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The bioactivity of chemical extracts from silverleaf nightshade Solanum elaeagnifolium Cav. seeds and leaves were tested for herbicidal activities, through water and ethanol extracts, against Portulaca oleracea L., Corchorus olitorius L., Convolvulus arvensis L.and Echinochloa crus-galli (L.) found in most Zea mays L.fields. Characterization of the isolated constituents from ethanol extract was conducted by various spectroscopic techniques. Purification of chloroform (100%) column fraction carried out by TLC plate using developing system; chloroform: ethanol: acetic acid (92:4:4) and hexane: chloroform: ethyl acetate (16:16:1) resulted chlorogenic acid, kaempferol and mangiferin. The second active column fraction eluted by chloroform: ethyl acetate was purified on TLC by chloroform: methanol: water (13:7:1) and butanol:water:formic acid (4:5:1) resulted in (coumaroyl glucoside, coumaroyl quince acid) and (kaempferol β-D-(6”-O-cis-cinnamoyl glucoside), dicaffeoyl quinic acids) respectively. The most active isolated component fromS. elaeagnifolium seeds was chlorogenic acid which decreased P.oleracea total biomass fresh weight by (86.5%) followed by kaempferol β-D-(6”-O-cis-cinnamoyl glucoside) (84.4%), while a moderate effect was achieved from coumaroyl glucoside (79.37%), mangiferin (76.98), kaempferol (72.48%) and coumaroyl quince acid (66.47%); finally the lowest activity (63.6%) was achieved by dicaffeoyl quinic acids compared with the controls. Thus, the herbicidal activity of these constituents suggests their potential for development as natural herbicides.

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Two pot experiments were performed in the wire greenhouse of the National Research Centre, Dokki, Giza, Egypt during two successive winter seasons of 2020/2021 and 2021/2022 to study the allelopathic efficiency of Anethum graveolens seed powder (AGSP) in comparison to the herbicidal effect of glyphosate treatment (0.375 ml/l) in controlling the parasitic weed broomrape infected faba bean as well as their effect on growth and yield of the crop. Treatments were applied by incorporating different AGSP concentrations (5, 10, 15, 20, 25, 30, 35 and 40 g/kg soil) into the soil. Broomrape seeds were obtained from the Weed Control Section, Ministry of Agriculture, Giza, Egypt. All pots, except healthy control, were infected with broomrape seeds (0.2 g/pot) at 5 cm depth from the soil surface. All AGSP concentrations used and herbicide treatment decreased all broomrape parameters i.e. number, fresh and dry weight of tubercles/pot  at 90 days after sowing (DAS) and at harvest as well as tubercles length at harvest only. The best treatments for controlling broomrape were recorded with 40 and 35 g/kg soil AGSP concentrations compared to the herbicide glyphosate treatment at harvest. AGSP treatments at 35 and 30 g/kg soil concentrations achieved the maximum significant increases, exceeding their corresponding healthy control and glyphosate treatment. Therefore, the allelopathic effect of AGSP due to the presence of allelochemicals, mainly phenolic compounds and flavonoid contents, could play an essential role as a natural selective bioherbicide in controlling parasitic weed broomrape infesting faba bean plant and increasing the plant growth and yield.

 

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Effects of yeast extract (YE) (0, 0.05, 0.1, 0.2, 0.5 and 1%) were investigated on rosmarinic acid (RA) accumulation and tyrosine aminotransferase (TAT) gene expression in Melissa officinalis seedlings at different time intervals (4 and 17 hours). Based on the results, only YE concentrations of 0.05%, 0.1%, and 0.2%, for the 17-hour treatment, significantly stimulated RA biosynthesis pathway. At this elicitation time, flavonoid content and TAT gene expression significantly increased by the increase in YE concentration up to 0.2% as compared to the control. The maximum amount for both of them was seen at 0.1% YE treatment, where the RA accumulation was drastically elevated. Furthermore, the aerial parts were improved when root lengths were decreased; this was observed in seedlings that were treated by YE for 30 days. Overall, these observations can be attributed to the oxidative stress induced by YE, as a consequence of its uptake by the plant, as revealed by increasing activities in superoxide dismutase and catalase.

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The content of phytochemicals of medicinal plants including total phenols, flavonoids, fatty acid compounds, etc. are mainly affected by drought stress.  In this study, the effects of different levels of water stress (Full irrigation at field capacity, irrigation at 70% of field capacity and irrigation at 40% of field capacity) on the phytochemicals of the medicinal plant of Milk thistle were evaluated. Soil moisture was measured by weight method and drought stress was applied to plants during the flowering stage for 8 days. Then, the seeds were oiled by Soxhlet and methanol extracted. Next, the phytochemicals of the extract were analyzed using GC-MS. GC-MS peak analysis indicated that 20 compounds were present in methanolic extract of Milk thistle. Oleic acid was the most abundant compound in irrigation treatments of Field Capacity (F.C) (75.8%) and 40%F.C. (73.7%), while methyl linoleate (22.5%) was highest in 70%F.C. Except of oleic acid, which had the highest amount in F.C and 40%F.C, the other compounds had the highest amount in 70%F.C compared to the other two treatments. According to the results, mild stress increased most of the plant's phytochemical compounds, possibly due to the osmotic regulation of the plant in dehydration. However, under extreme stress, these compounds were reduced, and these metabolites may have been used to provide energy for plant growth and survival. According to the results of this study, since the seeds of this plant have important phytochemical compounds such as fatty acids, phytosterols, methyl esters, flavonoids, etc. Therefore, the above compounds can be used in the food, pharmaceutical, health and other industries after extraction and purification.

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In this study, the graphene oxide was used as adsorbent for the separation (adsorption and desorption) of flavonoids from lemon peel. Properties of desorption extract (total phenolic content, total flavonoid content, scavenging ability of DPPH free radicals) were determined. Antioxidant activity of desorption extract at three levels of 250, 500 and 1000 ppm and BHT synthetic antioxidant at 200 ppm in antioxidant-free frying oil were evaluated by measuring peroxide value, thiobarbituric acid test, conjugated DN and color index. Each gram of lemon peel extract contained 19767.20 μg phenolic compounds and 33.552 μg flavonoids on dry matter. Each gram of desorption extract contained 5861.56 μg phenolic compounds and 3.446 μg flavonoids on dry matter. Peroxide value, thiobarbituric acid, conjugated DN and color index of oil increased with increasing heating time and the highest increase was observed in the control treatment without antioxidants. Treatments containing desorption extract at 500 and 1000 ppm, can compete with BHT antioxidant. The results of this study indicated that desorption extract can be used as a replacement for synthetic antioxidants in oil.

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The present study aimed to evaluate effectiveness of Superheated Solvent Extraction (SSE) compared with instant Controlled Pressure Drop (DIC) assisted Solvent Extraction (DIC-SE) on total phenolic, flavonoids, and anthocyanins compounds from pomegranate peels. The effects of temperature, extraction time, and water:ethanol ratio for SSE method, and temperature and heating time for DIC-SE were studied. The highest phenolic compounds, flavonoids, and extraction yields by SSE was achieved at 160˚C, ethanol: water 50:50 and 20 minutes, subsequently in the DIC-SE, the most effectiveness was approached at 150˚C for 5 seconds (P< 0.05). The SSE improved the total phenolic compounds (563.16±1.04 mg g^-1), anthocyanins (285.11±1.02 mg 100 g^-1), extraction yield (68.7%) and shortened the extraction times compared to DIC-SE, but flavonoid content was more in DIC-SE extract (439.07±0.05 mg g^-1). Based on HPLC analyses, gallic acid was not detected in any of the obtained extracts, but the amount of ellagic acid and punicalagin A and B in DIC-SE extract was higher than SSE. The current study clearly shows that the SSE is an effective extraction method to obtain phenolic compounds and the DIC is an advantageous pretreatment for extraction of flavonoids from pomegranate peels.
 

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This study developed carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) as sorbents to extract flavonoids from grapefruit peel. The impact of solution pH and desorption conditions on extraction efficiency was investigated. In addition, Fourier transforms infrared spectroscopy, thermogravimetry, UV-visible spectroscopy, and scanning electron microscopy were used to characterize the carbon nanotubes. After five cycles, the desorption percentage of flavonoids was 82.7%. HPLC analysis indicated that naringin was the dominant flavonoid in the grapefruit extracts, followed by rutin and quercetin. Insights into the adsorption mechanism of naringin to the MWCNT-COOH were obtained using the Freundlich isotherm equation to model the results. The carbon nanotubes developed in this study offer a cost-effective and straightforward method of extracting value-added functional ingredients from food waste, thereby improving the sustainability and economic viability of the food supply.
 

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The purpose of this study was to compare the efficacy of citrus peel phenolic compounds extracted using carboxylated multi-walled carbon nanotubes (MWCNT–COOH) with common synthetic antioxidants [butylhydroxyanisole (BHA) and butylhydroxytoluene (BHT)] in stabilizing sunflower oil (SO) during frying (180 ± 5 °C, 24 h). To evaluate the antioxidant activity of these compounds, total phenolic, and flavonoid contents, reducing power, ABTS scavenging activity, β-carotene bleaching ability, and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity were measured. Extracts were combined at various concentrations (100-1000 ppm) with SO, and both synthetic antioxidants were standardized at 200 ppm. Thermal-oxidative stability was investigated by assessing the change in peroxide value (PV), color, free fatty acid (FFA) content, conjugated diene value (CDV), and thiobarbituric acid (TBA). Bitter orange peel extract (BPE) displayed a higher content of phenolic compounds and antioxidant activity. At 1000 ppm, it showed a lower FFA content, PV, TBA, and CDV. It can be used as an alternative to synthetic antioxidants. As a result, citrus peel phenolic compounds extracted with MWCNT–COOH can be used as preservatives in frying oils.
 

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The new Coronavirus, which was named SARS-CoV-2 is one of the members of the Coronavirus family, which induces Covid-19 or acute respiratory infection. This virus was firstly known in 2019 in Wuhan, China; and then, rapidly propagated around the world. In this review, we will present the structure and function of the Spike (S) protein in this virus and its receptors on the host cells. In addition to ACE2, which was initially identified as the cell surface receptor of this virus, it was observed that CD147 and GRP 78 also act as the receptors on host cells. Also, based on the mechanism of action, a brief introduction will present the drugs used to treat this Coronavirus. The drugs that target S protein, Proteinases; RNA-dependent RNA polymerases, helicases, or structural lipids of the virus membrane. In addition, the proposed natural products which are currently recommended as supplements are discussed. For example, flavonoids, polyphenols, and polar compounds are substances whose antiviral effects against Coronavirus have been studied and demonstrated. In conclusion, since the effective drug to eradicate this virus is not yet known, it seems that according to the structural characteristics and mechanism of action, using natural compounds as a complementary or preventive medicine will be useful to inhibit or delay the entrance, proliferation, and/ or infectivity of the virus.