Lysosomal Exocytosis of Olivacine on the Way to Explain Drug Resistance in Cancer Cells.

Ellipticine is an indole alkaloid with proven antitumor activity against various tumors in vitro and a diverse mechanism of action, which includes topoisomerase II inhibition, intercalation, and cell cycle impact. Olivacine-ellipticine's isomer-shows similar properties. The objectives of this work were as follows: (a) to find a new path of olivacine synthesis, (b) to study the cytotoxic properties of olivacine and ellipticine in comparison to doxorubicin as well as their impact on the cell cycle, and (c) to investigate the cellular pharmacokinetics of the tested compounds to understand drug resistance in cancer cells better. SRB and MTT assays were used to study the anticancer activity of olivacine and ellipticine in vitro. Both compounds showed a cytotoxic effect on various cell lines, most notably on the doxorubicin-resistant LoVo/DX model, with olivacine's cytotoxicity approximately three times higher than doxorubicin. Olivacine proved to be less effective against cancer cells and less cytotoxic to normal cells than ellipticine. Olivacine proved to have fluorescent properties. Microscopic observation of cells treated with olivacine showed the difference in sensitivity depending on the cell line, with A549 cells visibly affected by a much lower concentration of olivacine than normal NHDF cells. An increased percentage of cells in G0/G1 was observed after treatment with olivacine and ellipticine, suggesting an impact on cell cycle progression, potentially via higher p53 protein expression, which blocks the transition from G0/G1 to the S phase. Ellipticine induced apoptosis at a concentration as low as 1 µM. It has been proved that the tested compounds (ellipticine and olivacine) undergo lysosomal exocytosis. Reducing exocytosis is possible through the use of compounds that inhibit the activity of the proton pump. Olivacine and ellipticine exhibited diverse cytotoxicity against a panel of cancer cells. Analysis of the lysosomal exocytosis of olivacine and ellipticine shows the need to look for derivatives with comparable anticancer activity but reduced weak base character.

Synthesis and cytotoxicity evaluation of olivacine-indole hybrids tethered by alkyl linkers.

In this work, eleven new derivatives were prepared of the alkaloid olivacine (1), which was isolated from the bark of Aspidosperma australe. These compounds (7a-k) are hybrids of olivacine and indoles or carbazole, tethered by alkyl chains of variable lengths (C-4, C-5 or C-6). Compounds 7a-k showed increased cytotoxicity towards a panel of four cell lines. The subcellular localization of olivacine and of the synthetic derivatives was studied by fluorescence microscopy. The cycles of K562 cells exposed to olivacine or compounds 7a-k were analysed by flow cytometry, and showed, for some of the new derivatives, a different profile of cell distribution among the phases of the cycle when compared to olivacine, which is indicative of lysosomal apoptosis.

S16020 Pyridocarbazole Derivatives Display High Activity to Lung Cancer Cells.

BACKGROUND: Despite the dynamic development of medicine, globally cancer diseases remain the second leading cause of death. Therefore, there is a strong necessity to improve chemotherapy regimens and search for new anticancer agents. Pyridocarbazoles are compounds with confirmed antitumor properties based on multimodal mechanisms, i.e. DNA intercalation and topoisomerase II-DNA complex inhibition. One of them, S16020, displayed a wide spectrum of activity. OBJECTIVE: The aim of the study was to investigate the antitumor potency of six S16020 derivatives, synthesized according to the SAR (structure-activity relationship) method. METHODS: The biological evaluation included influence on cancer cell viability, proliferation, and migration, as well as P-glycoprotein activity. NHDF, A549, MCF-7, LoVo, and LoVo/DX cell lines were used in the study. RESULTS: All derivatives displayed low toxicity to normal (NHDF) cells at 1 and 2 µM (≤ 20% of cell growth inhibition). The highest reduction in cell viability was noted in A549 cells, which was accompanied by significant disruption of cells proliferation and motility. Compound 1 exhibited the strongest cytotoxic, antiproliferative, and antimigratory effects, higher than the reference olivacine. A significant reduction in P-glycoprotein activity was found for derivatives 6 and 1. CONCLUSION: S16020 derivatives could be considered as potential candidates for new anticancer drugs.

Evaluation of Interactions of Selected Olivacine Derivatives with DNA and Topoisomerase II.

Olivacine and ellipticine are model anticancer drugs acting as topoisomerase II inhibitors. Here, we present investigations performed on four olivacine derivatives in light of their antitumor activity. The aim of this study was to identify the best antitumor compound among the four tested olivacine derivatives. The study was performed using CCRF/CEM and MCF-7 cell lines. Comet assay, polarography, inhibition of topoisomerase II activity, histone acetylation, and molecular docking studies were performed. Each tested compound displayed interaction with DNA and topoisomerase II, but did not cause histone acetylation. Compound 2 (9-methoxy-5,6-dimethyl-1-({[1-hydroxy-2-(hydroxymethyl)butan-2-yl]amino}methyl)-6H-pyrido[4,3-b]carbazole) was found to be the best candidate as an anticancer drug because it had the highest affinity for topoisomerase II and caused the least genotoxic damage in cells.

Bioactive Olivacine Derivatives-Potential Application in Cancer Therapy.

Olivacine and its derivatives are characterized by multidirectional biological activity. Noteworthy is their antiproliferative effect related to various mechanisms, such as inhibition of growth factors, enzymes, kinases and others. The activity of these compounds was tested on cell lines of various tumors. In most publications, the most active olivacine derivatives exceeded the effects of doxorubicin (a commonly used anticancer drug), so in the future, they may become the main new anticancer drugs. In this publication, we present the groups of the most active olivacine derivatives obtained. In this work, the in vitro and in vivo activity of olivacine and its most active derivatives are presented. We describe olivacine derivatives that have been in clinical trials. We conducted a structure-activity relationship (SAR) analysis that may be used to obtain new olivacine derivatives with better properties than the available anticancer drugs.

Antitumor Activity of New Olivacine Derivatives.

Olivacine is an alkaloid-containing pyridocarbazole structure. It is isolated from the bark of the evergreen timber tree, Aspidosperma olivaceum. Its well-documented anticancer activity led to the synthesis of new derivatives, which are semisynthetic and fully synthetic pyridocarbazoles. This study aimed to evaluate the potential antineoplastic activity of four newly synthesized olivacine derivatives. Multidrug resistance is a common phenomenon causing failure in the chemotherapy of many tumors. It is mainly related to increased function of P-glycoprotein, an efflux pump removing cytostatic out of the cells. The cell lines used in the study were colorectal carcinoma cell lines: LoVo (doxorubicin-sensitive) and LoVo/DX (doxorubicin-resistant). The NHDF cell line was used to assess cell viability. First, the cells were incubated with olivacine derivatives. In the next step, the following assays were performed: DCF-DA assay, MTT assay, rhodamine 123 assay, detection of apoptosis, proliferation inhibition-mitotic index. The tested compounds showed higher antineoplastic potential and lower toxicity than the reference compound ellipticine. The results indicate that the new olivacine derivatives are good candidates for future anticancer drugs.

Effect of new olivacine derivatives on p53 protein level.

BACKGROUND: The p53 protein is a transcription factor for many genes, including genes involved in inhibiting cell proliferation and inducing apoptosis in genotoxically damaged and tumor-transformed cells. In more than 55% of cases of human cancers, loss of the essential function of p53 protein is found. In numerous reports, it has been shown that small molecules (chemical compounds) can restore the suppressor function of the mutant p53 protein in tumor cells. The aim of this study was to evaluate the potential anticancer activity of three newly synthesized olivacine derivatives. METHODS: The study was performed using two cell lines-CCRF/CEM (containing the mutant p53 protein) and A549 (containing a non-mutant, wild-type p53 protein). The cells were incubated with olivacine derivatives for 18 h and then assays were carried out: measurement of the amount of p53 and p21 proteins, detection of apoptosis, cell cycle analysis, and rhodamine 123 accumulation assay (evaluation of P-glycoprotein inhibition). Multiple-criteria decision analysis was used to compare the anticancer activity of the tested compounds. RESULTS: Each tested compound caused the reconstitution of suppressor activity of the p53 protein in cells with the mutant protein. In addition, one of the compounds showed significant antitumor activity in both wild-type and mutant cells. For all compounds, a stronger effect on the level of the p53 protein was observed than for the reference compound-ellipticine. CONCLUSIONS: The observed effects of the tested new olivacine derivatives (pyridocarbazoles) suggest that they are good candidates for new anticancer drugs.

Synthesis and Activity against Mycobacterium tuberculosis of Olivacine and Oxygenated Derivatives.

The tetracyclic pyrido[4,3-b]carbazole olivacine and four of its oxygenated derivatives have been synthesized by a late-stage palladium-catalyzed Heck-type cyclization of the pyrrole ring as a key step. In a test for the inhibition of the growth of Mycobacterium tuberculosis, 9-methoxyolivacine showed the most significant inhibitory activity against Mycobacterium tuberculosis, with an MIC90 value of 1.5 µM.