Anticancer activities of vitamin K3 analogues.

In a previous study we reported on the synthesis of 1,4-naphthoquinone-sulfides by thiolation of 1,4-naphthohydroquinones with primary aryl and alkyl thiols using laccase as catalyst. These compounds were synthesized as Vitamin K3 analogues. Vitamin K3 (VK3; 2-methyl-1,4-naphthoquinone; menadione) is known to have potent anticancer activity. This investigation reports on the anticancer activity of these VK3 analogues against TK10 renal, UACC62 melanoma, MCF7 breast, HeLa cervical, PC3 prostate and HepG2 liver cancer cell lines to evaluate their cytostatic effects. A 1,4-naphthohydroquinone derivative exhibited potent cytostatic effects (GI50 = 1.66-6.75 µM) which were better than that of etoposide and parthenolide against several of the cancer cell lines. This compound produces reactive oxygen species and disrupts the mitochondrial membrane potential in the MCF7 breast cancer cell line which is an indication that the cells undergo apoptosis. The 1,4-naphthoquinone sulfides also had potent cytostatic effects (GI50 = 2.82-9.79 µM) which were also better than that of etoposide, parthenolide and VK3 against several of the cancer cell lines. These compounds are generally more selective for cancer cells than for normal human lung fetal fibroblasts (WI-38). They also have moderate to weak cytostatic effects compared to etoposide, parthenolide and VK3 which have potent cytostatic effects against WI-38. One analogue induces apoptosis by activating caspases without arresting the cell cycle in the MCF7 breast cancer cell line. These results inspire further research for possible application in cancer chemotherapy.

Synthesis, computational studies and antiproliferative activities of coumarin-tagged 1,3,4-oxadiazole conjugates against MDA-MB-231 and MCF-7 human breast cancer cells.

A novel library of coumarin tagged 1,3,4 oxadiazole conjugates was synthesized and evaluated for their antiproliferative activities against MDA-MB-231 and MCF-7 breast cancer cell lines. The evaluation studies revealed that compound 9d was the most potent molecule with an IC50 value of <5 µM against the MCF-7 cell line. Interestingly, compounds 10b and 11a showed a similar trend with lower inhibitory concentration (IC50 = 7.07 µM), in Estrogen Negative (ER-) cells than Estrogen Positive (ER+) cells. Structure-activity relationship (SAR) studies revealed that conjugates bearing benzyl moieties (9b, 9c and 9d) had superior activities compared to their alkyl analogues. The most potent compound 9d showed ∼1.4 times more potent activity than tamoxifen against MCF-7 cell line; while the introduction of sulfone unit in compounds 11a, 11b and 11c resulted in significant cytotoxicity against both MCF-7 and MDA-MB-231 cell lines. These results were further supported by docking studies, which revealed that the stronger binding affinity of the synthesized conjugates is due to the presence of sulfone unit attached to the substituted benzyl moiety in their pharmacophores.

2-Hydroxypropyl-ß-cyclodextrin (HPßCD) as a Potential Therapeutic Agent for Breast Cancer.

Cholesterol accumulation is documented in various malignancies including breast cancer. Consequently, depleting cholesterol in cancer cells can serve as a viable treatment strategy. We identified the potency of 2-hydroxypropyl-ß-cyclodextrin (HPßCD), a cholesterol-depletor in vitro against two breast cancer cell lines: MCF-7 (Oestrogen-receptor positive, ER+) and MDA-MB-231 (Triple negative breast cancer (TNBC)). The results were then compared against two non-cancerous cell lines using cytotoxic-, apoptosis-, and cholesterol-based assays. Treatment with HPßCD showed preferential and significant cytotoxic potential in cancer cells, inducing apoptosis in both cancer cell lines (p < 0.001). This was mediated due to significant depletion of cholesterol (p < 0.001). We further tested HPßCD in a MF-1 mice (n = 14) xenograft model and obtained 73.9%, 94% and 100% reduction in tumour size for late-, intermediate-, and early-stage TNBC, respectively. We also detected molecular-level perturbations in the expression patterns of several genes linked to breast cancer and cholesterol signalling pathways using RT2-PCR arrays and have identified SFRP1 as a direct binding partner to HPßCD through SPR drug interaction analysis. This work unravels mechanistic insights into HPßCD-induced cholesterol depletion, which leads to intrinsic apoptosis induction. Results from this study potentiate employing cholesterol depletion as a promising unconventional anticancer therapeutic strategy, which warrants future clinical investigations.

Synthesis and in vitro anti-proliferative evaluation of naphthalimide-chalcone/pyrazoline conjugates as potential SERMs with computational validation.

A series of naphthalimide-chalcone/pyrazoline conjugates was prepared and evaluated for their anti-breast cancer potential against estrogen responsive, i.e. MCF-7 (ER+), and triple-negative, i.e. MDA-MB-231 (ER-), cell lines. The structure-activity-relationship (SAR) was deduced based on the influence of linker length, substituents on the phenyl ring and the generated functionalities, on anti-proliferative activities. Docking simulations further delineate the type of interactions of the designed molecules with the selected targets. This report discloses the scope of triazole tethered naphthalimide-chalcone/pyrazoline conjugates as anti breast cancer agents.

Design, Synthesis, Antiproliferative Evaluation, and Molecular Docking Studies of N-(3-Hydroxyindole)-Appended ß-Carbolines/Tetrahydro-ß-Carbolines Targeting Triple-Negative and Non-Triple-Negative Breast Cancer.

The present manuscript pertains to the design and synthesis of a series of 3-hydroxyindole-substituted ß-carbolines/tetrahydro-ß-carbolines with an aim to explore their antiproliferative structure-activity relationship against breast cancer. The conjugate with an optimum combination of a flexible tetrahydro-ß-carboline core, a tertiary alcoholic group along with a chloro substituent on the indole ring, proved to be the most active compound. It displayed IC50 values of 13.61 and 22.76 µM against MCF-7 (ER+) and MDA-MB-231 (ER-) cells, respectively. The docking studies were found to be consistent with experimental results owing to the stronger binding affinity of the synthesized conjugates via hydrophobic and H-bonding interactions.

Targeting cellular cholesterol for anticancer therapy.

Cholesterol dyshomeostasis in cancer cells leads to intracellular cholesterol accumulation, which imparts drug resistance and allows these cells to evade apoptotic signalling processes and maintain continuous cell division and proliferation. Therefore, cholesterol lowering in cancer cells has been envisaged as a potential anticancer strategy. In this direction, two therapeutic strategies have been proposed: (a) to inhibit the biosynthesis of cholesterol in the cells and (b) to deplete excess cholesterol from cancer cells. In the first phase of this review, we collate the cancer signalling pathways (particularly in breast cancer) that are perturbed by cholesterol dyshomeostasis and highlight recent drug discovery efforts to develop cholesterol-lowering compounds, some of which are currently under clinical trials. In the second phase, based on the analysis of the available scientific evidence, we conceptualize and argue that the depletion of excess cholesterol could sensitize cancer cells to available therapeutics and may also help to alleviate cancer drug resistance.

Diastereoselective approach to rationally design tetrahydro-ß-carboline-isatin conjugates as potential SERMs against breast cancer.

A series of tetrahydro-ß-carboline-isatin conjugates, with varying substituents as well as stereochemistry at C-1 and C-5 position of tetrahydro-ß-carboline (THßC) and isatin ring, were prepared and assayed for anti-proliferative efficacy on Estrogen Responsive ER(+) (MCF-7) and ER(-ve) MDA-MB-231 cell-lines. The synthesized scaffolds displayed selective anti-proliferative efficacy against MCF-7 cell-line with the most active conjugate 8b exhibiting an IC50 value of 37.42 µM, comparable to that of peganumine A, a tetrahydro-ß-carboline analogue, isolated from Peganum harmala. The synthesized compound 8b was also more potent than the standard drug tamoxifen (IC50 = 50 µM against MCF-7). The observed activities were further corroborated via docking studies in ER-α (PDB ID: 3ERT).

Azide-Alkyne Cycloaddition En Route to 1H-1,2,3-Triazole-Tethered Isatin-Ferrocene, Ferrocenylmethoxy-Isatin, and Isatin-Ferrocenylchalcone Conjugates: Synthesis and Antiproliferative Evaluation.

Diverse series of isatin-ferrocene conjugates were synthesized via Cu-promoted azide-alkyne cycloaddition reaction with an aim of probing their antiproliferative structure-activity relationship against MCF-7 (estrogen receptor positive) and MDA-MB-231 (triple negative) cell lines. Among the synthesized conjugates, isatin-ferrocenes proved to be more potent against MCF-7, whereas ferrocenylmethoxy-isatins exhibited activity against MDA-MB-231 cell lines. However, the introduction of chalcone moiety among these hybrids resulted in the complete loss of activity against the tested cell lines, as evident by isatin-ferrocenylchalcones. The conjugates 5a and 9c proved to be the most potent among the series against MCF-7 and MDA-MB-213 cell lines, exhibiting IC50 values of 31.62 and 20.26 µM, respectively.

1H-1,2,3-Triazole Tethered Nitroimidazole-Isatin Conjugates: Synthesis, Docking, and Anti-Proliferative Evaluation against Breast Cancer.

1H-1,2,3-Triazole tethered imidazole-isatin and imidazole-isatin-thiosemicarbazone conjugates were synthesized and evaluated against MCF-7 and MDA-MB-231 cell lines. Antiproliferative activities of the synthesized conjugates revealed an optimum combination of longer alkyl chain length as spacer and a halogen-substituent on the isatin ring as a pre-requisite for good activity. The compound 6g with an optimum combination of chloro-substituent at C-5 position of isatin ring and a butyl chain length proved to be most active and noncytotoxic with IC50s of 54.25 and 26.12 µM against MCF-7 and MDA-MB-231 cell lines, respectively.