Floret Biofortification of Broccoli Using Amino Acids Coupled with Selenium under Different Surfactants: A Case Study of Cultivating Functional Foods

Broccoli serves as a functional food because it can accumulate selenium (Se), well-known bioactive amino-acid-derived secondary metabolites, and polyphenols. The chemical and physical properties of Se are very similar to those of sulfur (S), and competition between sulfate and selenate for uptake and assimilation has been demonstrated. Towards an efficient agronomic fortification of broccoli florets, the working questions were whether we could overcome this competition by exogenously applying the S-containing amino acids cysteine (Cys) or/and methionine (Met), or/and the precursors of Glucosinolate (GSL) types along with Se application. Broccoli plants were cultivated in a greenhouse and at the beginning of floret growth, we exogenously applied sodium selenate in the concentration gradient of 0, 0.2, 1.5, and 3.0 mM to study the impact of increased Se concentration on the organic S (S_org) content of the floret. The Se concentration of 0.2 mM (Se0.2) was coupled with the application of Cys, Met, their combination, or a mixture of phenylalanine, tryptophane, and Met. The application took place through fertigation or foliar application (FA) by adding isodecyl alcohol ethoxylate (IAE) or a silicon ethoxylate (SiE) surfactant. Fresh biomass, dry mass, and Se accumulation in florets were evaluated, along with their contents of S_org, chlorophylls (Chl), carotenoids (Car), glucoraphanin (GlRa), glucobrassicin (GlBra), glucoiberin (GlIb), and polyphenols (PPs), for the biofortification efficiency of the three application modes. From the studied selenium concentration gradient, the foliar application of 0.2 mM Se using silicon ethoxylate (SiE) as a surfactant provided the lowest commercially acceptable Se content in florets (239 μg or 0.3 μmol g^-1 DM); it reduced S_org (-45%), GlIb (-31%), and GlBr (-27%); and it increased Car (21%) and GlRa (27%). Coupled with amino acids, 0.2 mM Se provided commercially acceptable Se contents per floret only via foliar application. From the studied combinations, that of Met,Se0.2/FA,IAE provided the lowest Se content per floret (183 μg or 0.2 μmol g^-1 DM) and increased S_org (35%), Car (45%), and total Chl (27%), with no effect on PPs or GSLs. Cys,Met,Se0.2/FA,IAE and amino acid mix,Se0.2/FA,IAE increased S_org content, too, by 36% and 16%, respectively. Thus, the foliar application with the IAE surfactant was able to increase S_org, and methionine was the amino acid in common in these treatments, with varying positive effects on carotenoids and chlorophylls. Only the Cys,Met,Se0.2 combination presented positive effects on GSLs, especially GlRa, but it reduced the fresh mass of the floret. The foliar application with SiE as a surfactant failed to positively affect the organic S content. However, in all studied combinations of Se 0.2 mM with amino acids, the Se content per floret was commercially acceptable, the yield was not affected, the content of GSLs was increased (especially that of GlRa and GlIb), and PPs were not affected. The content of GlBr decreased except for the treatment with methionine (Met,Se0.2/FA,SiE) where GlBr remained unaffected. Hence, the combination of Se with the used amino acids and surfactants can provide enhanced biofortification efficiency in broccoli by providing florets as functional foods with enhanced functional properties.

Identification of Auxin Metabolites in Brassicaceae by Ultra-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry

Auxins are signaling molecules involved in multiple stages of plant growth and development. The levels of the most important auxin, indole-3-acetic acid (IAA), are regulated by the formation of amide and ester conjugates with amino acids and sugars. In this work, IAA and IAA amide conjugates with amino acids bearing a free carboxylic group or a methyl ester group, along with some selected IAA metabolites, were studied in positive and negative electrospray ionization (ESI) modes, utilizing high-resolution mass spectrometry (HRMS) as a tool for their structural analysis. HRMS/MS spectra revealed the fragmentation patterns that enable us to identify IAA metabolites in plant extracts from eight vegetables of the Brassicaceae family using a fast and reliable ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) method. The accurate m/z (mass to charge) ratio and abundance of the molecular and fragment ions of the studied compounds in plant extracts matched those obtained from commercially available or synthesized compounds and confirmed the presence of IAA metabolites.

High resolution mass spectrometry studies of sulforaphane and indole-3-carbinol in broccoli

Broccoli is a rich source of bioactive compounds. Among them, sulforaphane and indole-3-carbinol have attracted a lot of attention, since their consumption is associated with reduced risk of cancer. In this work, the development of an efficient and direct method for the simultaneous determination of sulforaphane and indole-3-carbinol in broccoli using UPLC-HRMS/MS is described. The correlation coefficient, and limits of detection (LOD) and quantification (LOQ) were 0.993, 0.77mg/L and 2.35mg/L for sulforaphane and 0.997, 0.42mg/L, 1.29mg/L for indole-3-carbinol, respectively. The content of sulforaphane and indole-3-carbinol varied between 72±9-304±2mg and 77±1-117±3mg per 100g of fresh florets, respectively. Taking into consideration the differences in cultivar, geography, season and environmental factors, the results agreed with values published in the literature using other techniques.

2-Oxoamides based on dipeptides as selective calcium-independent phospholipase A2 inhibitors

Calcium-independent phospholipase A₂ (GVIA iPLA₂) has recently attracted interest as a medicinal target. The number of known GVIA iPLA₂ inhibitors is limited to a handful of synthetic compounds (bromoenol lactone and polyfluoroketones). To expand the chemical diversity, a variety of 2-oxoamides based on dipeptides and ether dipeptides were synthesized and studied for their in vitro inhibitory activity on human GVIA iPLA₂ and their selectivity over the other major intracellular GIVA cPLA₂ and the secreted GV sPLA₂. Structure-activity relationship studies revealed the first 2-oxoamide derivative (GK317), which presents potent inhibition of GVIA iPLA₂ (X_I(50) value of 0.007) and at the same time significant selectivity over GIVA cPLA₂ and GV sPLA₂.

Inhibitors of secreted phospholipase A2 suppress the release of PGE2 in renal mesangial cells

The upregulation of PGE2 by mesangial cells has been observed under chronic inflammation condition. In the present work, renal mesangial cells were stimulated to trigger a huge increase of PGE2 synthesis and were treated in the absence or presence of known PLA2 inhibitors. A variety of synthetic inhibitors, mainly developed in our labs, which are known to selectively inhibit each of GIVA cPLA2, GVIA iPLA2, and GIIA/GV sPLA2, were used as tools in this study. Synthetic sPLA2 inhibitors, such as GK115 (an amide derivative based on the non-natural amino acid (R)-γ-norleucine) as well as GK126 and GK241 (2-oxoamides based on the natural (S)-α-amino acid leucine and valine, respectively) presented an interesting effect on the suppression of PGE2 formation.

Inhibition of group IVA cytosolic phospholipase A2 by thiazolyl ketones in vitro, ex vivo, and in vivo

Group IVA cytosolic phospholipase A2 (GIVA cPLA2) is the rate-limiting provider of pro-inflammatory mediators in many tissues and is thus an attractive target for the development of novel anti-inflammatory agents. In this work, we present the synthesis of new thiazolyl ketones and the study of their activities in vitro, in cells, and in vivo. Within this series of compounds, methyl 2-(2-(4-octylphenoxy)acetyl)thiazole-4-carboxylate (GK470) was found to be the most potent inhibitor of GIVA cPLA2, exhibiting an XI(50) value of 0.011 mole fraction in a mixed micelle assay and an IC50 of 300 nM in a vesicle assay. In a cellular assay using SW982 fibroblast-like synoviocytes, it suppressed the release of arachidonic acid with an IC50 value of 0.6 μM. In a prophylactic collagen-induced arthritis model, it exhibited an anti-inflammatory effect comparable to the reference drug methotrexate, whereas in a therapeutic model, it showed results comparable to those of the reference drug Enbrel. In both models, it significantly reduced plasma PGE2 levels.

Synthesis of medicinally useful lipidicα-amino acids, 2-amino alcohols and diamines

The lipidicα-amino acids (LAAs) are non-naturalα-amino acids with saturated or unsaturated long aliphatic side chains. LAAs and their derivatives (lipid mimetics) together with the lipidic peptides represent a class of compounds which combine structural features of lipids with those of amino acids and peptides. Racemic LAAs may be prepared by classical methods and resolved by chemical or enzymatic methods. LAA amides and esters with saturated or unsaturated long chain amines and alcohols respectively, as well as lipidic dipeptide derivatives inhibit both pancreatic and human platelet phospholipase A2. Lipophilic peptide derivatives are inhibitors of human neutrophil elastase. LAAs and their oligomers have been used as drug delivery system. A Lipid-Core-Peptide system has been designed and used as a combined adjuvant-carrier-vaccine system. A variety of lipid mimetics such as lipidic 2-amino alcohols, lipidic 1,2- and 1,3-diamines have been prepared based upon LAAs. Some of them are potent inhibitors of phospholipase A2. A general approach to enantioselective synthesis of LAAs and lipid mimetics is based on the oxidative cleavage of 3-amino-1,2-diols obtained by the regioselective opening of enantiomerically enriched long chain 2,3-epoxy alcohols.

New potent and selective polyfluoroalkyl ketone inhibitors of GVIA calcium-independent phospholipase A2

Group VIA calcium-independent phospholipase A2 (GVIA iPLA2) has recently emerged as an important pharmaceutical target. Selective and potent GVIA iPLA2 inhibitors can be used to study its role in various neurological disorders. In the current work, we explore the significance of the introduction of a substituent in previously reported potent GVIA iPLA2 inhibitors. 1,1,1,2,2-Pentafluoro-7-(4-methoxyphenyl)heptan-3-one (GK187) is the most potent and selective GVIA iPLA2 inhibitor ever reported with a XI(50) value of 0.0001, and with no significant inhibition against GIVA cPLA2 or GV sPLA2. We also compare the inhibition of two difluoromethyl ketones on GVIA iPLA2, GIVA cPLA2, and GV sPLA2.

Binding conformation of 2-oxoamide inhibitors to group IVA cytosolic phospholipase A2 determined by molecular docking combined with molecular dynamics

The group IVA cytosolic phospholipase A(2) (GIVA cPLA(2)) plays a central role in inflammation. Long chain 2-oxoamides constitute a class of potent GIVA cPLA(2) inhibitors that exhibit potent in vivo anti-inflammatory and analgesic activity. We have now gained insight into the binding of 2-oxoamide inhibitors in the GIVA cPLA(2) active site through a combination of molecular docking calculations and molecular dynamics simulations. Recently, the location of the 2-oxoamide inhibitor AX007 within the active site of the GIVA cPLA(2) was determined using a combination of deuterium exchange mass spectrometry followed by molecular dynamics simulations. After the optimization of the AX007-GIVA cPLA(2) complex using the docking algorithm Surflex-Dock, a series of additional 2-oxoamide inhibitors have been docked in the enzyme active site. The calculated binding affinity presents a good statistical correlation with the experimental inhibitory activity (r(2) = 0.76, N = 11). A molecular dynamics simulation of the docking complex of the most active compound has revealed persistent interactions of the inhibitor with the enzyme active site and proves the stability of the docking complex and the validity of the binding suggested by the docking calculations. The combination of molecular docking calculations and molecular dynamics simulations is useful in defining the binding of small-molecule inhibitors and provides a valuable tool for the design of new compounds with improved inhibitory activity against GIVA cPLA(2).

Phospholipase A2 superfamily members play divergent roles after spinal cord injury

Spinal cord injury (SCI) results in permanent loss of motor functions. A significant aspect of the tissue damage and functional loss may be preventable as it occurs, secondary to the trauma. We show that the phospholipase A(2) (PLA(2)) superfamily plays important roles in SCI. PLA(2) enzymes hydrolyze membrane glycerophospholipids to yield a free fatty acid and lysophospholipid. Some free fatty acids (arachidonic acid) give rise to eicosanoids that promote inflammation, while some lysophospholipids (lysophosphatidylcholine) cause demyelination. We show in a mouse model of SCI that two cytosolic forms [calcium-dependent PLA(2) group IVA (cPLA(2) GIVA) and calcium-independent PLA(2) group VIA (iPLA(2) GVIA)], and a secreted form [secreted PLA(2) group IIA (sPLA(2) GIIA)] are up-regulated. Using selective inhibitors and null mice, we show that these PLA(2)s play differing roles. cPLA(2) GIVA mediates protection, whereas sPLA(2) GIIA and, to a lesser extent, iPLA(2) GVIA are detrimental. Furthermore, completely blocking all three PLA(2)s worsens outcome, while the most beneficial effects are seen by partial inhibition of all three. The partial inhibitor enhances expression of cPLA(2) and mediates its beneficial effects via the prostaglandin EP1 receptor. These findings indicate that drugs that inhibit detrimental forms of PLA(2) (sPLA(2) and iPLA2) and up-regulate the protective form (cPLA2) may be useful for the treatment of SCI.

Differing roles for members of the phospholipase A2 superfamily in experimental autoimmune encephalomyelitis

The phospholipase A(2) (PLA(2)) superfamily hydrolyzes phospholipids to release free fatty acids and lysophospholipids, some of which can mediate inflammation and demyelination, hallmarks of the CNS autoimmune disease multiple sclerosis. The expression of two of the intracellular PLA(2)s (cPLA(2) GIVA and iPLA(2) GVIA) and two of the secreted PLA(2)s (sPLA(2) GIIA and sPLA(2) GV) are increased in different stages of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. We show using small molecule inhibitors, that cPLA(2) GIVA plays a role in the onset, and iPLA(2) GVIA in the onset and progression of EAE. We also show a potential role for sPLA(2) in the later remission phase. These studies demonstrate that selective inhibition of iPLA(2) can ameliorate disease progression when treatment is started before or after the onset of symptoms. The effects of these inhibitors on lesion burden, chemokine and cytokine expression as well as on the lipid profile provide insights into their potential modes of action. iPLA(2) is also expressed by macrophages and other immune cells in multiple sclerosis lesions. Our results therefore suggest that iPLA(2) might be an excellent target to block for the treatment of CNS autoimmune diseases, such as multiple sclerosis.

Synthesis of polyfluoro ketones for selective inhibition of human phospholipase A2 enzymes

The development of selective inhibitors for individual PLA(2) enzymes is necessary in order to target PLA(2)-specific signaling pathways, but it is challenging due to the observed promiscuity of known PLA(2) inhibitors. In the current work, we present the development and application of a variety of synthetic routes to produce pentafluoro, tetrafluoro, and trifluoro derivatives of activated carbonyl groups in order to screen for selective inhibitors and characterize the chemical properties that can lead to selective inhibition. Our results demonstrate that the pentafluoroethyl ketone functionality favors selective inhibition of the GVIA iPLA(2), a very important enzyme for which specific, potent, reversible inhibitors are needed. We find that 1,1,1,2,2-pentafluoro-7-phenyl-heptan-3-one (FKGK11) is a selective inhibitor of GVIA iPLA(2) (X(I)(50) = 0.0073). Furthermore, we conclude that the introduction of an additional fluorine atom at the alpha' position of a trifluoromethyl ketone constitutes an important strategy for the development of new potent GVIA iPLA(2) inhibitors.

Synthesis of 2-oxoamides based on sulfonamide analogs of gamma-amino acids and their activity on phospholipase A2

A variety of lipophilic 2-oxoamides containing sulfonamide analogs of gamma-amino acids as well as acyl sulfonamides of gamma-aminobutyric acid were synthesized. Their ability to inhibit intracellular GIVA cPLA2 and GVIA iPLA2 as well as secreted GV sPLA2 was evaluated. The sulfonamide group seems a bioisosteric group suitable to replace the carboxyl group in 2-oxoamide inhibitors of GVIA cPLA2.

Structure-activity relationships of natural and non-natural amino acid-based amide and 2-oxoamide inhibitors of human phospholipase A(2) enzymes

A variety of 2-oxoamides and related amides based on natural and non-natural amino acids were synthesized. Their activity on two human intracellular phospholipases (GIVA cPLA(2) and GVIA iPLA(2)) and one human secretory phospholipase (GV sPLA(2)) was evaluated. We show that an amide based on (R)-gamma-norleucine is a highly selective inhibitor of GV sPLA(2).

Intracellular phospholipase A(2) group IVA and group VIA play important roles in Wallerian degeneration and axon regeneration after peripheral nerve injury

We provide evidence that two members of the intracellular phospholipase A(2) family, namely calcium-dependent group IVA (cPLA(2) GIVA) and calcium-independent group VIA (iPLA(2) GVIA) may play important roles in Wallerian degeneration in the mouse sciatic nerve. We assessed the roles of these PLA(2)s in cPLA(2) GIVA(-/-) mice, and mice treated with a selective inhibitor of iPLA(2) GVIA (FKGK11). Additionally, the effects of both these PLA(2)s were assessed by treating cPLA(2) GIVA(-/-) mice with the iPLA(2) inhibitor. Our data suggest that iPLA(2) GVIA may play more of a role in the early stages of myelin breakdown, while cPLA(2) GIVA may play a greater role in myelin clearance by macrophages. Our results also show that the delayed myelin clearance and Wallerian degeneration after sciatic nerve crush injury in mice lacking cPLA(2) and iPLA(2) activities is accompanied by a delay in axon regeneration, target re-innervation and functional recovery. These results indicate that the intracellular PLA(2)s (cPLA(2) GIVA and iPLA(2) GVIA) contribute significantly to various aspects of Wallerian degeneration in injured peripheral nerves, which is then essential for successful axon regeneration. This work has implications for injury responses and recovery after peripheral nerve injuries in humans, as well as for understanding the slow clearance of myelin after CNS injury and its potential consequences for axon regeneration.

Structure-activity relationship of 2-oxoamide inhibition of group IVA cytosolic phospholipase A2 and group V secreted phospholipase A2

The Group IVA cytosolic phospholipase A2 (GIVA cPLA2) is a key provider of substrates for the production of eicosanoids and platelet-activating factor. We explored the structure-activity relationship of 2-oxoamide-based compounds and GIVA cPLA2 inhibition. The most potent inhibitors are derived from delta- and gamma-amino acid-based 2-oxoamides. The optimal side-chain moiety is a short nonpolar aliphatic chain. All of the newly developed 2-oxoamides as well as those previously described have now been tested with the human Group V secreted PLA2 (GV sPLA2) and the human Group VIA calcium-independent PLA2 (GVIA iPLA2). Only one 2-oxoamide compound had appreciable inhibition of GV sPLA2, and none of the potent GIVA cPLA2 inhibitors inhibited either GV sPLA2 or GVIA iPLA2. Two of these specific GIVA cPLA2 inhibitors were also found to have potent therapeutic effects in animal models of pain and inflammation at dosages well below the control nonsteroidal anti-inflammatory drugs.

Enzymatic removal of carboxyl protecting groups. III. Fast removal of allyl and chloroethyl esters by Bacillus subtilis esterase (BS2)

An esterase from Bacillus subtilis (BS2) allows the fast and selective removal of allyl, 2-chloroethyl, and 2,2,2-chloroethyl esters under mild conditions in high yields. In addition, BS2 easily hydrolyzes phenacyl esters, while the hydrolysis of sterically hindered diphenylmethyl esters is slow, requiring longer reaction time and higher enzyme/substrate ratio.

Differential inhibition of group IVA and group VIA phospholipases A2 by 2-oxoamides

Inhibitors of the Group IVA phospholipase A(2) (GIVA cPLA(2)) and GVIA iPLA(2) are useful tools for defining the roles of these enzymes in cellular signaling and inflammation. We have developed inhibitors of GVIA iPLA(2) building upon the 2-oxoamide backbone that are uncharged, containing ester groups. Although the most potent inhibitors of GVIA iPLA(2) also inhibited GIVA cPLA(2), there were three 2-oxoamide compounds that selectively and weakly inhibited GVIA iPLA(2). We further show that several potent 2-oxoamide inhibitors of GIVA cPLA(2) containing free carboxylic groups (Kokotos et al. J. Med. Chem. 2002, 45, 2891-2893) do not inhibit GVIA iPLA(2) and are, therefore, selective GIVA cPLA(2) inhibitors.

Enzymatic Removal of Carboxyl Protecting Groups. 2. Cleavage of the Benzyl and Methyl Moieties

[reaction: see text] Enzymes are versatile reagents for the efficient removal of methyl and benzyl protecting groups. An esterase from Bacillus subtilis (BS2) and a lipase from Candida antarctica (CAL-A) allow a mild and selective removal of these moieties in high yields without affecting other functional groups.

Phase transitions in crystals of racemic long chain 2-amino alcohols

Various techniques, namely differential scanning calorimetry, optical microscopy, dielectric and Raman spectroscopy, all covering a wide range of temperatures, were used to study the thermodynamically stable phases and molecular mobility of crystals of long chain 2-amino alcohols. The results showed that two different crystal forms are present in each sample. The temperature behaviour of the phases is studied in details.

Enzymatic Removal of Carboxyl Protecting Groups. 1. Cleavage of thetert-Butyl Moiety

[reaction: see text] A recent discovery that a certain amino acid motif (GGG(A)X-motif) in lipases and esterases determines their activity toward tertiary alcohols prompted us to investigate the use of these biocatalysts in the mild and selective removal of tert-butyl protecting groups in amino acid derivatives and related compounds. An esterase from Bacillus subtilis (BsubpNBE) and lipase A from Candida antarctica (CAL-A) were identified as the most active enzymes, which hydrolyzed a range of tert-butyl esters of protected amino acids (e.g., Boc-Tyr-O(t)Bu, Z-GABA-O(t)Bu, Fmoc-GABA-O(t)Bu) in good to high yields and left Boc, Z, and Fmoc-protecting groups intact.

Synthesis and activity of 2-oxoamides containing long chain β-amino acids

2-Oxoamides based on long chain beta-amino acids were synthesized. 1-Benzyl substituted long chain amines, needed for such synthesis, were synthesized starting from Boc-phenylalaninol. The oxidative conversion of a phenyl group to a carboxyl group was used as the key transformation synthetic step. The compounds synthesized were studied for their activity against GIVA PLA(2), and were proven to be weak inhibitors.

Inhibition of Group IVA Cytosolic Phospholipase A2by Novel 2-Oxoamides in Vitro, in Cells, and in Vivo

The Group IVA cytosolic phospholipase A(2) (GIVA PLA(2)) is a particularly attractive target for drug development because it is the rate-limiting provider of proinflammatory mediators. We previously reported the discovery of novel 2-oxoamides that inhibit GIVA PLA(2) [Kokotos, G.; et al. J. Med. Chem. 2002, 45, 2891-2893]. In the present work, we have further explored this class of inhibitors and found that the 2-oxoamide functionality is more potent when it contains a long 2-oxoacyl residue and a free carboxy group. Long-chain 2-oxoamides based on gamma-aminobutyric acid and gamma-norleucine are potent inhibitors of GIVA PLA(2). Such inhibitors act through a fast and reversible mode of inhibition in vitro, are able to block the production of arachidonic acid and prostaglandin E(2) in cells, and demonstrate potent in vivo anti-inflammatory and analgesic activity.

Triacylglycerols based on 2-(N-tert-butoxycarbonylamino)oleic acid are potent inhibitors of pancreatic lipase

A novel class of potent human pancreatic lipase (HPL) inhibitors was developed. Triacylglycerol analogues containing 2-(N-tert-butoxycarbonylamino) fatty acids were synthesized, and their ability to form stable films at the air/water interface was studied. The inhibition of human digestive lipases by the compounds synthesized was studied by the monolayer technique, and the triesters of glycerol and 2-methylglycerol with 2-(N-tert-butoxycarbonylamino)oleic acid were found to be potent inhibitors of HPL.

Sterically Hindered Triacylglycerol Analogues as Potent Inhibitors of Human Digestive Lipases

A novel class of inhibitors of human digestive lipases have been developed. Various sterically hindered triacylglycerols based on 2-methyl- and 2-butylglycerol, and/or 2-methyl fatty acids were synthesized. The triacylglycerol analogues were tested for their ability to form stable monomolecular films at the air/water interface by recording their surface-pressure/molecular-area compression isotherms. The inhibition of human pancreatic and gastric lipases by the sterically hindered triacylglycerol analogues was studied by using the monolayer technique with mixed films of 1,2-dicaprin, which contained variable proportions of each inhibitor. Triolein analogues that contain a butyl group at the 2-position of the glycerol backbone or methyl groups both at the 2-position of glycerol, and the alpha-position of each oleic acid residue were potent inhibitors; this caused a 50% decrease in HPL activity at 0.003 molar fraction.

Synthesis and use of N, N-di-Boc-glutamate gamma-semialdehydes and related aldehydes

This review article focuses on the synthesis and reactions of N, N-di-Boc glutamate and aspartate semialdehydes as well as related aldehydes. These building blocks are prepared according to various strategies from glutamic and aspartic acids and find interesting synthetic applications. In the first part, the methods for the synthesis of N, N-di-Boc-amino aldehydes are summarized. The applications of these chiral synthons for the synthesis of unnatural amino acids and other bioactive compounds are discussed in the second section.

Synthesis and In vivo anti-inflammatory activity of long-chain 2-amino-alcohols

The synthesis of optically pure long-chain 2-amino-alcohols and 1-O-dodecyl-2-deoxy-2-amino-sn-glycerol was carried out starting from L- or D-Boc-Ser(OBn)-ol by oxidation and consecutive Wittig reaction or etherification reaction. 2-Amino-oleyl alcohol was synthesized by reduction of the corresponding 2-amino-oleic acid. All the long chain amino-alcohols presented interesting inhibition of carrageenin-induced paw edema in rats (ED(50) from 0.017 to 0.010 mmol/kg).

Novel 2-oxoamide inhibitors of human group IVA phospholipase A(2)

A novel class of potent human cytosolic phospholipase A(2) (GIVA PLA(2)) inhibitors was developed. These inhibitors were designed to contain the 2-oxoamide functionality and a free carboxyl group. Among the compounds tested, a long-chain 2-oxoamide containing L-gamma-norleucine was the most potent inhibitor, causing a 50% decrease in GIVA PLA(2) activity at 0.009 mole fraction.

Synthesis of (S)-alpha-amino oleic acid

An efficient synthesis of (S)-alpha-amino oleic acid was developed. The fully protected FA derivative was obtained in four steps starting from methyl (2S)-2-[bis(tert-butoxycarbonyl)amino]-5-oxopentanoate. These steps are (i) olefination of the starting aldehyde with the appropriate phosphonate anion, (ii) hydrogenation of the double bonds, (iii) controlled reduction of omega-ethyl ester to an aldehyde in the presence of alpha-methyl ester, and (iv) a Wittig reaction of the latter aldehyde with the suitable ylide. Free alpha-amino oleic acid was prepared after deprotection of the amino group followed by saponification in a total yield of 24%. N-tert-Butoxycarbonyl-protected amino oleic acid and the corresponding amino alcohol were prepared in high yield. The structures of the products have been established by various spectroscopic techniques.

Synthesis of enantiopure non-natural alpha-amino acids using tert-butyl (2S)-2-[bis-(tert-butoxycarbonyl)amino]-5-oxopentanoate as key-intermediate:the first synthesis of(S)-2-amino-oleic acid

A general method for the synthesis of enantiopure non-natural alpha-amino acids is described. The key intermediate tert-butyl (2S)-2-[bis(tert-butoxycarbonyl)amino]-5-oxopentanoate was obtained from l-glutamic acid after suitable protection and selective reduction of the gamma-methyl ester group by DIBALH. Wittig reaction of this chiral aldehyde with various ylides led to a variety of delta,epsilon-unsaturated alpha-amino acids. This methodology was applied to the synthesis of (S)-2-amino-oleic acid.

Synthesis and in vitro cytotoxicity of novel long chain busulphan analogues

Two novel long chain alkanediol dimethanesulphonates, analogues of busulphan, were synthesized. Their in vitro cytotoxicity was evaluated against six solid tumor cell lines (A2780, H322, LL, WiDr, C26-10 and UMSCC-22B). 2-Tetradecylbutane-1,4-diol dimethanesulphonate was proved to be the most active compound exhibiting IC50 values between 20.82 and 26.36 microM.

Inhibition of lipoprotein lipase by alkanesulfonyl fluorides

A number of alkanesulfonyl halides (chlorides and fluorides) and esters were synthesized and their effect on the activity of lipoprotein lipase (LPL) was studied. Sulfonyl fluorides proved to be efficient inhibitors of LPL when the enzyme was incubated with a 10-fold molar excess of the inhibitors in a buffer containing bile salts (deoxycholate). Hexadecane- and dodecanesulfonyl fluorides caused 50% inhibition of LPL activity at concentrations of 10 to 20 microM.

Synthesis and study of a lipophilic alpha-keto amide inhibitor of pancreatic lipase

[reaction: see text] A lipophilic alpha-keto amide, inhibitor of pancreatic lipase, was synthesized using a lipidic 2-amino alcohol as backbone. The chiral key intermediate 2-(tert-butyloxycarbonylamino)-D-undecen-5-ol was synthesized starting from D-glutamic acid. The inhibitor formed a stable monomolecular film at the air/water interface as shown by a force/area curve. Inhibition studies using the monomolecular film technique with mixed films of 1,2-dicaprin containing variable proportions of the inhibitor showed a 50% decrease in lipase activity at a 0.14 molar fraction.

Synthesis of optically active lipidic alpha-amino acids and lipidic 2-amino alcohols

Lipidic alpha-amino acids (LAAs) are a class of compounds combining structural features of amino acids with those of fatty acids. They are non-natural alpha-amino acids with saturated or unsaturated long aliphatic side chains. Synthetic approaches to optically active LAAs and lipidic 2-amino alcohols (LAALs) are summarized in this review. A general approach to enantioselective synthesis of saturated LAAs is based on the oxidative cleavage of 3-amino-1,2-diols obtained by the regioselective opening of enantiomerically enriched long chain 2,3-epoxy alcohols. Unsaturated LAAs are prepared in their enantiomeric forms by Wittig reaction via methyl (S)-2-di-tert-butoxycarbonylamino-5-oxo-pentanoate. This key intermediate aldehyde is obtained by selective reduction of dimethyl N,N-di-Boc glutamate with DIBAL. (R) or (S) LAALs may be prepared starting from D-mannitol or L-serine. LAAs are converted into LAALs by chemoselective reduction of their fluorides using sodium borohydride with retention of optical purity. Replacement of the hydroxyl group of LAALs by the azido group, followed by selective reduction leads to unsaturated optically active lipidic 1,2-diamines.

Synthesis, in vitro cytotoxicity and in vivo anti-inflammatory activity of long chain 3-amino-1,2-diols

The synthesis of long chain 3-amino-1,2-diols was carried out based on Sharpless asymmetric epoxidation of long chain allylic alcohols and regioselective nucleophilic ring opening by azido group. The in vitro cytotoxicity of the compounds prepared was evaluated against six solid tumor cell lines (A2780, H322, LL, WiDr, C26-10, UMSCC-22B). Free 3-amino-1,2-diols exhibited IC50 values between 1.45 microM and 32 microM. These compounds also presented interesting inhibition of carrageenin-induced paw edema in rats (85.3% - 79.6% at a concentration of 0.15 mmol/kg).

Synthetic routes to lipidic diamines and amino alcohols: a class of potential antiinflammatory agents

Simple and efficient methods for the synthesis of lipidic amino alcohols and diamines are described in this paper. Lipidic 2-amino alcohols and 1,3-diamines can be synthesized starting from synthetic lipidic alpha-amino acids. Alternatively, commercially available lipidic 1,2-diols may be used as starting material for the synthesis of 2-amino alcohols. Initial experiments on the in vivo antiinflammatory activity of the compounds synthesized gave promising results.

Synthesis and in vitro cytotoxicity of lipidic alcohols and amines

General methods for the conversion of unsaturated fatty acids into alcohols and amines and the preparation of lipidic 1,2-diamines were developed. The in vitro cytotoxicity of the synthetic lipidic compounds was tested against two different cell lines (P388 and NSCLCN6). Oleyl amine was the most active among the lipidic alcohols and monoamines. However, the saturated lipidic 1,2-hexadecanediamine exhibited the highest cytotoxicity (IC50 0.1 microgram/ml and 1.1 micrograms/ml).

Mass spectrometric studies on the fragmentation and structural characterization of aminoacyl derivatives of kanamycin A

Described herein are the fragmentation pathways of kanamycin A and its 6'-N- and 1-N-acyl derivatives, as well as the determination of their positional isomers by FABMS and ESIMS in combination with tandem mass spectrometry. The presence or absence of key ions and the difference in abundance of common ions are correlated with the position of the substitution.

Synthesis and in vitro cytotoxicity of lipophilic platinum(II) complexes

A number of lipophilic platinum(II) complexes of the general structures cis-[Pt(LA)2Cl2] and [Pt(LD)Cl2] were synthesised. Long chain amines (LA) and diamines (LD), prepared from lipidic amino acids, were used as ligands. The in vitro cytotoxicity of the complexes was evaluated against four cell lines (P388, NSCLC-N6, E39, M96). cis-Dichloro-bis(2-aminohexadecanol)platinum(II) was the most active against P388, NSCLC-N6 and E39 (IC50: 11 micrograms/ml, 25 micrograms/ml, 31 micrograms/ml), while dichloro(1,3-heptadecanediamine)platinum(II) presented the highest activity against M96 (IC50: 13 micrograms/ml).

Synthesis and properties of novel lipopeptides and lipid mimetics

Lipid mimetics, synthetic molecules that resemble natural lipids either structurally or functionally, have been developed as potential medicinal substances. They have been successfully applied in the development of drug and peptide delivery systems and for the development of inhibitors or lipid metabolizing enzymes. Phospholipase A2 is considered to be involved as the rate-limiting step in the production of lipid mediators of inflammatory responses and, as such, it has been a target for drug design. A series of lipid mimetics including lipopeptides, amides and alcohols of lipidic alpha-amino acids, have been tested by bulk and monolayer assay techniques. The findings suggested the direct interaction of the tested compounds with porcine pancreatic phospholipase A2. The inactivation of the enzyme occurred in a competitive manner. The most active compound I (2-amino-N-hexadecyl-L-hexanamide) showed an apparent IC50 of 12 microM and inhibitory power Z = 13 in the monolayer assay.