A comparison of apoptosis and necrosis induced by ent-kaurene-type diterpenoids in HL-60 cells

Activation of (un)regulated cell death as a new perspective for bispyridinium and imidazolium oximes

Oximes, investigated as antidotes against organophosphates (OP) poisoning, are known to display toxic effects on a cellular level, which could be explained beyond action on acetylcholinesterase as their main target. To investigate this further, we performed an in vitro cell-based evaluation of effects of two structurally diverse oxime groups at concentrations of up to 800 μM, on several cell models: skeletal muscle, kidney, liver, and neural cells. As indicated by our results, compounds with an imidazolium core induced necrosis, unregulated cell death characterized by a cell burst, increased formation of reactive oxygen species, and activation of antioxidant scavenging. On the other hand, oximes with a pyridinium core activated apoptosis through specific caspases 3, 8, and/or 9. Interestingly, some of the compounds exhibited a synergistic effect. Moreover, we generated a pharmacophore model for each oxime series and identified ligands from public databases that map to generated pharmacophores. Several interesting hits were obtained including chemotherapeutics and specific inhibitors. We were able to define the possible structural features of tested oximes triggering toxic effects: chlorine atoms in combination with but-2(E)-en-1,4-diyl linker and adding a second benzene ring with substituents such as chlorine and/or methyl on the imidazolium core. Such oximes could not be used in further OP antidote development research, but could be introduced in other research studies on new specific targets. This could undoubtedly result in an overall improved wider use of unexplored oxime database created so far in OP antidotes field of research in a completely new perspective.

Chemical Constituents of Bryophytes: Structures and Biological Activity

Comparatively little attention has been paid to the bryophytes for use in the human diet or medicine in spite of the presence of 23 000 species globally. Several hundred new compounds have been isolated from the liverworts (Marchantiophyta), and more than 40 new carbon skeletons of terpenoids and aromatic compounds were found. Most of the liverworts studied elaborate characteristic odiferous, pungent, and bitter-tasting compounds, of which many show antimicrobial, antifungal, antiviral, allergic contact dermatitis, cytotoxic, insecticidal, anti-HIV, plant growth regulatory, neurotrophic, NO production and superoxide anion radical release inhibitory, muscle relaxing, antiobesity, piscicidal, and nematocidal activities. The biological effects ascribed to the liverworts are mainly due to lipophilic sesqui- and diterpenoids, phenolic compounds, and polyketides, which are the principal constituents of their oil bodies. Some mosses and liverworts produce significant levels of vitamin B₂ and tocopherols, as well as prostaglandin-like highly unsaturated fatty acids. The most characteristic chemical phenomenon of the liverworts is that most of the sesqui- and diterpenoids are enantiomers of those found in higher plants. In this review, the chemical constituents and potential medicinal uses of bryophytes are discussed.

Determination and pharmacokinetic study of the novel anti-tumor candidate drug DG-7 in rat plasma by liquid chromatography-tandem mass spectrometry

DG-7 (11,14-dihydroxy-7,20-epoxy-20-O-derivative of ent-kaurene diterpenoid) is a novel anti-tumor candidate drug. A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of DG-7 in rat plasma. An aliquot of 50 μL plasma sample was prepared by liquid-liquid extraction with ethyl acetate. Chromatographic separation was accomplished on a Waters XTerra C18 column (2.1 mm × 150 mm, 5 μm) with an isocratic elution system consisting of methanol and water. Detection was performed by multiple reaction monitoring (MRM) mode using electrospray ionization in the positive ion mode. The optimized fragmentation transitions for MRM were m/z 590.1→m/z 260.0 for DG-7 and m/z 180.3→m/z 110.1 for phenacetin (internal standard). The method was linear over the concentration range of 5-2,500 ng/mL. The intra- and inter-day precisions were less than 7.9% and the accuracy was within ± 9.0%. The mean recovery of DG-7 ranged from 76.8% to 79.2%. The validated method has been successfully applied to a pharmacokinetic study in rats after intravenous administration of DG-7.

Study on the immunomodulation effect of Isodon japonicus extract via splenocyte function and NK anti-tumor activity

Here we investigated the potential immune-enhancing activity of Isodon japonicus on murine splenocyte and natural-killer (NK) cells in vitro. The ethanol extract of I. japonicus significantly enhanced the proliferation of splenocyte and induced the significant enhancement of NK cells' activity against tumor cells (YAC-1). In addition, I. japonicus increased the production of interferon (IFN)-γ and tumor necrosis factor (TNF)-α, suggesting that the increase in NK cell cytotoxicity could be due to the enhancement of the NK cell production of both cytokines. Taken together, I. japonicus extract inhibited the growth of human leukemia cells (K562) by 74%. Our observation indicated that the anti-tumor effects of I. japonicus may be attributed to its ability to serve as a stimulant of NK anti-tumor activity. In addition, our results support the development of functional food studies on I. japonicus.

Kaurane diterpenes protect against apoptosis and inhibition of phagocytosis in activated macrophages

BACKGROUND AND PURPOSE

The kaurane diterpenes foliol and linearol are inhibitors of the activation of nuclear factor kappaB, a transcription factor involved in the inflammatory response. Effects of these diterpenes on apoptosis and phagocytosis have been analysed in cultured peritoneal macrophages and in the mouse macrophage cell line, RAW 264.7.

EXPERIMENTAL APPROACH

Macrophages were maintained in culture and activated with pro-inflammatory stimuli in the absence or presence of diterpenes. Apoptosis and the phagocytosis in these cells under these conditions were determined.

KEY RESULTS

Incubation of macrophages with a mixture of bacterial lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma) induced apoptosis through a NO-dependent pathway, an effect significantly inhibited by foliol and linearol in the low muM range, without cytotoxic effects. Apoptosis in macrophages induced by NO donors was also inhibited. The diterpenes prevented apoptosis through a mechanism compatible with the inhibition of caspase-3 activation, release of cytochrome c to the cytosol and p53 overexpression, as well as an alteration in the levels of proteins of the Bcl-2 family, in particular, the levels of Bax. Cleavage of poly(ADP-ribose) polymerase, a well-established caspase substrate, was reduced by these diterpenes. Treatment of cells with foliol and linearol decreased phagocytosis of zymosan bioparticles by RAW 264.7 cells and to a greater extent by peritoneal macrophages.

CONCLUSIONS AND IMPLICATIONS

Both diterpenes protected macrophages from apoptosis and inhibited phagocytosis, resulting in a paradoxical control of macrophage function, as viability was prolonged but inflammatory and phagocytic functions were impaired.

Kaurene diterpenes from Laetia thamnia inhibit the growth of human cancer cells in vitro

Four ent-kaurene diterpenes were isolated from the leaves of Laetia thamnia L.: ent-kaur-16-en-19-oic acid (1a), ent-3beta-hydroxykaur-16-ene (2), ent-kaur-16-en-3alpha,19-diol (3a), and ent-17-hydroxykaur-15-en-19-oic acid (4). The methyl ester (1b) of compound 1a and the acetate diester (3b) of compound 3a were prepared, and all compounds were evaluated for cytotoxicity against human prostate (22Rv1, LNCaP), colon (HT29, HCT116, SW480, SW620), and breast (MCF-7) tumor cells at concentrations ranging from 6 to 50microg/mL. The kaurenes showed activity in all cell lines tested, with the prostate cells demonstrating the most sensitivity as follows: 22 Rv1 cells towards 1a (IC(50) 5.03microg/mL) and 1b (IC(50) 6.81microg/mL), and LNCaP towards 2 (IC(50) 12.83microg/mL) and 4 (IC(50) 17.63microg/mL).