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The in vitro activity of L. donovani (promastigotes, axenic amastigotes and intracellular amastigotes in THP1 cells) and T. brucei , from the fractions obtained from the hydroalcoholic extract of the aerial part of Hypericum afrum and the isolated compounds, has been evaluated. The chloroform, ethyl acetate and n -butanol extracts showed significant antitrypanosomal activity towards T. brucei , with IC 50 values of 12.35, 13.53 and 12.93 µg/mL and with IC 90 values of 14.94, 19.31 and 18.67 µg/mL, respectively. The phytochemical investigation of the fractions led to the isolation and identification of quercetin ( 1 ), myricitrin ( 2 ), biapigenin ( 3 ), myricetin ( 4 ), hyperoside ( 5 ), myricetin-3- O -β-d-galactopyranoside ( 6 ) and myricetin-3'- O -β-d-glucopyranoside ( 7 ). Myricetin-3'- O -β-d-glucopyranoside ( 7 ) has been isolated for the first time from this genus. The chemical structures were elucidated by using comprehensive one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopic data, as well as high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). These compounds have also been evaluated for their antiprotozoal activity. Quercetin ( 1 ) and myricetin ( 4 ) showed noteworthy activity against T. brucei , with IC 50 and IC 90 values of 7.52 and 5.71 µM, and 9.76 and 7.97 µM, respectively. The T. brucei hexokinase (TbHK1) enzyme was further explored as a potential target of quercetin and myricetin, using molecular modeling studies. This proposed mechanism assists in the exploration of new candidates for novel antitrypanosomal drugs.

The aim of this study was to evaluate the total phenolic and flavonoid content, and the in vitro antioxidant, anti-inflammatory, antibacterial, antifungal, antimalarial, cytotoxicity, and antiprotozoal activities of the Algerian plant Cytisus villosus Pourr. (Syn. Cytisus triflorus L'Hérit.). Additionally, the radioligand displacement affinity on opioid and cannabinoid receptors was assessed for the extracts and isolated pure compounds. The hydro alcoholic extract of the aerial part of C. villosus was partitioned with chloroform (CHCl 3 ), ethyl acetate (EtOAc), and n -butanol ( n -BuOH). The phenolic content of the C. villosus extracts was evaluated using a modified Folin-Ciocalteau method. The total flavonoid content was measured spectrometrically using the aluminum chloride colorimetric assay. The known flavonoids genistein ( 1 ), chrysin ( 2 ), chrysin-7- O -β-d-glucopyranoside ( 3 ), and 2″- O -α-l-rhamnosylorientin ( 4 ) were isolated. The antioxidant activities of the extracts and isolated compounds were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DDPH) and cellular antioxidant activity (CAA) assays. The plant extracts showed moderate antioxidant activity. EtOAc and n -BuOH extracts showed moderate anti-inflammatory activity through the inhibition of induced nitric oxide synthase (iNOS) with IC 50 values of 48 and 90 µg/mL, respectively. The isolated pure compounds 1 and 3 showed good inhibition of Inducible nitric oxide synthase (iNOS) with IC 50 values of 9 and 20 µg/mL, respectively. Compounds 1 and 2 exhibited lower inhibition of Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) with IC 50 values of 28 and 38 µg/mL, respectively. Furthermore, the extracts and isolated pure compounds have been shown to exhibit low affinity for cannabinoid and opioid receptors. Finally, n -BuOH extract was a potent inhibitor of Trypanosoma brucei with IC 50 value of 7.99 µg/mL and IC 90 value of 12.61 µg/mL. The extracts and isolated compounds showed no antimicrobial, antimalarial nor antileishmanial activities. No cytotoxic effect was observed on cancer cell lines. The results highlight this species as a promising source of anti-inflammatory and antitrypanosomal agents.

Background: Monoamine oxidases (MAOs) are outer mitochondrial membrane flavoenzymes. They catalyze the oxidative deamination of a variety of neurotransmitters. MAO-A and MAO-B may be considered as targets for inhibitors to treat neurodegenerative diseases and depression and for managing symptoms associated with Parkinson's and Alzheimer's diseases., Purpose: The objective was to evaluate the inhibitory effect of Hypericum afrum and Cytisus villosus against MAO-A and B and to isolate the compounds responsible for the MAO-inhibitory activity., Methods: The inhibitory effect of extracts and purified constituents of H. afrum and C. villosus were investigated in vitro using recombinant human MAO-A and B, and through bioassay-guided fractionation of ethyl acetate fractions of areal parts of the two plants collected in northeastern Algeria. In addition, computational protein-ligand docking and molecular dynamics simulations were carried out to explain the MAO binding at the molecular level., Results: The ethyl acetate (EtOAc) fractions of H. afrum and C. villosus showed the highest MAO inhibition activity against MAO A and B with IC 50 values of 3.37 µg/ml and 13.50 µg/ml as well as 5.62 and 1.87 µg/ml, respectively. Bioassay-guided fractionation of the EtOAc fractions resulted in the purification and identification of the known flavonoids quercetin, myricetin, genistein and chrysin as the principal MAO-inhibitory constituents. Their structures were established by extensive 1 and 2D NMR studies and mass spectrometry. Quercetin, myricetin and chrysin showed potent inhibitory activity towards MAO-A with IC 50 values of 1.52, 9.93 and 0.25 µM, respectively, while genistein more efficiently inhibited MAO-B (IC 50 value: 0.65 µM). The kinetics of the inhibition and the study of dialysis dissociation of the complex of quercetin and myricetin and the isoenzyme MAO-A showed competitive and mixed inhibition, respectively. Both compounds showed reversible binding. Molecular docking experiments and molecular dynamics simulations allowed to estimate the binding poses and to identify the most important residues involved in the selective recognition of molecules in the MAOs enzymatic clefts., Conclusion: Quercetin and myricetin isolated from H. afrum together with genistein and chrysin isolated from C. villosus have been identified as potent MAO-A and -B inhibitors. H. afrum and C. villosus have properties indicative of potential neuroprotective ability and may be new candidates for selective MAO-A and B inhibitors., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

In this paper we report the isolation and structural elucidation of a new flavonoid (1) and three known compounds, 6,8-di-C-methylkaempferol 3-methyl ether (2), oleanolic acid, and 2 alpha,3 beta-dihydroxyurs-12-en-28-oic acid, from aerial parts of Eucalyptus occidentalis collected in Algeria. Flavonoids 1 and 2 were used to study their biological activities on the human promyelocytic leukemia cell line, HL-60. Our data show that these compounds induce morphological changes and internucleosomal DNA fragmentation characteristic of apoptotic cell death, which is mediated by caspase-8/caspase-3 activation and cytochrome c release.

The aim of this study was to isolate the phytoconstituents and evaluate the biological activities of Berberis hispanica. Three phenolic compounds (tamarixetin, caffeic acid and rutin) were isolated from B. hispanica. The structures of the pure compounds were elucidated by spectroscopic and mass-spectrometric analyses, including 1D-, 2D-NMR, and HPLC-TOF/MS. In addition, antimicrobial, anti-oxidant and anti-proliferative effects of the extracts, some fractions and isolated compounds were evaluated. The extracts of B. hispanica were evaluated against six bacterial strains and exhibited the highest activity against Klebsiella pneumonia (15 mm at 100 mg/mL). Fraction T36 (IC50<5 μg/ mL) from the n-butanol extract displayed higher radical scavenging activity than butylated hydroxytoluene. The isolated compounds were evaluated for their anti-proliferative effects against human cervical adenocarcinoma (HeLa) cell line by real time cell analyzer assay and tamarixetin exhibited the remarkable effect (IC50<50 μg/mL) on HeLa cells. This study supports the documented medicinal effects of B. hispanica. [ABSTRACT FROM AUTHOR]