Optically active stereoisomers of 5-(1-iodoethyl)-4-(4'-isopropylphenyl)dihydrofuran-2-one: The effect of the configuration of stereocenters on apoptosis induction in canine cancer cell lines

Some 2-[4-(1H-benzimidazol-1-yl) phenyl]-1H-benzimidazole derivatives overcome imatinib resistance by induction of apoptosis and reduction of P-glycoprotein activity

Imatinib (IMA) is a tyrosine kinase inhibitor (TKI) introduced for the chronic myeloid leukemia (CML) therapy. Emergence of IMA resistance leads to the relapse and failure in CML therapy. Benzimidazole is a heterocyclic organic compound which is widely investigated for the development of anticancer drugs. In this study, we aimed to explore the anticancer effects of some 2-[4-(1H-benzimidazol-1-yl) phenyl]-1H-benzimidazole derivatives on K562S (IMA-sensitive) and K562R (IMA-resistant) cells. To analyze the cytotoxic and apoptotic effects of the compounds, K562S, K562R, and L929 cells were exposed to increasing concentrations of the derivatives. Cytotoxic effects of compounds on cell viability were analyzed with MTT assay. Apoptosis induction, caspase3/7 activity were investigated with flow cytometry and BAX, BIM, and BAD genes expression levels were analyzed with qRT-PCR. Rhodamine123 (Rho-123) staining assays were carried out to evaluate the effect of compounds on P-glycoprotein (P-gp) activity. The hit compounds were screened using molecular docking, and the binding preference of each compounds to BCR-ABL protein was evaluated. Our results indicated that compounds triggered cytotoxicity, caspase3/7 activation in K562S and K562R cells. Rho-123 staining showed that compounds inhibited P-gp activity in K562R cells. Overall, our results reveal some benzimidazole derivatives as potential anticancer agents to overcome IMA resistance in CML.

Antimicrobial Activity of Lactones

The development of bacterial resistance to antibiotics and the consequent lack of effective therapy is one of the biggest problems in modern medicine. A consequence of these processes is an urgent need to continuously design and develop novel antimicrobial agents. Among the compounds showing antimicrobial potential, lactones are a group to explore. For centuries, their antimicrobial activities have been used in folk medicine. Currently, novel lactone compounds are continuously described in the literature. Some of those structures exhibit high antimicrobial potential and some are an inspiration for design and synthesis of future drugs. This paper describes recent developments on antimicrobial lactones with smaller ring sizes, up to seven membered ε-lactones. Their isolation from natural sources, chemical synthesis, synergistic activity with antibiotics, and effects on quorum sensing are presented herein.

Methoxy-Substituted γ-Oxa-ε-Lactones Derived from Flavanones-Comparison of Their Anti-Tumor Activity In Vitro

Background: The study investigated four flavanone-derived γ-oxa-ε-lactones: a parent unsubstituted compound and its three derivatives with the methoxy group in positions 2′, 4′ and 8. Our objective was to find out if the introduction of the methoxy group into the aromatic ring affects in vitro anti-tumor potency of the investigated lactones. Methods: Cytotoxic and pro-apoptotic effects were assessed with cytometric tests with propidium iodide, annexin V, and Western blot techniques. We also investigated potential synergistic potency of the tested lactones and glucocorticoids in canine lymphoma/leukemia cell lines. Results: The tested flavanone-derived lactones showed anti-cancer activity in vitro. Depending on its location, the methoxy group either increased or decreased cytotoxicity of the derivatives as compared with the parent compound. The most potent lactone was the one with the methoxy group at position 4′ of the B ring (compound 3), and the weakest activity was observed when the group was located at C-8 in the A ring. A combination of the lactones with glucocorticoids confirmed their synergy in anti-tumor activity in vitro. Conclusions: Methoxy-substituted flavanone-derived lactones effectively kill canine lymphoma/leukemia cells in vitro and, thanks to their synergistic action with glucocorticoids, may potentially be applied in the treatment of hematopoietic cancers.

α-Solanine Inhibits Proliferation, Invasion, and Migration, and Induces Apoptosis in Human Choriocarcinoma JEG-3 Cells In Vitro and In Vivo

α-Solanine, a bioactive compound mainly found in potato, exhibits anti-cancer activity towards multiple cancer cells. However, its effects on human choriocarcinoma have not been evaluated. In the present study, we investigated the effect of α-solanine on cell proliferation and apoptosis in human choriocarcinoma in vitro and in vivo. The results showed that α-solanine, at concentrations of 30 μM or below, did not affect the cell viability of the choriocarcinoma cell line JEG-3. However, colony formation was significantly decreased and cell apoptosis was increased in response to 30 μM α-solanine. In addition, α-solanine (30 μM) reduced the migration and invasion abilities of JEG-3 cells, which was associated with a downregulation of matrix metalloproteinases (MMP)-2/9. The in vivo findings provided further evidence of the inhibition of α-solanine on choriocarcinoma tumor growth. α-Solanine suppressed the xenograft tumor growth of JEG-3 cells, resulting in smaller tumor volumes and lower tumor weights. Apoptosis was promoted in xenograft tumors of α-solanine-treated mice. Moreover, α-solanine downregulated proliferative cellular nuclear antigen (PCNA) and Bcl-2 levels and promoted the expression of Bax. Collectively, α-solanine inhibits the growth, migration, and invasion of human JEG-3 choriocarcinoma cells, which may be associated with the induction of apoptosis.

Assessment of azithromycin as an anticancer agent for treatment of imatinib sensitive and resistant CML cells

INTRODUCTION

Chronic Myeloid Leukemia (CML) is a hematological disease which is characterized by the presence of BCR-ABL fusion protein. Imatinib (IMA), a tyrosine kinase inhibitor of BCR-ABL, is used as a frontline treatment.Although IMA aids in killing a majority of leukemia cells, it may not kill CML stem cells which are the primary roots of disease and therapy resistance. Recently, antimicrobial drugs have been gaining attention because of their selective targeting of cancer cells. Therefore, we now ask if combinational therapy of IMA with a targeted antimicrobial drug Azithromycin (AZT) can enhance the treatment efficiency in IMA resistant CML.

METHODS

K562S (IMA sensitive) and K562R (IMA resistant) cells were treated with increasing concentrations of AZT to determine its effects on cell proliferation and apoptosis. Cell viability, apoptosis, caspase3/7 activity and P-glycoprotein (Pgp) function were investigated with spectrophotometric MTT assay and flow cytometric Annexin V staining, caspase 3/7 activity, and Rhodamine123 staining assays respectively. The expression levels of pro-apoptotic (BAX, BAD and BIM), anti- apoptotic (BCL-XL and BCL-2) and drug transporter (MDR-1 and MRP-1) genes were assessed with qRT-PCR.

RESULTS

AZT treatment alone inhibited cell viability, induced apoptosis and enhanced caspase 3/7 activity in both K562S and high MDR-1 (Pgp) expressing K562R cells. Moreover, combination of AZT/IMA suppressed cell viability, induced apoptosis and caspase3/7 activity more effectively and significantly compared to K562R cells treated with only IMA or AZT. Furthermore, AZT and AZT/IMA combination decreased Pgp function in K562R cells in comparison with their controls. Based on qRT-PCR data, single AZT and combined AZT/IMA treatment also induced BAX/BCL-2 ratio significantly in both K562S and K562R cells.

CONCLUSION

Single AZT and AZT/IMA combinational treatment can be proposed as a promising and effective treatment strategy for CML. One of the mechanisms underlying the potent anticancer effect of combined AZT/IMA could be its ability to inhibit Pgp function and increase intracellular accumulation of IMA which leads to the induction of apoptosis in K562R cells.

Biotechnological Approach for the Production of Enantiomeric Hydroxylactones Derived from Benzaldehyde and Evaluation of Their Cytotoxic Activity

The β-aryl-δ-halo-γ-lactones are known for their antiproliferative activity towards numerous cancer cell lines. The aim of this study was to obtain in the biotransformation process new β-aryl-δ-hydroxy-γ-lactones and compare their activity with the antiproliferative activity of parent compounds. The racemic cis-5-(1-iodoethyl)-4-phenyldihydrofuran-2-one as well as separate enantiomers were transformed in fungal cultures. Among ten tested biocatalysts, three (Absidia cylindrospora AM336, Absidia glauca AM254, and Fusarium culmorum AM10) were able to catalyze the hydrolytic dehalogenation process. The biotransformations processes were highly stereoselective and enantiomerically pure hydroxylactones were obtained (ee ≥ 99%). The iodo- and hydroxylactone enantiomers were subjected to cytotoxic activity evaluation on canine leukemia and lymphoma cell lines. The iodolactones exhibited higher biological potential towards tested cell lines than hydroxylactones. Higher cytotoxic potential was also characteristic for (+)-(4S,5S,6R)-enantiomer of iodolactone compared to its antipode.

Synthesis, antibacterial activities, and sustained perfume release properties of optically active5-hydroxy- and 5-acetoxyalkanethioamide analogues

5-Acetoxy- and 5-hydroxyalkanethioamide analogues showed high antibacterial activity against Staphylococcus aureus. Antibacterial thioamides were prepared from 5-alkyl-δ-lactones by amidation, thionation, and subsequent deacetylation. Optically active thioamides with 99% diastereomeric excesses were prepared by diastereomeric resolution using Cbz-L-proline as the resolving agent. Antibacterial thioamides were slowly lactonized by a lipase catalyst. Therefore, these thioamides are potential sustained-release perfume compounds having antibacterial properties.

Microbial Asymmetric Functionalization of β-Cyclocitral-Derived Tetramethyl-Substituted γ-Lactone

Searching for the new anticancer compounds we prepared three new β-cyclocitral-derived hydroxyl-γ-lactones by microbial hydroxylation of tetramethyl-substituted bicyclic γ-lactone. The substrate was transformed by the enzymatic system of filamentous fungi. Three out of fifteen strains were selected as effective biocatalysts (Fusarium culmorum AM10, Armillaria mellea AM296, Trametes versicolor AM536). The hydroxylation processes were not only regioselective but also stereoselective. The hydroxylation products of each secondary carbon atom in the cyclohexane ring were obtained by the application of the selected fungal strains. The Fusarium culmorum AM10 introduced the hydroxy function at C-3 and C-4, Armillaria mellea AM296 incorporated the hydroxy function at C-3 and C-5 and Trametes versicolor AM536 transformed the substrate to the mixture of C-3, C-4 and C-5 hydroxylactones. The hydroxylactones obtained were enantiomericaly enriched (ee values in the range 17–99%). The in vitro antiproliferative activities of the functionalization products were also evaluated. Regardless of the hydroxy substituent location all tested lactones exhibited similar, significant activity towards selected cancer cell lines (IC₅₀ in the range 22.8–33.9 µg/mL).

Determination of the Apoptotic Effect and Molecular Docking of Benzamide Derivative XT5 in K562 Cells

Background:

The tyrosine kinase inhibitor, imatinib, used as a first line treatment in Chronic Myeloid Leukemia (CML) patients, may lead to resistance and failure to therapy. Novel combinations of imatinib with other drugs is a strategy to improve treatment efficiency.

Objective:

In this study, the antileukemic and apoptotic effects of a benzamide derivative XT5 and benzoxazole derivative XT2B and their combination with imatinib were investigated in imatinib-sensitive (K562S) and imatinib-resistant (K562R) CML cells.

Methods:

In vitro cytotoxicity was determined by MTT assay. Then, apoptotic effect of XT5 on CML cell lines was tested by Annexin V flow cytometry, caspase activation and RT-PCR. Docking calculation was performed using AutoDock Vina in PyMOL environment using AutoDock/Vina plugin for PyMOL.

Results:

According to our MTT assay data, XT5 indicated significant antiproliferative effect on cell lines, therefore we investigated apoptotic effects of XT5. Treatment of K562 cell lines with a combination of XT5 and imatinib-XT5 increased cytotoxicity, the Annexin V binding and caspase 3/7 activation. In addition to apoptosis assays, we observed an increase in the expression levels of the pro-apoptotic (BAX, BAD and BIM) genes in XT5 treated K562R and K562S cells. Molecular modelling experiments showed that XT5 showed hydrogenbonding interactions with important amino acids of BCR-ABL kinase receptor; however XT2B did not show any hydrogen bond interaction.

Conclusion:

Our results indicate that XT5 could be a potential candidate to be used as a new anticancer drug and XT5 combination with imatinib as an alternate treatment strategy for overcoming imatinib resistance.

Preparation of Enantiomeric β-(2',5'-Dimethylphenyl)Bromolactones, Their Antiproliferative Activity and Effect on Biological Membranes

Three novel enantiomeric pairs of bromolactones possesing a 2,5-dimethylphenyl substituent at the β-position of the lactone ring have been synthesized from corresponding enantiomeric (E)-3-(2',5'-dimethylphenyl)hex-4-enoic acids (4) by kinetically controlled bromolactonization with N-bromosuccinimide (NBS). γ-Bromo-δ-lactones (5) were isolated as the major products. Absolute configurations of stereogenic centers of γ-bromo-δ-lactones (5) were assigned based on X-ray analysis; configurations of cis δ-bromo-γ-lactones (6) and trans δ-bromo-γ-lactones (7) were determined based on mechanism of bromolactonization. Synthesized compounds exhibited significant antiproliferative activity towards the four canine cancer cell lines (D17, CLBL-1, CLB70, and GL-1) and one human cancer line (Jurkat). Classifying the compounds in terms of activity, the most active were enantiomers of trans δ-bromo-γ-lactones (7) followed by enantiomers of cis isomer (6) and enantiomeric γ-bromo-δ-lactones (5). Higher activity was observed for all stereoisomers with S configuration at C-4 in comparison with their enantiomers with 4R configuration. Synthesized compounds did not induce hemolysis of erythrocytes. The results of the interaction of bromolactones with red blood cell membranes suggest that these compounds incorporate into biological membranes, concentrating mainly in the hydrophilic part of the bilayer but have practically no influence on fluidity in the hydrophobic region. The differences in interactions with the membrane between particular enantiomers were observed only for γ-lactones: stronger interactions were found for enantiomer 4R,5R,6S of cis γ-lactone (6) and for enantiomer 4S,5R,6S of trans γ-lactone (7).

The inhibitory effect of gypenoside stereoisomers, gypenoside L and gypenoside LI, isolated from Gynostemma pentaphyllum on the growth of human lung cancer A549 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Gypenosides are major constituents in Gynostemma pentaphyllum (Thunb.) Makino. Previous studies have shown that gypenosides isolated from G. pentaphyllum possess inhibitory effect on the growth of cancer cells, especially A549 cells, with structure-activity relationship (SAR). However, the underlying mechanism of gypenoside-induced A549 cell death remains to be clarified.

AIM OF THE STUDY

To further investigate SAR and the underlying mechanism of gypenosides in A549 cells.

MATERIALS AND METHODS

Gypenosides were isolated from G. pentaphyllum using chromatography methods and identified using MS and NMR data. The cytotoxicity was determined with CCK-8 assay. The effects of gypenosides on apoptosis, cell cycle and migration were investigated through cell morphology observation, flow cytometry analysis and key proteins detection.

RESULTS

Three gypenosides, 2α,3β,12β,20(S)-tetrahydroxydammar-24-ene-3-O-β-D-glucopyranoside-20-O-β-D-glucopyranoside, gypenoside L and gypenoside LI were isolated from G. pentaphyllum. Gypenoside stereoisomers, gypenoside L (S configuration at C20) and gypenoside LI (R configuration at C20) showed stronger activity against A549 cells. Furthermore, both induced A549 cell apoptosis through intrinsic and extrinsic pathways evidenced by reducing mitochondrial membrane potential (MMP), generating reactive oxygen species (ROS), releasing more cytochrome c and down-regulating procaspase 8. However, gypenoside L blocked A549 cells in G0/G1, while gypenoside LI induced G2/M arrest, which was further verified by different expression of CDK1, CDK2 and CDK4. In addition, both inhibited A549 cell migration, which was evidenced by down-regulation of MMP-2/9 as well as scratch wound assay and transwell assay.

CONCLUSION

C₂₀ of gypenoside played an important role in A549 cell cytotoxicity and gypenoside stereoisomers could be used as potential multi-target chemopreventive agents for cancer.

Enantiomeric trans β-aryl-δ-iodo-γ-lactones derived from 2,5-dimethylbenzaldehyde induce apoptosis in canine lymphoma cell lines by downregulation of anti-apoptotic Bcl-2 family members Bcl-xL and Bcl-2

For many years, studies focused on developing new natural or synthetic compounds with antineoplastic activity have attracted the attention of researchers. An interesting group of such compounds seem to be those with both lactone moiety and an aromatic ring which, in addition to antimicrobial or antiviral activity, also exhibit antitumor properties. The study shows antitumor activity of two enantiomeric trans isomers of 5-(1-iodoethyl)-4-(2',5'-dimethylphenyl)dihydrofuran-2-one. Our aim was to determine their antitumor activity manifested as an ability to induce apoptosis in selected canine cancer cell lines as well as to evaluate differences in their strength depending on the configuration of their stereogenic centers. The enantiomers (+)-(4R,5S,6R)-1 and (-)-(4S,5R,6S)-2 were found to induce classical caspase-dependent apoptosis through downregulation of the expression of anti-apoptotic proteins Bcl-xL and Bcl-2. Although the mechanism of apoptosis induction was the same for both enantiomers, they differed in their strength, as stronger antineoplastic activity in vitro was exhibited by isomer (+)-(4R,5S,6R)-1.

Regio- and enantioselective microbial hydroxylation and evaluation of cytotoxic activity of β-cyclocitral-derived halolactones

Three β-cyclocitral-derived halolactones, which exhibit antifeedant activity towards storage product pests, were subjected to microbial transformation processes. Among the thirty tested strains of filamentous fungi and yeast, the most effective biocatalysts were Absidia cylindrospora AM336, Mortierella isabellina AM212 and Mortierella vinaceae AM149. As a result of regio- and enantioselective hydroxylation four new oxygenated derivatives were obtained. Regardless of the biocatalyst applied, the δ-iodo- and δ-bromo-γ-lactones were hydroxylated in an inactivated position C-5 of cyclohexane ring. The analogous transformation of chlorolactone was observed in Mortierella isabellina AM212 culture but in the case of two other biocatalysts the hydroxy group was introduced at C-3 position. All obtained hydroxylactones were enantiomerically pure (ee = 100%) or enriched (ee = 50%). The highest enantioselectivity of hydroxylation was observed for M. isabellina AM212. The cytotoxic activity of halolactones was also examined by WST-1 assay wherein tested compounds did not exhibit significant effect on the viability of tumor HeLa and normal CHO-K1 cells.