Hydroxycinnamoyl Amides Research Articles

Phytochemical profiling of three Amaranthus species using LC-MS/MS metabolomic approach and chemometric tools

Several Amaranthus vegetables (Amaranthaceae) have been recognized as valuable sources of minerals, vitamins, proteins, and phytonutrients, with health-promoting characteristics. In this study, three edible Amaranthus species, namely A. hybridus (AH), A. blitum (AB), and A. caudatus (AC), were chemically characterized using non-targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. Further, multivariate chemometric analyses were conducted, including principal component analysis (PCA) and correlation-covariance plot (C-C plot). As a result, forty-one diverse compounds were identified, which varied in distribution and abundance across the investigated species. Amino acids and flavonoid glycosides were the most prevalent metabolites. Other identified compounds comprised nucleoside, chlorogenic acids, hydroxy cinnamoyl amides, and triterpenoid saponins. The most discriminant metabolites were flavonoid glycosides and hydroxy cinnamoyl amides, giving each species a chemotaxonomic identity. Advancing the chemotaxonomy of Amaranthaceae, adenosine nucleoside and N-coumaroyl-ʟ-tryptophan were first reported from this family. Isorhamnetin and tricin glycosides were uniquely identified in AC, offering useful chemotaxonomic markers for this species. Notably, AB and AH profiles shared most metabolites, yet with varying abundance. These include adenosine, nicotiflorin, dicaffeoylquinic acids, and N-trans-feruloyl-4-O-methyldopamine. However, N-coumaroyl-ʟ-tryptophan and kaempferol dirhamnoside were exclusively found in AB, separating it from AH. In conclusion, the applied analytical techniques established molecular fingerprints for the included species, identified specific biomarkers, and investigated their interconnections.

Engineering Alfalfa to Produce 2-O-Caffeoyl-L-Malate (Phaselic Acid) for Preventing Post-harvest Protein Loss via Oxidation by Polyphenol Oxidase.

Many plants accumulate high levels of hydroxycinnamoyl esters and amides in their tissues, presumably to protect against biotic and abiotic stress. Red clover (Trifolium pretense) leaves accumulate high levels [5–15 mmol/kg fresh weight (FW)] of caffeic acid derivatives, including phaselic acid (2-O-caffeoyl-L-malate). Oxidation of caffeoyl-malate by an endogenous polyphenol oxidase (PPO) has been shown to help preserve forage protein after harvest and during storage as silage, which should improve N use efficiency in dairy and other ruminant production systems. The widely grown forage alfalfa lacks both PPO and PPO substrates and experiences substantial loss of protein following harvest. We previously identified a hydroxycinnamoyl-coenzyme A (CoA):malate hydroxycinnamoyl transferase (HMT, previously called HCT2) responsible for phaselic accumulation in red clover. With the goal of producing PPO-oxidizable compounds in alfalfa to help preserve forage protein, we expressed red clover HMT in alfalfa. Leaves of these alfalfa accumulated mainly p-coumaroyl- and feruloyl-malate (up to 1.26 and 0.25 mmol/kg FW, respectively). Leaves of HMT-expressing alfalfa supertransformed with an RNA interference (RNAi) construct to silence endogenous caffeoyl-CoA acid O-methyltransferase (CCOMT) accumulated high levels of caffeoyl-malate, as well as the p-coumaroyl and feruloyl esters (up to 2.16, 2.08, and 3.13 mmol/kg FW, respectively). Even higher levels of caffeoyl- and p-coumaroyl-malate were seen in stems (up to 8.37 and 3.15 mmol/kg FW, respectively). This level of caffeoyl-malate accumulation was sufficient to inhibit proteolysis in a PPO-dependent manner in in vitro experiments, indicating that the PPO system of post-harvest protein protection can be successfully adapted to alfalfa.

Hydroxycinnamoyl Amino Acids Conjugates: A Chiral Pool to Distinguish Commercially Exploited Coffea spp.

The synthesis of five hydroxycinnamoyl amides (HCAs) was accomplished and their identification and quantification in the green coffee bean samples of Coffea arabica, Coffea canephora, and Coffea liberica was performed. The HCAs p-coumaroyl-N-tyrosine 1b, caffeoyl-N-phenylalanine 2b, caffeoyl-N-tyrosine 3b, and p-coumaroyl-N-tryptophan 4b were characteristic of the C. canephora species while caffeoyl-N-tryptophan 5b was present in both C. canephora and C. arabica, but with higher content in C. canephora. The HCAs presence was also analyzed in C. liberica for the first time and none of the targeted compounds was found, indicating that this species is very similar to C. arabica species. Between C. canephora samples from various origins, significant differences were observed regarding the presence of all the HCAs, with C. canephora from Tanzania containing all five derivatives.

Computational molecular modelling of N-cinnamoyl and hydroxycinnamoyl amides as potential α-glucosidase inhibitors

In the present work, a molecular modelling has been performed on a total of 17 cinnamic acids, derived with different amino acids. These have recently been evaluated as potential α-glucosidase inhibitors. Consequently, we proposed a quantitative 3D structure–activity relationships in order to obtain predictive models of the biological activity. Two types of descriptors were used for the modelling: quantum chemical and multi-linear algebraic maps. The first one was obtained by using Density Functional Theory (DFT) at the M06/6-311++G(d,p) level, while for the second, attribute sets were obtained by using 3D molecular topology, atom weighed by physicochemical properties including the polar surface area, hardness, softness, van der Waals volume and charges. A genetic algorithm scheme was employed to determine the best subset of attributes for the application of the multiple linear regression. The most robust model (M4R_TD) was obtained with four multi-linear algebraic map descriptors (R2 = 0.946, Q2 = 0.901, F = 85.70), which indicate a good correlation between experimental and calculated results. Seven new simple structural modifications in the molecular core were suggested specifically for the three most active compounds (1, 2 and 5). The modifications to compound 1 appear to lead to an increase in the predicted activity from a pIC50 value of 9.872 to 10.656 in compound 1.3. The modifications to compound 2 do not affect an increase in the biological activity, and finally the modifications to compound 5 seem to increase the activity with a predicted pIC50= log[10/(10−6×IC50)]IC50 value of 10.094 for compound 5.1.

Structure-Activity Relationships ofN-Cinnamoyl and Hydroxycinnamoyl Amides onα-Glucosidase Inhibition

Currently, there is an increasing interest towardsα-glucosidase inhibition of various diseases including diabetes mellitus type 2, cancer, HIV, and B- and C-type viral hepatitis. Cinnamic acid derivatives have been shown to be potentially valuable as a new group ofα-glucosidase inhibitors. Therefore, herein, theα-glucosidase inhibitory activity oftrans-N-cinnamoyl and hydroxycinnamoyl amides was studied in vitro. Results revealed that the tested hydroxycinnamoyl amides (1–16) inhibiteda-glucosidase with IC50s ranging between 0.76 and 355.1 μg/ml. Compounds1,2,5,6,9,14, and15showed significant inhibition of yeastα-glucosidase, being even more potent ones than the used positive inhibitor acarbose (IC50=2.50±0.21 μg/ml).

Antioxidant activity and mechanism of action of some synthesised phenolic acid amides of aromatic amines

The antioxidative activities and mechanism of action were studied of eight synthesised cinnamoyl- and hydroxycinnamoyl amides of biogenic amines (caffeoyldopamine, cinnamoyldopamine, p-coumaroyldopamine, feruloyldopamine, sinapoyldopamine, caffeoylphenylethylamine, caffeoyltyramine, and caffeoyltryptamine) in a wide concentration range (2.5–20 × 10<sup>–4</sup>M) during autoxidation of triacylglycerols of sunflower oil. It was established that all amides exhibited excellent antioxidant activity, higher than or comparable with that of caffeic acid. The best activity was shown by caffeoyldopamine followed by cinnamoyldopamine and caffeoyltyramine. The analysis of the kinetic data obtained showed that the presence of hydroxyl groups in the amino part (derivatives of dopamine and tyramine) led to direct oxidation of the molecules during the process and stabilisation of the resulting radicals. In contrast, the amides without hydroxyl groups in the amino part participated in the side reaction with peroxides and the resulting radicals took part in one side reaction of the chain propagation as did caffeic acid.  

Antimicrobial and Radical Scavenging Activities of N-Hydroxycinnamoyl - L-Cysteine and - L-Proline Ethyl Esters

Hydroxycinnamic acids are widely distributed in the plant kingdom secondary metabolites, found also as simple derivatives including amides, esters, and glycosides. These acids and their derivatives are known to possess antibacterial, antiviral, anti-inflammatory, antioxidative, antiproliferative, immunostimulatory and neuroprotective properties. The aim of the present work was the synthesis of new hydroxycinnamoyl amides of the (L)- cysteine and (L)- proline and evaluation of their radical scavenging and antimicrobial activity. The structures of the synthesized analogues were characterized by UV, 1H NMR, 13C NMR, ESI-MS. The compounds were screened for their antibacterial (against Staphylococcus aureus 209, Streptococcus pyogenes 10535, Bacillus subtilis 1A95, Listeria monocytogenes C12) and antifungal (against Candida albicans 62) activities. All amides demonstrated the most potent activity against Streptococcus pyogenes, even higher in comparison with the free hydroxycinnamic acids. The ability of hydroxycinnamoyl amides to interact with 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical in vitro was also evaluated. The results obtained showed that the radical scavenging activity of the sinapoyl- and caffeoyl amides of L-cysteine is superior to the standards ferulic acid, eugenol and isoeugenol. Keywords: Antimicrobial activity, DPPH radical, L-Cysteine and - L-Proline Ethyl Esters, radical scavenging activity, N-hydroxycinnamoyl amides, amides, synthesis, microorganisms, analytical thin layer chromatography

Changes in wheat leaf phenolome in response to cold acclimation

A study of wheat ( Triticum aestivum L.) leaves phenolome was carried out during cold acclimation of the winter (Claire) and spring (Bounty) varieties using a combination of HPLC–ESI–MS techniques. A total of 40 phenolic and flavonoid compounds were identified, and consisted mainly of two coumarin derivatives, eight simple phenolic derivatives, 10 hydroxycinnamoyl amides and 20 flavonoid derivatives. Identification and quantification of individual compounds were performed using an HPLC system coupled with a photodiode array detector and two different ESI–MS systems, in combination with a multiple reaction monitoring (MRM) technique. The analyses indicated that, although there were no qualitative differences in their profiles, the winter variety exhibited a higher phenolic content compared to the spring variety when both were grown under non-acclimated (control) conditions. Cold acclimation, on the other hand, resulted in a significant differential accumulation of phenolic compounds in both varieties: mostly as luteolin C-glycosides and their O-methyl derivatives in the winter variety (Claire) and a derivative of hydroxycinnamoyl amide in the spring variety (Bounty). These compounds accumulated in relatively large amounts in the apoplastic compartment. The accumulation of the O-methylated derivatives was associated with a marked increase in O-methyltransferase (OMT) activity. In addition, the trimethylated flavone, 3′,4′,5′-trimethyltricetin was identified for the first time in the native extracts of both control and cold-acclimated wheat leaves. The accumulation of a mixture of beneficial flavonoids, such as iso-orientin, vitexin and tricin in cold acclimated wheat leaves, attests for its potential as an inexpensive source of a health-promoting supplement to the human diet.

Synthesis of N-hydroxycinnamoyl amino acid ester analogues and their free radical scavenging and antioxidative activities

Hydroxycinnamic acids have a variety of biological activities, including antioxidant activity. To find more active antioxidants with hydroxycinnamoyl moiety, we synthesized a series of N-hydroxycinnamoyl amino acid esters and evaluated their antioxidative activities by 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging and human red blood cells (RBCs) haemolysis methods. It was found that N-caffeoyl amides exhibited the highest DPPH-scavenging activities, whereas N-feruloyl amides demonstrated the highest antihaemolysis activities among the three different hydroxycinnamamides (caffeoyl, feruloyl, and p-coumaroyl), and that hydroxycinnamoyl amides were more effective than their corresponding free acid and ester compounds in both DPPH and RBC haemolysis tests.

Cinnamoyl- and hydroxycinnamoyl amides of glaucine and their antioxidative and antiviral activities

The aporphine alkaloid glaucine has been converted into 3-aminomethylglaucine and its free amino group has been linked to cinnamic, ferulic, sinapic, o-, and p-coumaric acids. The antioxidative potential of the synthesized amides was studied against DPPH ∗ test. All of the tested compounds demonstrated higher radical scavenging activity than glaucine and 3-aminomethylglaucine, and lower antioxidative effect than the free hydroxycinnamic acids. The newly synthesized compounds were tested in vitro for antiviral activity against viruses belonging to different taxonomic groups.

Feruloyl‐ and caffeoylputrescine in stem explants from photoperiodically determined Nicotiana species

The distribution and formation of hydroxycinnamoyl amides (HCA) in in vitro grown stem explants from day‐neutral Nicotiana tabacum L. var. Xanthi no were investigated using [14C]‐labelled precursors. Feruloylputrescine (FP) (labelled from [14C]‐putrescine) was continually formed with a decreasing formation rate during a culture period of 35 days. The specific radioactivity, however, remained constant. In contrast, caffeoylputrescine (CP) was labelled in the second part of culture only. [UC]‐Label from putrescine, spermidine, spermine, and cinnamic acid was incorporated into FP and p‐coumaroylspermidine. CP was labelled from [14C]‐putreseine and [14C]‐spermidine only, while diferuloylputrescine (diFP) failed to be labelled by any of the precursors used. Tissue investigations showed that FP is dominant in cortex during formation of cortical callus, while CP showed a sequential gradient from pith to cortical callus to floral buds. Experiments with photoperiodical Nicotiana species were used to investigate the pattern of HCAs in induced and non‐induced plants. The origin of explants had no influence on the pattern of FP and CP but resulted in different growth responses. FP is a marker of cortical callus formation in all explants. CP does not trigger the growth processes observed in the expants since CP also increased in photoperiodically non‐induced explants of tobacco, which stopped growing after the formation of cortical callus.

Hydroxycinnamoyl amides in stem explants from flowering and non‐flowering Nicotiana tabacum

Flower formation in stem explants was chosen as an experimental system for the study of the function of hydroxycinnamoyl amides (HCAs) in plants. The explants, derived from flowering and non‐flowering Nicotiana tabacum L. var. Xanthi nc., differentiated to two types of callus and afterwards to flower buds. A novel reversed‐phase high performance liquid chromatography method, following sample clean‐up on CM‐Fractogel columns, enabled us to examine HCA concentrations in small tissue samples. Two different groups of HCA could be distinguished during in vitro flower formation: Firstly, feruloyl‐ and diferuloyputrescine, the major detectable HCAs that accumulated during callus proliferation; secondly, caffeoylputrescine, which accumulated during the later stage of flower differentiation and reached higher concentrations than feruloylputrescine.