Effect of Hydroxyl Groups Esterification with Fatty Acids on the Cytotoxicity and Antioxidant Activity of Flavones

Flavonoids and polyunsaturated fatty acids due to low cytotoxicity in vitro studies are suggested as potential substances in the prevention of diseases associated with oxidative stress. We examined novel 6-hydroxy-flavanone and 7-hydroxy-flavone conjugates with selected fatty acids (FA) of different length and saturation and examined their cytotoxic and antioxidant potential. Our findings indicate that the conjugation with FA affects the biological activity of both the original flavonoids. The conjugation of 6-hydroxy-flavanone increased its cytotoxicity towards prostate cancer PC3 cells. The most noticeable effect was found for oleate conjugate. A similar trend was observed for 7-hydroxy-flavone conjugates with the most evident effect for oleate and stearate. The cytotoxic potential of all tested conjugates was not specific towards PC3 because the viability of human keratinocytes HaCaT cells decreased after exposure to all conjugates. Additionally, we showed that esterification of the two flavonoids decreased their antioxidant activity compared to that of the original compounds. Of all the tested compounds, only 6-sorbic flavanone showed a slight increase in antioxidant potential compared to that of the original compound. Our data show that conjugated flavonoids are better absorbed and enhance cytotoxic effects, but the presence of FA lowered the antioxidant potential.

Antioxidant and Cardioprotective Evaluation of Some N-(3-Chloro-2-oxo-4- arylazetidin-1-yl)-2-[(4-oxo-2-aryl-4H-chromen-7-yl)oxy]acetamide Derivatives

A series of N-(3-chloro-2-oxo-4-arylazetidin-1-yl)-2-[(4-oxo-2-aryl-4H-chromen-7-yl)oxy]acetamide derivatives [SLP VI 1(a-d)-2(a-d)] were synthesized from 7-hydroxy flavone derivatives through the intermediate Schiff bases. The synthesized compounds were investigated for in vitro antioxidant property by DPPH radical scavenging assay. The title compounds with good antioxidant potency were further evaluated for possible cardioprotective effect by doxorubicin induced cardiotoxicity. All biochemical changes were normalized after oral administration of the test compounds at the dose of 50 μg/kg. The results showed the significant (p < 0.05) increase in antioxidant enzymes catalase and superoxide dismutase in heart tissue homogenates. These observations enable us to conclude that the synthesized derivatives SLP VI 1b, VI 1c, VI 2b and VI 2d have cardioprotective activity against doxorubicin induced cardiotoxicity. Further, an attempt has been made to perform in silico studies on the synthesized compounds to predict the interaction between test ligands and prospective cardiovascular protein targets using molecular docking tools. The title compounds have good binding affinity with MAPkinase P38 and PKCβ cardiovascular targets.

Synthesis of New Class of Functionalized Flavones/Isoxazole Derivatives-Nitrile oxide 1,3-Dipolar Cycloaddition

A new series of functionalized flavone-isoxazole derivatives have been synthesized from alkyne tethered 3-hydroxy flavone by adopting facile synthetic method, intermolecular nitrile oxide 1,3-dipolar cycloaddition in the presence of eco-friendly sodium hypochloride oxidant under mild reaction conditions. Structures of all the synthesized compounds were established on the basis of 1H NMR, 13C NMR and ESI-mass.

Effect of Flavone Derivatives on Vincristine and Oxaliplatin Induced Peripheral Neuropathy in Mice

Introduction: Therapy with anticancer drugs like paclitaxel, platinum complexes and vincristine result in severe peripheral neuropathy. Very few treatment options are available to overcome this debilitating side effect. Flavone and its monohydroxy derivatives have been proved to possess anti-nociceptive and anti-inflammatory effects in animal models. Aim: To investigate flavone, 5-hydroxy flavone, 6-hydroxy flavone and 7-hydroxy flavone for their effect on neuropathy induced by vincristine and oxaliplatin in mice. Materials and Methods: In this experimental animal study, neuropathy was induced in mice by multiple doses of vincristine or a single dose of oxaliplatin. The manifestations of mechanical allodynia, cold allodynia and thermal hyperalgesia were measured by von Frey’s hair aesthesiometer, acetone spray test and hot water tail immersion test. The data was subjected to ANOVA followed by Dunnett’s test for multiple comparison and paired t-test at appropriate places. Results: Flavone and monohydroxy flavones significantly reduced the paw withdrawal response scores due to mechanical allodynia and cold allodynia resulting from vincristine or oxaliplatin administration (p<0.05). The tail withdrawal latency due to thermal hyperalgesia was also significantly increased by different flavone derivatives (p<0.05). However, 7-hydroxy flavone was ineffective in oxaliplatin-induced mechanical allodynia and vincristine induced thermal hyperalgesia. Analysis of the results indicated that the manifestations of neuropathy induced by vincristine or oxaliplatin were amenable to treatment with flavone derivatives in the following order; cold allodynia>thermal hyperalgesia>mechanical allodynia. Opioid mediated antinociceptive effect, interaction with cation channels and anti-inflammatory effect of the investigated flavones may be suggested as possible mechanisms for their beneficial effects in neuropathy due to chemotherapeutic agents. Conclusion: Various neuropathic manifestations induced by vincristine and oxaliplatin were effectively attenuated by flavone and monohydroxy flavones.

Enhanced susceptibility to apoptosis and growth arrest of human breast carcinoma cells treated with silica nanoparticles loaded with monohydroxy flavone compounds

The treatment of drug-resistant cancer is a clinical challenge, hence screening for novel anticancer drugs is critically important. In this study, we investigated the anti-tumor potential of three plant-derived flavone compounds: 3-hydroxy flavone (3-HF), 6-hydroxy flavone (6-HF), and 7-hydroxy flavone (7-HF), either alone or combined with silica nanoparticles (3-HF + NP, 6-HF + NP, and 7-HF + NP), on the human breast carcinoma cell lines MDA-MB-231 and MCF-7, as well as on non-tumorigenic normal breast epithelial cells (MCF-10). The IC50values of these flavone compounds loaded with NP (flavones + NP) in these cell lines were determined to be 1.5 μg/mL without affecting the viability of normal MCF-10 cells. Additionally, using annexin V – propidium iodide double-staining followed by flow cytometry analysis, we found that the combination of flavones with NP significantly induced apoptosis in MCF-7 and MDA-MB-231 cancer cells. Furthermore, flavones + NP increased the expression of cytochrome c and caspase-9, mediating the growth arrest of these cancer cells. Most importantly, the combination of flavones with NP significantly abolished the expression of ATF-3, which is responsible for the proliferation and invasion of bone-metastatic breast cancer cells. Our data revealed the potential therapeutic effects of these flavones in fighting breast cancer cells, and provide the first insights concerning the underlying molecular mechanisms.

Antiaging, antioxidant flavonoids; synthesis, antimicrobial screening as well as 3D QSAR CoMFA models for the prediction of biological activity

Flavonoids, polyphenolic heteronuclear compounds which are naturally occurring antioxidants are widely used as antiaging substances. Synthesis of new naturally occuring organic compounds with basic skeleton of chalcones, flavones and oxygenated flavones and their antimicrobial activity were reported by this research group for long. Presently comparative molecular field analysis (CoMFA) implemented in Sybyl 7.3 was conducted on a series of substituted flavones. CoMFA is an effective computer implemented 3D QSAR technique deriving a correlation between set of the biologically active molecules and their 3D shape, electrostatic and hydrogen bonding characteristics employing both interactive graphics and statistical techniques. Evaluation of 38 compounds were served to establish the models with grid spacing (2.0 Å). CoMFA produced best predictive model for compound 1C (2 ? Phenyl ? 1,4 ? benzopyrone) and compound 2C (5 ? Fluoro ? 3?? hydroxy flavone ) among all. Model for compound 2C [r2 conv (no-validation) = 0.956, SEE = 0.211, F value = 111.054) is better than that of compound 1C [r2 conv (no-validation) = 0.955, SEE = 0.212, F value = 110.261) but comparing superimposed model 1C being suggested as the best predictive model. 3D contour maps were generated to correlate the biological activities with the chemical structures of the examined compounds and for further design. DOI: http://dx.doi.org/10.3329/jasbs.v39i2.17856 J. Asiat. Soc. Bangladesh, Sci. 39(2): 191-199, December 2013