Investigation of antitumor properties of semi-synthetic flavonoid derivatives on gynecological cancer cell lines

Latif Ahmed Dhahir
Investigation of antitumor properties of semi-synthetic flavonoid derivatives on gynecological cancer cell lines.

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Abstract in foreign language

The present PhD work aimed to contribute to the knowledge available on the antitumor properties of flavonoids through the in vitro evaluation of the bioactivity of some uncommon semi-synthetic derivatives against a panel of breast and cervical cancer cell lines that are well-established models for certain types of gynecological cancer. The work included the semi-synthetic preparation of seven naringenin oxime and oxime ether derivatives prior to their bioactivity testing, and the in vitro evaluation of nine protoflavone-chalcone hybrid compounds and their reference fragments against breast (hormone-dependent MCF-7 and triple-negative MDA-MB-231), and cervical (SiHa & HeLa) cancer cell lines in addition to human HL-60 leukemia cells and non-cancerous mouse embryonic fibroblasts (NIH/3T3). The work included cytotoxicity, cell cycle distribution, caspase-3 activity, and antioxidant activity evaluations. Further, the cytotoxic activity of the hybrid compounds was evaluated in comparison with that of their corresponding fragments in a virtual and experimental combination study. In summary, our work led to the following results.  Two naringenin oxime isomers and five oxime ether derivatives were synthesized, purified and characterized. Four of these compounds, such as the minor product naringenin Z-oxime, and the ethyl, allyl, and tert-butyl ethers of naringenin E-oxime were prepared as new compounds.  When evaluating the in vitro cytotoxicity of the prepared derivatives of naringenin, tert-butyl oxime ether (6) showed the most potent effects on different gynecological cancer cells, with significant activity against MCF-7 and HeLa cells.  The flow cytometric analysis of compound (6) on gynecological cancer cells revealed significant accumulation of cells in the hypodiploid (subG1) phase in HeLa & SiHa cell lines, indicating the apoptosis induction effect, and induced cycle suppression at G2/M stage in MCF-7 cancer cells. Further, the proapoptotic activity of this compound was confirmed in HeLa cells by detecting the increased activity of caspase-3.  To our surprise, naringenin methyl oxime ether was more potent in the ORAC assay than its parent compound, while all other analogs were up to an order of magnitude less active. This suggests good peroxyl radical scavenging capacity for this compound. There was no apparent correlation between the in vitro cytotoxic and antioxidant activities of the tested compounds, suggesting that their anticancer effects are likely not related to their antioxidant properties.  Four protoflavone hybrid compounds were identified as promising antitumor lead compounds based on their prominent in vitro cytotoxic effects and their selectivity on different breast and cervical cancer cells with antiproliferative effects better than cisplatin.  The most potent compounds have an intense proapoptotic effect on TNBC, as evidenced by flow cytometric investigation and caspase-3 activity. It was shown that compound 10c induces a considerable expansion in caspase-3 activity in a concentration-time dependent manner with a significant increase in the sub G1 phase.  A novel approach was used to evaluate the bioactivity of the hybrid compounds in comparison with that of their corresponding fragments. A virtual combination study was performed by using the Chou-Talalay method as a mathematical tool, and results were compared to the corresponding experimental combinations of the cells with non-coupled fragments. This gave valuable extra information as virtual combination index values and confirmed that the studied hybrid compounds are much more potent than what would be expected by a mathematical sum of the bioactivity of their fragments.  Based on the above, we demonstrated the use of a novel approach to evaluate the bioactivity of hybrid compounds in general, and suggested an extension of the applicability of the Chou-Talalay method, one of the currently available most popular platforms for drug-drug combination studies. Altogether, our present study provided valuable information about the antitumor potential of two series of unusual semi-synthetic flavonoid derivatives, and made a significant contribution to identifying a set of highly potent hybrid lead compounds obtained through fragment-based drug design. Further, by providing a novel use for an existing convenient and very widely used mathematical platform, we believe our study may have contributed to the research of hybrid compounds also in a more general manner.

Item Type: Thesis (Doktori értekezés)
Creators: Latif Ahmed Dhahir
Subjects: 03. Medical and health sciences > 03.01. Basic medicine > 03.01.06. Pharmacology and pharmacy
Divisions: Doctoral School of Pharmaceutical Sciences
Tudományterület / tudományág: Medicine > Pharmacy
Nyelv: English
Date: 2020. August 28.
Item ID: 10588
A mű MTMT azonosítója: 31637700
Date Deposited: 2020. Jul. 04. 08:46
Last Modified: 2021. Jul. 02. 10:14
Depository no.: B 6785
Defence/Citable status: Defended.

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