Caffeic Acid Phenethyl Ester-Incorporated Radio-Sensitive Nanoparticles of Phenylboronic Acid Pinacol Ester-Conjugated Hyaluronic Acid for Application in Radioprotection

We synthesized phenylboronic acid pinacol ester (PBPE)-conjugated hyaluronic acid (HA) via thiobis(ethylamine) (TbEA) linkage (abbreviated as HAsPBPE conjugates) to fabricate the radiosensitive delivery of caffeic acid phenetyl ester (CAPE) and for application in radioprotection. PBPE was primarily conjugated with TbEA and then PBPE-TbEA conjugates were conjugated again with hyaluronic acid using carbodiimide chemistry. CAPE-incorporated nanoparticles of HAsPBPE were fabricated by the nanoprecipitation method and then the organic solvent was removed by dialysis. CAPE-incorporated HAsPBPE nanoparticles have a small particle size of about 80 or 100 nm and they have a spherical shape. When CAPE-incorporated HAsPBPE nanoparticles were irradiated, nanoparticles became swelled or disintegrated and their morphologies were changed. Furthermore, the CAPE release rate from HAsPBPE nanoparticles were increased according to the radiation dose, indicating that CAPE-incorporated HAsPBPE nanoparticles have radio-sensitivity. CAPE and CAPE-incorporated HAsPBPE nanoparticles appropriately prevented radiation-induced cell death and suppressed intracellular accumulation of reactive oxygen species (ROS). CAPE and CAPE-incorporated HAsPBPE nanoparticles efficiently improved survivability of mice from radiation-induced death and reduced apoptotic cell death. We suggest that HAsPBPE nanoparticles are promising candidates for the radio-sensitive delivery of CAPE.

Synthesis of Caffeoyl-Prolyl-Histidyl-Xaa Derivatives and Evaluation of Their Activities and Stability upon Long-Term Storage

Antioxidants play a critical role in the treatment of degenerative diseases and delaying the aging of dermal tissue. Caffeic acid (CA) is a representative example of the antioxidants found in plants. However, CA is unsuitable for long-term storage because of its poor stability under ambient conditions. Caffeoyl-Pro-His-NH₂ (CA-Pro-His-NH₂, CA-PH) exhibits the highest antioxidant activity, free radical scavenging and lipid peroxidation inhibition activity among the histidine-containing CA-conjugated dipeptides reported to date. The addition of short peptides to CA, such as Pro-His, is assumed to synergistically enhance its antioxidative activity. In this study, several caffeoyl-prolyl-histidyl-Xaa-NH₂ derivatives were synthesized and their antioxidative activities evaluated. CA-Pro-His-Asn-NH₂ showed enhanced antioxidative activity and higher structural stability than CA-PH, even after long-term storage. CA-Pro-His-Asn-NH₂ was stable for 3 months, its stability being evaluated by observing the changes in its NMR spectra. Moreover, the solid-phase synthetic strategy used to prepare these CA-Pro-His-Xaa-NH₂ derivatives was optimized for large-scale production. We envision that CA-Pro-His-Xaa-NH₂ derivatives can be used as potent dermal therapeutic agents and useful cosmetic ingredients.

Thermoresponsive Catechol Based-Polyelectrolyte Complex Coatings for Controlled Release of Bortezomib

To overcome the high relapse rate of multiple myeloma (MM), a drug delivery coating for functionalization of bone substitution materials (BSM) is reported based on adhesive, catechol-containing and stimuli-responsive polyelectrolyte complexes (PECs). This system is designed to deliver the MM drug bortezomib (BZM) directly to the anatomical site of action. To establish a gradual BZM release, the naturally occurring caffeic acid (CA) is coupled oxidatively to form poly(caffeic acid) (PCA), which is used as a polyanion for complexation. The catechol functionalities within the PCA are particularly suitable to form esters with the boronic acid group of the BZM, which are then cleaved in the body fluid to administer the drug. To achieve a more thorough control of the release, the thermoresponsive poly(N-isoproplyacrylamide-co-dimethylaminoethylmethacrylate) (P(NIPAM-co-DMAEMA)) was used as a polycation. Using turbidity measurements, it was proven that the lower critical solution temperature (LCST) character of this polymer was transferred to the PECs. Further special temperature dependent attenuated total reflection infrared spectroscopy (ATR-FTIR) showed that coatings formed by PEC immobilization exhibit a similar thermoresponsive performance. By loading the coatings with BZM and studying the release in a model system, via UV/Vis it was observed, that both aims, the retardation and the stimuli control of the release, were achieved.

Preservation of Cichoric Acid Antioxidant Properties Loaded in Heat Treated Lactoferrin Nanoparticles

In the current research, a new cichoric acid (CA) encapsulation system was investigated. The optimal condition for the formation of lactoferrin-cichoric acid nanoparticles (LF-CA NPs) was determined by controlling the solution pH, the thermal treatment conditions, and the concentration of CA. Fluorescence indicated that the electrostatic force and the hydrophobic force were the main forces in the formation of LF-CA NPs. LF-CA NPs prepared under different conditions were spherical in shape with smaller particle sizes and good zeta potential demonstrating good colloidal stability. Especially, the prepared particle size of the LF-CA NPs at pH 7 and 95 °C was about 67.20 ± 1.86 nm. The circular dichroism (CD) and the Fourier transform infrared spectroscopy (FTIR) results showed that the combination of LF (lactoferrin) and CA affected the secondary structure of the LF. The differential scanning calorimetry (DSC) results indicated that the addition of CA increased the thermal stability of LF. In vitro antioxidant experiments confirmed the antioxidant capacity of LF-CA NPs was better than CA. CA was successfully encapsulated into LF NPs with high encapsulated efficiency (97.87⁻99.87%) by high performance liquid chromatography (HPLC). These results showed that LF could be used as the wall material of CA with excellent nature.

Synthesis and Antioxidant Activity of Caffeic Acid Derivatives

A series of caffeic acid derivatives were synthesized via a modified Wittig reaction which is a very important tool in organic chemistry for the construction of unsaturated carbon⁻carbon bonds. All reactions were performed in water medium at 90 °C. The aqueous Wittig reaction worked best when one unprotected hydroxyl group was present in the phenyl ring. The olefinations in the aqueous conditions were also conducted with good yields in the presence of two unprotected hydroxyl groups. When the number of the hydroxyl groups was increased to three, the reaction yields were worse, and the derivatives 12, 13, and 18 were obtained with 74%, 37%, and 70% yields, respectively. Nevertheless, the Wittig reaction using water as the essential medium is an elegant one-pot synthesis and a greener method, which can be a safe alternative for implementation in organic chemistry. The obtained compounds were tested for their antioxidant activity, and 12, 13, and 18 showed the highest activities. Moreover, all synthesized compounds displayed no cytotoxicity, and can therefore be used in the pharmaceutical or cosmetic industry.

Examination of α-exosite inhibitors against Botulinum neurotoxin A protease through structure-activity relationship studies of chicoric acid

Botulinum neurotoxins (BoNT) are among the most toxic known substances and currently there are no effective treatments for intraneuronal BoNT intoxication. Chicoric acid (ChA) was previously reported as a BoNT/A inhibitor that binds to the enzyme's α-exosite. Herein, we report the synthesis and structure-activity relationships (SARs) of a series of ChA derivatives, which revealed essential binding interactions between ChA and BoNT/A. Moreover, several ChA-based inhibitors with improved potency against the BoNT/A were discovered.

Synthesis and biological evaluation of caffeic acid derivatives as potent inhibitors of α-MSH-stimulated melanogenesis

We have disclosed our effort to develop caffeic acid derivatives as potent and non-toxic inhibitors of α-MSH-stimulated melanogenesis to treat pigmentation disorders and skin medication including a cosmetic skin-whitening agent. The SAR studies revealed that cyclohexyl ester and secondary amide derivatives of caffeic acid showed significant inhibitory activities.

Identification and Quantification of Potential Anti-inflammatory Hydroxycinnamic Acid Amides from Wolfberry

Wolfberry or Goji berry, the fruit of Lycium barbarum, exhibits health-promoting properties that leads to an extensive study of their active components. We synthesized a set of hydroxycinnamic acid amide (HCCA) compounds, including trans-caffeic acid, trans-ferulic acid, and 3,4-dihydroxyhydrocinnamic acid, with extended phenolic amine components as standards to identify and quantify the corresponding compounds from wolfberry and to investigate anti-inflammatory properties of these compounds using in vitro model. With optimized LC-MS/MS and NMR analysis, nine amide compounds were identified from the fruits. Seven of these compounds were identified in this plant for the first time. The amide compounds with a tyramine moiety were the most abundant. In vitro studies indicated that five HCCA compounds showed inhibitory effect on NO production inuded by lipopolysaccharides with IC₅₀ less than 15.08 μM (trans-N-feruloyl dopamine). These findings suggested that wolfberries demonstrated anti-inflammatory properties.

Finding Potent Sirt Inhibitor in Coffee: Isolation, Confirmation and Synthesis of Javamide-II (N-Caffeoyltryptophan) as Sirt1/2 Inhibitor

Recent studies suggest that Sirt inhibition may have beneficial effects on several human diseases such as neurodegenerative diseases and cancer. Coffee is one of most popular beverages with several positive health effects. Therefore, in this paper, potential Sirt inhibitors were screened using coffee extract. First, HPLC was utilized to fractionate coffee extract, then screened using a Sirt1/2 inhibition assay. The screening led to the isolation of a potent Sirt1/2 inhibitor, whose structure was determined as javamide-II (N-caffeoyltryptophan) by NMR. For confirmation, the amide was chemically synthesized and its capacity of inhibiting Sirt1/2 was also compared with the isolated amide. Javamide-II inhibited Sirt2 (IC₅₀; 8.7μM) better than Sirt1(IC₅₀; 34μM). Since javamide-II is a stronger inhibitor for Sirt2 than Sirt1. The kinetic study was performed against Sirt2. The amide exhibited noncompetitive Sirt2 inhibition against the NAD⁺ (K_i = 9.8 μM) and showed competitive inhibition against the peptide substrate (K_i = 5.3 μM). Also, a docking simulation showed stronger binding pose of javamide-II to Sirt2 than AGK2. In cellular levels, javamide-II was able to increase the acetylation of total lysine, cortactin and histone H3 in neuronal NG108-15 cells. In the same cells, the amide also increased the acetylation of lysine (K382) in p53, but not (K305). This study suggests that Javamide-II found in coffee may be a potent Sirt1/2 inhibitor, probably with potential use in some conditions of human diseases.

Antioxidant properties and efficacies of synthesized alkyl caffeates, ferulates, and coumarates

Caffeic, ferulic, and coumaric acids were lipophilized with saturated fatty alcohols (C1-C20). The antioxidant properties of these hydroxycinnamic acids and their alkyl esters were evaluated in various assays. Furthermore, the antioxidant efficiency of the compounds was evaluated in a simple o/w microemulsion using the conjugated autoxidizable triene (CAT) assay. All evaluated phenolipids had radical scavenging, reducing power, and metal chelating properties. Only caffeic acid and caffeates were able to form a complex with iron via their catechol group in the phenolic ring. In the o/w emulsion, the medium chain phenolipids of the three homologues series were most efficient. The antioxidant properties and efficacies were dependent upon functional groups substituted to the ring structure and were in the following order: caffeic acid and caffeates > ferulic acid and ferulates > coumaric acid and coumarates. Moreover, the results demonstrated that the test system has an impact on the antioxidative properties measured.

Bioactivity and chemical synthesis of caffeic acid phenethyl ester and its derivatives

Caffeic acid phenethyl ester (CAPE), as one of the main active ingredients of the natural product propolis, shows the unique biological activities such as anti-tumor, anti-oxidation, anti-inflammatory, immune regulation, and so on. These have attracted the attention of many researchers to explore the compound with potent biological activities. This review aims to summarize its bioactivities, synthetic methods and derivatives, which will be helpful for further study and development of CAPE and its derivatives.

A CAPE analogue as novel antiplatelet agent efficiently inhibits collagen-induced platelet aggregation

OBJECTIVE

Platelet activation plays a pivotal role in the pathogenesis of thrombosis, which can lead to fatal diseases such as myocardial or cerebral infarction, and atherosclerosis. The present study focused on investigating the effect of CAPE-NO2 against collagen-induced platelet aggregation.

METHODS

Caffeic acid phenethyl ester (CAPE) is an active component in propolis. CAPE-NO2 is a nitro derivative of CAPE. Its effects on rat platelet aggregation induced by collagen were tested in vitro and the potential mechanisms underlying the activities were investigated.

RESULTS

CAPE-NO2 significantly inhibited collagen-induced platelet aggregation in a concentration-dependent manner. It also reduced TXB2 formation and COX-1 activity in collagen-activated platelets. Moreover, CAPE-NO2 caused an increase in NO production and cGMP levels and attenuated 5-HT release in the collagen-activated platelets.

CONCLUSION

These findings suggest that the inhibitory mechanism of CAPE-NO2 on collagen-induced platelet aggregation might be associated with the down-regulation of TXB2, COX-1 and 5-HT and the elevation of NO and cGMP production. These indicators are closely related to platelet function. So CAPE-NO2 may be a promising candidate for the extension of the current spectrum of antiplatelet drugs.

Synthesis of caffeic acid phenethyl ester derivatives, and their cytoprotective and neuritogenic activities in PC12 cells

Twenty-one caffeic acid phenethyl ester (CAPE) derivatives were synthesized, and characterized by IR, HR-MS, (1)H and (13)C NMR analyses. All compounds were evaluated for their cytoprotective effects against H2O2-induced cytotoxicity and neuritogenic activities in the neurite outgrowth in PC12 cells. Compounds 1 and 20 exhibited stronger cytoprotective activities than their parent compound CAPE at 4 nM. Compounds 1, 4, 12 and 13 showed potential neuritogenic activities at 0.5 nM, while compounds 19 and 20 induced neurite outgrowth at 10 nM. The results from this study suggested that CAPE and its derivatives may be potential functional food ingredients for the prevention of neurodegenerative diseases.

Conversion of salvianolic acid B into salvianolic acid A in tissues of Radix Salviae Miltiorrhizae using high temperature, high pressure and high humidity

Salvianolic acid A (Sal A), an important constituent of Radix Salviae Miltiorrhizae (RSM), is effective for the treatment of myocardial infarction (MI) and coronary heart disease due to its potential in the improvement of acute myocardial ischemia. However, its content is very low in RSM. So it is obvious to find a rich source of Sal A or to improve its content by conversion of other related components into Sal A modifying reaction conditions. In this research we focused on the conversion of Sal B into Sal A in aqueous solutions of RSM by using different reaction conditions including pH, temperature, pressure and humidity. During the reactions, the contents of Sal A, Sal B and danshensu in the RSM were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LCMS). The results indicated that the conversion of Sal B into Sal A in RSM tissues under the conditions of a high temperature, high pressure and high humidity was efficient and thereby, was readily utilized to prepare rich Sal A materials in practice.

Alkyl caffeates improve the antioxidant activity, antitumor property and oxidation stability of edible oil

Caffeic acid (CA) is distributed widely in nature and possesses strong antioxidant activity. However, CA has lower solubility in non-polar media, which limits its application in fat-soluble food. To increase the lipophilicity of natural antioxidant CA, a series of alkyl caffeates were synthesized and their antioxidant and antitumor activities were investigated. The antioxidant parameters, including the induction period, acid value and unsaturated fatty acid content, of the alkyl caffeates in edible oil were firstly investigated. The results indicated that alkyl caffeates had a lower DPPH IC₅₀ (14–23 µM) compared to CA, dibutyl hydroxy toluene (BHT) and Vitamin C (24–51 µM), and significantly inhibited four human cancer cells (SW620, SW480, SGC7901 and HepG2) with inhibition ratio of 71.4–78.0% by a MTT assay. With regard to the induction period and acid value assays, methyl and butyl caffeates had higher abilities than BHT to restrain the oxidation process and improve the stability of edible oil. The addition of ethyl caffeate to oil allowed maintenance of a higher unsaturated fatty acid methyl ester content (68.53%) at high temperatures. Overall, the alkyl caffeats with short chain length (n<5) assessed better oxidative stability than those with long chain length. To date, this is the first report to the correlations among the antioxidant activity, anticancer activity and oxidative stability of alkyl caffeates.

A novel chemoenzymatic synthesis of propyl caffeate using lipase-catalyzed transesterification in ionic liquid

Propyl caffeate has the highest antioxidant capacity in the caffeate alkyl esters family, but industrial production of propyl caffeate is hindered by low yields using either the chemical or enzymatic catalysis method. To set up a high-yield process for obtaining propyl caffeate, a novel chemoenzymatic synthesis method using lipase-catalyzed transesterification of an intermediate methyl caffeate or ethyl caffeate and 1-propanol in ionic liquid was established. The maximum propyl caffeate yield of 98.5% was obtained using lipase-catalyzed transesterification under the following optimal conditions: Novozym 435 as a biocatalyst, [Bmim][CF3SO3] as a medium, a molar ratio of methyl caffeate to 1-propanol of 1:5, a mass ratio of methyl caffeate to lipase of 1:20, and a reaction temperature of 60°C. The two-step conversion of caffeic acid to propyl caffeate via methyl caffeate is an efficient way to prepare propyl caffeate with an overall yield of 82.7%.

Neuroprotection of a novel synthetic caffeic acid-syringic acid hybrid compound against experimentally induced transient cerebral ischemic damage

We investigated effects of caffeic acid, syringic acid, and their synthesis on transient cerebral ischemic damage in the gerbil hippocampal CA1 region. In the 10 mg/kg caffeic acid-, syringic acid-, and 20 mg/kg syringic-treated ischemia groups, we did not find any significant neuroprotection in the ischemic hippocampal CA region. In the 20 mg/kg caffeic acid- and 10 mg/kg caffeic acid-syringic acid-treated ischemia groups, moderate neuroprotection was found in the hippocampal CA1 region. In the 20 mg/kg caffeic acid-syringic acid-treated ischemia group, a strong neuroprotective effect was found in the ischemic hippocampal CA1 region: about 89 % of hippocampal CA1 region pyramidal neurons survived. We also observed changes in glial cells (astrocytes and microglia) in the ischemic hippocampal CA1 region in all the groups. Among them, the distribution pattern of the glial cells was only in the 20 mg/kg caffeic acid-syringic acid-treated ischemia group similar to that in the sham group (control). In brief, 20 mg/kg caffeic acid-syringic acid showed a strong neuroprotective effect with an inhibition of glia activation in the hippocampal CA1 region induced by transient cerebral ischemia.

Synthesis and antiradical/antioxidant activities of caffeic acid phenethyl ester and its related propionic, acetic, and benzoic acid analogues

Caffeic acid phenethyl ester (CAPE) is a bioactive component isolated from propolis. A series of CAPE analogues was synthesized and their antiradical/antioxidant effects analyzed. The effect of the presence of the double bond and of the conjugated system on the antioxidant effect is evaluated with the analogues obtained from 3-(3,4-dihydroxyphenyl) propanoic acid. Those obtained from 2-(3,4-dihydroxyphenyl) acetic acid and 3,4-dihydroxybenzoic acid allow the evaluation of the effect of the presence of two carbons between the carbonyl and aromatic system.

[Design, synthesis and activity of a new type of influenza virus N1 neuraminidase inhibitors]

In this study, the "150-cavity", next to the H5N1 influenza virus neuraminidase activity site, has been used as the target to design and synthesize a structural analogue of chlorogenic acid, N-caffeoyl-GABA, using the flexible docking simulation. The docking study showed that the N-caffeoyl-GABA could be inserted into the "150-cavity" and combined with the Arg156 side chain by hydrogen bond. The best binding free energy of H5N1 NA-N-caffeoyl-GABA complex was -7.70 kcal mol(-1), equivalent that of the NA-oseltamivir. At the same time, using the H5N1 pseudotyping virus-based NA inhibitors screening model, we determined the inhibitory effect of oseltamivir, chlorogenic acid and N-caffeoyl-GABA on the NA. Compared with chlorogenic acid, N-caffeoyl-GABA significantly enhanced the inhibitory effect on NA, but less than oseltamivir. This study showed that the "150-cavity" could possibly be used as a new neuraminidase inhibitors target, and provided a path for the development of new neuraminidase inhibitors.

[Preparation and anti-oxidant activity of cinnamic acid derivatives-g-CTS]

OBJECTIVE

To prepare cinnamic acid derivatives-g-CTS and to study its antioxidation activity.

METHOD

The ability of catching oxygen of the products and raw material were determined through two methods, Marklund method and trace pyrogallic acid method, with autoxidation reaction of pyrogallol as the oxygen anion source.

RESULT

The antioxidation activities of all products were better than the raw material.

CONCLUSION

Cinnamic acid derivatives-g-CTS is suitable as the O2-* -capture agent.

Synthesis of ethyl ferulate in organic medium using celite-immobilized lipase

In the present work we have evaluated synthesis of ethyl ferulate by the esterification reaction of ferulic acid and ethanol catalyzed by a commercial lipase (Steapsin) immobilized onto celite-545 in a short period of 6h in DMSO. The immobilized lipase was treated with cross-linking agent glutaraldehyde (1%; v/v). The optimum synthesis of ethyl ferulate was recorded at 45°C, pH 8.5 and 1:1 ratio of ethanol and ferulic acid. Co(2+), Ba(2+)and Pb(2+) ions enhanced the synthesis of ethyl ferulate Hg(2+), Cd(3+)and NH(4+) ions had mild inhibitory effect. The celite-bound lipase produced 68 mM of ethyl ferulate under optimized reaction conditions.

Optimization of ultrasound-accelerated synthesis of enzymatic caffeic acid phenethyl ester by response surface methodology

The ultrasound-accelerated enzymatic synthesis of caffeic acid phenethyl ester (CAPE) from caffeic acid and phenethyl alcohol was investigated in this study. A commercial immobilized lipase from Candida antarctica, called Novozym® 435, was used as the catalyst. A 5-level-4-factor central-composite rotatable design (CCRD) and response surface methodology (RSM) were employed to evaluate the effects of reaction time, substrate molar ratio, enzyme amount, and ultrasonic power on percent molar conversion of CAPE. The results indicated that reaction time, substrate molar ratio, and ultrasonic power significantly affected percent molar conversion, whereas enzyme amount did not. A model for synthesis of CAPE was established. Based on ridge max analysis, the optimum condition for CAPE synthesis was predicted to be reaction time 9.6 h, substrate molar ratio 1:71, enzyme amount 2938 PLU, and ultrasonic power 2 W/cm(2) with the molar conversion value of 96.03 ± 5.18%. An experiment was performed under this optimal condition and molar conversion of 93.08 ± 0.42% was obtained.

Antihyperglycemic effect of a caffeamide derivative, KS370G, in normal and diabetic mice

The antihyperglycemic actions of caffeamide derivatives, especially KS370G, in normal ICR, streptozotocin-induced diabetic (T1DM) and diet-induced diabetic (T2DM) mice were investigated in this study. Oral administration of the compound decreased the plasma glucose levels in both normal and diabetic mice, and appeared to be in a dose-dependent manner in normal and diet-induced type 2 diabetic mice. It was found that KS370G could stimulate the release of insulin in both normal and T2DM mice, and a dose of 1 mg per kg KS370G could significantly attenuate the increase of plasma glucose induced by an intraperitoneal glucose challenge test in normal and diabetic mice. Similar treatment with KS370G significantly increased glycogen content in both liver and skeletal muscle. Hence, the hypoglycemic effect of KS370G in normal and diabetic mice could be attributed to the stimulation of insulin release and the increase of glucose utilization.

Synthesis and evaluation of the platelet antiaggregant properties of phenolic antioxidants structurally related to rosmarinic acid

Polyphenols, such as rosmarinic acid, are widely distributed natural products with relevant antioxidant activity. Oxidative stress plays an important role in the pathogenesis of a number of disorders. Here, we report on the synthesis and biological effects of the polyphenolic esters hydroxytyrosyl gallate (1), hydroxytyrosyl protocatechuate (2) and hydroxytyrosyl caffeate (3), structurally related to rosmarinic acid. The three compounds showed a greater free radical scavenging activity than their precursors and also than rosmarinic acid. Esters 1 and 3 significantly reduced thrombin-evoked platelet aggregation, which is likely mediated to the attenuation of thrombin-stimulated Ca(2+) release and entry. The three compounds reduced the ability of platelets to accumulate Ca(2+) in the intracellular stores, probably by enhancing the Ca(2+) leakage rate and reduced store-operated Ca(2+) entry in these cells. These observations suggest that the structurally-simplified analogs to rosmarinic acid, compounds 1 and 3, might be the base of therapeutic strategies to prevent thrombotic complications associated to platelet hyperaggregability due to oxidative stress.

Botulinum neurotoxin A protease: discovery of natural product exosite inhibitors

A new mechanistic class of BoNT/A zinc metalloprotease inhibitors, from Echinacea, exemplified by the natural product d-chicoric acid (I1) is disclosed. A detailed evaluation of chicoric acid's mechanism of inhibition reveals that the inhibitor binds to an exosite, displays noncompetitive partial inhibition, and is synergistic with a competitive active site inhibitor when used in combination. Other components found in Echinacea, I3 and I4, were also inhibitors of the protease.

Synthesis and biological evaluation of caffeic acid 3,4-dihydroxyphenethyl ester

A high-yield synthesis of caffeic acid 3,4-dihydroxyphenethyl ester (1) has been achieved through Knoevenagel condensation of 3,4-dihydroxybenzaldehyde and 3,4-dihydroxyphenethyl monomalonate as the key step. Compound 1 was tested against a 56-cell-line cytotoxicity panel and for its free-radical-scavenging activity in the DPPH test.

Optimized enzymatic synthesis of caffeic acid phenethyl ester by RSM

In this study, optimization of enzymatic synthesis of caffeic acid phenethyl ester (CAPE), catalyzed by immobilized lipase (Novozym 435) from Candida antarctica was investigated. Novozym 435 was used to catalyze caffeic acid and 2-phenylethanol in an isooctane system. Response surface methodology (RSM) and 5-level-4-factor central-composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction temperature (30-70 degrees C), reaction time (24-72 hours), substrate molar ratio of caffeic acid to 2-phenylethanol (1:10-1:90) and enzyme amounts (100-500 PLU) on percentage conversion of CAPE by direct esterification. Reaction temperature and time had significant effects on percent conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were: reaction time 59 hours, reaction temperature 69 degrees C, substrate molar ratio 1:72 and enzyme amount 351 PLU. The molar conversion of predicted values and actual experimental values were 91.86+/-5.35% and 91.65+/-0.66%, respectively.

Total synthesis of phenylpropanoid glycosides, grayanoside A and syringalide B, through a common intermediate

Phenylpropanoid glycosides are known as bioactive natural products. Two of them, grayanoside A (1) and syringalide B (2), were synthesized through a common intermediate, using benzyl as temporary protecting group following a shorter route.

Synthesis of safflomide and its HPLC measurement in mouse plasma after oral administration

Safflomide (N-caffeoyltryptamine) is a compound belonging to a group of phenylpropanoid amides found in plants. In this study, safflomide was chemically synthesized and confirmed by LC-MS, LC-MS/MS and NMR spectroscopic methods, and a high-performance liquid chromatography (HPLC) method was developed for quantifying safflomide in biological samples. The synthesis was simple, and the yield of safflomide was greater than 50%. Using the synthesized safflomide as a standard, HPLC separation was performed on a Nova-Pak C18 column using an isocratic buffer, and the separation was detected using a coulometric electrochemical detector. The detection of safflomide yielded an excellent peak resolution at the retention time of 21 min, and the lower limit of the detection was as little as 100 fmol. Using this HPLC method, the plasma concentrations of safflomide were determined in mouse blood, collected at 5, 10, 15, 20, 25, 30, and 35 min following its oral administrations (1 and 3 mg/30 g body weight). This HPLC method standardized with safflomide is the first reported method able to quantify the compound in standard and plasma samples with good detection limit and consistent reproducibility.

Caffeoylglycolic and caffeoylamino acid derivatives, halfmers of L-chicoric acid, as new HIV-1 integrase inhibitors

Human immunodeficiency virus (HIV) integrase (IN) catalyzes the integration of HIV DNA copy into the host cell DNA. L-Chicoric acid (1) has been found to be one of the most potent HIV-1 integrase inhibitor. Caffeoylglycolic and caffeoylamino acid derivatives' halfmeric structures of L-chicoric acid 2 were synthesized for the purpose of simplifying the structure of L-chicoric acid. Among synthesized, compounds 2c and 3f showed HIV-1 IN inhibitory activities with IC(50) values of 10.5 and 12.0 microM, respectively, comparable to that of parent compound L-chicoric acid (IC(50)=15.7 microM).

N-caffeoylphenalkylamide derivatives as bacterial efflux pump inhibitors

As part of an ongoing project to identify plant natural products as efflux pump inhibitors (EPIs), bioassay-guided fractionation of the methanolic extract of Mirabilis jalapa Linn. (Nyctaginaceae) led to the isolation of an active polyphenolic amide: N-trans-feruloyl 4'-O-methyldopamine. This compound showed moderate activity as an EPI against multidrug-resistant (MDR) Staphylococcus aureus overexpressing the multidrug efflux transporter NorA, causing an 8-fold reduction of norfloxacin MIC at 292 microM (100 microg/mL). This prompted us to synthesize derivatives in order to provide structure-activity relationships and to access more potent inhibitors. Among the synthetic compounds, some were more active than the natural compound and N-trans-3,4-O-dimethylcaffeoyl tryptamine showed potentiation of norfloxacin in MDR S. aureus comparable to that of the standard reserpine.

Synthesis and bioactivity of novel caffeic acid esters from Zuccagnia punctata

Synthesis of novel caffeic acid esters (1 and 2) was accomplished starting from appropriately substituted benzaldehydes (3 and 9). While compound 2 exhibited potent anti-oxidative activity in both the nitroblue tetrazolium and 1,1-diphenyl-2-picrylhydrazyl radical-scavenging models, compound 1 showed moderate 5-lipoxygenase inhibitory activity.

Impact of alkyl esters of caffeic and ferulic acids on tumor cell proliferation, cyclooxygenase enzyme, and lipid peroxidation

The antioxidant ferulic and caffeic acid phenolics are ubiquitous in plants and abundant in fruits and vegetables. We have synthesized a series of ferulic and caffeic acid esters and tested for tumor cell proliferation, cyclooxygenase enzymes (COX-1 and -2) and lipid peroxidation inhibitory activities in vitro. In the tumor cell proliferation assay, some of these esters showed excellent growth inhibition of colon cancer cells. Among the phenolics esters assayed, compounds 10 (C12-caffeate), 11 (C16-caffeate), 21 (C8-ferulate), and 23 (C12-ferulate) showed strong growth inhibition with IC50 values of 16.55, 13.46, 18.67, and 7.57 microg/mL in a breast cancer cell line; 9.65, 7.45, 17.05, and 4.35 microg/ mL in a lung cancer cell line; 5.78, 3.5, 4.29, and 2.46 microg/mL in a colon cancer cell line; 12.04, 12.21, 14.63, and 8.09 microg/ mL in a central nervous system cancer cell line; and 8.62, 7.76, 11.0, and 5.37 in a gastric cancer cell line. In COX enzyme inhibitory assays, ferulic and caffeic acid esters significantly inhibited both COX-1 and COX-2 enzymes. Caffeates 5-10 (C4-C12), inhibited COX-1 enzyme between 50% and 90% and COX-2 enzyme by about 70%, whereas ferulates 15-21 (C3-C8) inhibited COX-1 and COX-2 enzymes by 85-95% 25 microg/mL. Long-chain caffeates 11-14 (C16-C22) and short-chain ferulates 15-20 (C3-C5) were the most active in lipid peroxidation inhibition and showed 60-70% activity at 5 microg/mL concentration.

Cytoprotective effect of caffeic acid phenethyl ester (CAPE) and catechol ring-fluorinated CAPE derivatives against menadione-induced oxidative stress in human endothelial cells

Caffeic acid phenethyl ester (CAPE), a natural polyphenolic compound with many biological activities, has been shown to be protective against ischemia-reperfusion injury. We have synthesized six new catechol ring-fluorinated CAPE derivatives and evaluated their cytotoxic and cytoprotective effects against menadione-induced cytotoxicity in human umbilical vein endothelial cells. These results provide some insights into the structural basis of CAPE cytoprotection in this assay, which does not appear to be based solely on direct antioxidant properties.

Evaluation of Natural and Synthetic Compounds from East Asiatic Folk Medicinal Plants on the Mediation of Cancer

In this review are presented various lead compounds bearing a polyphenolic moiety and their biological targets. The relevance of these targets to develop the desired compounds as potential anti-cancer agents is discussed. For instance, caffeic acid phenethyl ester (CAPE) has preliminary been studied in our group to hold various biochemical responses. When C6 glioma cells were grown as xenografts in nude mice, treatment with CAPE (1-10 mg/kg; ip) induced a significant dose dependent decrease in tumor growth by evaluating tumor volume and tumor weight. Histochemical and immunohistochemical analysis revealed that CAPE treatment significantly reduced the number of mitotic cells and proliferating cell nuclear antigen (PCNA)-positive cells in C6 glioma. Moreover, the ability of flavonoids to scavenge free-radicals and block lipid peroxidation raises the possibility that they may act as protective factors against carcinogenesis. Furthermore, protocatechuic acid (PCA) seems to be a promising compound regarded as a candidate group for cancer preventive agents. We have isolated and investigated Hibiscus protocatechuic acid from Hibiscus sabdariffa L. Hibiscus PCA showed against oxidative damage induced by t-butyl hydroperoxide in rat primary hepatocytes, and inhibitory effect on tumor promotion in mouse skin. Finally, we review here recent progress with the analogs of natural and synthetic lead compounds in Asiatic folk medicine. Since phenolic dimmers or trimers are significantly more potent than monomer in vitro and in vivo, a large number of phenolic dimmers or trimers with linker lengths and their pharmacological properties have been investigated.

Analogues of N-hydroxycinnamoylphenalkylamides as inhibitors of human melanocyte-tyrosinase

Melanin play a major role in human skin protection and their biosynthesis is vital. Due to their color, they contribute to the skin pigmentation. Tyrosinase is a key enzyme involved in the first stage of melanin synthesis, catalyzing the transformation of tyrosine to l-dopaquinone. The aim of the present study was to study molecules able to inhibit melanin synthesis through inhibition of tyrosinase and their potential use in treating pigmentation-related disorders. We targeted amides obtained from coupling p-hydroxycinnamic acid derivatives with phenylalkylamines. The biological activity was evaluated on human melanocytes by an assay which measures tyrosine-catalyzed L-Dopa oxidation. The most active amides were: trans-N-caffeoyltyramine, N-dihydrocaffeoyltyramine, and trans-N-dihydro-p-hydroxycinnamoyltyramine which induce complete inhibition at 0.1mM. At the latter concentration, kojic acid, which was used as the reference inhibitor, was inactive.

Enzymatic production of caffeic acid by koji from plant resources containing caffeoylquinic acid derivatives

The effect of a koji (Aspergillus awamori mut.) extract on the caffeoylquinic acid derivatives purified from sweetpotato (Ipomoea batatas L.) leaves was examined to develop the mass production of caffeic acid. A koji extract hydrolyzed the caffeoylquinic acid derivatives, chlorogenic acid, 3,4-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, 4,5-di-O-caffeoylquinic acid and 3,4,5-tri-O-caffeoylquinic acid, to caffeic acid. Furthermore, the koji extract also converted the major polyphenolic components from sweetpotato, burdock (Arctium lappa L.), and mugwort (Artemisia indica var. maximowiczii) leaves to caffeic acid. These results suggest that the production of caffeic acid from plant resources containing caffeoylquinic acid derivatives is possible.

N-coumaroyldopamine and N-caffeoyldopamine increase cAMP via beta 2-adrenoceptors in myelocytic U937 cells

N-caffeoyldopamine is a phytochemical found in various plants, including cocoa (Theobroma cacao L.). N-caffeoyldopamine and its natural analogs (N-cinnamoyldopamine, N-coumaroyldopamine, N-feruloyldopamine, and N-sinapoyldopamine) were synthesized and investigated to determine their potency as beta-adrenoceptor agonists, because they have chemical structural moieties found in beta-adrenoceptor agonists. Among the compounds tested in this study, N-coumaroyldopamine and N-caffeoyldopamine were the two most potent compounds, able to increase cAMP at the concentrations < 0.05 microM in U937 cells. The decreasing order of potency was N-coumaroyldopamine > N-caffeoyldopamine > N-feruloyldopamine > N-sinapoyldopamine > N-cinnamoyldopamine. Using beta2-specific antagonists (butoxamine and ICI 118551), N-coumaroyldopamine and N-caffeoyldopamine were found to increase cAMP via beta2-adrenoceptors in U937 cells. In producing cAMP in U937 cells, N-coumaroyldopamine and N-caffeoyldopamine were as potent as several well-known beta2-adrenoceptor agonists (salbutamol, procaterol, and fenoterol). These results indicate that N-coumaroyldopamine and N-caffeoyldopamine are potent compounds able to increase cAMP via beta2-adrenoceptors in U937 cells, and may have potential effects on human health.

Peroxidase-catalyzed in situ polymerization of surface orientated caffeic acid

Nanoscale surface patterning and polymerization of caffeic acid on 4-aminothiophenol-functionalized gold surfaces has been demonstrated with dip pen nanolithography (DPN). The diphenolic moiety of caffeic acid can be polymerized by biocatalysis with laccase or horseradish peroxidase. In the present study, the DPN patterned features were polymerized in situ through the use of the peroxidase. Using samples prepared by DPN, microcontact printing, and adsorption on macroscopic substrates, the products were characterized by electrostatic force microscopy (EFM), MALDI-TOF, X-ray photoelectron spectroscopy (XPS), UV-vis, and FT-IR. The in situ surface polymerization resulted in the formation of a quinone structure, while the phenyl ester formed in bulk polymerization reactions was not detected. A different coupling site was observed when comparing the polymers obtained from solution (bulk) vs the surface DPN reactions. The structural differences were attributed to surface-induced pre-organization and orientation of the monomers prior to the enzymatic polymerization step. The results of this study expand the application of DPN technology to surface modification and surface chemistry reactions wherein stereo-regularity and regioselectivity can be exploited.

Anticholesterolemic effect of 3,4-di(OH)-phenylpropionic amides in high-cholesterol fed rats

Two amide synthetic derivatives of 3,4-di(OH)-hydrocinnamate (HC), 3,4-dihydroxyphenylpropionic (l-serine methyl ester) amide (E030) and 3,4-dihydroxyphenylpropionic (l-aspartic acid) amide (E076), were investigated to compare their lipid-lowering efficacy with HC. Male rats were fed a 1 g/100 g high-cholesterol diet for 6 weeks with supplements of either clofibrate (0.02%, w/w), HC (0.025%, w/w), E030 (0.039%, w/w) or E076 (0.041%, w/w). The clofibrate supplement was used as a positive control for the lipid-lowering efficacy. The food intakes and body weight gains were not significantly different among the groups. The plasma and hepatic cholesterol and triglyceride levels were lower in clofibrate, HC, E030, and E076-supplemented groups compared to the control group. The supplementation of HC and its amide derivatives was as effective as clofibrate in increasing the ratio of HDL-cholesterol to total plasma cholesterol and reducing the atherogenic index (AI). The hepatic cholesterol level in the HC and E076 groups was significantly lower than that in the clofibrate group. The hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA reductase) and acyl-CoA:cholesterol acyltransferase (ACAT) activities were significantly lower in the all test groups than in the control group. The excretion of neutral sterol was significantly higher in the HC, E030, and E076-supplemented groups compared to the control group. The plasma AST and ALT activities, indirect indexes of hepatic toxicity, were significantly lower in the HC, E030, and E076-supplemented groups than in the control group. Accordingly, the current results suggest that E030 and E076, two amide synthetic derivatives of HC, are effective in lowering lipid activity.

Synthesis and HIV-1 integrase inhibitory activities of caffeic acid dimers derived from Salvia officinalis

The synthesis of two caffeoyl-coumarin conjugates, derived from sagecoumarin, has been accomplished, starting from ferulic acid, isoferulic acid and sesamol. Both compounds exhibited potent inhibitory activities at micromolar concentrations against HIV-1 integrase in 3'-end processing reaction but were less effective against HIV-1 replication in a single-round infection assay of HeLa-beta-gal-CD4+ cells.

Synthesis of [13C]- and [14C]-labeled phenolic humus and lignin monomers

Natural phenolic monomers are ubiquitous in the environment and are involved in the stabilization of atmospheric carbon and the transformation of xenobiotics. Investigations on the stabilization of phenolic carbons and their environmental fate are hampered by the unavailability of commercial [13C]- and [14C]-labeled phenols. Here we report the complete chemical synthesis of the lignin and humus structural monomers p-coumaric, ferulic, and caffeic acids, p-hydroxybenzaldehyde, protocatechualdehyde, vanillin, catechol, and guaiacol, uniformly [13C]- or [14C]-labeled in the aromatic ring, starting from commercially available [U-ring-13C]- or [U-ring-14C]-labeled phenol. The synthesis of these compounds involved selective ortho-hydroxylation of the aromatic ring, Friedel-Crafts alkylation, and Knoevenagel condensation. [U-ring-13C]- or [U-ring-14C]-p-coumaric acid was synthesized via p-hydroxybenzaldehyde with a 75% yield with respect to phenol. Synthesis of [U-ring-13C]- or [U-ring-14C]-ferulic acid, consisting of six single steps via guaiacol and vanillin, had an overall yield of up to 45%. Uniformly ring-labeled caffeic acid was synthesized either via catechol and protocatechualdehyde in five single steps, yielding [U-ring-14C]-caffeic acid with a 37% yield, or via guaiacol, vanillin, and ferulic acid in seven steps, yielding [U-ring-13C]-caffeic acid with an 18% yield. Ferulic acid, [14C]-labeled at beta-C of the propenoic side chain, was synthesized from [2-14C]-malonic acid under Knoevenagel conditions with a 67% yield with respect to malonic acid. Demethylation of the [beta-14C]-ferulic acid with BBr3 in CH3CN resulted in [beta-14C]-caffeic acid with a 62% yield. All [U-ring-13C]-labeled phenolic products were analyzed by 13C nuclear magnetic resonance (13C-NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS).

Synthesis and biological evaluation of geminal disulfones as HIV-1 integrase inhibitors

Integration of HIV-1 viral DNA into the host genome is carried out by HIV-integrase (IN) and is a critical step in viral replication. Although several classes of compounds have been reported to inhibit IN in enzymatic assays, inhibition is not always correlated with antiviral activity. Moreover, potent antiviral IN inhibitors such as the chicoric acids do not act upon the intended enzymatic target but behave as entry inhibitors instead. The charged nature of the chicoric acids contributes to poor cellular uptake, and these compounds are further plagued by rapid ester hydrolysis in vivo. To address these critical deficiencies, we designed neutral, nonhydrolyzable analogues of the chicoric acids. Herein, we report the synthesis, enzyme inhibition studies, and cellular antiviral data for a series of geminal disulfones. Of the 10 compounds evaluated, 8 showed moderate to high inhibition of IN in purified enzyme assays. The purified enzyme data correlated with antiviral assays for all but two compounds, suggesting alternative modes of inhibition. Time-of-addition studies were performed on these analogues, and the results indicate that they inhibit an early stage in the replication process, perhaps entry. In contrast, the most potent member of the correlative group shows behavior consistent with IN being the cellular target.

Radical scavenging activity of dicaffeoyloxycyclohexanes: Contribution of an intramolecular interaction of two caffeoyl residues

Six regio- and stereoisomers of dicaffeoyloxycyclohexanes and 2,4-di-O-caffeoyl-1,6-anhydro-beta-D-glucose were synthesized as model compounds of dicaffeoylquinic acids, and their radical scavenging activity was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt) radical scavenging tests. Both DPPH and ABTS radical scavenging reactions of these compounds consisted of two different steps. In the first step, catechol moieties of the caffeoyl residues were rapidly converted to o-quinone structures and no significant difference in the reactivity was observed among the tested compounds. In the second step, however, the rate of the reaction increased as the intramolecular distance of the two caffeoyl residues decreased. A novel intramolecular coupling product, which could scavenge additional radicals, was isolated from the reaction mixture of trans-1,2-dicaffeoyloxycyclohexane and DPPH radical. The result suggests that the second step of the radical scavenging reaction is arising from an intramolecular interaction between the two caffeoquinone residues to regenerate catechol structures, and that the closer their distance is, the more rapidly they react. The radical scavenging activity of natural dicaffeoylquinic acids in a biological aqueous system might also depend on the positions of caffeoyl ester groups.

Total synthesis of syringalide B, a phenylpropanoid glycoside

The first total synthesis of syringalide B, 2-(4-hydroxyphenyl)ethyl 4-O-[(E)-feruloyl]-beta-D-glucopyranoside, is described. The hydroxyl groups were protected with allyloxycarbonyl (Aoc) and allyl groups, which successfully prevent the migration of the feruloyl group during the deblocking procedure.

Phenolic acid derivatives with potential anticancer properties--a structure-activity relationship study. Part 1: methyl, propyl and octyl esters of caffeic and gallic acids

The antiproliferative and cytotoxic properties of polyphenolic acid derivatives, structurally related with the natural models caffeic and gallic acids, have been tested in human cervix adenocarcinoma cells (HeLa). Simultaneous structural information was obtained for these compounds through theoretical ab initio methods. This study was conducted for the following esters: methyl caffeate (MC, 1), propyl caffeate (PC, 2), octyl caffeate (OC, 3), methyl gallate (MG, 4), propyl gallate (PG, 5) and octyl gallate (OG, 6). A significant growth-inhibition effect was assessed for some of these compounds, clearly dependent on their structural characteristics. Marked structure-activity relationships (SARs)--namely the number of hydroxyl ring substituents--were found to rule the biological effect of such systems.

Purification and characterization of a chlorogenic acid hydrolase from Aspergillus niger catalysing the hydrolysis of chlorogenic acid

Among 15 Aspergillus strains, Aspergillus niger BRFM 131 was selected for its high chlorogenic acid hydrolase activity. The enzyme was purified and characterized with respect to its physico-chemical and kinetic properties. Four chromatographic steps were necessary to purify the protein to homogeneity with a recovery of 2%. Km of the chlorogenic acid hydrolase was estimated to be 10 microM against chlorogenic acid as substrate. Under native conditions, the protein presented a molecular mass of 170 kDa, and SDS-PAGE analysis suggested the presence of two identical 80 kDa subunits. Isoelectric point was 6.0; pH optimum for activity was determined to be 6.0 and temperature optima to be 55 degrees C. The N-terminal sequence did not present any homology with other cinnamoyl ester hydrolases previously described suggesting the purification of a new protein. The chlorogenic acid hydrolase was used successfully for the production of caffeic acid, which possesses strong antioxidant properties, from natural substrates specially rich in chlorogenic acid like apple marc and coffee pulp.

Design, synthesis, and activity of caffeoyl pyrrolidine derivatives as potential gelatinase inhibitors

The synthesis and biological evaluation of caffonyl pyrrolidine derivatives as MMPs inhibitors are reported in this paper. Inhibiting activities of synthesized compounds on gelatinase (MMP-2 and -9) were tested by using succinylated gelatin as substrate. Structure-activity relationship results from these tested compounds demonstrated that longer and more flexible side chain linked to the pyrrolidine ring at C(4) produced higher activity at gelatinase. Furthermore, aromatic heterocycle and sulfamide in the same position could enhance the activities. Compounds with free phenol hydroxyl group showed higher activity compared to methylated derivatives (or counterparts), which confirms the importance of phenol hydroxyl functionality in the interaction with gelatinase. The anti-metastasis model of mice bearing H(22) tumor cell was used to evaluate their in vivo inhibiting activities. All tested compounds were orally administered at a dose of 50 or 100mg/kg, 6days/week for two weeks. The test results demonstrated that most of these inhibitors showed significant anti-cancer activities (inhibitory rate>35%) and were devoid of toxic effects. Compound 29 showed the highest inhibitory rate at 69.25%, indicating that it might be a promising lead compound.

N-Caffeoyltyramine arrests growth of U937 and Jurkat cells by inhibiting protein tyrosine phosphorylation and inducing caspase-3

N-Cinnamoyltyramine, N-caffeoyltyramine, N-feruloyltyramine, and N-sinapoyltyramine were synthesized and investigated to identify the most potent compound with anti-proliferation effect on HL-60, U937 and Jurkat cells. N-Caffeoyltyramine was the most potent with GI(50)=10 microM. The treatment of the cells with N-caffeoyltyramine activated caspase-3 activity, and inhibited the growth of cells via decreasing in protein tyrosine kinase activity including epidermal growth factor receptor. These data indicate that N-caffeoyltyramine is most potent compound, inducing cell death of the cancer cells by inhibiting protein tyrosine kinases and activating caspase-3 activity.

Anticancer activity of phenolic acids of natural or synthetic origin: a structure-activity study

Several phenolic acids-caffeic and gallic acid derivatives-were synthesized and screened for their potential antiproliferative and cytotoxic properties, in different human cancer cell lines: mammary gland and cervix adenocarcinomas and lymphoblastic leukemia. The selected phenols were structurally related, which allowed us to gather important information regarding the structure-activity relationships underlying the biological activity of such compounds. This is proposed to be due to a balance between the antioxidant and pro-oxidant properties of this kind of agent. Distinct effects were found for different cell lines, which points to a significant specificity of action of the drugs tested. It was verified, for the types of cancer investigated, that the trihydroxylated derivatives yielded better results than the dihydroxylated ones. Tests in noncancerous cells, human lung fibroblasts, were also undertaken, in view of determining the toxic side effects of the compounds studied.