Variations in Total Phenolic, Total Flavonoid Contents, and Free Radicals' Scavenging Potential of Onion Varieties Planted under Diverse Environmental Conditions

HPLC-DAD and GC-MS profiling of an Algerian Senecio massaicus, with its antiproliferative and antioxidant capacities

This study was aimed at determining the phenolic and volatile bioactive components of Senecio massaicus extracts. According to GC-MS results, the main constituents of the petroleum ether extract were 2-(2, 2, 6-trimethylcyclohex-1-enyl) cyclopropane carboxylic acid, methyl ester, (-) caryophyllene oxide, 1-methoxy-3, 5-dimethyl cyclohexene, and dihydroactinidiolide. The HPLC-DAD results reported gallic, chlorogenic, caffeic, vanillic, p-coumaric, trans-ferulic, and o-coumaric acids as the main detected phenolic acids. The n-BuOH and AcOEt extracts had the greatest amounts of phenolics, which were directly correlated with their strongest antioxidant potential. The AcOEt extract showed the best antiproliferative ability (IC50 = 38.5 ± 0.03 µg/ml and IC75 = 60.1 ± 0.03 µg/ml). To our knowledge, this is the first report examining the volatile and phenolic contents as well as the antioxidant and antiproliferative properties of S. massaicus extracts. These results provide scientific justification for looking into this plant as a possible source of bioactive compounds.

Guadua angustifolia biochar/TiO2 composite and biochar as bio-based materials with environmental and agricultural application

Globally, the companies that make commercial use of bamboo culms produce different kinds of solid waste rich in lignocellulosic biomass, which in some cases is not used and is discarded in landfills or incinerated in the open air; losing the possibility of recovering them and using them in other productive sectors. The research objective were to produce a biochar from Guadua agustifolia  Kunth sawdust, evaluate its potential environmental and agricultural use, obtain a biochar/TiO2  composite to inactivate Escherichia coli and use the biochar as a soil conditioner in medicinal plants producing phenolic compounds and flavonoids. Biochar composite (produced at 300 °C for 1 h) involved TiO2 at 450 °C for 1 h for inactivation of E. coli (initial concentration: 6.5 ± 0.3 Log10 CFU mL- 1). For agriculture, 2% biochar was used to evaluate B. pilosa L. and G. angustifolia  plant growth for 90 days. The biochar/TiO2  composite had a high photocatalytic activity on E. coli, generating a final count of 1.97 ± 0.2 Log10 CFU mL- 1 after 60 min. Biochar (2%) increased the total phenol and flavonoid content in the medicinal plant B. pilosa L. and total phenols in G. angustifolia, tested at the nursery stage. This study provides new information on the conversion and use of G. angustifolia sawdust as an alternative for new bio-based materials with environmental and agricultural applications. In addition, obtaining biochar and composite could positively impact the bamboo production chain in Colombia because of renewable and globally accepted alternatives that help capture gaseous emissions causing the greenhouse effect.

Analyzing the Chemical Constituents and In Vitro Biological Effects of Extracts Artemisia absinthium L. Extracts Obtained Using Different Methodologies and Solvents

The present study aimed to investigate the chemical constituents of different extracts from aerial parts of A. absinthium and to evaluate their antioxidant and enzyme inhibition activity. Extracts were prepared by maceration, infusion or Soxhlet techniques. Results showed that the highest total phenolic and flavonoids contents was recorded respectively from the hexane extract prepared by maceration and ethyl acetate extract obtained by Soxhlet method. The characteristic compounds of Artemisia species artemetin, casticin, sesartemin and yangambin in addition to coumarins were identified in all extracts. Aqueous extract obtained by infusion exerted the highest radical scavenging and ions reducing properties while that prepared by maceration displayed the highest chelating power. Methanol extracts obtained by the two methods of extraction exerted the highest anti-Tyr activity while that obtained by maceration showed the best α-glucosidase inhibition activity. These findings indicated that A. absinthium is a rich source of bioactive molecules with possible therapeutic applications.

Diversity of the Morphometric and Biochemical Traits of Allium cepa L. Varieties

Several Allium cepa L. varieties, representing a versatile set of vegetables widely utilized by consumers, are appreciated for their bioactive properties, including antimicrobial, anticarcinogenic, and antioxidant capacities. The aim of this study is to compare the morphometric characteristics and biochemical profiles of four cultivars of A. cepa, two of them represented by the perennial Sicilian landrace "Cipudda agghiarola" (Allium × proliferum (Moench) Schrader), widely known as the Egyptian walking onion (WO), and by the landrace "Cipudduzza" belonging to the variety known as aggregatum (ON), which were compared with two commercial cultivars of A. cepa var. cepa (onion), Stoccarda (OS) and Rossa Carmen (OR). The experimental trial was conducted in Catania (Sicily), following organic growing practices. The randomized complete block experimental design was adopted with one experimental factor, the genotype (GE) effect. The harvested plants were characterized for their main morphometric parameters, according to the International Plant Genetic Resources (IGPR) descriptors. The biochemical activity was assessed by analyzing the total phenolic content (TPC) and the total flavonoid content (TFC). The antioxidant capacity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC). The sugar profile (total sugars, sucrose, glucose, fructose, and fructooligosaccharides-FOS) and the volatile compounds by headspace-gas chromatography/mass spectrometry (HS-GC/MS) were also determined. The OR bulb exhibited the highest TPC (16.3 mg GAE/g d.w., p < 0.01) and TFC (8.5 mg QE/g d.w., p < 0.01), with the highest antioxidant capacity measured by the FRAP (27.1 µmol TE/g d.w., p < 0.01) and DPPH assays (46.2 µmol TE/g d.w., p < 0.01). The ON bulb showed the highest ORAC value (209 µmol TE/g d.w., p < 0.01). Generally, the bulbs were richer in sugars (584 mg/g d.w., p < 0.01) than the leaf blade (239 mg/g d.w., p < 0.01), except for OR. Significant interaction between the genotype and plant organ was noted in the volatile compound profiles (p < 0.05) except for total ketones and carboxylic acids, where higher content was observed in the leaf blade compared to the bulb, regardless of the genotype. These findings highlight WO's potential for use in ready-to-eat products, enhancing its market value.

Leaves of Allium cepa and Xylopia aethiopica fruits as potent sources of natural antioxidant for stabilization of viscera FISH oil during accelerated storage

The present study investigated the antioxidant activities of methanolic extracts of two local plants and their capacities to preserve the quality of viscera fish oil during storage. The total phenolic, total flavonoids and tannins contents were analyzed by colorimetry, the preliminary antioxidant tests done and identification of phenolic compounds by HPLC-DAD (Diode Array Detector) and ESI-MS. After these evaluation, the plant extracts were added in viscera fish oil at concentration 200-1000 ppm. The oxidative stability of these fish oil samples was evaluated by measuring their qualities indices during 16 days at 70 °C. Here, oils were collected at the day 0, 4, 8, 12 and 16. The total phenolic, flavonoids and tannins contents in Xylopia aethiopica fruits were 15.62 g Eq acid galic/100g of dry extract, 10.85 mg Eq quercetin/100g of dry extract and 0.79 mg Eq cathechin/100 mg of dry extract. Those of Allium cepa leaves were 6.85 g Eq acid galic/100g of dry extract, 1.50 mg Eq quercetin/100g of dry extract and 0.11 mg Eq cathechin/100 mg of dry extract. All the methanolic extracts exhibited antioxidant activity. The results recorded after FRAP assay revealed the low IC50 (12.87 mg/mL) in Allium cepa extract compared to that of Xylopia aethiopica extract (44.90 mg/mL). These local plants contain many classes of phenolic compounds and they can be used in oil and fat industries as alternative of synthetic antioxidants.

Exploring Chemical Composition, Antioxidant, Enzyme Inhibitory and Cytotoxic Properties of Glaucium acutidentatum Hausskn. & Bornm. from Turkey Flora: A Novel Source of Bioactive Agents to Design Functional Applications

The present study was performed to determine the chemical constituents, cytotoxicity, antioxidant and enzyme inhibition activities of the aerial parts of Glaucium acutidentatum Hausskn. and Bornm. (family Papaveraceae). Methanolic and aqueous extracts were prepared by maceration, homogenizer-assisted extraction (HAE) and infusion. Results showed that the highest total phenolic and flavonoids contents were obtained from the methanol extracts obtained by HAE (53.22 ± 0.10 mg GAE/g) and maceration (30.28 ± 0.51 mg RE/g), respectively. The aporphine, beznyltetrahydroisoquinoline, and protopine types of Glaucium alkaloids have been tentatively identified. Among them, glaucine was identified in all extracts. Flavonoids, phenolic acids, coumarins, organic acids and fatty acids were also detected. Methanolic extract obtained using the HAE method displayed the highest anti-DPPH (41.42 ± 0.62 mg TE/g), total antioxidant (1.20 ± 0.17 mmol TE/g), Cu2+ (113.55 ± 6.44 mg TE/g), and Fe3+ (74.52 ± 4.74 mg TE/g) reducing properties. The aqueous extracts obtained by infusion and HAE methods exerted the best anti-ABTS (103.59 ± 1.49 mg TE/g) and chelating (19.81 ± 0.05 mg EDTAE/g) activities, respectively. Methanolic extract from HAE recorded the highest acetylcholinesterase (2.55 ± 0.10 mg GALAE/g) and α-amylase (0.51 ± 0.02 mmol ACAE/g) inhibition activities, while that obtained by maceration showed the best butyrylcholinesterase (3.76 ± 0.31 mg GALAE/g) inhibition activity. Both extracts revealed the best tyrosinase inhibitory activity (25.15 ± 1.00 and 26.79 ± 2.36 mg KAE/g, p ≥ 0.05). G. acutidentatum maceration-derived aqueous extract showed selective anticancer activity against cells originating from human hypopharyngeal carcinoma. In conclusion, these findings indicated that G. acutidentatum is a promising source of alkaloids and phenolic compounds for variable pharmaceutical formulations.

Comparative Analysis of Polyphenol Content and Antioxidant Activity of Different Parts of Five Onion Cultivars Harvested in Korea

Onions are typically consumed as the bulb, but the peel and root are discarded as by-products during processing. This study investigated the potential functional use of these by-products by analyzing the polyphenols, antioxidant compounds, and antioxidant activity contained in onions. In this study, the bulb, peel, and root of five onion cultivars ('Tank', 'Bomul', 'Gujji' 'Cobra', and 'Hongbanjang') harvested in Korea were investigated. Caffeic acid and quercetin were most abundant in the peel, whereas methyl gallate was the predominant polyphenol in the bulb. Both DPPH and ABTS radical scavenging activity were higher in onion peel and root than in the bulb. These findings suggest that onion peel and roots, which are often discarded, have abundant antioxidant substances and excellent antioxidant activity. This study provides basic data for the future use of onion peel and roots as functional ingredients with high added value.

Photocatalytic evaluation of synthesized MnO2/Fe3O4 NCs by Q. infectoria extract for removal Ni(II) and phenol: Study phytochemical, kinetics, thermodynamics, and antibioactivity

In the present study, the plant extract of the Quercus infectoria galls was used as a reducing, capping, and stabilizer agent for green synthesized MnO2 nanoparticles (NPs) and MnO2/Fe3O4 nanocomposites (NCs) due to its reduction ability from polyphenol and antioxidant content. The green synthesized nanomaterials have been characterized by various techniques such as FTIR, UV-vis, XRD, SEM, EDS, and TEM. The average size of about 7.4 and 6.88 nm was estimated for the NCs crystals of SEM images and XRD analysis by the Scherrer and Williamson-Hall methods. The green synthesized MnO2/Fe3O4 NCs (dosage: 0.1 g) have shown high photocatalytic activity for the removal of Ni(II) in acidic and basic solutions under visible irradiation (220 V lamp). The removal efficiency for the Ni(II) solution (3.6 × 10-3 M) at pH = 3 was increased to pH = 12 from 56 % to 98 %. The oxidase-like activity of MnO2/Fe3O4 NCs at different dosages (0.05, 0.1, and 0.15 g) for the removal and colorimetric of phenol (1 g/40 mL) in the presence 4-AAp (1 g) was seen after only 28, 13, and 5 s, respectively. The kinetic evaluation results showed the pseudo-second-order kinetics model closely matched the adsorption capacity theoretical values qe,cal (578.03, 854.70, 892.85, and 917.43 mg.g-1) and experimental values qe,exp (521.84, 839.74, 887.86, and 913.22 mg.g-1) at different initial pH solution (3-12) for Ni(II) removal. In addition, the investigation of isotherm models revealed that the Langmuir model (R2 = 0.9955) explains a better estimate for a monolayer and favorable removal of Ni(II) ions onto NCs. Also, the low Temkin constant, BT < 0 (0.0200 kJ.mol-1), and positive ∆H° value (0.103 kJ.mol-1.K-1) illustrated that Ni(II) removal is physical sorption and endothermic process. However, the obtained thermodynamic results showed the negative values ΔG° with the increase in temperature (303-318 K) toward a spontaneous removal process of Ni(II). Finally, the plant antioxidant (200 to 3200 μg/mL) and antimicrobial activities (0.001 to 0.1 g/mL) for plant extract, MnO2 NPs, and MnO2/Fe3O4 NCs were evaluated against Gram-positive and Gram-negative bacteria species.

Phytochemistry, Biological, and Toxicity Study on Aqueous and Methanol Extracts of Chromolaena odorata

The medicinal plant Chromolaena odorata is traditionally used by people living in different communities of Nepal and the globe against diabetes, soft tissue wounds, skin infections, diarrhea, malaria, and several other infectious diseases. The present study focuses on the qualitative and quantitative phytochemical analyses and antioxidant, antidiabetic, antibacterial, and toxicity of the plant for assessing its pharmacological potential. The extracts of flowers, leaves, and stems were prepared using methanol and distilled water as the extracting solvents. Total phenolic content (TPC) and total flavonoid content (TFC) were estimated by using the Folin-Ciocalteu phenol reagent method and the aluminum chloride colorimetric method. Antioxidant and antidiabetic activities were assessed using the DPPH assay and α-glucosidase inhibition assay. A brine shrimp assay was performed to study the toxicity, and the antibacterial activity test was performed by the agar well diffusion method. Phytochemical analysis revealed the presence of phenols, flavonoids, quinones, terpenoids, and coumarins as secondary metabolites. The methanol extract of leaves and flowers displayed the highest phenolic and flavonoid content with 182.26 ± 1.99 mg GAE/g, 128.57 ± 7.62 mg QE/g and 172.65 ± 0.48 mg GAE/g, 121.74 ± 7.06 mg QE/g, respectively. The crude extracts showed the highest DPPH free radical scavenging activity with half maximal inhibitory concentration (IC50) of 32.81 ± 5.26 µg/mL and 41.00 ± 1.10 µg/mL, respectively. The methanol extract of the leaves was found to be effective against bacterial strains such as K. pneumoniae (ZOI = 9.67 ± 0.32 mm), B. subtilis (ZOI = 15.00 ± 0 mm), and E. coli (7.3 ± 0.32 mm). The methanol extract of the flowers showed the most α-glucosidase inhibitory activity (IC50 227.63 ± 11.38 µg/mL), followed by the methanol extract of leaves (IC50 249.50 ± 0.97 µg/mL). The aqueous extract of the flowers showed the toxic effect with LC50 107.31 ± 49.04 µg/mL against the brine shrimp nauplii. In conclusion, C. odorata was found to be a rich source of plant secondary metabolites such as phenolics and flavonoids with potential effects against bacterial infection, diabetes, and oxidative stress in humans. The toxicity study showed that the aqueous extract of flowers possesses pharmacological activities. This study supports the traditional use of the plant against infectious diseases and diabetes and provides some scientific validation.

Flavonoid synthesis in Lamiophlomis rotata from Qinghai-Tibet Plateau is influenced by soil properties, microbial community, and gene expression

Lamiophlomis rotata is a medicinal plant in Qinghai-Tibet Plateau, in which flavonoid compounds are the major medicinal components. However, it remains unclear how flavonoid metabolism of L. rotata is influenced by soil properties and microbial community. In this study, we collected L. rotata seedlings and rhizosphere soils from five habitats ranging from 3750 to 4270 m of altitude and analyzed the effects of habitat conditions on flavonoid metabolism. The activities of peroxidase, cellulase, and urease were increased with altitude, while those of alkaline phosphatase, alkaline protease, and sucrase were decreased with altitude. Analysis of OTUs showed that the total number of bacterial genera was higher than that of fungal genera. The highest number of fungal genera was 132, and that of bacterial genera was 33 in Batang (BT) town in Yushu County at an altitude of 3880 m, suggesting that the fungal communities may play a critical role in L. rotata rhizosphere soils. Flavonoids in leaves and roots of L. rotata shared a similar pattern, with a trend of increasing levels with altitude. The highest flavonoid content measured, 12.94 mg/g in leaves and 11.43 mg/g in roots, was from Zaduo (ZD) County at an altitude of 4208 m. Soil peroxidases affected quercetin content in leaves of L. rotata, while the fungus Sebacina affected flavonoid content in leaves and roots of L. rotata. The expression of PAL, F3'H, FLS, and FNS genes showed a declining trend in leaves with altitude, while F3H showed an increasing trend in both leaves and roots. Overall, soil physicochemical properties and microbial community affect flavonoid metabolism in L. rotata in Qinghai-Tibet Plateau. The variations in flavonoid content and gene expression as well as their associations with soil factors revealed the complexity of the growth conditions and genetic makeup in L. rotata habitats of Qinghai-Tibet Plateau.

An Ethyl Acetate Extract of Eryngium carlinae Inflorescences Attenuates Oxidative Stress and Inflammation in the Liver of Streptozotocin-Induced Diabetic Rats

Secondary metabolites such as flavonoids are promising in the treatment of non-alcoholic fatty liver disease (NAFLD), which is one of the complications of diabetes due to oxidative stress and inflammation. Some plants, such as Eryngium carlinae, have been investigated regarding their medicinal properties in in vitro and in vivo assays, showing favorable results for the treatment of various diseases such as diabetes and obesity. The present study examined the antioxidant and anti-inflammatory effects of the phenolic compounds present in an ethyl acetate extract of the inflorescences of Eryngium carlinae on liver homogenates and mitochondria from streptozotocin (STZ)-induced diabetic rats. Phenolic compounds were identified and quantified by UHPLC-MS. In vitro assays were carried out to discover the antioxidant potential of the extract. Male Wistar rats were administered with a single intraperitoneal injection of STZ (45 mg/kg) and were given the ethyl acetate extract at a level of 30 mg/kg for 60 days. Phytochemical assays showed that the major constituents of the extract were flavonoids; in addition, the in vitro antioxidant activity was dose dependent with IC50 = 57.97 mg/mL and IC50 = 30.90 mg/mL in the DPPH and FRAP assays, respectively. Moreover, the oral administration of the ethyl acetate extract improved the effects of NAFLD, decreasing serum and liver triacylglycerides (TG) levels and oxidative stress markers and increasing the activity of the antioxidant enzymes. Likewise, it attenuated liver damage by decreasing the expression of NF-κB and iNOS, which lead to inflammation and liver damage. We hypothesize that solvent polarity and consequently chemical composition of the ethyl acetate extract of E. carlinae, exert the beneficial effects due to phenolic compounds. These results suggest that the phenolic compounds of the ethyl acetate extract of E. carlinae have antioxidant, anti-inflammatory, hypolipidemic, and hepatoprotective activity.

Assessment of the phytochemical composition and antimicrobial properties of Tapinanthus bangwensis leaves hosted by the branches of Persea americana

BACKGROUND

Medicinal plants represent a valuable source for new effective and safe antimicrobial drugs making them an alternative therapy. Existing antimicrobial agents are costly and mostly associated with possible side effects. The aim of the present study therefore, was to assess the antimicrobial property and phytochemical composition of hydroethanolic extract of Tapinanthus bangwensis leaves and its fractions.

METHOD

T. bangwensis leaves (harvested from its host plant, Persea americana) was extracted by cold maceration with 70% ethanol and further fractionated with different organic solvents using the solvent partitioning method to obtain the crude extract, petroleum ether, chloroform, ethyl acetate and the resulting aqueous fractions. The phytochemical constituents of the extracts were screened and quantified. Also, the TLC of the extracts were analyzed to serve as a fingerprint. Using the agar diffusion and broth dilution methods, the antimicrobial properties of the extracts were assessed.

RESULTS

The study showed that the hydroethanolic (70%) crude extract of T. bangwensis leaves and its fractions contain phenolic compounds, flavonoids, saponins, phytosterols and reducing sugars. The phytoconstituents were well extracted into the ethyl acetate fraction than the other fractions evidenced in the high levels (p < 0.0001) of saponins (66.47 ± 1.72% w/w), phenolic compounds (77.75 ± 1.06 mg/100 mg GAE) and flavonoids (44.34 ± 0.06 mg/100 mg QE) contents. From the antimicrobial studies, all the microorganisms tested exhibited varying degrees of susceptibility to the extracts with MIC values between 0.78 to 12.5 mg/mL. The crude extract of T. bangwensis leaves, its ethyl acetate and chloroform fractions also exhibited lethal antimicrobial activity with MLC between 6.25 to 50 mg/mL.

CONCLUSION

The crude extract of T. bangwensis leaves and its fractions demonstrated antimicrobial properties against Escherichia coli, Staphylococcus aureus, Staphylococcus saprophyticus and Candida albicans, thereby representing a potential source of natural antimicrobial agent. Further study is required to identify and isolate antimicrobial compounds from the plant for the development of the natural bioactive antimicrobial agents.

Mycorrhizal symbiosis alleviate salinity stress in pistachio plants by altering gene expression and antioxidant pathways

This study investigated how inoculation of salt-stressed Pistacia vera seedlings with Rhizophagus irregularis, an arbuscular mycorrhizal fungus (AMF), affects their biomass, oxidative damage, antioxidant enzyme activity, and gene expression. Pistachio seedlings (N:36) were randomly assigned to AMF inoculation and non-inoculation groups in a pot experiment with 9 replications. Each group was further divided and randomly assigned to two salinity treatments (0 and 300 mM NaCl). At the end of week 4, three pistachio plantlets were randomly selected from each group for Rhizophagus irregularis colonization inspection, physiological and biochemical assays, and biomass measurements. Salinity activated enzymatic and non-enzymatic antioxidant systems in the pistachio plants were studied. The negative effects of salinity included reduced biomass and relative water content (RWC), increased O2 ·-, H2O2, MDA, and electrolytic leakage. Generally, Rhizophagus irregularis was found to mitigate the adverse effects of salinity in pistachio seedlings. AMF inoculation resulted in even further increases in the activities of SODs, POD, CAT, and GR enzymes, upregulating Cu/Zn-SOD, Fe-SOD, Mn-SOD, and GR genes expression in plants under salinity stress. Moreover, AMF significantly increased AsA, α-tocopherol, and carotenoids under both control and salinity conditions. The study concludes with a call for future research into the mechanisms of mycorrhiza-induced tolerance in plants under salinity stress.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01279-8.

Synergistic effect of Trikatuk, a traditional Thai formulation, on antioxidant and alpha-glucosidase inhibitory activities

Oxidative stress and hyperglycemia are known to be responsible for several diseases, including diabetes. To prevent these diseases, efforts are ongoing to identify novel antioxidants with hypoglycemic effects. Trikatuk is a traditional Thai formulation composed of three herbs in equal quantities: the fruits of Piper nigrum and Piper retrofractum and the rhizomes of Zingiber officinale. This formulation has been reported to have antioxidant activity and the three individual herbs have been traditionally used for managing diabetes. Therefore, the present study aimed to investigate the phytochemical contents, antioxidant activity (DPPH and ABTS radical scavenging assays), and alpha-glucosidase inhibitory activity of Trikatuk. As Trikatuk is a combination of herbs, the synergistic effect and two different preparation methods from powder or extract mixtures were also explored. The results revealed that Trikatuk, particularly prepared from a mixture of extracts, exhibited high contents of piperine, total phenolics and total flavonoids, as well as significant antioxidant and alpha-glucosidase inhibitory activities. Trikatuk also exhibited additive or synergistic effects in all experiments. Overall, Trikatuk is potentially an alternative traditional medicine and dietary supplement offering antioxidant activity and diabetes management.

Unveiling the Potential of Polyphenols as Anti-Amyloid Molecules in Alzheimer's Disease

Alzheimer's disease (AD) is a devastating neurodegenerative disease that mostly affects the elderly population. Mechanisms underlying AD pathogenesis are yet to be fully revealed, but there are several hypotheses regarding AD. Even though free radicals and inflammation are likely to be linked with AD pathogenesis, still amyloid-beta (Aβ) cascade is the dominant hypothesis. According to the Aβ hypothesis, a progressive buildup of extracellular and intracellular Aβ aggregates has a significant contribution to the AD-linked neurodegeneration process. Since Aβ plays an important role in the etiology of AD, therefore Aβ-linked pathways are mainly targeted in order to develop potential AD therapies. Accumulation of Aβ plaques in the brains of AD individuals is an important hallmark of AD. These plaques are mainly composed of Aβ (a peptide of 39-42 amino acids) aggregates produced via the proteolytic cleavage of the amyloid precursor protein. Numerous studies have demonstrated that various polyphenols (PPHs), including cyanidins, anthocyanins, curcumin, catechins and their gallate esters were found to markedly suppress Aβ aggregation and prevent the formation of Aβ oligomers and toxicity, which is further suggesting that these PPHs might be regarded as effective therapeutic agents for the AD treatment. This review summarizes the roles of Aβ in AD pathogenesis, the Aβ aggregation pathway, types of PPHs, and distribution of PPHs in dietary sources. Furthermore, we have predominantly focused on the potential of food-derived PPHs as putative anti-amyloid drugs.

Impression of foliar-applied folic acid on coriander (Coriandrum sativum L.) to regulate aerial growth, biochemical activity, and essential oil profiling under drought stress

Drought is one of the major environmental limitations in the crop production sector that has a great impact on food security worldwide. Coriander (Coriandrum sativum L.) is an herbaceous angiosperm of culinary significance and highly susceptible to rootzone dryness. Elucidating the drought-induced physio-chemical changes and the foliar-applied folic acid (FA; vitamin B9)-mediated stress tolerance mechanism of coriander has been found as a research hotspot under the progressing water scarcity challenges for agriculture. The significance of folic acid in ameliorating biochemical activities for the improved vegetative growth and performance of coriander under the mild stress (MS75), severe stress (SS50), and unstressed (US100) conditions was examined in this study during two consecutive seasons. The results revealed that the plants treated with 50 mM FA showed the highest plant fresh biomass, leaf fresh biomass, and shoot fresh biomass from bolting stage to seed filling stage under mild drought stress. In addition, total soluble sugars, total flavonoids content, and chlorophyll content showed significant results by the foliar application of FA, while total phenolic content showed non-significant results under MS75 and SS50. It was found that 50 mM of FA upregulated the activity of catalase, superoxide dismutase, and ascorbate peroxidase enzymes in MS75 and SS50 plants compared with untreated FA plants. Thus, FA treatment improved the overall biological yield and economic yield regardless of water deficit conditions. FA-accompanied plants showed a decline in drought susceptibility index, while it improved the drought tolerance efficiency, indicating this variety to become stress tolerant. The optimum harvest index, essential oil (EO) percentage, and oil yield were found in MS75 followed by SS50 in FA-supplemented plants. The gas chromatography-mass spectrometry analysis revealed a higher abundance of linalool as the major chemical constituent of EO, followed by α-terpeniol, terpinene, and p-Cymene in FA-treated SS50 plants. FA can be chosen as a shotgun tactic to improve drought tolerance in coriander by delimiting the drastic changes due to drought stress.