Boronated derivatives of chlorin <Emphasis Type="Italic">e</Emphasis><Subscript>6</Subscript> and fluoride-containing porphyrins as penetrating anions: a study using bilayer lipid membranes

Boronated derivatives of porphyrins are studied extensively as promising compounds for boron-neutron capture therapy and photodynamic therapy. Understanding of the mechanism of their permeation across cell membranes is a key step in screening for the most efficient compounds. In the present work, we studied the ability of boronated derivatives of chlorin e ₆ and porphyrins, which are mono-, di-, and tetra-anions, to permeate through planar bilayer lipid membranes (BLM). The translocation rate constants through the hydrophobic part of the lipid bilayer were estimated for monocarborane and its conjugate with chlorin e ₆ by the method of electrical current relaxation. They were similar, 6.6 and 6.8 sec⁻¹, respectively. Conjugates of porphyrins carrying two and four carborane groups were shown to permeate efficiently through a BLM although they carry two charges and four charges, respectively. The rate of permeation of the tetraanion estimated by the BLM current had superlinear dependence on the BLM voltage. Because the resting potential of most mammalian cells is negative inside, it can be concluded that the presence of negatively-charged boronated groups in compounds should hinder the accumulation of the porphyrins in cells.     

Novel boronated chlorin e6-based photosensitizers: Synthesis,binding to albumin and antitumour efficacy

Chlorins, a class of plant porphyrins, are perspective as photosensitizing agents due to light absorption in the long wavelength spectral region and deeper photodamage of tissues. Aiming at optimization of antitumour properties of chlorins, we synthesized a series of boronated derivatives of chlorin e₆ and their complexes containing Zn(II), Pd(II) or Sn(IV). The compounds were synthesized by alkylation of amino or hydroxy derivatives of chlorin e₆ with 1-trifluoromethanesulfonylmethyl-o-carborane. Chlorin e₆ 13(1)-N-{2-[N-(o-carboran-1-yl)methyl]aminoethyl}amide-15(2), 17(3)-dimethyl ester (compound 5) formed complexes with serum albumin, a major porphyrin carrier. The binding constant of these complexes was ～4 times bigger than the respective value for the complexes of albumin with boron-free aminochlorin e₆. Compound 5 potently sensitized rat fibroblasts to illumination with monochromatic red light: >98% of cells were necrotic by 24 h post-illumination with 1 μM of 5. This compound demonstrated high efficacy in photodynamic therapy of rat M-1 sarcoma. After PDT with 25 mg/kg of 5 the residual tumours were significantly smaller than in animals subjected to PDT with equal concentration of boron-free aminochlorin e₆. No signs of general toxicity were detectable after PDT with 5. Thus, boronation can enhance the potency of chlorins in PDT, in particular, due to an increased binding to albumin. Our data expand the therapeutic applicability of boronated chlorins beyond boron neutron capture therapy; these agents emerge as dual efficacy photoradiosensitizers.     

Comparing a thioglycosylated chlorin and phthalocyanine as potential theranostic agents

Herein we describe the design, efficient synthesis, and photophysical properties of two macrocycle dyes for cancer theranostics. This study compares a glycosylated chlorin with a glycosylated phthalocyanine designed to specifically target cancer, wherein the photophysical properties enable both fluorescence imaging and the sensitization of the formation of reactive oxygen species (ROS) for photodynamic therapy. Both the compounds show low darktoxicity (IC₅₀ > 100 μM). The glycosylated phthalocyanine showed low phototoxicity (IC₅₀ > 100 μM) while glycosylated chlorin showed high phototoxicity (IC₅₀ = 1–2 μM). ZnPcGlc₈ has low solubility and also form aggregates in aqueous media, thus resulting in minimal uptake in two different human breast cancer cell lines: MDA-MB-231 and MCF-7. The glycosylated chlorin however was efficiently taken up by these two cell lines, thus allows fluorescence imaging in cells and in xenograft tumor model in mice. In this study, we find that the chlorin conjugate is the more promising theranostic agent.     

Carboranyl-Chlorin e6 as a Potent Antimicrobial Photosensitizer

Antimicrobial photodynamic inactivation is currently being widely considered as alternative to antibiotic chemotherapy of infective diseases, attracting much attention to design of novel effective photosensitizers. Carboranyl-chlorin-e₆ (the conjugate of chlorin e₆ with carborane), applied here for the first time for antimicrobial photodynamic inactivation, appeared to be much stronger than chlorin e₆ against Gram-positive bacteria, such as Bacillus subtilis, Staphyllococcus aureus and Mycobacterium sp. Confocal fluorescence spectroscopy and membrane leakage experiments indicated that bacteria cell death upon photodynamic treatment with carboranyl-chlorin-e₆ is caused by loss of cell membrane integrity. The enhanced photobactericidal activity was attributed to the increased accumulation of the conjugate by bacterial cells, as evaluated both by centrifugation and fluorescence correlation spectroscopy. Gram-negative bacteria were rather resistant to antimicrobial photodynamic inactivation mediated by carboranyl-chlorin-e₆. Unlike chlorin e₆, the conjugate showed higher (compared to the wild-type strain) dark toxicity with Escherichia coli ΔtolC mutant, deficient in TolC-requiring multidrug efflux transporters.     

A novel piperazine linked β-amino alcohols bearing a benzosuberone scaffolds as anti-proliferative agents

A new series of 1-((9-chloro-2,3-dimethyl-6,7-dihydro-5H-benzo[7]annulen-8-yl)methoxy)-3-(4-phenylpiperzin-1-yl) propan-2-ols (6a-k) have been designed, synthesized and their structures were established by spectroscopic data (FT-IR, ¹H NMR, ¹³C NMR, HRMS) and further confirmed by X-ray analysis. The newly synthesized compounds 6a-k were evaluated for their in vitro anti-proliferative activity against four cancer cell lines such as HeLa (cervical), MDA-MB-231 (breast), A549 (lung) and MIAPACA (pancreatic). Among the compounds tested, the compound 6e displayed most potent activity against four cancer cell lines with GI₅₀ values ranging from 0.010 to 0.097 μM. The structure and anti-proliferative activity relationship was further supported by in silico molecular docking study of the active compounds against Colchicine binding site of β-tubulin.     

Novel 9-(2-(1-arylethylidene)hydrazinyl)acridine derivatives: Target Topoisomerase 1 and growth inhibition of HeLa cancer cells

A series of 9-(2-(1-arylethylidene)hydrazinyl)acridine and its analogs were designed, synthesized and evaluated for biological activities. Various biochemical assays were performed to determine the free radical scavenging capacity of synthesized compounds (4a–4j). Anticancer activity of these compounds was assessed against two different human cancer cell lines viz cervical cancer cells (HeLa) and liver cancer cells (HepG2) as well as normal human embryonic kidney cell line (HEK 293). Compounds 4b, 4d and 4e showed potential anti-proliferative effects on HeLa cells. Based on results obtained from antioxidant and cytotoxicity studies, 4b, 4d and 4e were further studied in detail for different biological activities. 4b, 4d and 4e reduced the cell growth, inhibited metastatic activity and declined the potential of cell migration in HeLa cell lines. Topoisomerase1 (Top1) treated with compounds 4b, 4d and 4e exhibited inhibition of Top1 and prevented DNA replication. Molecular docking results validate that interaction of compounds 4b, 4d and 4e with Top1-DNA complex, which might be accountable for their inhibitory effects. Further it was concluded that compounds 4b, 4d and 4e arrests the cells at S phase and consequently induces cell death through DNA damage in HeLa cells.     

The photodynamic activity of 131-[2′-(2-pyridyl)ethylamine] chlorin e6 photosensitizer in human esophageal cancer

A novel 13¹-pyridine substituted chlorin e₆ derivative (Chlorin A) was synthesized. It has characteristic long wavelength absorption at 664?nm and the emission wavelength at 667?nm. The generation rate of singlet oxygen of this compound is higher than Temoporfin. In vitro, Chlorin A showed higher phototoxicity against the human esophageal cancer cells than Temoporfin while with lower dark-toxicity. Its accumulation effect in mitochondria, lysosomes and endoplasmic reticulum was traced in subcellular localization tests. In flow cytometry obvious apoptosis cells were observed after 2?h irradiation. Significant in vivo photodynamic anti-tumor efficacy was also exhibited on mice bearing esophageal cancer. So Chlorin A could be suggested as a promising anti-tumor drug candidate in photodynamic therapy.     

Synthesis and Chemical Transformations of N-Hydroxy- and N-Hydroxyalkylcycloimides of Chlorin p6

Two series of chlorin p₆ 13,15-cycloimides that differ in their substituents at the nitrogen atom of the additional six-membered ring were synthesized. The compounds of the first series have a hydroxy, alkoxy, or acyloxy group at the 13,15-cycloimide nitrogen and those of the second series, residues of aliphatic alcohols. The cycloimides synthesized are satisfactorily stable and display an intensive light absorption maximum at 710–718 nm. Treatment of the cycloimides with sodium periodate in the presence of osmium tetroxide and with the Vilsmeier reagent resulted in the formation of 3-formyl- and 3-(2-formylvinyl)derivatives, respectively. The conversion of vinyl into formyl group or 2-formylvinyl group leads to an additional bathochromic shift of the long-wave maximum by 30 nm on average. An extra hydroxy group was introduced at position 18 of the macrocycle to increase the cycloimide hydrophilicity.     

Rational design,synthesis and anti-proliferative evaluation of novel benzosuberone tethered with hydrazide–hydrazones

Two different series of novel analogues of benzosuberones (5a–m and 9a–w) tethered with hydrazone–hydrazides (functional group alterations: Head group to Tail group and vice versa) have been synthesized by the reaction of appropriate aldehydes with substituted hydrazides in excellent yields (87–94%) and their structures were confirmed by ¹H NMR, ¹³C NMR, ESI-MS and HRMS. The newly synthesized compounds were evaluated for anti-proliferative activity against different human cancer cell lines (HeLa, MDA MB 231, MIAPACA and IMR32). Among the synthesized compounds, six compounds 5a, 5b, 5d, 5e, 5f and 9v exhibited potent anti-proliferative activity with GI₅₀ values less than 0.01 μM against MIAPACA, MDA-MB-231 and IMR32 human cancer cell lines.     

Lipophilic derivatives of natural chlorins: Synthesis,mixed micelles with phospholipids,and uptake by cultured cells

The chemical synthesis of six lipophilic conjugates of chlorins was carried out, in which lipophilic fragment (either hexadecyl- or cholest-5-en-3β-yloxyethyl-) bound to 13¹-, 15²-, 17³-positions of macrocycle by formation of related carboxamides. Structure of synthesized conjugates was studied by spectral methods and molecular modeling. Lipophilic conjugates of chlorins, being mixed with egg yolk phosphatidyl choline, formed mixed micelles stable in aqueous media under physiological conditions. Mixed micelles of conjugates with phosphatidyl choline differing in stoichiometric compositions were prepared and characterized by absorption spectra, electron microscopy and laser scattering. These micelles were found to bind and internalized by human breast carcinoma MCF-7 cells. The presented data reveal that modification of macrocycle with lipophilic substituents, solubilization of obtained conjugates in aqueous medium as mixed micelles with phospholipids, and transfer of mixed micelles to cells is simple approach for targeting of chlorin derivatives, which apparently may be used in photodynamic therapy.     

Click chemistry based multicomponent approach in the synthesis of spirochromenocarbazole tethered 1,2,3-triazoles as potential anticancer agents

A series of spirochromenocarbazole tethered 1,2,3-triazoles were synthesized via click chemistry based one-pot, five component reaction between N-propargyl isatins, malononitrile, 4-hydroxycarbazole, aralkyl halides and sodium azide using cellulose supported CuI nanoparticles (Cell-CuI NPs) as the heterogeneous catalyst. Antiproliferative activity of all the synthesized compounds was investigated against panel of cancer cell lines such as MCF-7, MDA-MB-231, HeLa, PANC-1, A-549, and THP-1. Many of the synthesized compounds exhibited good anti-proliferative activity against breast (MCF-7 and MDA-MB-231) and cervical (HeLa) cancer cells with IC₅₀ values less than 10 μM. In case of MCF-7 cells, among the nine compounds that showed good anti-proliferative activity, compounds 6f and 6j were found to be highly potent (IC₅₀ = 2.13 μM and 4.80 μM, respectively). In case of MDA-MB-231, three compounds (6k, 6j and 6s) showed antiproliferative activity amongst which 6k was the most potent one (IC₅₀ = 3.78 μM). On the other hand, in cervical cancer HeLa cells, compounds 6b, 6g, 6s and 6u showed excellent antiproliferative activity (IC₅₀ = 4.05, 3.54, 3.83, 3.35 μM, respectively). All the compounds were found to be nontoxic to the human umbilical vein endothelial cells (HUVECs). AO and EtBr staining and fluorescence microscopy studies of the active compounds (IC₅₀ < 5 μM) suggested that these compounds induce cell death by apoptosis.     

Synthesis and biological evaluation of podophyllotoxin congeners as tubulin polymerization inhibitors

A series of new podophyllotoxin derivatives containing structural modifications at C-7, C-8, and C-9 were synthesized and evaluated for their cytotoxic activity against three human cancer cell lines. All the synthesized compounds showed significant growth inhibition with GI₅₀ values in micromolar levels while some of the compounds were several times more potent against MCF-7 and HeLa cell lines than MIAPACA cell line. Three compounds (12a, 12d and 12e) emerged as potent compounds with broad spectrum of cytotoxic activity against all the tested cell lines with GI₅₀ values in the range of 0.01–2.1 μM. These compounds induce microtubule depolymerization and arrests cells at the G2/M phase of the cell cycle. Moreover, compounds 12d and 12e disrupted microtubule network and accumulated tubulin in the soluble fraction in a similar manner to their parent podophyllotoxin scaffold. In addition, structure activity relationship studies within the series were also discussed. Molecular docking studies of these compounds into the colchicine-binding site of tubulin, revealed possible mode of inhibition by these compounds.     

Base Induced Condensation of Malononitrile with Erlenmeyer Azlactones: An Unexpected Synthesis of Multi‐Substituted Δ2‐Pyrrolines and Their Cytotoxicity

An efficient, metal free approach to synthesize multi‐substituted Δ²‐pyrroline derivatives by mild base catalyzed cyclocondensation of malononitrile with Erlenmeyer azlactones via 1,2 addition was developed. The modularity of this reaction was used to assemble a range of poly‐substituted pyrrolines. Further, synthesized products were screened for cytotoxic properties on different cancer cell lines such as A549 (Human lung adenocarcinoma cells), HeLa (Human cervical adenocarcinoma cells), Jurkat (Human chronic myeloid leukemia cells) and K562 (Human leukemic T cell Lymphoblast cells). Among the synthesized library of compounds, 6f and 6q displayed potent cytotoxic activity.     

Synthesis and SAR study of novel anticancer and antimicrobial naphthoquinone amide derivatives

A series of novel naphthoquinone amide derivatives of the bioactive quinones, plumbagin, juglone, menadione and lawsone, with various amino acids were synthesized. The compounds were characterized by ¹H NMR, ¹³C NMR, Mass, IR and elemental analysis. All the compounds were evaluated for their anticancer activity against HeLa and SAS cancer cell lines and 3D-QSAR indicated the presence of electron donating group near sulphur enhanced the activity against HeLa cells. Among the derivatives synthesized, compounds 11f, 10a, 10b and 10g were the most active with IC₅₀ values of 16, 12, 14 and 24.5 μM, respectively. The analogues were also screened for antimicrobial activity against two human bacterial pathogens, the Gram-positive Methicillin resistant Staphylococcus aureus (MRSA) and the Gram-negative Pseudomonas aeruginosa and a human yeast pathogen, Fluconazole resistant Candida albicans (FRCA). Among the synthesized compounds, 8g, 10g and 11g exhibited maximum antibacterial activity towards MRSA and antifungal activity against FRCA in well diffusion method.     

Synthesis and anticancer evaluation of 3-aryl-6-phenylimidazo[2,1-b]thiazoles

A series of new 3,6-diphenylimidazo[2,1-b]thiazole derivatives (4a–l) are synthesized and evaluated for their anticancer activity. Some of the synthesized compounds have shown potent anti-proliferative activity against HeLa, MDA-MB-231, A549 and THP1 human cancer cell lines. Among the active compounds, 3-(3-trifluoromethylphenyl)-6-phenylimidazo[2,1-b]thiazole (4j) has caused significant cytotoxicity in HeLa cells, with IC₅₀ as low as 6.5 μM. Compound 4j has induced caspase-3 and caspase-8 activation, leading to an apoptotic cell death. FACS analysis has revealed that compound 4j arrests cells in G0/G1 phase. The presence of 3-(3-trifluoromethylphenyl)- or 3-(3-chlorophenyl)-substituent, in that order, on the 6-phenylimidazo[2,1-b]thiazole impacts more positively than other aryl-substituents, on the anti-proliferative properties of these compounds.     

Synthesis and antiproliferative activity of some steroidal lactams

Using cholesterol as starting material, a series of 6-substituted-3-aza-A-homo-3-oxycholestanes and 6-substituted-4-aza-A-homo-3-oxycholestanes were synthesized by the oxidation, reduction, oximation, Beckman rearrangement and condensation reaction. These synthesized compounds displayed a distinct cytotoxicity against MGC 7901, HeLa and SMMC 7404 cancer cells. Our results revealed that the structures of functional groups at position-6 on the steroidal ring are crucial for the IC₅₀ value of antiproliferative activities of these compounds and the cytotoxic activity against MGC 7901 and SMMC 7404 cells was not significantly different between 4-N-lactams and 3-N-lactams when its 6-substituted group was a carbonyl or a hydroximino, but all 3-N-lactams showed a higher cytotoxicity against HeLa cells than 4-N-lactams. In particular, compounds 6, 8, 9 (IC₅₀6: 6.5 μmol/L; 8: 7.7 μmol/L; 9: 5.6 μmol/L) were even more cytotoxic than cisplatin to HeLa cells (positive contrast, 10.1 μmol/L). The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.     

2-Phenyl-1-[4-(2-piperidine-1-yl-ethoxy)benzyl]-1H-benzimidazoles as ligands for the estrogen receptor: Synthesis and pharmacological evaluation

2-Phenyl-1H-benzimidazoles 7a–e were synthesized and tested for gene activation on ERα-positive MCF-7 breast cancer cells, stably transfected with the reporter plasmid ERE_wtcluc (MCF-7-2a cells). None of the compounds showed agonistic properties, but they antagonized dependent on hydroxyl groups at the benzimidazole core (5- or 6-OH) and at the aromatic ring in the 2-position (4-OH) in high concentrations the gene activation induced by estradiol (E2, 1 nM). All compounds exhibited significant antiproliferative properties on MCF-7 cells but they were inactive against hormone independent, ER negative MDA-MB-231 cells.     

Design,synthesis and evaluation of novel (S)-tryptamine derivatives containing an allyl group and an aryl sulfonamide unit as anticancer agents

A series of (S)-tryptamine derivatives containing an allyl group and an aryl sulfonamide unit were designed, synthesized and evaluated for their potential application as anticancer agents. The structures of the synthesized compounds were characterized by ¹H NMR, ¹³C NMR and ESI-MS spectral analyses. The target compounds were evaluated for their in vitro cytotoxicity against HepG2, HeLa, CNE1 and A549 human cancer cell lines. Some of the synthesized compounds showed moderate to good anticancer activities against four selected cancer cell lines, among of which 6ag was found to be the most active analogue possessing IC₅₀ values 16.5–18.7?μM. Further mechanism studies revealed that compound 6ag could significantly induce HepG2 cell cycle arrest at G1 phase, promote cell apoptosis, and inhibit the colony formation as well.     

Design and synthesis of 21-alkynylaryl pregnenolone derivatives and evaluation of their anticancer activity

A series of novel C21-alkynylaryl derivatives of pregnenolone were synthesized and screened for anticancer activity against a panel of seven human cancer cell lines (LNCaP, A549, MCF7, HeLa, A431, HepG2, HT29). The data revealed that these compounds can be potential antitumour agents against the specific cell models. Compound 6f bearing a 2-trifluoromethylphenyl group displayed improved cytotoxicity towards all cancer cell lines used. A431 cells were the most sensitive with derivatives 6e–6h bearing electron withdrawing substituents exhibiting high potency with IC₅₀ values ranging between 2.18 and 0.54 μM and drastic inhibition of the prosurvival PI3K-Akt/PKB pathway.