Ca2+ sensor-mediated ROS scavenging suppresses rice immunity and is exploited by a fungal effector.

Plant immunity is activated upon pathogen perception and often affects growth and yield when it is constitutively active. How plants fine-tune immune homeostasis in their natural habitats remains elusive. Here, we discover a conserved immune suppression network in cereals that orchestrates immune homeostasis, centering on a Ca2+-sensor, RESISTANCE OF RICE TO DISEASES1 (ROD1). ROD1 promotes reactive oxygen species (ROS) scavenging by stimulating catalase activity, and its protein stability is regulated by ubiquitination. ROD1 disruption confers resistance to multiple pathogens, whereas a natural ROD1 allele prevalent in indica rice with agroecology-specific distribution enhances resistance without yield penalty. The fungal effector AvrPiz-t structurally mimics ROD1 and activates the same ROS-scavenging cascade to suppress host immunity and promote virulence. We thus reveal a molecular framework adopted by both host and pathogen that integrates Ca2+ sensing and ROS homeostasis to suppress plant immunity, suggesting a principle for breeding disease-resistant, high-yield crops.

The miR6445-NAC029 module regulates drought tolerance by regulating the expression of glutathione S-transferase U23 and reactive oxygen species scavenging in Populus.

MicroRNAs are essential in plant development and stress resistance, but their specific roles in drought stress require further investigation. Here, we have uncovered that a Populus-specific microRNAs (miRNA), miR6445, targeting NAC (NAM, ATAF, and CUC) family genes, is involved in regulating drought tolerance of poplar. The expression level of miR6445 was significantly upregulated under drought stress; concomitantly, seven targeted NAC genes showed significant downregulation. Silencing the expression of miR6445 by short tandem target mimic technology significantly decreased the drought tolerance in poplar. Furthermore, 5' RACE experiments confirmed that miR6445 directly targeted NAC029. The overexpression lines of PtrNAC029 (OE-NAC029) showed increased sensitivity to drought compared with knockout lines (Crispr-NAC029), consistent with the drought-sensitive phenotype observed in miR6445-silenced strains. PtrNAC029 was further verified to directly bind to the promoters of glutathione S-transferase U23 (GSTU23) and inhibit its expression. Both Crispr-NAC029 and PtrGSTU23 overexpressing plants showed higher levels of PtrGSTU23 transcript and GST activity while accumulating less reactive oxygen species (ROS). Moreover, poplars overexpressing GSTU23 demonstrated enhanced drought tolerance. Taken together, our research reveals the crucial role of the miR6445-NAC029-GSTU23 module in enhancing poplar drought tolerance by regulating ROS homeostasis. This finding provides new molecular targets for improving the drought resistance of trees.

Silicon induces ROS scavengers, hormone signalling, antifungal metabolites, and silicon deposition against brown stripe disease in sugarcane.

Bipolaris setariae is known to cause brown stripe disease in sugarcane, resulting in significant yield losses. Silicon (Si) has the potential to enhance plant growth and biotic resistance. In this study, the impact of Si on brown stripe disease was investigated across susceptible and resistant sugarcane varieties, utilizing four Si concentrations (0, 15, 30, and 45 g per barrel of Na2SiO3·5H2O). Si significantly reduced the incidence of brown stripe disease (7.41-59.23%) and alleviated damage to sugarcane growth parameters, photosynthetic parameters, and photosynthetic pigments. Submicroscopic observations revealed that Si induced the accumulation of silicified cells in leaves, reduced spore accumulation, decreased stomatal size, and protected organelles from B. setariae damage. In addition, Si increased the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), reduced reactive oxygen species production (malondialdehyde and hydrogen peroxide) and modulated the expression of genes associated with hormone signalling (PR1, TGA, AOS, AOC, LOX, PYL8, and SnRK2), leading to the accumulation of abscisic acid and jasmonic acid and inhibiting SA synthesis. Si also activated the activity of metabolism-related enzymes (polyphenol oxidase and phenylalanine ammonia lyase) and the gene expression of PAL-dependent genes (PAL, C4H, and 4CL), regulating the accumulation of metabolites, such as chlorogenic acid and lignin. The antifungal test showed that chlorogenic acid (15ug µL-1) had a significant inhibitory effect on the growth of B. setariae. This study is the first to demonstrate the inhibitory effect of Si on B. setariae in sugarcane, highlighting Si as a promising and environmentally friendly strategy for managing brown stripe disease.

IPyA glucosylation mediates light and temperature signaling to regulate auxin-dependent hypocotyl elongation in Arabidopsis.

Auxin is a class of plant hormone that plays a crucial role in the life cycle of plants, particularly in the growth response of plants to ever-changing environments. Since the auxin responses are concentration-dependent and higher auxin concentrations might often be inhibitory, the optimal endogenous auxin level must be closely controlled. However, the underlying mechanism governing auxin homeostasis remains largely unknown. In this study, a UDP-glycosyltransferase (UGT76F1) was identified from Arabidopsis thaliana, which participates in the regulation of auxin homeostasis by glucosylation of indole-3-pyruvic acid (IPyA), a major precursor of the auxin indole-3-acetic acid (IAA) biosynthesis, in the formation of IPyA glucose conjugates (IPyA-Glc). In addition, UGT76F1 was found to mediate hypocotyl growth by modulating active auxin levels in a light- and temperature-dependent manner. Moreover, the transcription of UGT76F1 was demonstrated to be directly and negatively regulated by PIF4, which is a key integrator of both light and temperature signaling pathways. This study sheds a light on the trade-off between IAA biosynthesis and IPyA-Glc formation in controlling auxin levels and reveals a regulatory mechanism for plant growth adaptation to environmental changes through glucosylation of IPyA.

Oxidative Damage and Antioxidant Response in Frontal Cortex of Demented and Nondemented Individuals with Alzheimer's Neuropathology.

Alzheimer's disease (AD) is characterized by progressive neurodegeneration in the cerebral cortex, histopathologically hallmarked by amyloid ß (Aß) extracellular plaques and intracellular neurofibrillary tangles, constituted by hyperphosphorylated tau protein. Correlation between these pathologic features and dementia has been challenged by the emergence of "nondemented with Alzheimer's neuropathology" (NDAN) individuals, cognitively intact despite displaying pathologic features of AD. The existence of these subjects suggests that some unknown mechanisms are triggered to resist Aß-mediated detrimental events. Aß accumulation affects mitochondrial redox balance, increasing oxidative stress status, which in turn is proposed as a primary culprit in AD pathogenesis. To clarify the relationship linking Aß, oxidative stress, and cognitive impairment, we performed a comparative study on AD, NDAN, and aged-matched human postmortem frontal cortices of either sex. We quantitatively analyzed immunofluorescence distribution of oxidative damage markers, and of SOD2 (superoxide dismutase 2), PGC1α [peroxisome proliferator-activated receptor (PPAR) γ-coactivator 1α], PPARα, and catalase as key factors in antioxidant response, as well as the expression of miRNA-485, as a PGC1α upstream regulator. Our results confirm dramatic redox imbalance, associated with impaired antioxidant defenses in AD brain. By contrast, NDAN individuals display low oxidative damage, which is associated with high levels of scavenging systems, possibly resulting from a lack of PGC1α miRNA-485-related inhibition. Comparative analyses in neurons and astrocytes further highlighted cell-specific mechanisms to counteract redox imbalance. Overall, our data emphasize the importance of transcriptional and post-transcriptional regulation of antioxidant response in AD. This suggests that an efficient PGC1α-dependent "safety mechanism" may prevent Aß-mediated oxidative stress, supporting neuroprotective therapies aimed at ameliorating defects in antioxidant response pathways in AD patients.

Pitx2 promotes heart repair by activating the antioxidant response after cardiac injury.

Myocardial infarction results in compromised myocardial function and heart failure owing to insufficient cardiomyocyte self-renewal. Unlike many vertebrates, mammalian hearts have only a transient neonatal renewal capacity. Reactivating primitive reparative ability in the mature mammalian heart requires knowledge of the mechanisms that promote early heart repair. By testing an established Hippo-deficient heart regeneration mouse model for factors that promote renewal, here we show that the expression of Pitx2 is induced in injured, Hippo-deficient ventricles. Pitx2-deficient neonatal mouse hearts failed to repair after apex resection, whereas adult mouse cardiomyocytes with Pitx2 gain-of-function efficiently regenerated after myocardial infarction. Genomic analyses indicated that Pitx2 activated genes encoding electron transport chain components and reactive oxygen species scavengers. A subset of Pitx2 target genes was cooperatively regulated with the Hippo pathway effector Yap. Furthermore, Nrf2, a regulator of the antioxidant response, directly regulated the expression and subcellular localization of Pitx2. Pitx2 mutant myocardium had increased levels of reactive oxygen species, while antioxidant supplementation suppressed the Pitx2 loss-of-function phenotype. These findings reveal a genetic pathway activated by tissue damage that is essential for cardiac repair.

Anisotropic magnetic field effects in the re-oxidation of cryptochrome in the presence of scavenger radicals.

The avian compass and many other of nature's magnetoreceptive traits are widely ascribed to the protein cryptochrome. There, magnetosensitivity is thought to emerge as the spin dynamics of radicals in the applied magnetic field enters in competition with their recombination. The first and dominant model makes use of a radical pair. However, recent studies have suggested that magnetosensitivity could be markedly enhanced for a radical triad, the primary radical pair of which undergoes a spin-selective recombination reaction with a third radical. Here, we test the practicality of this supposition for the reoxidation reaction of the reduced FAD cofactor in cryptochrome, which has been implicated with light-independent magnetoreception but appears irreconcilable with the classical radical pair mechanism (RPM). Based on the available realistic cryptochrome structures, we predict the magnetosensitivity of radical triad systems comprising the flavin semiquinone, the superoxide, and a tyrosine or ascorbyl scavenger radical. We consider many hyperfine-coupled nuclear spins, the relative orientation and placement of the radicals, their coupling by the electron-electron dipolar interaction, and spin relaxation in the superoxide radical in the limit of instantaneous decoherence, which have not been comprehensively considered before. We demonstrate that these systems can provide superior magnetosensitivity under realistic conditions, with implications for dark-state cryptochrome magnetoreception and other biological magneto- and isotope-sensitive radical recombination reactions.

Biochemical Characterization and Cold-Adaption Mechanism of a PL-17 Family Alginate Lyase Aly23 from Marine Bacterium Pseudoalteromonas sp. ASY5 and Its Application for Oligosaccharides Production.

As an important enzyme involved in the marine carbon cycle, alginate lyase has received extensive attention because of its excellent degradation ability on brown algae, which is widely utilized for alginate oligosaccharide preparation or bioethanol production. In comparison with endo-type alginate lyases (PL-5, PL-7, and PL-18 families), limited studies have focused on PL-17 family alginate lyases, especially for those with special characteristics. In this study, a novel PL-17 family alginate lyase, Aly23, was identified and cloned from the marine bacterium Pseudoalteromonas carrageenovora ASY5. Aly23 exhibited maximum activity at 35 °C and retained 48.93% of its highest activity at 4 °C, representing an excellent cold-adaptation property. Comparative molecular dynamics analysis was implemented to explore the structural basis for the cold-adaptation property of Aly23. Aly23 had a high substrate preference for poly ß-D-mannuronate and exhibited both endolytic and exolytic activities; its hydrolysis reaction mainly produced monosaccharides, disaccharides, and trisaccharides. Furthermore, the enzymatic hydrolyzed oligosaccharides displayed good antioxidant activities to reduce ferric and scavenge radicals, such as hydroxyl, ABTS+, and DPPH. Our work demonstrated that Aly23 is a promising cold-adapted biocatalyst for the preparation of natural antioxidants from brown algae.

Assembly of a heptameric STRIPAK complex is required for coordination of light-dependent multicellular fungal development with secondary metabolism in Aspergillus nidulans.

Eukaryotic striatin forms striatin-interacting phosphatase and kinase (STRIPAK) complexes that control many cellular processes including development, cellular transport, signal transduction, stem cell differentiation and cardiac functions. However, detailed knowledge of complex assembly and its roles in stress responses are currently poorly understood. Here, we discovered six striatin (StrA) interacting proteins (Sips), which form a heptameric complex in the filamentous fungus Aspergillus nidulans. The complex consists of the striatin scaffold StrA, the Mob3-type kinase coactivator SipA, the SIKE-like protein SipB, the STRIP1/2 homolog SipC, the SLMAP-related protein SipD and the catalytic and regulatory phosphatase 2A subunits SipE (PpgA), and SipF, respectively. Single and double deletions of the complex components result in loss of multicellular light-dependent fungal development, secondary metabolite production (e.g. mycotoxin Sterigmatocystin) and reduced stress responses. sipA (Mob3) deletion is epistatic to strA deletion by supressing all the defects caused by the lack of striatin. The STRIPAK complex, which is established during vegetative growth and maintained during the early hours of light and dark development, is mainly formed on the nuclear envelope in the presence of the scaffold StrA. The loss of the scaffold revealed three STRIPAK subcomplexes: (I) SipA only interacts with StrA, (II) SipB-SipD is found as a heterodimer, (III) SipC, SipE and SipF exist as a heterotrimeric complex. The STRIPAK complex is required for proper expression of the heterotrimeric VeA-VelB-LaeA complex which coordinates fungal development and secondary metabolism. Furthermore, the STRIPAK complex modulates two important MAPK pathways by promoting phosphorylation of MpkB and restricting nuclear shuttling of MpkC in the absence of stress conditions. SipB in A. nidulans is similar to human suppressor of IKK-ε(SIKE) protein which supresses antiviral responses in mammals, while velvet family proteins show strong similarity to mammalian proinflammatory NF-KB proteins. The presence of these proteins in A. nidulans further strengthens the hypothesis that mammals and fungi use similar proteins for their immune response and secondary metabolite production, respectively.

Oleuropein Protects Against Cerebral Ischemia Injury in Rats: Molecular Docking, Biochemical and Histological Findings.

This study was designed to evaluate the underlying protective mechanisms of oleuropein involved in alleviating brain damage in a rat model of ischemic stroke. Male Wistar rats were divided into four groups; Control, stroke (MCAO), MCAO + clopidogrel (Clop) and MCAO + oleuropein (Ole). Results showed that the MCAO group evidenced significant brain edema (+ 9%) as well as increases of plasma cardiac markers such as lactate deshydrogenase (LDH), creatine kinase (CK-MB), fibrinogen and Trop-T by 11 %, 43%, 168 and 590%, respectively, as compared to the control group. Moreover, infarcted rats exhibited remarkable elevated levels of angiotensin converting enzyme (ACE), both in plasma and brain tissue, with astrocyte swelling and necrotic neurons in the infarct zone, hyponatremia, and increased rate of thiobarbituric acid-reactive substances (TBARS) by 89% associated with decreases in the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (Cat) by 51%, 44 and 42%, respectively, compared to normal control rats. However, MCAO rats treated with oleuropein underwent mitigation of cerebral edema, correction of hyponatremia, remarkable decrease of plasma fibrinogen and cardiac dysfunctional enzymes, inhibition of ACE activity and improvement of oxidative stress status in brain tissue. Furthermore, in silico analysis showed considerable inhibitions of ACE, protein disulfide isomerase (PDI) and TGF-ß1, an indicative of potent anti-embolic properties. Overall, oleuropein offers a neuroprotective effect against ischemic stroke through its antioxidative and antithrombotic activities.

Design, synthesis and biological evaluation of naringenin carbamate derivatives as potential multifunctional agents for the treatment of Alzheimer's disease.

A series of naringenin derivatives were designed and synthesized as multifunctional anti-Alzheimer's disease (AD) agents. The results showed that these derivatives displayed moderate-to-good acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities at the micromolar range (IC50, 12.91 ~ 62.52 µM for AChE and 0.094 ~ 13.72 µM for BuChE). Specifically, compound 1 showed the highest inhibitory activity against BuChE with the IC50 value of (0.094 ± 0.0054) µM. A Lineweaver-Burk plot and molecular docking studies demonstrated that 1 targeted both the catalytically active site (CAS) and the peripheral anion site (PAS) of BuChE. Besides, all derivatives showed excellent hydroxyl free radicals (·OH) scavenging ability than vitamin C and cyclic voltammetry results displayed that 1 could effectively scavenge superoxide anion radical (·O2-). In addition, compound 1 displayed good metal chelating properties and had anti-Aß aggregation activities. Therefore, compound 1 might be the potential anti-AD agent for further developments.

Synthesis, characterization and anti-inflammatory properties of karanjin (Pongamia pinnata seed) and its derivatives.

Karanja (Pongamia pinnata) is a medicinal tree used in the Indian traditional ayurvedic system for treating several ailments. The seeds contain a unique furano-flavonoid karanjin, which has shown to possess many medicinal properties. Its usage at the clinical level is affected due to poor solubility and absorption. In the present investigation, molecular modifications of karanjin were attempted and evaluated their effect on anti-inflammatory activity. Firstly, Karanja ketone was obtained from karanjin by hydrolysis, and it was converted into karanja ketone oxime. The oxime undergoes Beckmann rearrangement and cyclized to yield furano benzoxazole (karanja oxazole). The new derivatives were purified with >95% purity (HPLC) and spectrally characterized (HR-MS, FTIR, and NMR). Among the test compounds, karanja ketone oxime exhibited higher antioxidant activity with an IC50 value of 360 µg/ml (DPPH). Soy lipoxygenase-1 (LOX-1) inhibitory activity of oxime was higher (IC50 = 65.4 µM) than other compounds. Fluorescence studies showed that oxime had higher quenching capacity with a Qmax of 76.3% and a binding constant of 0.9 × 105 M-1 for soy LOX-1. In-silico interaction studies showed that karanja ketone oxime had the least binding energy of -5.76 kcal/mol with LOX-1 by forming two hydrogen bonds with hydrophobic amino acids Leu 390 and Gly 392. The compounds were evaluated for their acute anti-inflammatory activity by the paw and ear edema in the rat model. Karanjin inhibits paw edema and ear edema by 34.13% and 51.13%, respectively, whereas the derivatives inhibited by 45-57 % and 70-76.8%. This study reports a rational approach to synthesize karanjin derivatives with considerable anti-inflammatory properties, both in-vitro and in-vivo.

Melatonin as a Potential Adjuvant Treatment for COVID-19 beyond Sleep Disorders.

Melatonin is registered to treat circadian rhythm sleep-wake disorders and insomnia in patients aged 55 years and over. The essential role of the circadian sleep rhythm in the deterioration of sleep quality during COVID-19 confinement and the lack of an adverse effect of melatonin on respiratory drive indicate that melatonin has the potential to be a recommended treatment for sleep disturbances related to COVID-19. This review article describes the effects of melatonin additional to its sleep-related effects, which make this drug an attractive therapeutic option for treating patients with COVID-19. The preclinical data suggest that melatonin may inhibit COVID-19 progression. It may lower the risk of the entrance of the SARS-CoV-2 virus into cells, reduce uncontrolled hyper-inflammation and the activation of immune cells, limit the damage of tissues and multiorgan failure due to the action of free radicals, and reduce ventilator-induced lung injury and the risk of disability resulting from fibrotic changes within the lungs. Melatonin may also increase the efficacy of COVID-19 vaccination. The high safety profile of melatonin and its potential anti-SARS-CoV-2 effects make this molecule a preferable drug for treating sleep disturbances in COVID-19 patients. However, randomized clinical trials are needed to verify the clinical usefulness of melatonin in the treatment of COVID-19.

Cloning, Functional Characterization and Response to Cadmium Stress of the Thioredoxin-like Protein 1 Gene from Phascolosoma esculenta.

Cadmium (Cd) is a heavy metal toxicant and is widely distributed in aquatic environments. It can cause excessive production of reactive oxygen species (ROS) in the organism, which in turn leads to a series of oxidative damages. Thioredoxin (Trx), a highly conserved disulfide reductase, plays an important role in maintaining the intracellular redox homeostasis in eukaryotes and prokaryotes. Phascolosoma esculenta is an edible marine worm, an invertebrate that is extensively found on the mudflats of coastal China. To explore the molecular response of Trx in mudflat organisms under Cd stress, we identified a new Trx isoform (Trx-like protein 1 gene) from P. esculenta for the first time, designated as PeTrxl. Molecular and structural characterization, as well as multiple sequence and phylogenetic tree analysis, demonstrated that PeTrxl belongs to the Trx superfamily. PeTrxl transcripts were found to be ubiquitous in all tissues, and the highest expression level occurred in the coelomic fluid. Exposure to three sublethal concentrations of Cd resulted in the upregulation and then downregulation of PeTrxl expression levels over time in coelomic fluid of P. esculenta. The significant elevation of PeTrxl expression after 12 and 24 h of Cd exposure at 6 and 96 mg/L, respectively, might reflect its important role in the resistance to Cd stress. Recombinant PeTrxl (rPeTrxl) showed prominent dose-dependent insulin-reducing and ABTS free radical-scavenging abilities. After exposure to 96 mg/L Cd for 24 h, the ROS level increased significantly in the coelomic fluid, suggesting that Cd induced oxidative stress in P. esculenta. Furthermore, the injection of rPeTrxl during Cd exposure significantly reduced the ROS in the coelomic fluid. Our data suggest that PeTrxl has significant antioxidant capacity and can protect P. esculenta from Cd-induced oxidative stress.

Melatonin, Its Metabolites and Their Interference with Reactive Nitrogen Compounds.

Melatonin and several of its metabolites are interfering with reactive nitrogen. With the notion of prevailing melatonin formation in tissues that exceeds by far the quantities in blood, metabolites come into focus that are poorly found in the circulation. Apart from their antioxidant actions, both melatonin and N1-acetyl-5-methoxykynuramine (AMK) downregulate inducible and inhibit neuronal NO synthases, and additionally scavenge NO. However, the NO adduct of melatonin redonates NO, whereas AMK forms with NO a stable product. Many other melatonin metabolites formed in oxidative processes also contain nitrosylatable sites. Moreover, AMK readily scavenges products of the CO2-adduct of peroxynitrite such as carbonate radicals and NO2. Protein AMKylation seems to be involved in protective actions.

Proximate composition, polyphenols, and antioxidant activity of solid state fermented peanut press cake.

The current research was led to assess the influence of solid-state fermentation (SSF) with Aspergillus oryzae (MTCC 3107) on polyphenols, antioxidant activities, and proximate composition from peanut press cake of variety HNG-10. Total phenolic, flavonoid, and tannin contents were calculated for polyphenols quantification whereas DPPH, ABTS, FRAP, and metal chelating assay were performed for antioxidant activity. Quantification of polyphenols was confirmed by High Performance Liquid Chromatography technique. Maximum value of total phenolic, flavonoid, and tannin content was found to be 25.55 µM/g GAE, 101.17 µM/g QE, and 245.33 µg/g TAE, respectively. The highest inhibition of free radicals scavenging was noticed on the 5th day of fermentation after that decreased gradually with the increase of fermentation time. Significant increase in fat, i.e. 7.05-12.80% and protein content i.e. 44.05-49.60% was observed. Significant difference in proximate composition of fermented and non-fermented press cake concluded that the progressive role of fermentation improved or transformed physico-chemical properties of substrates.

Claulansine F-Donepezil Hybrids as Anti-Alzheimer's Disease Agents with Cholinergic, Free-Radical Scavenging, and Neuroprotective Activities.

The multifactorial nature of Alzheimer's disease (AD) calls for the development of multitarget agents addressing key pathogenic processes. A total of 26 Claulansine F-donepezil hybrids were designed and synthesized as multitarget drugs. Among these compounds, six compounds exhibited excellent acetylcholinesterase (AChE) inhibitory activity (half maximal inhibitory concentration (IC50) 1.63-4.62 µM). Moreover, (E)-3-(8-(tert-Butyl)-3,3-dimethyl-3,11-dihydropyrano[3,2-a]carbazol-5-yl)-N-((1-(2-chlorobenzyl)piperidin-4-yl)methyl)acrylamide (6bd) exhibited better neuroprotective effects against OGD/R (oxygen-glucose deprivation/reoxygenation) than lead compound Claulansine F. Furthermore, 6bd could cross the blood-brain barrier in vitro. More importantly, compared to edaravone, 6bd had stronger free-radical scavenging activity. Molecular docking studies revealed that 6bd could interact with the catalytic active site of AChE. All of these outstanding in vitro results indicate 6bd as a leading structure worthy of further investigation.

Metabolomic Profiling of Antioxidant Compounds in Five Vachellia Species.

The genus Vachellia, previously known as Acacia, belongs to the family Fabaceae, subfamily Leguminosae, which are flowering plants, commonly known as thorn trees. They are traditionally used medicinally in various countries including South Africa for the treatment of ailments such as fever, sore throat, Tuberculosis, convulsions and as sedatives. The aim of this study was to determine biochemical variations in five Vachellia species and correlate their metabolite profiles to antioxidant activity using a chemometric approach. The antioxidant activity of five Vachellia aqueous-methanolic extracts were analyzed using three methods: 2,2-di-phenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) analysis and the ferric reducing antioxidant power (FRAP) assay by means of serial dilution and bioautography with the thin-layer chromatography (TLC) method. Amongst the Vachellia extracts tested, V. karroo, V. kosiensis and V. xanthophloea demonstrated the highest DPPH, ABTS+ and FRAP inhibitory activity. The antioxidant activities of DPPH were higher than those obtained by ABTS+, although these values varied among the Vachellia species. Proton nuclear magnetic resonance (1H NMR), coupled with multivariate statistical modeling tools such as principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), were performed to profile metabolites responsible for the observed activity. The OPLS-DA categorized the five Vachellia species, separating them into two groups, with V. karroo, V. kosiensis and V. xanthophloea demonstrating significantly higher radical scavenging activity than V. tortilis and V. sieberiana, which clustered together to form another group with lower radical scavenging activity. Annotation of metabolites was carried out using the ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-qTOF-MS), and it tentatively identified 23 metabolites of significance, including epigallocatechin (m/z = 305.0659), methyl gallate (m/z = 183.0294) and quercetin (m/z = 301.0358), amongst others. These results elucidated the metabolites that separated the Vachellia species from each other and demonstrated their possible free radical scavenging activities.

Genotoxic and Cytotoxic Properties of Zinc Oxide Nanoparticles Phyto-Fabricated from the Obscure Morning Glory Plant Ipomoea obscura (L.) Ker Gawl.

The study was undertaken to investigate the antioxidant, genotoxic, and cytotoxic potentialities of phyto-fabricated zinc oxide nanoparticles (ZnO-NPs) from Ipomoea obscura (L.) Ker Gawl. aqueous leaf extract. The UV-visible spectral analysis of the ZnO-NPs showed an absorption peak at 304 nm with a bandgap energy of 3.54 eV, which are characteristics of zinc nanoparticles. Moreover, the particles were of nano-size (~24.26 nm) with 88.11% purity and were agglomerated as observed through Scanning Electron Microscopy (SEM). The phyto-fabricated ZnO-NPs offered radical scavenging activity (RSA) in a dose-dependent manner with an IC50 of 0.45 mg mL-1. In addition, the genotoxicity studies of ZnO-NPs carried out on onion root tips revealed that the particles were able to significantly inhibit the cell division at the mitotic stage with a mitotic index of 39.49%. Further, the cytotoxic studies on HT-29 cells showed that the phyto-fabricated ZnO-NPs could arrest the cell division as early as in the G0/G1 phase (with 92.14%) with 73.14% cells showing early apoptotic symptoms after 24 h of incubation. The results of the study affirm the ability of phyto-fabricated ZnO-NPs from aqueous leaf extract of I. obscura is beneficial in the cytotoxic application.

Antidementia Effects of Alternanthera philoxeroides in Ovariectomized Mice Supported by NMR-Based Metabolomic Analysis.

The crude ethanol extract of the whole plant of Alternanthera philoxeroides (Mart.) Griseb was investigated for its potential as antidementia, induced by estrogen deprivation, based on in vitro antioxidant activity, ß-amyloid aggregation inhibition and cholinesterase inhibitory activity, as well as in vivo Morris water maze task (MWMT), novel object recognition task (NORT), and Y-maze task. To better understand the effect of the extract, oxidative stress-induced brain membrane damage through lipid peroxidation in the whole brain was also investigated. Additionally, expressions of neuroinflammatory cytokines (IL-1ß, IL-6 and TNF-α) and estrogen receptor-mediated facilitation genes such as PI3K and AKT mRNA in the hippocampus and frontal cortex were also evaluated. These effects were confirmed by the determination of its serum metabolites by NMR metabolomic analysis. Both the crude extract of A. philoxeroides and its flavone constituents were found to inhibit ß-amyloid (Aß) aggregation.