Neuroprotective effects of sonochemical- synthesized SiO2 nanoparticles in vivo models of ischemic/reperfusion injury in stroke

Cerebral ischemic injury is one of the debilitating diseases that showed inflammation plays an essential role in aggravating ischemic damage. After synthesizing silica nanoparticles (SiO₂ NPs) by sonochemical method, serum parameters in the presence of different concentrations of SiO₂ NPs are measured for toxicity assay. Rats were separated randomly into control, ischemia/reperfusion, and ischemia/reperfusion + SiO₂ NPs groups. Transient forebrain ischemia induced with bilateral occlusion of both common carotid arteries followed by 60minuts of reperfusion. SiO₂ NPs were administered (500 mg/kg/day p.o.) 21 days before ischemia/reperfusion time. Animals sacrificed and frontal cortex and hippocampal tissues used to determine malondialdehyde (MDA) level, nitric oxide (NO), glutathione (GSH) levels, an essential antioxidant, superoxide dismutase (SOD), alterations in the level of cytokines, TNFα, IL-1β, MCP-1, and phosphor Ik-кB. We also revealed the involvement of NF-κB downregulation by using western blotting. We reported on a histological investigation. The results showed that SiO₂ NPs with a diameter of around 50 nm in dose of 500 mg/kg didn't change the level of liver enzyme (including ALT, AST and ALP) and hematological parameters. 500 mg/kg SiO₂ NPs showed significant effects on remission of behavioral impairment. Ischemia/reperfusion oxidative injury in the rat hippocampus demonstrated a significant increase in MDA, TNFα, MCP-1, IL-1β, phosphor Ik-кB, NO levels, and a significant decrease in GSH contents and SOD activities in the hippocampal tissue compared to the control group. Pretreatment of ischemic rats with SiO₂ NPs decreased the elevated levels of MDA, TNFα, MCP-1, IL-1β, phosphor Ik-кB, and NO levels. A significant alteration observed in SOD activities and GSH content results between treated and untreated ischemia/reperfusion brains in rats. Decreased protein level of NF-κB also measured in SiO₂ NPs-treated animals. Untreated ischemia/reperfusion brains had significantly decreased in number of cells in CA1 hippocampus, nevertheless SiO₂ NPs increase the normal cell and decrease the neurodegeneration in hippocampus but it was not significant alteration. SiO₂ NPs reduced the damage caused by cerebral ischemia/reperfusion in rats and its molecular mechanism attributed to the downregulation of NF-κB signaling pathway.     

Dual-bioactivity-based liquid chromatography-coupled quadrupole time-of-flight mass spectrometry for NF-κB inhibitors and β2AR agonists identification in Chinese Medicinal Preparation Qingfei Xiaoyan Wan

Traditional Chinese medicine (TCM) preparations have been used as an effective multitarget strategy for the treatment of complex diseases; however, their bioactive constituents are undefined and difficult to identify. In this study, a simple and dual-target method based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry combined with dual-bioactive (NF-κB and β₂-adrenergic receptor) luciferase reporter assay systems was developed for the rapid determination of various bioactive compounds of TCM preparations. Qingfei Xiaoyan Wan, a TCM preparation used for the clinical therapy of asthma, was analyzed with this method. Potential anti-inflammatory and spasmolytic constituents were screened using NF-κB and β₂-adrenergic receptor activity luciferase reporter assay systems and simultaneously identified according to the time-of-flight mass spectrometry data. One β₂-adrenergic receptor agonist (ephedrine) and four structural types of NF-κB inhibitors (arctigenin derivatives, cholic acid derivatives, chlorogenic acid, and sinapic acid) were characterized. Tracheloside was considered a new NF-κB inhibitor. Further cytokine and chemokine detection confirmed the anti-inflammatory effects of the potential NF-κB inhibitors. The integration of ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and dual-bioactive human cell functional evaluation systems proved to be a simple and effective strategy for the rapid screening of various bioactive compounds in TCM preparations used to treat complex diseases.     

Identification of caffeic acid derivatives in Actea racemosa (Cimicifuga racemosa,black cohosh) by liquid chromatography/tandem mass spectrometry

Caffeic acid derivatives occurring in black cohosh [Cimicifuga racemosa (L.) Nutt., Actaea racemosa (Ranunculaceae)], some of which may have pharmacological activity, were analyzed using high-performance liquid chromatography (HPLC) electrospray ionization tandem mass spectrometry (ESI-MS/MS) with the aim of developing a methodology for their rapid identification in a complex plant matrix. Based on these studies, structurally characteristic product ions and neutral molecule losses were identified, which were then used during LC/MS/MS with product ion scanning, precursor scanning and constant neutral loss scanning to detect caffeic acid derivatives in a crude extract of black cohosh. Several caffeic acid derivatives were detected, and the identification of six of them were confirmed by comparison with authentic standards including caffeic acid, ferulic acid, isoferulic acid, fukinolic acid, cimicifugic acid A, and cimicifugic acid B. Four other compounds were detected that appeared to be caffeic acid derivatives based on LC/MS/MS retention times, molecular weights, and fragmentation patterns during MS/MS. Since standards were unavailable for these four compounds, they were tentatively identified using LC/MS/MS as cimicifugic acid E, cimicifugic acid F, dehydrocimicifugic acid A, and dehydrocimicifugic acid B. Dehydrocimicifugic acid A and dehydrocimicifugic acid B have not been reported previously to be constituents of black cohosh.     

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid suppresses UV-induced IL-6 synthesis in keratinocytes, exerting an anti-inflammatory activity

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid (12- HHT) is an enzymatic product of prostaglandin H(2) (PGH(2)) derived from cyclooxygenase (COX)-mediated arachidonic acid metabolism. Despite the high level of 12-HHT present in tissues and bodily fluids, its precise function remains largely unknown. In this study, we found that 12-HHT treatment in HaCaT cells remarkably down-regulated the ultraviolet B (UVB) irradiation-induced synthesis of interleukin-6 (IL-6), a pro-inflammatory cytokine associated with cutaneous inflammation. In an approach to identify the down-stream signaling mechanism by which 12-HHT down-regulates UVB-induced IL-6 synthesis in keratinocytes, we observed that 12-HHT inhibits the UVB-stimulated activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB). In addition, we found that 12-HHT markedly up-regulates MAPK phosphatase-1 (MKP-1), a critical negative regulator of p38 MAPK. When MKP-1 was suppressed by siRNA knock-down, the 12-HHT-mediated inhibitory effects on the UVB-stimulated activation of p38 MAPK and NF-κB, as well as the production of IL-6, were attenuated in HaCaT cells. Taken together, our results suggest that 12-HHT exerts anti-inflammatory effect via up-regulation of MKP-1, which negatively regulates p38 MAPK and NF-κB, thus attenuating IL-6 production in UVB-irradiated HaCaT cells. Considering the critical role of IL-6 in cutaneous inflammation, our findings provide the basis for the application of 12-HHT as a potential anti-inflammatory therapeutic agent in UV-induced skin diseases.     

Co-delivery of Andrographolide and Notch1-targeted siRNA to Macrophages with Polymer-based Nanocarrier for Enhanced Anti-inflammation

Chronic inflammatory responses induced by macrophages play a pivotal role in the progression of atherosclerosis.In the present study,a multifunctional nanocarrier based on poly(ethylene glycol)-block-poly(L-aspartic acid)grafted with diethylenetriamine,lysine and cholic acid(PEG-PAsp(DETA)-Lys-CA2)polymer was synthesized for co-delivery of andrographolide and siRNA targeting Notch1 gene to alleviate the inflammatory response in macrophages.The nanocarrier exerted low cytotoxicity as well as high performance in drug/siRNA co-delivery.In vitro studies demonstrated the co-delivery of andrographolide and Notch1 siRNA not only significantly inhibited lipopolysaccharide(LPS)-activated interleukin-6(IL-6)and monocytes chemotactic protein 1(MCP-1)expression as well as blocked nuclear factor-κB(NF-κB)signal activation,but also interfered the Notch1 gene expression and increased anti-inflammatory cytokines such as interleukin-10(IL-10)and arginase-1 expression obviously in macrophages.These results suggested that the combination therapy based on Notch1 siRNA and andrographolide co-delivered nanocarrier,i.e.suppressing the expression of proinflammatory cytokines while simultaneously increasing anti-inflammatory factors expression,be a feasible strategy for atherosclerosis treatment.     

Analysis of caffeic acid derivatives in echinacea extracts by liquid chromatography particle beam mass spectrometry (LC–PB/MS) employing electron impact and glow discharge ionization sources

A liquid chromatography–particle beam/mass spectrometry (LC–PB/MS) method with electron impact (EI) and glow discharge (GD) ionization sources is presented for the determination of caffeic acid derivatives in echinacea tinctures. In this work, two commercially available echinacea ethanolic extracts were used as the test samples for the separation, identification, and quantification of the caffeic acid derivatives (caffeic acid, chlorogenic acid, cichoric acid, and caftaric acid), which are suggested to have beneficial medicinal properties. Detailed evaluations of the two primary controlling parameters for EI (electron energy and source block temperature) and GD (discharge current and pressure) sources were performed to determine optimal instrument operation conditions. The mass spectra obtained from both ion sources provide clear and simple molecular fragmentation patterns for each of the target analytes. The absolute detection limits for the caffeic acid derivatives were determined to be at subnanogram levels for both the EI and GD sources. The separation of the caffeic acid derivatives in echinacea was accomplished by reversed-phase chromatography using a C₁₈ column and a gradient elution system of water containing 0.1% trifluoroacetic acid and methanol, with an analysis time of less than 40 min. A standard addition method was employed for the quantification of each of the caffeic acid derivatives in the tincture.     

A new synthetic chalcone derivative, 2-hydroxy-3',5,5'-trimethoxychalcone (DK-139), suppresses the Toll-like receptor 4-mediated inflammatory response through inhibition of the Akt/NF-κB pathway in BV2 microglial cells

Microglial cells are the resident innate immune cells that sense pathogens and tissue injury in the central nervous system (CNS). Microglial activation is critical for neuroinflammatory responses. The synthetic compound 2-hydroxy-3',5,5'-trimethoxychalcone (DK-139) is a novel chalcone-derived compound. In this study, we investigated the effects of DK-139 on Toll-like receptor 4 (TLR4)-mediated inflammatory responses in BV2 microglial cells. DK-139 inhibited lipopolysaccharide (LPS)-induced TLR4 activity, as determined using a cell-based assay. DK-139 blocked LPS-induced phosphorylation of IκB and p65/RelA NF-κB, resulting in inhibition of the nuclear translocation and trans-acting activity of NF-κB in BV2 microglial cells. We also found that DK-139 reduced the expression of NF-κB target genes, such as those for COX-2, iNOS, and IL-1β, in LPS-stimulated BV2 microglial cells. Interestingly, DK-139 blocked LPS-induced Akt phosphorylation. Inhibition of Akt abrogated LPS-induced phosphorylation of p65/RelA, while overexpression of dominant- active p110CAAX enhanced p65/RelA phosphorylation as well as iNOS and COX2 expression. These results suggest that DK-139 exerts an anti-inflammatory effect on microglial cells by inhibiting the Akt/IκB kinase (IKK)/NF-κB signaling pathway.     

Integrating approach to discover novel bergenin derivatives and phenolics with antioxidant and anti-inflammatory activities from bio-active fraction of Syzygium brachythyrsum

Syzygium brachythyrsum is an important folk medicinal and edible plant in Yunnan ethnic minority community of China, however, little is known about the chemical and bio-active properties. The present study is aimed to identify the bioactive constituents with antioxidant and anti-inflammatory properties by an integrating approach. First, two new bergenin derivatives, brachythol A (1) and brachythol B (2), together with eleven known phenolic compounds (3–13) were isolated from bioactive fractions by phytochemical method. Among these isolated chemicals, five bergenin derivatives, along with 3 phenolics were found in Syzygium genus for the first time. Then, a further chemical investigation based on ultra-high-performance liquid chromatography-Q Exactive Orbitrap mass spectrometry resulted in a total of 107 compounds characterized in the bio-active fractions, including 50 bergenin derivatives, among which 14 bergenin derivatives and 14 phenolics were potential new natural chemicals. Most of the isolated compounds showed obvious antioxidant activities, while compounds 11, 12, and 13 had favorable performance. Eight compounds (2–5, 7, and 9–11) showed good inhibitory activity on nitric oxide (NO) production in macrophage RAW 264.7 cells. The structure–activity correlation analysis indicated that the antioxidation and anti-inflammatory activities enhanced when bergenin was esterified with gallic acid, caffeic acid or ferulic acid. This is the first report of bergenins in Syzygium genus and the richness in new bio-active bergenins and gallic acid derivatives indicated that Syzygium brachythyrsum is a promising functional and medicinal resource.     

A comparative study of the radical-scavenging activity of the phenolcarboxylic acids caffeic acid, p-coumaric acid, chlorogenic acid and ferulic acid, with or without 2-mercaptoethanol, a thiol, using the induction period method

Phenolcarboxylic acid antioxidants do not act in vivo as radical-scavengers in isolation, but rather together with GSH (glutathione), a coantioxidant, they constitute an intricate antioxidant network. Caffeic acid, p-coumaric acid, ferulic acid and chlorogenic acid with or without 2-mercaptoethanol (ME), as a substitute for GSH, was investigated by the induction period (IP) method for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN, a source of alkyl radicals, R(.)) and benzoyl peroxide (BPO, a source of peroxy radicals, PhCOO(.)) using differential scanning calorimetry (DSC). Upon PhCOO(. )radical scavenging, the stoichiometric factors (n, number of free radical trapped by one mole of antioxidant) for caffeic acid, ferulic acid, p-coumaric acid and chlorogenic acid were 2.4, 1.8, 1.7 and 0.9, whereas upon R(.) radical scavenging, the corresponding values were 1.3, 1.2, 1.0 and 0.8, respectively. Antioxidants with n values close to 2 suggest the stepwise formation of semiquinone radicals and quinones. By contrast, those with n values close to 1 suggest the formation of dimers after single-electron oxidation, possibly due to recombination of corresponding aryloxy radicals. The ratio of the rate constant of inhibition to that of propagation (k(inh)/k(p)) declined in the order chlorogenic acid > p-coumaric acid > ferulic acid > caffeic acid. The ratio of the observed IP for the phenolcarboxylic acid/2-mercapto-ethanol (ME) mixture (1:1 molar ratio) (A) to the calculated IP (the simple sum of phenol acid antioxidant and ME) (B) was investigated. Upon R(.) scavenging, the caffeic acid or p-coumaric acid/ME mixture was A/B > 1, particularly the former was 1.2, suggesting a synergic effect. By contrast, upon PhCOO(.) scavenging, the corresponding mixture was A/B < 1, particularly the latter was 0.7, suggesting an antagonistic effect. Upon both radicals scavenging, the A/B for the ferulic acid or chlorogenic acid/ME mixture was approximately 1. The reported beneficial antioxidant, anti-inflammatory and anticancer effects of caffeic acid and p-coumaric acid may be related to their prooxidant-antioxidant balance in the presence of GSH.     

Inhibitory effect of Astragalus polysaccharides on lipopolysaccharide-induced TNF-a and IL-1β production in THP-1 cells

Astragalus polysaccharides (APS), one of main bioactive components in Astragalus membranaceus Bunge, has been reported to possess anti-inflammatory activities, but the molecular mechanisms behind this activity are largely unknown. This study aimed to investigate expression of inflammatory cytokines and the MAPK/NF-κB pathway in human THP-1 macrophages induced by lipopolysaccharide (LPS). The results showed that the concentrations of TNF-a and IL-1β released from LPS stimulated THP-1 cells increased significantly compared to control (p < 0.01). After treatment with APS, the TNF-a and IL-1β levels were significantly lower than those in the LPS group (p < 0.05). The mRNA expression of TNF-a and IL-1β were also inhibited. Mechanistic studies indicated that APS strongly suppressed NF-κB activation and down-regulated the phosphorylation of ERK and JNK, which are important signaling pathways involved in the production of TNF-a and IL-1β, demonstrating that APS could suppress the production of TNF-a and IL-1β by LPS stimulated macrophages by inhibiting NF-κB activation and ERK and JNK phosphorylation.     

Effects of lipoic acid, caffeic acid and a synthesized lipoyl-caffeic conjugate on human hepatoma cell lines

Hepatocellular carcinoma (HCC) is among the most aggressive and fatal cancers. Its treatment with conventional chemotherapeutic agents is inefficient, due to several side effects linked to impaired organ function typical of liver diseases. Consequently, there exists a decisive requirement to explore possible alternative chemopreventive and therapeutic strategies. The use of dietary antioxidants and micronutrients has been proposed for HCC successful management. The aim of this work was to test in vitro the effects of lipoic acid, caffeic acid and a new synthesized lipoyl-caffeic conjugate on human hepatoma cell lines in order to assess their effect on tumor cell growth. The results of cytotoxicity assays at different times showed that the cell viability was directly proportional to the molecule concentrations and incubation times. Moreover, to evaluate the pro- or anti-inflammatory effects of these molecules, the cytokine concentrations were evaluated in treated and untreated cellular supernatants. The obtained cytokine pattern showed that, at the increasing of three molecules concentrations, three pro-inflammatory cytokines such as IL-1β, IL-8 and TNF-α decreased whereas the anti-inflammatory cytokine such as IL-10 increased.     

Bioactivity‐based ultra‐performance liquid chromatography‐coupled quadrupole time‐of‐flight mass spectrometry for NF‐κB inhibitors identification in Chinese Medicinal Preparation Bufei Granule

Traditional Chinese medicine (TCM) preparations have become effective treatments for many diseases. However, their active ingredients are still uncertain and difficult to identify. In this study, we propose a strategy that integrates ultra‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry (UPLC/Q‐TOF‐MS) and bioactive (NF‐κB inhibitor) luciferase reporter assay systems for the rapid determination of various anti‐inflammatory compounds of TCM preparations. In this way, Bufei Granule (BFG), a TCM preparation used for the clinical therapy of asthma, was analyzed by the two ways of component identification and activity detection. Potential anti‐inflammatory constituents were screened by NF‐κB activity assay systems and simultaneously identified according to the mass spectrometry data. Three structural types of NF‐κB inhibitors (caffeic acid derivatives, flavonoids and Pentacyclic triterpenes) were characterized. Further cytokine detection confirmed the anti‐inflammatory effects of the potential NF‐κB inhibitors. Compared with conventional chromatographic separation and inhibitory activity detection, integrating UPLC/Q‐TOF‐MS identification and virtual validation was more convenient and more reliable. This strategy clearly demonstrates that MS data‐based fingerprinting is a meaningful tool not only in identifying constituents in complex matrix but also in directly screening for powerful trace ingredients in TCM preparations. Copyright © 2016 John Wiley & Sons, Ltd.     

Semisynthetic Abietic and Dehydroabietic Acid Derivatives and Triptoquinone Epimers Interfere with LPS-Triggered Activation of Dendritic Cells

Abietic acid (AA), dehydroabietic acid (DHA) and triptoquinones (TQs) are bioactive abietane-type diterpenoids, which are present in many edible vegetables and medicinal herbs with health-promoting properties. Evidence suggests that beneficial effects of diterpenes operate, at least in part, through effects on cells in the immune system. Dendritic cells (DCs) are a key type of leukocyte involved in the initiation and regulation of the immune/inflammatory response and natural or synthetic compounds that modulate DC functions could be potential anti-inflammatory/immunomodulatory agents. Herein, we report the screening of 23 known semisynthetic AA and DHA derivatives, and TQs, synthesized previously by us, in a multi-analyte DC-based assay that detects inhibition of pro-inflammatory cytokine production. Based on the magnitude of the inhibitory effect observed and the number of cytokines inhibited, a variety of activities among compounds were observed, ranging from inactive/weak to very potent inhibitors. Structurally, either alcohol or methyl ester substituents on ring A along with the introduction of aromaticity and oxidation in ring C in the abietane skeleton were found in compounds with higher inhibitory properties. Two DHA derivatives and two TQs exhibited a significant inhibition in all pro-inflammatory cytokines tested and were further investigated. The results confirmed their ability to inhibit, dose dependently, LPS-stimulated expression of the co-stimulatory molecules CD40 and/or CD86 and the production of the pro-inflammatory cytokines IL-1β, IL-6, IL-12 and TNFα. Our results demonstrate that DC maturation process can be targeted by semisynthetic DHA derivatives and TQ epimers and indicate the potential of these compounds as optimizable anti-inflammatory/immunomodulatory agents.     

Simultaneous analysis of caffeic acid derivatives and alkamides in roots and extracts of Echinacea purpurea by high-performance liquid chromatography-photodiode array detection-electrospray mass spectrometry

High-performance liquid chromatography (HPLC) coupled with UV photodiode-array detection and electrospray ionization mass spectrometry was developed for the simultaneous analysis of caffeic acid derivatives and alkamides in the roots and extracts of Echinacea purpurea. Caffeic acid derivatives and alkamides produced very abundant peaks in the total ion current chromatogram during negative and positive cone voltage switching. Cichoric acid and the isomer pair, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, were used as a standard for quantification of caffeic acid derivatives and alkamides in E. purpurea. This novel method surpasses previously published ones in product quality control and providing the HPLC chromatographic fingerprints of biological active components in E. purpurea.     

Hepatoprotective effect of chiisanoside against acetaminophen-induced acute liver injury in mice

This study was designed to investigate the hepatoprotective effect of chiisanoside (CSS) and its possible mechanisms on acetaminophen (APAP)-induced acute liver damage in mice. The serum activities of alanine transaminase (ALT), aspartate transaminase (AST), tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and the hepatic levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) were determined using the commercially available assay kits. The hepatic mRNA levels were measured by RT-PCR. The hepatic protein expressions of nuclear factor-kappa B (NF-κB), MAPK and their phosphorylated isoforms were evaluated by western blot assays. The results indicated that CSS (240 mg/kg) exhibited the hepatoprotective effects by inhibiting oxidative stress and inflammation on APAP-induced acute liver injury. Furthermore, the anti-inflammatory activity of CSS is largely related to the regulation of the NF-κB and MAPKs signaling pathways. These findings suggested that CSS possessed hepatoprotective effect against APAP-induced hepatotoxicity in mice.     

In-capillary screening and quantifying the antioxidants of Yangxinshi Tablet using field-enhanced sample injection-micellar electrokinetic chromatography

An in-capillary 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) as oxyradicals combining field-enhanced sample injection with micellar electrokinetic chromatography was developed for screening and determination of the major antioxidants in Yangxinshi Tablet. To obtain simultaneous separation and detection of radicals and analytes, relevant factors were optimized separately. Under the optimum conditions, four compounds including salvianolic acid B, hyperoside, puerarin, and caffeic acid were identified as the major antioxidants. All validation results covering recovery, precision, and stability demonstrated good applicability of the method. On this basis, the total antioxidant activity was successfully evaluated in terms of the decreased peak area of radicals. There was a correlation coefficient of 0.8974 between the total contents of major antioxidants and the total antioxidative activity of the sample. Therefore, these four compounds were selected as combinatorial markers for the quality evaluation of Yangxinshi Tablet. It was concluded that the established method presented a powerful potential to screen and quantify active ingredients in the complex preparation of Chinese medicine.     

Theoretical Elucidation of the Radical‐Scavenging‐Activity Difference of Hydroxycinnamic Acid Derivatives

To elucidate the nitrogen dioxide radical‐scavenging‐activity difference of three hydroxycinnamic acid derivatives (HCAs), i.e., caffeic acid (=3‐(3,4‐dihydroxyphenyl)prop‐2‐enoic acid; 1 ), ferulic acid (=3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoic acid; 2 ), and sinapic acid (=3‐(4‐hydroxy‐3,5‐dimethoxyphenyl)prop‐2‐enoic acid; 3 ), a combined density‐functional‐theory (DFT) method, labeled as B3LYP/6‐31G(d)//AM1, was employed to calculate adiabatic ionization potentials (IPs) for parent molecules and anions derived by proton dissociation. It was found that not the IPs of the parent HCAs but those of the anions account well for the experimentally observed higher activity of caffeic acid as compared to those of the other two HCAs, suggesting that the antioxidant anion should be taken into consideration in the selection or rational design of novel antioxidants; this, however, was neglected in previous studies.     

Characterization of caffeic acid enzymatic oxidation by-products by liquid chromatography coupled to electrospray ionization tandem mass spectrometry

The products of tyrosinase-catalyzed caffeic acid oxidation at pH 6.5 were investigated using high-performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometry (ESI-MS). Aliquots of reaction mixtures were withdrawn at different times, varying from 0 to 24 h, and directly analysed by HPLC-ESI-MS and, in the case of 1 and 5 h, by HPLC-ESI-MS/MS to obtain structural information on caffeic acid derivatives. In particular, two different classes of caffeic acid dimers were identified: caffeicins-like structures and dimers originated by CC coupling between the benzene rings. Evidences for the presence of trimeric derivatives of caffeic acid were also obtained from MS data.     

Natural product propolis: chemical composition

The chemical composition of propolis from East Mediterranean (Hatay, Adana and Mersin) was studied in order to determine the major compounds by using GC-MS. In this study, the ethanolic extract of propolis prepared by mixing 1900mL 70% ethanol and 100g propolis was used. Chemical analysis of propolis extracts indicated that the propolis samples had high concentrations of the aromatic acids, esters and other derivatives which are responsible for the anti-bacterial, anti-fungal, anti-viral, anti-inflammatory and anti-cancer properties of propolis such as benzyl cinnamate, methyl cinnamate, caffeic acid, cinnamyl cinnamate and cinnamoylglcine besides the most common compounds as fatty acid, terpenoids, esters, alcohols hydrocarbons and aromatic acids.