The synthesis and cytotoxic evaluation of a series of benzodioxole substituted titanocenes

An Environment-friendly Synthesis of Piperonal Chalcones and Their Cytotoxic and Antioxidant Evaluation

Background:

Grindstone technique has been widely used as an efficient, consistent, more environmentally benign, solvent-free protocol for the preparation of many compounds with higher atom economy.

Methods:

A series of fourteen piperonal chalcone compounds were synthesized by this method and characterized by physical and spectral data (FT-IR, 1H NMR, Mass and elemental analysis). All chalcones were evaluated for their cytotoxic action against the cancer cell lines, MCF-7 and HepG2. One 2-pyridyl-substituted compound 14 with IC50 values 17.4±0.2 towards MCF-7 and 15.4±0.6µmol L-1 towards HepG2 cells.

Results:

The results demonstrated that the cytotoxic activity of 2-pyridyl-substituted compound shown higher activity as compared with the standard cisplatin towards HepG2 cells.

Conclusion:

Compound 14 showed good antioxidant activities in the DPPH test and H2O2 assay (IC50 = 17.23± 33/µg/mL and 20.17± 0.33µg/mL) when compared with the standard ascorbic acid (IC50=µg/mL 18.26 ± 0.22and 21.66± 1.06 µg/mL).

Enantioselective Synthesis of 6,6-Disubstituted Pentafulvenes Containing a Chiral Pendant Hydroxy Group

Simple enantioselective synthesis of 6,6-disubstituted pentafulvenes bearing chiral pendant hydroxy groups are attained by cascade reactivity using commercially available proline-based organocatalysts. Condensation of cyclopentadiene with the acetyl function of a 1,2-formylacetophenone, followed by cyclization of a resulting fulvene-stabilized carbanion with the formyl group, generates bicyclic chiral alcohols with initial er values up to 94:6. Exceptional enantio-enrichment of the resultant alcohols results upon crystallization-even near racemic samples spontaneously de-racemize. This enables new families of substituted cyclopentadienes that are both enantiomerically and diastereomerically pure to be rapidly attained.

Ruthenium-conjugated chrysin analogues modulate platelet activity, thrombus formation and haemostasis with enhanced efficacy

The constant increase in cardiovascular disease rate coupled with significant drawbacks of existing therapies emphasise the necessity to improve therapeutic strategies. Natural flavonoids exert innumerable pharmacological effects in humans. Here, we demonstrate the effects of chrysin, a natural flavonoid found largely in honey and passionflower on the modulation of platelet function, haemostasis and thrombosis. Chrysin displayed significant inhibitory effects on isolated platelets, however, its activity was substantially reduced under physiological conditions. In order to increase the efficacy of chrysin, a sulfur derivative (thio-chrysin), and ruthenium-complexes (Ru-chrysin and Ru-thio-chrysin) were synthesised and their effects on the modulation of platelet function were evaluated. Indeed, Ru-thio-chrysin displayed a 4-fold greater inhibition of platelet function and thrombus formation in vitro than chrysin under physiologically relevant conditions such as in platelet-rich plasma and whole blood. Notably, Ru-thio-chrysin exhibited similar efficacy to chrysin in the modulation of haemostasis in mice. Increased bioavailability and cell permeability of Ru-thio-chrysin compared to chrysin were found to be the basis for its enhanced activity. Together, these results demonstrate that Ru-thio-coupled natural compounds such as chrysin may serve as promising templates for the development of novel anti-thrombotic agents.

Synthesis and cytotoxicity studies of titanocene C analogues

From the carbolithiation of 6-N,N-dimethylamino fulvene (3) and 2,4[bis(N,N-dimethylamino)methyl]-N-methylpyrrolyl lithium (2a), N-(N′,N′-dimethylaminomethyl)benzimidazolyl lithium (2b), or p-(N,N-dimethylamino)methylphenyl lithium (2c), the corresponding lithium cyclopentadienide intermediate (4a–c) was formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl_4' resulting in N,N-dimethylamino-functionalised titanocenes 5a–c. When these titanocenes were tested against a pig kidney epithelial cell line (LLC-PK), the IC50 values obtained were of 23, and 52  μM for titanocenes 5a and 5b, respectively. The most cytotoxic titanocene in this paper, 5c with an IC50 value of 13 μM, was found to be approximately two times less cytotoxic than its analogue Titanocene C (IC50=5.5  μM) and almost four times less cytotoxic than cisplatin, which showed an IC50 value of 3.3 μM when tested on the LLC-PK cell line.

Synthesis and cytotoxicity studies of steroid-functionalized titanocenes as potential anticancer drugs: sex steroids as potential vectors for titanocenes

Six titanocenyls functionalized with steroidal esters have been synthesized and characterized by infrared, (1)H, and (13)C NMR spectroscopy and elemental analysis. Among those steroids, dehydroepiandrosterone, trans-androsterone, and androsterone are androgens and pregnenolone is a progesterone precursor. Clionasterol is a natural steroid compound. These steroid-functionalized titanocenyls were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for in vitro cytotoxicity for MCF-7 breast cancer and HT-29 colon cancer cells. All complexes exhibited more cytotoxicity than titanocene dichloride. The titanocenyls containing androgen and progesterone derivatives as pendant groups had higher antiproliferative activities than those with cholesterol steroid compounds. Of particular significance is titanocenyl-dehydroepiandrosterone complex, which is 2 orders of magnitude more cytotoxic than titanocene dichloride and also shows much more sensitivity and selectivity for the MCF-7 cell line.

Functionalised cyclopentadienyl zirconium compounds as potential anticancer drugs

New neutral and ionic functionalised zirconocene dichloride compounds have been isolated and characterised. The ionic zirconocene exhibits excellent cytotoxicity against a range of human tumour cell lines, which represents the first active anticancer zirconocene dichloride compound.

Synthesis and cytotoxicity studies of new dimethylamino-functionalised and aryl-substituted titanocene anti-cancer agents

From the carbolithiation of 6-N,N-dimethylamino fulvene (3a) and different lithiated aryl species [p-N,N-dimethylanilinyl lithium, p-anisyl lithium and 4-lithio-benzo[1.3]dioxole (2a-c)], the corresponding lithium cyclopentadienide intermediates 4a-c were formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4 resulting in dimethylamino-functionalised and aryl-substituted titanocenes 5a-c. When these titanocenes were tested against LLC-PK cells, the IC50 values obtained were of 54, 45 and 26microM for titanocenes 5a, b and c, respectively. The most cytotoxic titanocene in this paper, 5c is approximately 10 times less cytotoxic than cis-platin, which showed an IC50 value of 3.3microM, when tested on the LLC-PK cell line, but approximately 100 times better than titanocene dichloride.

Novel achiral titanocene anti-cancer drugs synthesised from bis-N,N-dimethylamino fulvene and lithiated heterocyclic compounds

From the carbolithiation of 6-bis-N,N-dimethylamino fulvene (3a) and different ortho-lithiated heterocycles (furan, thiophene and N-methylpyrrole), the corresponding lithium cyclopentadienide intermediate (4a-c) was formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl(4) resulting in bis-N,N-dimethylamino-functionalised titanocenes 5a-c. When these titanocenes were tested against LLC-PK cells, the IC(50)-values obtained were of 240, and 270 microM for titanocenes 5b and 5c, respectively. The most cytotoxic titanocene in this paper, 5a with an IC(50)-value of 36 microM was found to be approximately six times less cytotoxic than its mono-N,N-dimethylamino substituted analogue Titanocene C (IC(50) = 5.5 microM) and almost ten times less cytotoxic than cisplatin, which showed an IC(50)-value of 3.3 microM, when tested on the LLC-PK cell line.

Dimethylamino-functionalised and N-heteroaryl-substituted titanocene anticancer drugs: synthesis and cytotoxicity studies

From the carbolithiation of 6-N,N-dimethylamino fulvene (3a) and different lithiated N-heterocyclic compounds (N,N-dimethylaminomethylpyrrole, 1-methylimidazole and 2,4-[bis(N',N'-dimethylaminomethyl)]-N-methyl pyrrole), the corresponding lithium cyclopentadienide intermediate (4a-c) was formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4 resulting in dimethylamino-functionalised titanocenes 5a-c. When these titanocenes were tested against LLC-PK cells, the IC50 values obtained were of 13, and 63 microM for titanocenes 5b and 5c, respectively. The most cytotoxic titanocene in this paper (5a) with an IC50 value of 6.8 microM is found to be almost as cytotoxic as cis-platin, which showed an IC50 value of 3.3 microM, when tested on the epithelial pig kidney LLC-PK cell line, and titanocene 5c is approximately 400 times better than titanocene dichloride itself.