Effect of ß-cyclodextrin encapsulation on cytotoxic activity of acetylshikonin against HCT-116 and MDA-MB-231 cancer cell lines.

Acetylshikonin (AcSh), as a red colored pigment found in roots of the plants from family Boraginaceae, showed excellent cytotoxic activity. Due to its hydrophobic nature, and thus poor bioavailability, the aim of this study was to prepare acetylshikonin/ß-cyclodextrin (AcSh/ß-CD) inclusion complex by using coprecipitation method, characterize obtained system by using UV/VIS, IR and 1H NMR spectroscopy, and determine cytotoxic activity. Phase solubility test indicated formation of AL-type binary system (substrate/ligand ratio was 1:1 M/M), with stability constant Ks of 306.01 M-1. Formation of noncovalent bonds between inner layer of the hole of ß-CD and AcSh was observed using spectroscopic methods. Notable changes in chemical shifts of two protons (-0.020 ppm) from naphthoquinone moiety (C6-H and C7-H), as well as protons from hydroxyl groups (-0.013 and -0.009, respectively) attached to C5 and C8 carbons from naphthoquinone part indicate that the molecule of AcSh enters the ß-CD cavity from the aromatic side. Cytotoxic activity against HCT-116 and MDA-MB-231 cell lines was measured by MTT test and clonogenic assay. Mechanisms of action of free AcSh and inclusion complex were assessed by flow cytometry. In comparison to free AcSh, AcSh/ß-CD showed stronger short-term effect on HCT-116 cells and superior long-term effect on both cell lines. Inclusion complex induced more pronounced cell cycle arrest and autophagy inhibition, and induced increase in accumulation of intracellular ROS more effectively than free AcSh. In conclusion, AcSh/ß-CD binary system showed better performances regarding cytotoxic activity against tested tumor cell lines.

Antibacterial and cytotoxic activities of naphthoquinone pigments from Onosma visianii Clem.

In this study, the antibacterial and cytotoxic activities of isolated compounds from the roots of Onosma visianii were investigated. By using different chromatographic techniques and appropriate spectroscopic methods, the seven naphthoquinones were described: deoxyshikonin ( 1 ), isobutyrylshikonin ( 2 ), α-methylbutyrylshikonin ( 3 ), acetylshikonin ( 4 ), ß-hydroxyisovalerylshikonin ( 5 ), 5,8-O-dimethyl isobutyrylshikonin ( 6 ) and 5,8-O-dimethyl deoxyshikonin ( 7 ). Among the tested compounds, 3 and 4 exhibited the highest antibacterial activities toward all tested bacterial species (MIC50 and MIC90 for gram positive bacteria: 6.40 µg/mL-12.79 µg/mL and 6.82 µg/mL-13.60 µg/mL, respectively; for gram negative bacteria: 4.27 µg/mL-8.53 µg/mL and 4.77 µg/mL-9.54 µg/mL, respectively). Also, naphthoquinones 3 and 4 exhibited strong cytotoxic activity against MDA-MB-231 cells (IC50 values 86.0 µg/mL and 80.2 µg/mL, respectively), while compounds 1 , 3 , 4 and 5 significantly decreased viability of HCT116 cells (IC50 values of 97.8 µg/mL, 15.2 µg/mL, 24.6 µg/mL and 30.9 µg/mL, respectively). Our results indicated that all tested naphthoquinone pigments are potential candidates for clinical uses as antibacterial and cytotoxic agents.

Chemical composition, cytotoxic and antioxidative activities of ethanolic extracts of propolis on HCT-116 cell line.

BACKGROUND: Propolis is a complex resinous sticky substance that honeybees collect from buds and exudates of various plants. Owing to its versatile biological and pharmacological activities, propolis is widely used in medicines, cosmetics and foods. The aim of this study was to evaluate the cytotoxic and antioxidative effects of various ethanolic extracts of propolis (EEPs) on human colon cancer cell line HCT-116 and compare them with their composition determined by HPLC-DAD. RESULTS: The most abundant flavonoids in all samples were chrysin, pinocembrin and galangin (12.697-40.811 µg mg⁻¹), while the main phenolic acids were caffeic acid, ferulic acid and isoferulic acid. Dose- and time-dependent inhibition of growth of HCT-116 cells was observed for all propolis samples, with IC50 values ranging from 26.33 to 143.09 µg mL⁻¹. Differences in cytotoxic activity of propolis samples were associated with differences in their composition. All EEP samples reduced both superoxide anion radical and nitrite levels and also had strong DPPH-scavenging activity. CONCLUSION: All tested propolis samples had pronounced cytotoxic and antioxidative activities.