licochalcone-a and Hemolysis

The anti-inflammatory, immunomodulatory, and antimicrobial Glycyrrhiza inflata extract component licochalcone A triggers apoptosis of tumor cells and is thus considered for the treatment of malignancy. Similar to apoptosis of nucleated cells, erythrocytes may enter eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Signaling involved in the triggering of eryptosis includes Ca2+ entry with increase of cytosolic Ca2+ activity ([Ca2+]i), and ceramide. The present study explored, whether and how licochalcone A induces eryptosis.. Human erythrocytes drawn from healthy individuals were exposed for 24 hours to 1-10 µg/ml licochalcone A. Flow cytometry was subsequently employed to estimate phosphatidylserine exposure at the cell surface from annexin V binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, and ceramide utilizing specific antibodies. In addition, hemolysis was quantified from hemoglobin release.. Licochalcone A significantly increased the percentage of annexin-V-binding cells (≥ 5 µg/ml), significantly decreased forward scatter (2.5 - 5 µg/ml), significantly increased Fluo3-fluorescence (≥ 7.5 µg/ml), and significantly increased ceramide abundance (10 µg/ml). The effect of licochalcone on annexin-V-binding was not significantly modified, but hemolysis significantly enhanced by removal of extracellular Ca2+.. Licochalcone triggers cell shrinkage and phospholipid scrambling of the erythrocyte cell membrane, an effect independent from Ca2+ entry and presumably in part due to ceramide.

Topics: Aniline Compounds; Apoptosis; Calcium; Cell Size; Ceramides; Chalcones; Erythrocytes; Flow Cytometry; Hemolysis; Humans; Phosphatidylserines; Xanthenes

Streptococcus suis (S.suis) is an important emerging worldwide pig pathogen and zoonotic agent with rapid evolution of virulence and drug resistance. In this study, we wanted to investigate the effect of licochalcone A on growth and properties of Streptococcus suis. The antimicrobial activity of licochalcone A was tested by growth inhibition assay and the minimal inhibitory concentrations (MICs) also were determined. The effect of licochalcone A on S.suis biofilm formation was characterized by crystal violet staining. The effect of licochalcone A on suilysin secretion was evaluated by titration of hemolytic activity. To understand the antimicrobial effect, gene expression profile of S.suis treated by licochalcone A was analyzed by DNA microarray. Our results demonstrated that licochalcone A showed antimicrobial activity on S.suis with MICs of 4 µg/ml for S.suis serotype 2 strains and 8 µg/ml for S.suis serotype 7 strains. Biofilm formation was inhibited by 30-40% in the presence of licochalcone A (3 µg/ml) and suilysin secretion was also significantly inhibited in the presence of licochalcone A (1.5 µg/ml). The gene expression profile of S.suis in the presence of licochalcone A showed that 132 genes were differentially regulated, and we analyzed the regulated genes in the aspect of the bacterial cell cycle control. Among the deregulated genes, the genes responsible for the mass doubling was increased expression, but the genes responsible for DNA replication and cell division were inhibited the expression. So, we think the regulation of the cell cycle genes might provide a mechanistic understanding of licochalcone A mediated antimicrobial effect against S.suis.

Topics: Biofilms; Chalcones; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genes, Bacterial; Hemolysin Proteins; Hemolysis; Humans; Microbial Sensitivity Tests; Oligonucleotide Array Sequence Analysis; Streptococcus suis

Use of artemisinin based combination therapies (ACTs) is increasing in treatment of malaria. Their extensive and indiscriminate deployment will ultimately lead to selection of resistance. Thus, alternate ACTs are needed. We reported in vitro antimalarial potential of chalcone derivatives. A few potent chalcones were selected for their antimalarial interaction in combination with artemisinin in vitro. Combinations evaluated show synergistic or additive interactions. Chalcones act on broad range of asexual stages of the parasite. The synergistic combinations decrease hemozoin formation in parasitized erythrocytes. These combinations do not affect new permeation pathways induced in the host cells. This is the first report showing antiplasmodial interactions between artemisinin and synthetic chalcone azole derivatives. Thus, chalcones and artemisinin combinations open the possibility of novel ACTs.

Topics: Animals; Antimalarials; Artemisinins; Chalcone; Drug Combinations; Drug Synergism; Erythrocytes; Hemeproteins; Hemolysis; Humans; Parasitic Sensitivity Tests; Plasmodium falciparum

This paper describes how the introduction of "cationic" aliphatic amino groups in the chalcone scaffold results in potent antibacterial compounds. It is shown that the most favorable position for the aliphatic amino group is the 2-position of the B-ring, in particular in combination with a lipophilic substituent in the 5-position of the B-ring. We demonstrate that the compounds act by unselective disruption of cell membranes. Introduction of an additional aliphatic amino group in the A-ring results in compounds that are selective for bacterial membranes combined with a high antibacterial activity against both Gram-positive and -negative pathogens. The most potent compound in this study (78) has an MIC value of 2 muM against methicillin resistant Staphylococus aureus.

Topics: Anti-Bacterial Agents; Cations; Chalcones; Colony Count, Microbial; Drug Design; Hemolysis; Humans; In Vitro Techniques; Kinetics; Methicillin Resistance; Microbial Sensitivity Tests; Quaternary Ammonium Compounds; Staphylococcus aureus; Structure-Activity Relationship