Cinnamic acid: a natural product with potential use in cancer intervention

Studies on the Interaction of Cinnamic Acid with Bovine Serum Albumin

The interaction between cinnamic acid and bovine serum albumin (BSA) have been studied at three temperatures, 296, 303 and 310 K. Fluorescence quenching spectra in combination with Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy was used to investigate the drug-binding mode, the binding constant and the protein structure changes in the presence of cinnamic acid in aqueous solution at pH 7.40. The fluorescence quenching constant K(q), K(sv) and the binding constant K were calculated according to Stern-Volmer equation based on the quenching of the fluorescence of BSA in the presence of cinnamic acid. The thermodynamic parameters, the enthalpy (DeltaH) and the entropy change (DeltaS) were estimated to be -16.457 kJ mol(-1) and 38.028 J mol(-1) K(-1) according to the van't Hoff equation. The displacement experiment shows that cinnamic acid can bind to the subdomain IIA (corresponding to Sudlow's drug binding site I). The distance between the tryptophan residues in BSA and cinnamic acid bound to site I was estimated to be 1.63 nm using Föster's equation on the basis of fluorescence energy transfer. The decreased binding constant in the presence of common ions indicates that common ions have effect on drug-BSA system.

Cinnamic acids as new inhibitors of 17beta-hydroxysteroid dehydrogenase type 5 (AKR1C3)

17Beta-hydroxysteroid dehydrogenase type 5 (AKR1C3) that is involved in the pre-receptor regulation of androgen and estrogen action in the human is an emerging therapeutic target in the treatment of hormone-dependent forms of cancer, such as prostate cancer, breast cancer and endometrial cancer. To discover novel inhibitors, we tested the effect of a series of cinnamic acids on the reductive activity of the human recombinant AKR1C3. The compounds were evaluated in a spectrophotometric assay using 9,10-phenanthrenequinone as a substrate. The best inhibitor in the series was alpha-methylcinnamic acid (IC50=6.4 microM). Also, unsubstituted cinnamic acid was a good inhibitor of AKR1C3 (IC50=50 microM). Small hydrophobic substituents of the phenyl ring did not alter the activity; however, substitution with polar groups decreased the potency of inhibition. The most active compounds in this series represent promising starting points for further structural modifications in the search for more potent inhibitors of AKR1C3.

Two related cinnamic Acid derivatives from Brazilian honey bee propolis, baccharin and drupanin, induce growth inhibition in allografted sarcoma S-180 in mice

Honey bee propolis is rich in cinnamic acid derivatives. Baccharin and drupanin from Brazilian honey bee propolis are cinnamic acid derivatives that contain prenyl moieties. We previously isolated these two compounds and demonstrated that they induce an apoptotic event in several tumor cell lines. In this study, we examined the tumoricidal activity of baccharin and drupanin in mice allografted with sarcoma S-180 and also studied the genotoxic effects on normal splenocytes using the alkaline single cell gel (comet) assay. We found that both baccharin and drupanin effectively suppressed growth of the tumor. Furthermore, these compounds induced a significant genotoxic effect on the tumor cells in comparison with normal splenocytes. Thus, baccharin and drupanin are potent tumor suppressive components of honeybee propolis.

Evaluation of Manisa propolis effect on leukemia cell line by telomerase activity

Propolis is a resinous substance which is used by bees to repair and maintain their hives. It has more than 180 compounds including flavonoids, phenolic acids and its esters which have anti-inflammatory, antibacterial, antiviral, immunomodulatory, antioxidant and antiproliferative effects. Propolis is shown to inhibit cell division and protein synthesis. However the exact mechanism underlying antitumor effect is not clearly described. On the other hand progressive telomere shortening to a critical level results with senescence of normal cells by inducing apoptosis and telomerase prevents erosion of telomeres. In this study we aimed to evaluate hTERT ratios in propolis-treated T-cell acute lymphoblastic leukemia (CCFR-CEM) cell line. Cell counts and cell viability of propolis-treated and propolis-free T-cell acute lymphoblastic leukemia (CCFR-CEM) cell line were assessed by trypan blue dye exclusion test and MTT assay. The LightCycler instrument was used (online real-time PCR) for the quantification of hTERT in CCFR-CEM cell line. The hTERT ratio significantly decreased 60 and 93% after 24 and 72 h respectively compared to the initial value of the cells incubated with propolis. It had almost no cytotoxic effect and caused 30, 30, 22 and 12% decrease in cell counts after 24, 48, 72 and 96 h respectively which is statistically significant. In conclusion propolis may show antitumor and apoptotic effect via inhibiting telomerase expression besides the mechanisms which have been described previously.

Structure–activity relationships of trans-cinnamic acid derivatives on α-glucosidase inhibition

trans-Cinnamic acid and its derivatives were investigated for the alpha-glucosidase inhibitory activity. 4-Methoxy-trans-cinnamic acid and 4-methoxy-trans-cinnamic acid ethyl ester showed the highest potent inhibitory activity among those of trans-cinnamic acid derivatives. The presence of substituents at 4-position in trans-cinnamic acid altered the alpha-glucosidase inhibitory activity. Increasing of bulkiness and the chain length of 4-alkoxy substituents as well as the increasing of the electron withdrawing group have been shown to decrease the inhibitory activity. 4-Methoxy-trans-cinnamic acid was a noncompetitive inhibitor for alpha-glucosidase, whereas, 4-methoxy-trans-cinnamic acid ethyl ester was a competitive inhibitor. These results indicated that trans-cinnamic acid derivatives could be classified as a new group of alpha-glucosidase inhibitors.

Synthesis and antiproliferative activity in vitro of 2-aminobenzimidazole derivatives

A novel series of Schiff bases 1-11, the derivatives of 2-aminobenzimidazole and substituted aromatic aldehydes, has been synthesised. Compounds 1-11 reduced by NaBH(4) formed 2-benzylaminobenzimidazoles 12-21. 2-(o-Bromobenzylamino)benzimidazole (15) acylated by cinnamoyl chloride gave 2-(o-bromobenzylamino)-1-cinnamoylbenzimidazole (22). Long heating of 15 and 19 with p-nitrocinnamoyl or cinnamoyl chloride led to the formation of pyrimido[1,2-a]benzimidazol-4-ones 23 and 24. The structures of 1-24 were identified by the results of elemental analysis and their IR, (1)H NMR and MS spectra. Among the compounds 1-24 evaluated for their antiproliferative activity in vitro, 16, 19, 20 and 22 exhibited cytotoxic activity against the cells of human cancer cell lines, namely SW707 (rectal), HCV29T (bladder), A549 (lung) and T47D (breast cancer).

Effect of phytosterols on cholesterol metabolism and MAP kinase in MDA-MB-231 human breast cancer cells

Epidemiological studies suggest that dietary phytosterols may offer protection form some types of cancer including breast cancer. In an attempt to investigate the mechanism by which phytosterols offer this protection, we investigated the effect of the two most common dietary phytosterols, beta-sitosterol and campesterol, on the mevalonate and MAP Kinase (MAPK) pathways in MDA-MB-231 cells. These pathways play a role in cell growth and apoptosis. MDA-MB-231 cell line was used in this study since it is a hormone-insensitive tumor cell line which represents the majority of advanced breast cancer cases. Cells grown in the presence of 16 microM beta-sitosterol or campesterol for 3 days exhibited a 70% and 6% reduction in cell growth, respectively, while cholesterol treatment had no effect on growth as compared to the control. Studies investigating the effect of sterol supplementation on the relative and total sterol composition of cells, showed that cells supplemented with cholesterol contained 23% more cholesterol than the control. Cells supplemented with campesterol had almost one-half the cholesterol of controls but accumulated campesterol to account for 40% of the total sterols. In the case of cells supplemented with beta-sitosterol, cells had only 25% of their sterols as cholesterol and the rest was in the form of beta-sitosterol. All sterols tested equally inhibited de novo cholesterol synthesis using 14C-acetate as substrate. beta-Sitosterol supplemented cells had reduced cholesterol synthesis when using 3H-mevalonolactone as substrate, which suggests that the inhibition in this pathway is downstream of mevalonate where processes such as isoprenylation of proteins may take place. Mevalonate supplementation to cells treated with beta-sitosterol did not completely correct the observed growth inhibition by beta-sitosterol. There was no effect of sterols on the concentrations of both low (21-26 kDa) or high (44-74 kDa) molecular weight isoprenylated proteins in these cells. On the other hand, both the quantity and activity of MAPK was elevated in the cells supplemented with beta-sitosterol. These data suggest that the down regulation of cholesterol synthesis from mevalonate and stimulation of the MAPK pathway may play roles in the inhibition of MDA-MB-231 cell growth by beta-sitosterol.

Cinnamamide, an antitumor agent with low cytotoxicity acting on matrix metalloproteinase

The antitumor activity of cinnamamide (CNM), an agent acting on matrix metalloproteinase (MMP), was investigated in the present study. CNM displayed low cytotoxicity. By the MTT assay the IC50 (50% inhibitory concentration) values of CNM on cell proliferation ranged from 1.29 to 1.94 mM in human oral epidermoid carcinoma KB cells, human hepatoma BEL-7402 cells and human fibrosarcoma HT-1080 cells. Moreover, the IC50 for human fetal lung 2BS cells reached 4.33 mM. The administration of CNM in the range of 50-150 mg/kg (i.p. or p.o.) showed moderate antitumor effects in mice. When administered i.p. or p.o., CNM (150 mg/kg) inhibited the growth of transplanted hepatoma 22 by 48.8 or 40.5%, respectively. At the dose of 100 mg/kg, CNM inhibited the growth of colon 26 carcinoma by 39.0% and that of Lewis lung carcinoma by 53.9%. In the Lewis lung carcinoma model, CNM at the dose of 100 mg/kg (i.p.) also reduced the lung metastasis by 59.1%. Gelatine zymography revealed that CNM was able to decrease the level of MMP-2 in conditioned medium of HT-1080 tumor cells in a concentration-dependent manner. These results indicate that CNM is an antitumor agent with low cytotoxicity acting on MMP and may serve as a lead compound in the development of antitumor drugs.

Antitumor components from an actinomycete strain 6011W

Three bioactive compounds that inhibited nucleoside transport were isolated from the cultured broth of Streptoverticillium sp. 6011W. The structures of those compounds were characterized as cinnamamide, N-(tetrahydro-2-oxo-3-thienyl)-acetamide and benzamide, respectively. They all inhibited radiolabeled thymidine transport into Ehrlich carcinoma cells, with IC50 values of 30.4, 97.2 and 85.4 microM, respectively. When administered i.p., cinnamamide not only inhibited the growth of transplanted tumors but also reduced the number of lung metastases in mice bearing Lewis lung carcinoma. The results suggest that nucleoside transport inhibition assay is a valuable model to search for antitumor agents of natural origin.

Cinnamic acid inhibits proliferation and modulates brush border membrane enzyme activities in Caco-2 cells

The objective of the present study was to examine whether cinnamic acid exerts antitumor activity against colon cancer cells in vitro. For this purpose we investigated the effect of cinnamic acid on cell proliferation and on the differentiation markers alkaline phosphatase, sucrase and aminopeptidase N in human colon adenocarcinoma cells (Caco-2). Cinnamic acid (2.5-8.0 mM) prolonged the doubling time and inhibited the DNA synthesis of growing cells. The antiproliferative effect occurred rapidly after 2 h of treatment with 8.0 mM cinnamic acid and reached nearly maximal values after 8 h of treatment. Sucrase and aminopeptidase N activities were stimulated under cinnamic acid treatment (4.0-8.0 mM), while alkaline phosphatase activity was inhibited in postconfluent cells (8.0 mM). Similar effects on enzyme activities were seen in non-proliferating cells. Cinnamic acid did not alter the adhesion to collagen matrix or cell viability. Intracellular cAMP levels were decreased significantly after 1 h of treatment with 8.0 mM cinnamic acid, suggesting that cinnamic acid induces its effects on enzyme activities partly by modulating the cAMP signaling pathway.