Oak Leaf Extracts Research Articles

Sustainable Removal of Cr(VI) from Wastewater Using Green Composites of Zero-Valent Iron and Natural Clays

Composites for efficient removal of hexavalent chromium Cr(VI) from industrial wastewater were obtained by deposition of nano-zero-valent iron (nZVI), synthesized by environmentally friendly synthesis using oak leaf extract, on inexpensive, natural, readily available and cheap natural raw materials, sepiolite (SEP) or kaolinite/illite (KUb) clay, as support. nZVI particles were deposited from the FeCl3 solution of different concentrations, with the same volume ratio extract/FeCl3 solution (3:1), and with different masses of SEP or KUb. Physico–chemical characterization (SEM/EDS, FTIR, BET, determination of point of zero charge) of the composites and nZVI was performed. The results of SEM and BET analyses suggested more homogeneous deposition of nZVI onto SEP than onto KUb, which ensures greater availability of the nZVI surface for Cr(VI) anions. Therefore, the higher Cr(VI) removal at all investigated initial pH values (pHi) of the solution (3, 4 and 5) was achieved with the SEP composites. The adsorption results indicated that the elimination of Cr(VI) was achieved via the combined effect of reduction and adsorption. The removal of total chromium at pHi = 3 was approximately the same as that of Cr(VI) removal for the KUb composites, but lower for the SEP composites, indicating lower removal of Cr(III) compared to the reduced Cr(VI). The SEP/nZVI composite with the highest removal efficiency was applied for Cr(VI) removal from real wastewater at pHi = 3 and pHi = 5. The results demonstrated the high Cr(VI) removal capacity, validated the assumption that a good dispersion of nZVI particles is beneficial for Cr(VI) removal and showed that the produced green composites can be efficient materials for the removal of Cr(VI) from wastewater.

Eco-friendly nanoparticles: mechanisms and capacities for efficient removal of heavy metals and phosphate from water using definitive screening design approach.

Can nano-zero-valent iron, synthesized using oak leaf extract, be the key solution for water preservation, efficiently removing heavy metal ions and phosphate anions simultaneously? This research unveils how this technology not only promises high efficiency in the remediation of water resources, but also sets new standards for environmentally friendly processes. The high antioxidant capacity and high phenol content indicate suggest the possibility of oak-nZVI synthesis using oak leaf extract as a stable material with minimal agglomeration. The simultaneous removal of Cd and phosphates, as well as and Ni and phosphates was optimized by a statistically designed experiment with a definitive screening design approach. By defining the key factors with the most significant impact, a more efficient and faster method is achieved, improving the economic sustainability of the research by minimizing the number of experiments while maximizing precision. In terms of significance, four input parameters affecting process productivity were monitored: initial metal concentration (1-9mgL-1), initial ion concentration (1-9mgL-1), pH value (2-10), and oak-nZVI dosage (2-16mL). The process optimization resulted in the highest simultaneous removal efficiency of 98.99 and 87.30% for cadmium and phosphate ions, respectively. The highest efficiency for the simultaneous removal of nickel and phosphate ions was 93.44 and 96.75%, respectively. The optimization process fits within the confidence intervals, which confirms the assumption that the selected regression model well describes the process. In the context of e of the challenges and problems of environmental protection, this work has shown considerable potential and successful application for the simultaneous removal of Cd(II) and Ni(II) in the presence of phosphates from water.

Effects of Oak Leaf Extract, Biofertilizer, and Soil Containing Oak Leaf Powder on Tomato Growth and Biochemical Characteristics under Water Stress Conditions

Drought stress is one of the most significant abiotic stresses on the sustainability of global agriculture. The finding of natural resources is essential for decreasing the need for artificial fertilizers and boosting plant growth and yield under water stress conditions. This study used a factorial experimental design to investigate the effects of oak leaf extract, biofertilizer, and soil containing oak leaf powder on the growth and biochemical parameters of four tomato genotypes under water stress throughout the pre-flowering and pre-fruiting stages of plant development. The experiment had two components. The first component represented the genotypes (two sensitive and two tolerant), while the second component represented the treatment group, which included irrigated plants (SW), untreated and stressed plants (SS), treated plants with oak leaf powder and stressed (SOS), treated plants with oak leaf powder and oak leaf extract and stressed (SOES), and treated plants with oak leaf powder and biofertilizers and stressed (SOBS). When compared with irrigated or control plants, drought stress under the treatments of SS, SOS, SOES, and SOBS conditions at two stages and their combination significantly lowered shoot length (12.95%), total fruit weight per plant (33.97%), relative water content (14.05%), and total chlorophyll content (26.30%). The reduction values for shoot length (17.58%), shoot fresh weight (22.08%), and total fruit weight per plant (42.61%) were significantly larger in two sensitive genotypes compared with tolerant genotypes, which recorded decreasing percentages of 8.36, 8.88, and 25.32% for shoot length, shoot fresh weight, and total fruit weight per plant, respectively. Root fresh weight and root dry weight of genotypes treated with SS, SOS, SOES, and SOBS, on the other hand, increased in comparison with control plants. Tomato fruits from stressed plants treated with SS, SOS, SOES, and SOBS had considerably higher levels of titratable acidity, ascorbic acid, and total phenolic compounds than irrigated plants during all stress stages. Under water stress conditions, the addition of oak leaf powder to soil, oak leaf extract, and biofertilizer improved the biochemical content of leaves in all genotypes. Furthermore, leaf lipid peroxidation was lower in plants treated with SOES and SOBS, and lower in the two tolerant genotypes than in the two susceptible genotypes. In conclusion, the application of SOS, SOES, and SOBS demonstrated a slight decrease in some morpho-physiological and fruit physicochemical traits compared with SS treatment. However, the application of oak leaf powder and oak leaf extract can be described as novel agricultural practices because they are low-cost, easy to use, time-consuming, and can meet the growing demands of the agricultural sector by providing environmentally sustainable techniques for enhancing plant resistance to abiotic stress. The usage of the combination of leaf crude extract, oak leaf powder, and arbuscular mycorrhizal fungus should be investigated further under stress conditions.

Antioxidants in Animal Nutrition: UHPLC-ESI-QqTOF Analysis and Effects on In Vitro Rumen Fermentation of Oak Leaf Extracts.

The genus Quercus supplies a large amount of residual material (e.g., bark, acorns, leaves, wood), the valorization of which can favor a supply of antioxidant polyphenols to be used in the pharmaceutical, nutraceutical, or cosmeceutical sector. The recovery of specialized metabolites could also benefit livestock feeding, so much so that polyphenols have gained attention as rumen fermentation modifiers and for mitigating the oxidative imbalance to which farm animals are subject. In this context, leaves of Quercus robur L. from Northern Germany were of interest and the alcoholic extract obtained underwent an untargeted profiling by means of ultra-high-performance liquid chromatography/high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) techniques. As triterpenes and fatty acids occurred, the alcoholic extract fractionation pointed out the obtainment of a polyphenol fraction, broadly constituted by coumaroyl flavonol glycosides and condensed tannins. Total phenol, flavonoid and condensed tannins content assays, as well as antiradical (DPPH● and ABTS+●) and reducing activity (PFRAP) were carried out on the alcoholic extract and its fractions. When the effects on rumen liquor was evaluated in vitro in terms of changes in fermentation characteristics, it was observed that oak leaf extract and its fractions promoted an increase in total volatile fatty acids and differently modulated the relative content of each fatty acid.

Green synthesis of zero iron nanoparticles and its application in the degradation of Sulphacetamide by using of PS/nZVI process

ABSTRACT In this study, oak leaf extract was used as a reducing agent in the green synthesis of zero iron nanoparticles (nZVI). The morphology characteristic of the nZVI was determined using transmission electron microscopy (TEM), and by scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR), and powder X-ray diffraction (XRD) were used to crystalline structure and functional group analysis. After that, degradation of the sulphacetamide (STM) was investigated by using the persulphate (PS)/nZVI process. The results showed that the PS/nZVI process effectively degraded STM (98.5%) at pH: 3, PS: 1.5 mM, nZVI: 2 g/L, and STM: 25 mg/L in a contact time of 90 min. The kinetic study also showed that the degradation process followed the pseudo-first-order kinetic model. Therefore, it can be concluded that the PS/nZVI process can be used to remove drug contaminants from aquatic environments.

Cork oak (Quercus suber L.) leaf extracts potential use as natural antioxidants in cooked meat

Different extracts (water, ethanol, water: ethanol (1:1 v/v), and water: ethanol (3:7 v/v)) were obtained from cork oak leaf and their antioxidant activities, antioxidant compounds (phenolics, flavonoids, condensed tannins, and tocopherols) and individual phenolic compounds were determined. The potential use of the obtained extracts to control oxidation and discolouration in a cooked meat model was investigated. Water: ethanol extracts presented a greater antioxidant activity, as well as a greater number of antioxidant compounds. Cork oak leaf extracts (COLEs) were applied (2 % v/w) in cooked chicken models, and their ability to prevent lipid oxidation and colour changes were evaluated during 5 and 10 days of storage, respectively, at 4 °C. In comparison with the control group, all tested COLEs effectively prevented lipid oxidation in the models reducing thiobarbituric acid reactive substances and the ability to control oxidation was equivalent to butylated hydroxytoluene (0.1 % ethanol) added at 2 % (v/w). Cork oak leaf extracts significantly modified instrumental colour coordinates L*a*b* producing significant total colour changes compared with the control group.

Investigation of the Antioxidant Activity and Phenolic Compounds of Andricus quercustozae Gall and Host Plant (Quercus infectoria)

Andricus quercustozae (Bosc, 1792) is a cynipid gall wasp, which induces gall on oaks (Quercus spp.). It is known that both cynipid galls and oaks are used in traditional medicine. In this study, some biological characteristics of various extracts (acetone and ethanol) of A. quercustozae asexual gall and its host plant, Quercus infectoria Olivier, were investigated. The antioxidant capacities of the extracts were evaluated using radical scavenging activity (ABTS and DPPH assays), the β-carotene-linoleic acid method, the phosphomolybdenum method, and the reducing power (CUPRAC method). Total phenolics, flavonoid and tannin contents were measured in the gall and the oak leaf extracts. Moreover, ethanol extracts of the gall and the host plant were evaluated using HPLC for the composition of phenolics. Generally, the gall extracts (acetone and ethanol, respectively) exhibited the strongest radical scavenging (DPPH, IC50 value of acetone extract: 11.00 μg/mL and IC50 value of ethanol extract: 8.67 μg/mL; ABTS, 52.27 μg/mL and 44.97 μg/mL) and antioxidant activities with the highest level of phenolics. The antioxidant activity of the gall extracts was in the range of 80.74 to 87.49 % for β-carotene-linoleic acid method, while and it was ranged from 75.68 to 78.20 mgAEs/g for phosphomolybdenum method. In the results of some antioxidant methods (ABTS and β-carotene-linoleic acid), it is observed that the host plant extract has values close or high to the gall extract. In this context, our results suggested that the cynipid gall extracts could be used as a natural agent in food, medicinal and pharmaceutical applications.

Effects of dietary oak (Quercus castaneifolia) leaf extract on growth, antioxidant, and immune characteristics and responses to crowding stress in common carp (Cyprinus carpio)

The aim of the present study was to assess the effects of dietary oak (Quercus castaneifolia) leaf extract supplementation on growth performance, antioxidant, immune and stress responses in common carp (Cyprinus carpio). Ethanolic extract of the oak leaf were prepared and tested for in vitro radical scavenging and antibacterial properties. The results showed that the extract has radical scavenging property below that of butylated hydroxytoluene (BHT) at 12.5–75 μg mL−1, but there was no significant difference between the two materials at 100 and 200 μg mL−1. Moreover, the extract had bactericidal effects against Aeromonas hydrophila, which was near 5-fold lower than tetracycline. Then, the extract was added to the fish diet at 0 (CTL), 0.5 (0.5E), 1 (1E) and 2 (2E) g kg−1 diet. The fish were fed with aforementioned diets for 60 days before subjecting to a 6-h crowding stress. The results showed that the extract had no significant effects on the fish growth performance (P > .05). Dietary extract supplementation (1E and 2E) significantly increased plasma superoxide dismutase (P = .003), catalase (P = .015), glutathione peroxidase (P < .001), reduced glutathione (P < .001), lysozyme (P < .001), complement (P = .001), and bactericidal activity (P = .020) and decreased malondialdehyde (P < .001) levels. Dietary oak leaf extract supplementation had no significant effects on basal cortisol and glucose levels, but significantly (P < .001) mitigated post-stress levels of these parameters, compared to the CTL fish. In conclusion, oak leaf extract stimulates antioxidant and immune system of common carp, without affecting the fish growth performance. Moreover, the extract was partially beneficial to reduce stress in the fish. Dietary levels of 1–2 g kg−1 oak leaf extract are recommended for common carp feed formulation.

Quercus leaf extracts display curative effects against Candidatus Liberibacter asiaticus that restore leaf physiological parameters in HLB-affected citrus trees

Citrus greening, also called Huanglongbing (HLB), is one of the most destructive citrus diseases worldwide. It is caused by the fastidious gram-negative α-proteobacteria bacterium Candidatus Liberibacter asiaticus (CLas) and vectored by the Asian citrus psyllid (ACP), Diaphorina citri. Currently, there is no cure for HLB, no compounds have been successful in controlling HLB, and no sustainable management practices have been established for the disease. Thus, searching for alternative citrus greening disease mitigation strategies is considered an urgent priority for a sustainable citrus industry. The aim of this study was to use compounds extracted from oak, Quercus hemisphaerica, and to assess the antibacterial effects of these against CLas-infected citrus plants. The application of aqueous oak leaf extracts showed substantial inhibitory effects against CLas in citrus plants and the activity of genes related to starch. Significant differences were also observed in plant phenotypic and physiological traits after treatments. Citrus plants treated with oak extracts displayed an increase in stomatal conductance, chlorophyll content and nutrient uptake concurrently with a reduction of CLas titer, when compared to citrus plants treated with just water. The information provided from this study suggests a new management treatment program to effectively deal with the HLB disease.

Improved astaxanthin production by Xanthophyllomyces dendrorhous SK984 with oak leaf extract and inorganic phosphate supplementation.

Astaxanthin is widely used in food, feed and nutraceutical industries. Xanthophyllomyces dendrorhous is one of the most promising natural sources of astaxanthin. However, the astaxanthin yield in the wild-type X. dendrorhous is considered low for industrial application. In the present study, X. dendrorhous ATCC 66272 was subjected to two-staged mutagenesis: (i) UV light and (ii) N-methyl-N'-nitro-N-nitroso-guanidine (NTG) toward attaining higher astaxanthin yield. The UV-irradiation mutant, X. dendrorhous SK974 showed 1.7-fold (1.07mg/g) higher astaxanthin production as compared with the wild-type strain (0.65mg/g). The UV mutant strain was then treated with NTG, designated as X. dendrorhous SK984, displayed further 1.4-fold (1.45mg/g) higher astaxanthin production. Furthermore, the oak leaf extract (5%, v/v) and inorganic phosphate (KH2PO4, 3mM) supplementation resulted about 1.4-fold (1.98mg/g) higher astaxanthin production ascompared with control (1.45mg/g) in X. dendrorhous SK984. These findings serve as a platform suggesting that intersecting approaches might be aimed toward systematically enhanced astaxanthin production.

Biocidal action of silver oak (Grevillea robusta) leaf extract on the termite Heterotermes indicola Wasmann (Blattodea: Rhinotermitidae)

The subterranean termite Heterotermes indicola (Blattodea: Rhinotermitidae) is a serious pest to wood in service causing significant annual economic loss in Southeast Asia. In the present study, silver oak (Grevillea robusta A. Cunn.) (Proteaceae) leaf extract was investigated for its termiticidal properties against the termite H. indicola in laboratory tests. An ethanol-solvent system was used to remove the extract from dry leaf powder via Soxhlet apparatus. A dose-dependent foraging response and mortality was observed after continuous exposure to a dose range of 1–20 mg/mL of extract based on dry extract weight. Results indicated that maximum (>90%) termite mortality occurred at 20 mg/mL along with a significant reduction in termite tunneling activity. An LC50 was calculated at 5.47 mg/mL using the concentration series data. In filter paper antifeeding and repellency bioassays, a significant reduction in the total population of gut protozoa compared to untreated and negative controls (solvent) was observed. After 2 weeks of no-choice continuous feeding on filter paper treated at 20 mg/mL, hindgut protozoan population was reduced by 62.90%. The extract conveyed resistance to the non-durable cotton wood and chir pine after vacuum pressure treatment. At the highest concentration tested, 100% mortality was recorded after exposing termites to cotton wood and chir pine treated with silver oak leaf extract. HPLC-DAD-ESI-MS results of the extract showed high level of phenolic compound, alkyl-resorcinol. Results indicated that silver oak leaf extract has termiticidal properties and could be of value in the development of botanical insecticides for termite control in wood products.

Biosynthesis of silver nanoparticles using oak leaf extract and their application for electrochemical sensing of hydrogen peroxide

A green method is proposed for synthesizing silver nanoparticles using oak leaf extract as a reductant, capper and stabilizing agent. The characterization of biosynthesized Ag@oak leaf extract (Ag@OLE) was performed using scanning electron microscopy–energy‐dispersive X‐ray analysis, X‐ray diffraction, transmission electron microscopy and UV–visible spectroscopy. The Ag@OLE nanocomposite was applied for immobilizing haemoglobin (Hb) on the surface of glassy carbon electrode (GCE) and its application as a hydrogen peroxide biosensor of was studied. Electrochemical properties of the biosensor were studied using cyclic voltammetry and electrochemical impedance spectroscopy. Direct electrical communication between the redox centre of Hb and GCE was created via conducting network of Hb–Ag@OLE.

Aqueous leaf extracts display endocrine activities in vitro and disrupt sexual differentiation of male Xenopus laevis tadpoles in vivo

The occurrence of natural substances acting as endocrine disrupting compounds (EDC) in the environment is to date poorly understood. Therefore, (anti)androgenic and (anti)estrogenic activities of three different aqueous leaf extracts (beech, reed and oak) were analyzed in vitro using yeast androgen and estrogen screen. The most potent extract was selected for in vivo exposure of Xenopus laevis tadpoles to analyze the potential effects on development and reproductive biology of amphibians. Tadpoles were exposed from stage 48 to stage 66 (end of metamorphosis) to aqueous oak leaf extracts covering natural occurring environmental concentrations of dissolved organic carbon. Gene expression analyses of selected genes of the hypothalamus–pituitary–gonad and of the hypothalamus–pituitary–thyroid axis as well as histological investigation of gonads and thyroid glands were used to evaluate endocrine disrupting effects on the reproductive biology and development. Female tadpoles remained unaffected by the exposure whereas males showed severe significant histological alterations of testes at the two highest oak leaf extract concentrations demonstrated by the occurrence of lacunae and oogonia. In addition, a significant elevation of luteinizing hormone β mRNA expression with increasing extract concentration in male tadpoles indicates an involvement of hypothalamus–pituitary–gonad axis mainly via antiandrogenic activity. These results suggest that antiandrogenic EDC of oak leaf extract are responsible for inducing the observed effects in male tadpoles. The present study demonstrates for the first time that in surface waters, natural occurring oak leaf compounds at environmentally relevant concentrations display antiandrogenic activities and have considerable effects on the endocrine system of anurans affecting sexual differentiation of male tadpoles.

Simultaneous measurement of proline and related compounds in oak leaves by high-performance ligand-exchange chromatography and electrospray ionization mass spectrometry for environmental stress studies

A mass spectrometer was coupled to high-performance ligand-exchange liquid chromatography (HPLEC) for simultaneous analysis of stress associated solutes such as proline, hydroxyproline, methylproline, glycine betaine and trigonelline extracted from leaves of drought stressed oaks and an internal standard namely N-acetylproline. Methanol/chloroform/water extracts were analyzed using an Aminex HPX-87C column and specifically quantified by the positive ion mode of an electrospray ionisation-mass spectrometry (ESI-MS) in single ion monitoring (SIM) mode. The recovery of N-acetyl proline added to oak leaf extracts ranged from 85.2 to 122.1% for an intra-day study. Standard calibration curves showed good linearity in the measured range from 0.3125 to 10 μmol L −1 with the lowest correlation coefficient of 0.99961 for trigonelline. The advantages of this alternative procedure, compared to previously published methods using fluorescence or amperometric detections, are the simultaneous and direct detection of osmoprotectants in a single chromatographic run, a minimal sample preparation, a good specificity and reduced limits of quantification, ranging from 0.1 to 0.6 μmol L −1. Fifty-six days of water deficit exposure resulted in increased foliar free proline levels (2.4-fold, P < 0.001, 155 μmol g −1 FW) and glycine betaine contents (2.5-fold, P < 0.05, 175 μmol g −1 FW) of drought stressed oak compared to control.

Oak leaf extract as topical antioxidant: Free radical scavenging and iron chelating activities and in vivo skin irritation potential

The topical application of antioxidants may be beneficial for the protection of the skin against UV damage. An extract of Quercus robur leaves was prepared and evaluated considering its putative application as topical antioxidant. The solvent and extractive method selection was monitored by 1,1-diphenyl-2-picryl hydrazyl (DPPH) free radical scavenging activity and polyphenols extraction (measured by the Folin Ciocalteu assay). Iron chelating activity and the phenolic composition (HPLC/DAD) were assessed on the extract obtained under optimized conditions. Skin irritation potential was investigated by performing an in vivo patch test in 19 volunteers. The extraction solvent which resulted in the highest activity was ethanol:water (4:6) and thus it was selected for further preparation of this extract. The IC50s for the iron chelation and DPPH scavenging assays were 153.8 +/- 26.3 microg x mL-1 and 7.53 +/- 0.71 microg x mL-1 (mean +/- SD), respectively. The total phenolic content was found to be 346.3 +/- 6.7 mg gallic acid equivalents (GAE)/g extract (mean +/- SD). Three phenolic compounds were identified in the extract namely: ellagic acid, rutin and hyperoside. The major identified component was ellagic acid. The patch test carried out showed that the extract can be regarded as safe for topical application.

Effects of Aqueous Extracts from Leaves and Leaf Litter on the Abundance and Diversity of Soil Gymnamoebae in Laboratory Microcosm Cultures

The distribution and abundance of microbiota in soil and litter may be significantly affected by the quality and quantity of localized patches of leaf organic matter. This study examined the relative effects of aqueous extracts of shed autumn leaves from American beech (Fagus grandifolia), sugar maple (Acer saccharum), red oak (Quercus rubra), and white oak (Quercus alba) on the density and diversity of gymnamoebae in laboratory cultures. Overall, the beech leaf extract produced the most growth of gymnamoebae followed by white oak with leaf extracts from maple and red oak producing least growth. Cultures using natural leaf litter from beneath beech trees had higher densities and diversity of gymnamoebae than leaf-litter cultures from a maple-oak stand. Soil microcosms confirmed that beech leaf extracts produced a higher density of gymnamoeba growth when added to soil cultures compared with maple and oak leaf extracts. Protein content, CHN (carbon and nitrogen content), and pH of the leaf extracts were assayed, but these alone were not sufficiently different to account for the effects. A dilution experiment indicated that some other concentration-dependent factor in the extract may produce the effects.

Experimental studies of the relative effects of leaf litter from four hardwood trees on protozoan community productivity

Leaf litter is an important source of organic matter as nutrients for aquatic and terrestrial microbial communities. Biogenic decomposition of leaf litter contributes substantially to atmospheric CO2, possibly producing global warming, and comprises an important part of the terrestrial carbon cycle. Small‐scale variability in terrestrial protozoan communities may be attributed to localized variations in leaf matter. This study examined the effect of aqueous leaf extracts from four trees (beech, maple, red oak, and white oak) on the abundance and diversity of protozoa in laboratory aquatic and soil cultures. Beech leaf extract was the most productive followed in the descending order by white oak, red oak, and maple in both aquatic and soil microcosm cultures. Dilution experiments indicated that concentration‐related inhibitory substance(s) in the maple and red oak leaves contribute to lower productivity. Removal of tannins by treatment with activated charcoal (Norit®) improved productivity especially for red oak leaf extracts, suggesting that tannins may contribute to the inhibition of protozoan standing stock. To determine if the lower productivity was mainly due to the inhibition of protozoan excystment, aliquots of thoroughly dried soil were inoculated into maple and red oak leaf extracts. A comparable growth of protozoa occurred in these treatments as in aliquots from moist soil indicating that inhibition of excystment is not a likely explanation for reduced productivity of the protozoan communities.