Correlation of antimutagenic activity and suppression of CYP1A with the lipophilicity of alkyl gallates and other phenolic compounds

Pharmacokinetic and toxicological overview of propyl gallate food additive

The progressive use of food additives in "ultra-processed" food has increased attention to them. Propyl gallate (PG) is an essential synthetic preservative that commonly used in food, cosmetics, and pharmacies as an antioxidant. This study aimed to outline the existing evidence on the toxicological studies of PG including its physicochemical properties, metabolism, and pharmacokinetics effects. The methods include updated searches for the relevant databases. The EFSA has evaluated the use of PG in food industry. It establishes an acceptable daily intake (ADI) of 0.5 mg/kg bw per day. Based on exposure assessment, it can be concluded that at the current level of use, PG is not of safety concern.

Hydrophobicity and antioxidant activity acting together for the beneficial health properties of nordihydroguaiaretic acid

Nordihydroguaiaretic acid (NDGA) and rosmarinic acid (RA), phenolic compounds found in various plants and functional foods, have known antioxidant and anti-inflammatory properties. In the present study, we comparatively investigated the importance of hydrophobicity and oxidisability of NDGA and RA, regarding their antioxidant and pharmacological activities. Using a panel of cell-free antioxidant protocols, including electrochemical measurements, we demonstrated that the anti-radical capacities of RA and NDGA were similar. However, the relative capacity of NDGA as an inhibitor of NADPH oxidase (ex vivo assays) was significantly higher compared to RA. The inhibitory effect on NADPH oxidase was not related to simple scavengers of superoxide anions, as confirmed by oxygen consumption by the activated neutrophils. The higher hydrophobicity of NDGA was also a determinant for the higher efficacy of NDGA regarding the inhibition of the release of hypochlorous acid by PMA-activated neutrophil and cytokine (TNF-α and IL-10) production by Staphylococcus aureus-stimulated peripheral blood mononuclear cells. In conclusion, although there have been extensive studies about the pharmacological properties of NDGA, our study showed, for the first time, the importance not only of its antioxidant activity, but also its hydrophobicity as a crucial factor for pharmacological action.

Study of lipophilicity of alpha-asarone derivatives and their deterrent activity against the Colorado potato beetle

Five positional isomers and thirty derivatives of alpha-asarone wereobtained as a bioactive set of substances, and their deterrent activity against the Colorado potato beetle was studied. The lipophilicity values of thirty-six compounds were determined by using experimental, chromatographic and theoretical methods. The logk w values for all compounds were determined by reversed-phase high-performance liquid chromatography using five different columns. The octan-1-ol/water partition coefficients values were determined experimentally as a measure of lipophilicity. For the purpose of comparison, theoretical lipophilic parameters for all compounds were calculated with the use of chemical programs. The experimental, chromatographic and calculated values were compared using linear regression analysis. The most significant correlations were found between the chromatographic lipophilicities using methanol/water for all tested columns and calculated values. It has been found that 13 compounds have the lowest lipophilicities, which correspond to deterrent activity. The presented results show that the computational method is useful for determining the lipophilicity of a series of homologues, but not for positional isomers. In addition, this study shows that determination of lipophilicity using HPLC with various stationary phases is practical and reasonable for all alpha-asarone derivatives.

Synthesis and antifeedant activity of novel alpha-asarone derivatives against stored-product pests

BACKGROUND

Alpha-asarone (2,4,5-trimethoxypropenylbenzene) derivatives represent a new series of compounds that possess good antifeedant activity against different stored-product pests.

RESULTS

A total of 23 novel alpha-asarone derivatives were synthesised and identified by (1) H NMR, (13) C NMR and IR, and their feeding deterrent activities were tested against Sitophilus granarius L., Trogoderma granarium Ev. and Tribolium confusum Duv. Ten compounds showed strong antifeedant activities.

CONCLUSION

Some of the title compounds displayed very good and broad-spectrum activities against adult and larval Coleoptera. The results indicate that the presence of a double bond in the side chain and three methoxy groups is important for antifeedant activity.

Synthesis, crystal structure, and growth inhibition of human hepatoma cell (HepG2) of polyphenolic compounds based on gallates

Seven compounds (1–7) based on gallate were synthesized and characterized by elemental analysis, 1H NMR, and MS spectra. 2-(3,5-Dibenzyloxy-4-methoxy)phenyl-2-propanol (6) was a new compound. Methyl 3,5-dihydroxy-4-methoxybenzoate (3), methyl 3,5-dibenzyloxy-4-methoxybenzoate (4), 3,5-dibenzyloxy-4-methoxybenzyl alcohol (5), and compound 6 were structurally determined by single-crystal X-ray diffraction for the first time. Crystallographic data for 3: space group P212121; a = 4.0750(8) Å, b = 7.5880(15) Å, c = 29.802(6) Å; V = 921.5(3) Å3; Z = 4. 4: space group P-1; a = 10.068(2) Å, b = 10.499(2) Å, c = 11.388(2) Å; α = 76.84(3)°, β = 66.79(3)°, γ = 64.10(3)°; V = 993.0(3) Å3, Z = 2. 5: space group P-1; a = 8.1410(16) Å, b = 8.7590(18) Å, c = 12.879(3) Å; α = 91.66(3)°, β = 94.69(3)°, γ = 91.73(3)°; V = 914.4(3) Å3; Z = 2. 6: space group P21/c; a = 5.8100(12) Å, b = 15.778(3) Å, c = 23.237(5) Å; β = 96.09(3)°; V = 2118.1(7) Å3; Z = 4. All of the seven compounds were evaluated for the inhibition of growth of human hepatoma (HepG2) cells. Comparison with the positive-control 5-fluorouracil (IC50 51.6 µmol/L), 5 showed stronger cytotoxic activity with an IC50 around 15.3 µmol/L, while IC50 value of 3 was 90.3 µmol/L. The effect of slight structural variations in this series of compounds was found to cause a marked change in their activity against HepG2 cells.Key words: gallates, benzyl alcohol, human hepatoma cells, crystal structure, anti-cancer activities.

Comparative cytotoxicity of alkyl gallates on mouse tumor cell lines and isolated rat hepatocytes

Alkyl esters of gallic acid inhibited the respiration rate of mouse sarcoma 786A and mouse mammary adenocarcinoma TA3 cell lines and its multiresistant variant TA3-MTX-R more effectively than gallic acid, both in the absence and in the presence of the uncoupler CCCP. The order of inhibition of the respiration rate by gallates in intact cells was n-octyl- approximately iso-amyl- approximately n-amyl- approximately iso-butyl->n-butyl->iso-propyl->n-propyl-gallate>>gallic acid. Sarcoma 786A was significantly more susceptible to all seven esters than the TA3 cell line. Respiration rates of the TA3-MTX-R cell line showed almost the same sensitivity to these esters as the TA3 cell line. However, hepatocytes were significantly less sensitive than all tumor cells tested. These alkyl gallates blocked mitochondrial electron flow, mainly at the NADH-CoQ segment, preventing ATP synthesis, which would lead to cellular death. These esters also inhibited, in the same order of potencies as respiration, the growth of 786A, TA3 and TA3-MTX-R cells in culture. In mice carrying TA3 or TA3-MTX-R tumor cells, an important decrease of the tumor growth rate and an increase of survival were observed when mice were treated with iso-butyl gallate alone or in combination with doxorubicin. These results indicate that alkyl gallates are selectively cytotoxic to tumor cells, which may be due to the mitochondrial dysfunctions of these cells.

Cytochrome P450 expression and activities in human tongue cells and their modulation by green tea extract

The expression, inducibility, and activities of several cytochrome P450 (CYP) enzymes were investigated in a human tongue carcinoma cell model, CAL 27, and compared with the human liver model HepG2 cells. The modulation effects of green tea on various CYP isoforms in both cell lines were also examined. RT-PCR analysis of CAL 27 cells demonstrated constitutive expression of mRNA for CYPs 1A1, 1A2, 2C, 2E1, 2D6, and 4F3. The results were negative for CYP2A6, 2B6/7, 3A3/4, and 3A7. Both cell lines displayed identical expression and induction profiles for all of the isoforms examined in this study except 3A7 and 2B6/7, which were produced constitutively in HepG2 but not Cal-27 cells. CYP1A1 and 1A2 were both induced by treatment with beta-napthoflavone as indicated by RT-PCR and Western blotting, while CYP2C mRNA was upregulated by all-trans retinoic acid and farnesol. RT-PCR and Western blot analysis showed that the expressions of CYP1A1 and 1A2 were induced by green tea extract (GTE), which also caused an increase in mRNA for CYP2E1, CYP2D6, and CYP2C isoforms. The four tea catechins, EGC, EC, EGCG and ECG, applied to either HepG2 or Cal-27 cells at the concentration found in GTE failed to induce CYP1A1 or CYP1A2, as determined by RT-PCR. Of the isoforms that were apparently induced by GTE, only 7-ethoxycoumarin deethylase (ECOD) activity could be detected in CAL 27 or HepG2 cells. Interestingly, mRNA and protein for CYP1A1 and CYP1A2 were detected in both cell lines, and although protein and mRNA levels of CYP1A1 and CYP1A2 were increased by GTE, the observed ECOD activity in both cell lines was decreased.