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Several pieces of evidence indicate that albumin modified by HNE is a promising biomarker of systemic oxidative stress and that HNE-modified albumin may contribute to the immune reactions triggered by lipid peroxidation-derived antigens. In this study, we found by HPLC analysis that HNE is rapidly quenched by human serum albumin (HSA) because of the covalent adduction to the different accessible nucleophilic residues of the protein, as demonstrated by electrospray ionization mass spectrometry (ESI-MS) direct infusion experiments (one to nine HNE adducts, depending on the molar ratio used, from 1:0.25 to 1:5 HSA:HNE). An LC-ESI-MS/MS approach was then applied to enzymatically digested HNE-modified albumin, which permitted the identification of 11 different HNE adducts, 8 Michael adducts (MA) and 3 Schiff bases (SB), involving nine nucleophilic sites, namely: His67 (MA), His146 (MA), His242 (MA), His288 (MA), His510 (MA), Lys 195 (SB), Lys 199 (MA, SB), Lys525 (MA, SB) and Cys34 (MA). The most reactive HNE-adduction site was found to be Cys34 (MA) followed by Lys199, which primarily reacts through the formation of a Schiff base, and His146, giving the corresponding HNE Michael adduct. These albumin modifications are suitable tags of HNE-adducted albumin and could be useful biomarkers of oxidative and carbonylation damage in humans.

Acrolein (ACR), the carbonyl toxin produced by lipid peroxidation, is significantly increased in Alzheimer's disease brain. Since ACR is one of the most reactive and neurotoxic aldehydes, and human brain contains both carnosine (beta-alanine-L-histidine) and homocarnosine (gamma-aminobutyryl-L-histidine), the aim of this work was first to evaluate the quenching ability of the two peptides towards ACR and then to characterize their reaction products by electrospray ionization tandem mass spectrometry (ESI-MS/MS; infusion experiments; positive-ion mode). The reaction progress of ACR with carnosine or homocarnosine was studied in phosphate buffer, by monitoring ACR consumption (by reverse-phase LC) and formation of the reaction products by ESI-MS/MS at different incubation times. N-Acetylcarnosine was used as reference compound to identify the sites of reaction. Both the dipeptides were able to quench ACR by almost 60% at 1 h and by more than 85% after 3 h incubation. Different reaction products between ACR and carnosine/homocarnosine were detected after 3 and 24 h, to indicate a complex reaction pathway involving sequential addition of 1, 2 and 3 moles of ACR/mole of the dipeptide to both the beta-alanine and histidine residues. The ESI mass spectra of ACR/carnosine reaction mixtures indicate formation of several molecular species, among which the predominant are: (a) the 14-membered macrocyclic derivatives, deriving from the formation of the iminic bond between the terminal amino group followed by intramolecular Michael addition of the C(3) of the ACR moiety to histidine; (b) the N(beta)-(3-formyl-3,4-dehydropiperidino) derivatives arising from the Michael addition of two acrolein molecules to the amino group of beta-alanine, followed by an aldol condensation and dehydration.The reaction of homocarnosine with ACR follows the same pathway, giving rise to the formation of homologous adducts. The results of this study shed light on the mechanism, until now never demonstrated, through which carnosine and homocarnosine detoxify the highly reactive aldehyde acrolein in a buffer system, and represent the starting point for further studies aimed at elucidating the biological role of these dipeptides in brain.

Since antiquity, Achillea millefolium L. (Asteraceae) has been used in traditional medicine of several cultures, from Europe to Asia. Its richness in bioactive compounds contributes to a wide range of medicinal properties. In this study, we assessed A. millefolium methanolic extract and its isolated components for free radical scavenging activity against 2,2-diphenyl-pycrilhydrazyl, total antioxidant capacity (based on the reduction of Cu(++) to Cu(+)), and ability to inhibit lipid peroxidation. The activity against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum was also tested. Chlorogenic acid, its derivatives and some flavonoids isolated by semipreparative HPLC and identified by NMR and spectrometric techniques were the major bioactive constituents of the methanolic extract. The latter exhibited significant antioxidant properties, as well as its flavonol glycosides and chlorogenic acids. With regard to the antiplasmodial activity, apigenin 7-glucoside was the most effective compound, followed by luteolin 7-glucoside, whereas chlorogenic acids were completely inactive. On the whole, our results confirmed A. millefolium as an important source of bioactive metabolites, justifying its pharmaceutical and ethnobotanical use.

We report on the virtual screening, synthesis, and biological evaluation of new furan derivatives targeting Mycobacterium tuberculosis salicylate synthase (MbtI). A receptor-based virtual screening procedure was applied to screen the Enamine database, identifying two compounds, I and III, endowed with a good enzyme inhibitory activity. Considering the most active compound I as starting point for the development of novel MbtI inhibitors, we obtained new derivatives based on the furan scaffold. Among the SAR performed on this class, compound 1a emerged as the most potent MbtI inhibitor reported to date (K = 5.3 μM). Moreover, compound 1a showed a promising antimycobacterial activity (MIC = 156 μM), which is conceivably related to mycobactin biosynthesis inhibition.

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