Matrix-Specific Effects on Caffeine and Chlorogenic Acid Complexation in a Novel Extract of Whole Coffea arabica Coffee Cherry by NMR Spectroscopy.

Coffee cherry is a rich source of caffeine and chlorogenic acids. In this study we investigate the structural analysis of caffeine-enriched whole coffee cherry extracts, CEWCCE by using 1H and 13C NMR spectroscopy. The changes in 1H chemical shift data in NMR spectra of CEWCCE compared to pure caffeine indicated the formation of complexes between caffeine and chlorogenic acids in aqueous solution. The effect of complexation on the peak position of caffeoylquinic acid and caffeine resonance with increasing addition of caffeine was investigated. 2D NOESY experiments show the presence of cross-peaks that are due to the proximity of chlorogenic acid and caffeine molecules in stable complexes in protic solvents. The quantification data of caffeine by 1H qNMR was found to be in close agreement with the data obtained by HPLC analysis.

Quantification of Major Bioactive Constituents, Antioxidant Activity, and Enzyme Inhibitory Effects of Whole Coffee Cherries (Coffea arabica) and Their Extracts.

Coffee cherry is a rich source of chlorogenic acids (CGAs) and caffeine. In this study we examined the potential antioxidant activity and enzyme inhibitory effects of whole coffee cherries (WCC) and their two extracts on α-amylase, α-glucosidase and acetylcholinesterase (AChE) activities, which are targets for the control of diabetes and Alzheimer's diseases. Whole coffee cherry extract 40% (WCCE1) is rich in chlorogenic acid compounds, consisting of a minimum of 40% major isomers, namely 3-caffeoylquinic acids, 4-caffeoylquinic acids, 5-caffeoylquinic acids, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, 4-feruloylquinc acid, and 5-feruloylquinc acid. Whole coffee cherry extract 70% (WCCE2) is rich in caffeine, with a minimum of 70%. WCCE1 inhibited the activities of digestive enzymes α-amylase and α-glucosidase, and WCCE2 inhibited acetylcholinesterase activities with their IC50 values of 1.74, 2.42, and 0.09 mg/mL, respectively. Multiple antioxidant assays-including DPPH, ABTS, FRAP, ORAC, HORAC, NORAC, and SORAC-demonstrated that WCCE1 has strong antioxidant activity.

Capsaicinoids, Polyphenols and Antioxidant Activities of Capsicum annuum: Comparative Study of the Effect of Ripening Stage and Cooking Methods.

Peppers (Capsicum annuum L.) are an important crop usually consumed as food or spices. Peppers contain a wide range of phytochemicals, such as capsaicinoids, phenolics, ascorbic acid, and carotenoids. Capsaicinoids impart the characteristic pungent taste. The study analyzed capsaicinoids and other bioactive compounds in different pepper cultivars at both the mature green and red stages. The effect of roasting on their nutritional content was also investigated. In the cultivars tested, the levels of capsaicin ranged from 0 to 3636 µg/g in the mature green stage and from 0 to 4820 µg/g in the red/yellow stage. The concentration of dihydrocapsaicin ranged from 0 to 2148 µg/g in the mature green stage and from 0 to 2162 µg/g in the red/yellow stage. The levels of capsaicinoid compounds in mature green and red /yellow stages were either reduced or increased after roasting depending on the cultivar. The ranges of total phenolic and total flavonoids compounds were 2096 to 7689, and 204 to 962 µg/g, respectively, in the green and red/yellow mature stage pods. Ascorbic acid levels in the peppers ranged from 223 to 1025 mg/ 100 g Dry Weight (DW). Both raw and roasted peppers possessed strong antioxidant activity as determined by 2,2-diphenyl-1-picrylhydrazyl) reagent (DPPH, 61-87%) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS, 73-159 µg/g) assays. Ascorbic acid and antioxidant activity decreased after roasting in the mature green and red stages, whereas total phenolics and flavonoids increased except in the mature green stage of Sweet Delilah and yellow stage of Canrio.

Inhibition of α-glucosidase, α-amylase, and aldose reductase by potato polyphenolic compounds.

Diabetes mellitus is a chronic disease that is becoming a serious global health problem. Diabetes has been considered to be one of the major risks of cataract and retinopathy. Synthetic and natural product inhibitors of carbohydrate degrading enzymes are able to reduce type 2 diabetes and its complications. For a long time, potatoes have been portrayed as unhealthy for diabetic patients by some nutritionist due to their high starch content. However, purple and red potato cultivars have received considerable attention from consumers because they have high levels of polyphenolic compounds that have potent antioxidant activities. In this study, we screened the total phenolics (TP) and total anthocyanins (TA) and analyzed the phenolic and anthocyanin compounds in selected potato cultivars and advanced selections with distinct flesh colors (purple, red, yellow and white). Purple and red potato cultivars had higher levels of TP and TA than tubers with other flesh colors. Chlorogenic acid is the predominant phenolic acid, and major anthocyanin is composed of the derivatives of petunidin, peonidin, malvidin and pelargonidin. We tested the potential inhibitory effect of potato extracts on the activities of α-amylase and α-glucosidase, which were targeted to develop antidiabetic therapeutic agents. We also measured inhibitory effect of potato extracts on aldose reductase (AR) which is a key enzyme that has been a major drug target for the development of therapies to treat diabetic complications. Purple flesh tubers extract showed the most effective inhibition of α-amylase, α-glucosidase, and aldose reductase with IC50 values 25, 42, and 32 µg/ml, respectively. Kinetic studies showed that anthocyanins are noncompetitive inhibitors of these enzymes, whereas phenolic acids behaved as mixed inhibitors for α-amylase and α-glucosidase and noncompetitive inhibitors for AR. This study supports the development of a positive and healthful image of potatoes, which is an important issue for consumers.

Reduction of acrylamide formation by vanadium salt in potato French fries and chips.

The effects of vanadyl sulphate on the formation of acrylamide have been studied in fried potato products, such as French fries and chips. Acrylamide formation was inhibited by 30.3%, 53.3% and 89.3% when the sliced potato strips were soaked in 0.001, 0.01 and 0.1 M vanadyl sulphate (VOSO(4)) solutions, respectively, for 60 min before frying. Moreover, 57.7%, 71.4% and 92.5% inhibition of acrylamide formation was observed when chips were soaked in the respective vanadyl sulphate solution before frying. In a separate model reaction, a solution containing an equimolar concentration of L-asparagine and D-glucose showed a significant inhibition of acrylamide formation when heated at 150 °C for 30 min in the presence of vanadyl sulphate (VOSO(4)). The results indicate that the binding of VO(2+) to asparagine and the decrease in the pH of the potato samples resulted in a significant reduction of acrylamide formation in fried potato products.

Polymer-anchored peroxo compounds of vanadium(V) and molybdenum(VI): synthesis, stability, and their activities with alkaline phosphatase and catalase.

We generated a series of new polymer-bound peroxo complexes of vanadium(V) and molybdenum(VI) of the type [VO(O(2))(2)(sulfonate)]-PSS [PSS = poly(sodium 4-styrene sulfonate)] (PV(3)), [V(2)O(2)(O(2))(4)(carboxylate)VO(O(2))(2)(sulfonate)]-PSSM [PSSM = poly(sodium styrene sulfonate-co-maleate)] (PV(4)), [Mo(2)O(2)(O(2))(4)(carboxylate)]-PA [PA = poly(sodium acrylate)] (PMo(1)), [MoO(O(2))(2)(carboxylate)]-PMA [PMA = poly(sodium methacrylate)] (PMo(2)), and [MoO(O(2))(2)(amide)]-PAm [PAm = poly(acrylamide)] (PMo(3)) by reacting V(2)O(5) (for PV(3) and PV(4)) or H(2)MoO(4) (for PMo(1), PMo(2), and PMo(3)) with H(2)O(2) and the respective water-soluble macromolecular ligand at pH 5-6. The compounds were characterized by elemental analysis (CHN and energy-dispersive X-ray spectroscopy), spectral studies (UV-vis, IR, (13)C NMR, (51)V NMR, and (95) Mo NMR), thermal (TGA) as well as scanning electron micrographs (SEM), and EDX analysis. It has been demonstrated that compounds retain their structural integrity in solutions of a wide range of pH values and are approximately 100 times weaker as substrate to the enzyme catalase relative to H(2)O(2), its natural substrate. The effect of the title compounds, along with previously reported compounds [V(2)O(2)(O(2))(4)(carboxylate)]-PA (PV(1)) and [VO(O(2))(2)(carboxylate)]-PMA (PV(2)) on rabbit intestine alkaline phosphatase (ALP) has been investigated and compared with the effect induced by the free diperoxometallates viz. Na[VO(O(2))(2)(H(2)O)] (DPV), [MoO(O(2))(2)(glycine)(H(2)O)] (DMo(1)), and [MoO(O(2))(2)(asparagine)(H(2)O)] (DMo(2)). It has been observed that although all the compounds tested are potent inhibitors of the enzyme, the polymer-bound and neat complexes act via distinct mechanisms. Each of the macromolecular compounds is a classical noncompetitive inhibitor of ALP. In contrast, the action of neat pV and heteroligand pMo compounds on the enzyme function is consistent with a mixed type of inhibition.

Vasomodulatory effect of novel peroxovanadate compounds on rat aorta: Role of rho kinase and nitric oxide/cGMP pathway.

The present study was undertaken to assess the role of reactive oxygen species (ROS) in rat aortic ring vasoreactivity and integrity by using various peroxovanadate (pV) compounds. All the pV compounds (1nM-300 µM) used in the present study exerted concentration-dependent contractions on endothelium intact rat aortic rings. All compounds with an exception of DPV-asparagine (DPV-asn) significantly altered vascular integrity as shown by diminished KCl responses. Phenylephrine (PE)-mediated contractions (3nM-300 µM) were unaltered in the presence of these compounds. Acetylcholine (Ach)-mediated relaxation in PE (1µM) pre-contracted rings was significantly reduced in presence of diperoxovanadate (DPV), poly (sodium styrene sulfonate-co-maleate)-pV (PSS-CoM-pV) and poly (sodium styrene 4-sulfonate)-pV (PSS-pV). However, no significant change in Ach-mediated responses was observed in the presence of poly (acrylate)-pV (PAA-pV) and DPV-asn. DPV-asn was thus chosen to further elucidate mechanism involved in peroxide mediated modulation of vasoreactivity. DPV-asn (30nM - 300 µM) exerted significantly more stable contractions, that was found to be catalase (100U/ml) resistant in comparison with H(2)O(2) (30nM-300 µM) in endothelium intact aortic rings. These contractile responses were found to be dependent on extracellular Ca(2+) and were significantly inhibited in presence of ROS scavenger N-acetylcysteine (100 µM). Intracellular calcium chelation by BAPTA-AM (10µM) had no significant effect on DPV-asn (30nM-300 µM) mediated contraction. Pretreatment of aortic rings by rho-kinase inhibitor Y-27632 (10µM) significantly inhibited DPV-asn-mediated vasoconstriction indicating role of voltage-dependent Ca(2+) influx and downstream activation of rho-kinase. The small initial relaxant effect obtained on addition of DPV-asn (30nM-1 µM) in PE (1 µM) pre-contracted endothelium intact rings, was prevented in the presence of guanylate cyclase inhibitor, methylene blue (10 µM) and/or nitric oxide synthase (NOS) inhibitor, l-NAME (100 µM) suggesting involvement of nitric oxide and cGMP. DPV-asn, like H(2)O(2), exerted a response of vasoconstriction in normal arteries and vasodilation at low concentrations (30nM-1 µM) in PE-pre contracted rings with overlapping mechanisms. These findings suggest usefulness of DPV-asn having low toxicity, in exploring the peroxide-mediated effects on various vascular beds. The present study also convincingly demonstrates role of H(2)O(2) in the modulation of vasoreactivity by using stable peroxide DPV-asn and warrants future studies on peroxide mediated signaling from a newer perspective.

Sub-optimal dose of Sodium Antimony Gluconate (SAG)-diperoxovanadate combination clears organ parasites from BALB/c mice infected with antimony resistant Leishmania donovani by expanding antileishmanial T-cell repertoire and increasing IFN-gamma to IL-10 ratio.

We demonstrate that the combination of sub-optimal doses of Sodium Antimony Gluconate (SAG) and the diperoxovanadate compound K[VO(O2)2(H2O)], also designated as PV6, is highly effective in combating experimental infection of BALB/c mice with antimony resistant (Sb(R)) Leishmania donovani (LD) as evident from the significant reduction in organ parasite burden where SAG is essentially ineffective. Interestingly, such treatment also allowed clonal expansion of antileishmanial T-cells coupled with robust surge of IFN-c and concomitant decrease in IL-10 production. The splenocytes from the treated animals generated significantly higher amounts of IFN-c inducible parasiticidal effector molecules like superoxide and nitric oxide as compared to the infected group. Our study indicates that the combination of sub-optimal doses of SAG and PV6 may be beneficial for the treatment of SAG resistant visceral leishmaniasis patients.

Kinetics of inhibition of rabbit intestine alkaline phosphatase by heteroligand peroxo complexes of vanadium(V) and tungsten(VI).

The present work was undertaken to examine and compare some biologically important properties of peroxo compounds of V(V) and W(VI) containing biogenic species as ancillary ligand. New anionic peroxovanadate(V) complex of the type Na[VO(O(2))(2)(triglycine)].3H(2)O (pV1) and a molecular peroxotungstate(VI) [WO(O(2))(2)(triglycine)].3H(2)O (pW1) were synthesized and characterized for the purpose and their stability in solution was ascertained. Studies on kinetics of inhibition of alkaline phosphatase activity by the newly synthesized compounds and series of dipeptide and amino acid containing peroxo complexes of vanadium and tungsten synthesized previously by us viz., Na[VO(O(2))(2)(gly-gly)(H(2)O)].H(2)O (gly-gly = glycyl-glycine), Na[VO(O(2))(2)(asn)].H(2)O (asn = asparagine), Na[VO(O(2))(2)(gln)].H(2)O (gln = glutamine), and [WO(O(2))(2)(gly-gly)(H(2)O)].3H(2)O, revealed that each of these species is a potent mixed-type inhibitor of the enzyme. Significant difference was noted between the peroxovanadium (pV) and peroxotungsten (pW) compounds in terms of their oxidant activity with reduced glutathione.

Mononuclear and dinuclear peroxotungsten complexes with co-ordinated dipeptides as potent inhibitors of alkaline phosphatase activity.

New molecular peroxotungstate(VI) complexes with dipeptides as ancillary ligands of the type, [WO(O(2))(2)(dipeptide)(H(2)O)].3H(2)O, dipeptide = glycyl-glycine or glycyl-leucine, have been synthesized and characterized by elemental analysis, spectral and physico-chemical methods including thermal analysis. The complexes contain side-on bound peroxo groups and a peptide zwitterion bonded to the metal centre unidentately through an O(carboxylate) atom. Investigations on certain biologically important key properties of these compounds and a set of dimeric compounds in analogous co-ligand environment, Na(2)[W(2)O(3)(O(2))(4)(dipeptide)(2)].3H(2)O, dipeptide = glycyl-glycine and glycyl-leucine, reported previously by us revealed interesting features of the compounds. Each of the compounds despite having a 7 co-ordinated metal centre exerts a strong inhibitory effect on alkaline phosphatase activity with a potency higher than that of the free dipeptide, tungstate or peroxotungstate. The compounds exhibit remarkable stability in solutions of acidic as well as physiological pH and are weaker as substrate to the enzyme catalase, compared to H(2)O(2). The mononuclear and dinuclear peroxotungsten compounds are efficient oxidants of reduced glutathione (GSH), a reaction in which only one of the peroxo groups of a diperoxotungsten moiety of the complexes was found to be active.

New oxo-bridged peroxotungsten complexes containing biogenic co-ligand as potent inhibitors of alkaline phosphatase activity.

Novel dinuclear peroxo complexes of tungsten with coordinated cystine of the type A(2)[W(2)O(3)(O(2))(4)(cystine)].4H(2)O, A = Na (1) or K (2) have been synthesized from the reaction of A(2)WO(4,)cysteine and 30% H(2)O(2)at pH 2.5. The synthesized compounds were characterized by elemental analysis, spectral and physico-chemical methods. The two W(VI) centres with side-on bound peroxo groups of the dinuclear complex species are bridged by an oxo group and a cystine ligand, formed from the oxidation of cysteine. Cystine occurring as zwitterion binds the metal centers of the complex ion through O(carboxylate) atoms leading to hepta co-ordination around each W(VI). The compounds exhibit high stability toward decomposition in solution of acidic as well as physiological pH and serve as weak substrates to catalase, undergoing degradation in presence of the enzyme at a rate much slower relative to H(2)O(2). The compounds efficiently oxidized GSH to GSSG, a reaction in which only two of the peroxide groups of the complex species were found to participate. The compounds induce strong inhibitory effect on alkaline phosphatase activity with a potency higher than that of the free cystine, tungstate, or peroxotungstate.