximal inhibitory levels of cyanide and salicylhydroxamic acid, a large residual O2 uptake remained. At chilling temperatures, in the absence of cyanide, salicylhydroxamic acid reduced O2 uptake by grapefruit flavedo tissue by 30% but had no effect on O2 uptake by orange flavedo tissue in the absence of cyanide. The results indicate that extra-mitochondrial oxidases may have a role in chilling injury of grapefruit flavedo.

6,7-Dimethoxycoumarin in the peel of gamma-irradiated grapefruit

6,7-Dimethoxycoumarin was isolated from the peel of gamma-irradiated mature grapefruit. It accumulates in fruits irradiated with relatively high doses (300 and 400 krads) and is absent from non-irradiated fruits.