Feature-Based Molecular Networking for the Exploration of the Metabolome Diversity of Common Egyptian Centaurea Species in Relation to Their Cytotoxic Activity.

Centaurea is a genus compromising over 250 herbaceous flowering species and is used traditionally to treat several ailments. Among the Egyptian Centaurea species, C. lipii was reported to be cytotoxic against multidrug-resistant cancer cells. In this context, we aimed to explore the metabolome of C. lipii and compare it to other members of the genus in pursuance of identifying its bioactive principles. An LC-MS/MS analysis approach synchronized with feature-based molecular networks was adopted to offer a holistic overview of the metabolome diversity of the Egyptian Centaurea species. The studied plants included C. alexandrina, C. calcitrapa, C. eryngioides, C. glomerata, C. lipii, C. pallescens, C. pumilio, and C. scoparia. Their constitutive metabolome showed diverse chemical classes such as cinnamic acids, sesquiterpene lactones, flavonoids, and lignans. Linking the recorded metabolome to the previously reported cytotoxicity identified sesquiterpene lactones as the major contributors to this activity. To confirm our findings, bioassay-guided fractionation of C. lipii was adopted and led to the isolation of the sesquiterpene lactone cynaropicrin with an IC50 of 1.817 µM against the CCRF-CEM leukemia cell line. The adopted methodology highlighted the uniqueness of the constitutive metabolome of C. lipii and determined the sesquiterpene lactones to be the responsible cytotoxic metabolites.

Naturally Available Flavonoid Aglycones as Potential Antiviral Drug Candidates against SARS-CoV-2.

Flavonoids are important secondary plant metabolites that have been studied for a long time for their therapeutic potential in inflammatory diseases because of their cytokine-modulatory effects. Five flavonoid aglycones were isolated and identified from the hydrolyzed aqueous methanol extracts of Anastatica hierochuntica L., Citrus reticulata Blanco, and Kickxia aegyptiaca (L.) Nabelek. They were identified as taxifolin (1), pectolinarigenin (2), tangeretin (3), gardenin B (4), and hispidulin (5). These structures were elucidated based on chromatographic and spectral analysis. In this study, molecular docking studies were carried out for the isolated and identified compounds against SARS-CoV-2 main protease (Mpro) compared to the co-crystallized inhibitor of SARS-CoV-2 Mpro (α-ketoamide inhibitor (KI), IC50 = 66.72 µg/mL) as a reference standard. Moreover, in vitro screening against SARS-CoV-2 was evaluated. Compounds 2 and 3 showed the highest virus inhibition with IC50 12.4 and 2.5 µg/mL, respectively. Our findings recommend further advanced in vitro and in vivo studies of the examined isolated flavonoids, especially pectolinarigenin (2), tangeretin (3), and gardenin B (4), either alone or in combination with each other to identify a promising lead to target SARS-CoV-2 effectively. This is the first report of the activity of these compounds against SARS-CoV-2.

Flavonoid constituents of Dobera glabra leaves: amelioration impact against CCl4-induced changes in the genetic materials in male rats.

CONTEXT: Dobera glabra (Forssk.) Poir (Salvadoraceae) is a highly valued tree with diverse importance as special mineral sourced feed and a folkloric tool for forecasting droughts. However, there are no reports on its phytochemical and biological investigations. OBJECTIVE: Phytochemical investigation of D. glabra leaves and its protective potential against CCl4 inducing changes in the genetic materials. MATERIALS AND METHODS: D. glabra extract, DGE (70% MeOH/H2O), was applied to polyamide column chromatography, eluting with MeOH/H2O of decreasing polarities, followed by preparative chromatographic tools, yielded seven compounds. Three DGE doses (50, 100 and 200 mg/kg bw/d) were administrated for 8 weeks intragastrically to male albino rats prior treated with CCl4 (0.5 mL/kg/bw). The reactive oxygen species (ROS) levels, expression changes of glutamate transporters (GLAST, GLT-1 and SNAT3) mRNA, DNA fragmentation and glutathione peroxidase (GPx) activity were investigated in the liver tissues of these rats. RESULTS: Isorhamnetin-3-O-ß-glucopyranoside-7-O-α-rhamnopyranoside, isorhamnetin-3-O-α-rhamnopyranoside-7-O-ß-glucopyranoside, kaempferol-3,7-di-O-α-rhamnopyranoside, isorhamnetin-3-O-ß-glucopyranoside, kaempferol-3-O-ß-glucopyranoside, isorhamnetin and kaempferol were identified. DGE (200 mg/kg bw) + CCl4 exhibited the most significant reduction in ROS levels and DNA fragmentation with 251.3% and141% compared to 523.1% and 273.2% for CCl4, respectively. Additionally, it increased significantly the mRNA expression of GLAST, GLT-1 and SNAT3 to 2.16-, 1.72- and 2.09-fold, respectively. Also, GPx activity was increased to 4.8 U/mg protein/min compared to CCl4 (1.8 U/mg protein/min). DISCUSSION AND CONCLUSION: Flavonoid constituents, antioxidant effect and genotoxic protection activity of D. glabra were first reported. DGE may be valuable in the treatment and hindrance of hepatic oxidative stress and genotoxicity.

Two new flavonol glycosides and biological activities of Diplotaxis harra (Forssk.) Boiss.

Two new flavonol glycosides, isorhamnetin 3-O-ß-glucopyranoside-4'-O-ß-xylopyranoside (1) and kaempferol 3-O-ß-glucopyranoside -4'-O-ß-xylopyranoside (2), were isolated from the defatted aqueous methanol extract of the whole plant Diplotaxis harra along with 12 known flavonols (3-14). They were characterised by chemical and spectral methods. The 70% aqueous methanol, chloroform and defatted aqueous methanol plant extracts exhibited significant antioxidant effects (nitroblue tetrazolium reduction method). Their cytotoxic activity was carried out against 11 tumour cell lines (sulphorhodamine B assay). The three extracts expressed the greatest antiproliferative activity against colon 38, P388 and MKN-28 with GI50 (0.45, 0.4, 0.07 µg/mL) and against P388 [3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay] with IC50 (0.26, 0.24, 0.25 µg/mL), respectively. The chloroform extract showed the highest activity as eukaryotic DNA topoisomerase II inhibitors of P388 with IC50 0.24 µg/mL. Antiviral screening of the extracts and the pure compounds against foot-and-mouth disease virus types A and O revealed a prominent inhibition of its cytopathic effect.