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IMPORTANCE: Sorsby fundus dystrophy is a typically adult-onset maculopathy with high risk for choroidal neovascularization. Sorsby fundus dystrophy, inherited as an autosomal dominant fully penetrant trait, is associated with TIMP3 variants that cause protein aggregation in the extracellular matrix. OBJECTIVE: To evaluate the phenotype and underlying biochemical mechanism of disease-causing TIMP3 variants altering the N-terminal signal peptide in 2 families who have early-onset diffuse maculopathy without choroidal neovascularization with cosegregation of TIMP3 variants in the signal peptide sequence. DESIGN, SETTING, AND PARTICIPANTS: This case series of 2 families with early-onset diffuse maculopathy was conducted at the National Eye Institute, National Institutes of Health Clinical Center. Data were collected and analyzed from October 2009 to December 2021. MAIN OUTCOMES AND MEASURES: Clinical imaging and molecular genetic testing were performed in 2 families with macular dystrophy. Cosegregation analysis of TIMP3 variants was performed in affected and unaffected family members. Candidate TIMP3 signal peptide variants were assessed for cleavage defects after transfection. RESULTS: Eleven individuals from 2 families with early-onset diffuse maculopathy without choroidal neovascularization harbor TIMP3 variants (L10H or G12R) in the N-terminal signaling peptide were analyzed. Cosegregation with phenotype was confirmed in additional family members. Biochemical analysis confirmed defects in both protein maturation and extracellular deposition. CONCLUSIONS AND RELEVANCE: This study found that TIMP3 variants altering signal peptide function deviated from classic Sorsby fundus dystrophy both in phenotypic features and underlying mechanism. These results suggest atypical patient presentations are caused by TIMP3 signal peptide defects, associated with impaired cleavage and deposition into the extracellular matrix, implicating a novel macular dystrophy disease.

There has been much interest in obtaining crystals for crystallographic analysis of biologically active glucosinolates. Crystals of potassium (2,3-dichlorophenyl)glucosinolate were obtained as a dual solvate, containing one methanol and one ethanol molecule of crystallization, K+·C13H14Cl2NO9S2−·CH3OH·C2H5OH. The three-dimensional polymeric network consists of chains containing the potassium ions coordinated and bridged by sugar O atoms, which run parallel to theaaxis and are further crosslinked through the sugar molecules. The channels of this network are occupied by the dichlorophenyl substituents and the ethanol and methanol solvent molecules. The structure of theS-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-2,3-dichlorophenylacetothiohydroxymate, C21H23Cl2NO10S, precursor has also been determined and the β-configuration andZisomer of the thiohydroximate substituent is confirmed.

We report a new strategy to develop low molecular weight (18–28 kDa) poly(N-acryloylmorpholine) (PNAM) polymers as bivalent inhibitors of cholera toxin (CT) using Reversible Addition–Fragmentation chain Transfer (RAFT) technology. The inhibitory activity of the galacto-conjugated polymers was examined (ELISA) and the series displayed moderate inhibitory activity (millimolar IC50).

A total synthesis of (R,S)S-glucoraphanin (GRP) has been completed by a novel, simple and convenient method in high overall yield (17% over seven steps). The study describes a method for the synthesis of natural and unnatural (methylsulfinyl)alkyl glucosinolates (GLs) and also opens useful pathways to synthesize GRP as well as other sulfinyl GLs.

The 4-substituted-1,3-oxazinan-6-one scaffold is a versatile synthon enabling access to a diverse array of β-amino acid derivatives. In this study, the synthetic utility of the 1,3-oxazinan-6-one is expanded to include the diastereoselective synthesis of cyclic β2,3-amino acids. Enolate chemistry is used to first alkylate the 4-vinyl, 4-allyl, and 4-butenyl oxazinan-6-ones with various alkenyl electrophiles, in high dr. The resulting 4,5-bis-alkene adducts are then transformed into 4,5-cyclic-1,3-oxazinan-6-ones utilizing the ring closing metathesis reaction. The metathesis products are subsequently converted into a variety of five-, six-, and seven-membered cyclic β2,3-amino acids. The research further highlights the 1,3-oxazinan-6-one as a versatile synthon for producing β-amino acid derivatives.

Stereoselective synthesis of N-Cbz-substituted β-amino ketones exploiting the versatile 1,3-oxazin-6-one scaffold is reported. The 4-substituted 1,3-oxazinan-6-ones were enolized and acylated diastereoselectively by addition of various acyl halides. Acidic decarboxylation was then employed to smoothly transform the 5-acylated products to chiral β-amino ketones. This methodology further highlights the utility of the 1,3-oxazinan-6-one as a scaffold to access valuable synthons that are used in the peptidomimetic field.

Current methods of homologation of α-amino acids to β-amino acids have limitations. To overcome these shortfalls the Nef reaction has been utilized in the multistep synthesis of β3-amino acids from α-amino acids. In this approach, N-protected amino aldehydes, easily accessed from α-amino acids, were transformed into the N-protected γ-amino nitroalkanes. The Nef reaction was then used to smoothly convert the nitroalkanes into the corresponding N-protected β3-amino acids without notable racemization.

Oxazinan-6-ones were used to generate substituted b 2,2,3 -substituted amino acid derivatives. The enolates of 1,3-oxazinan-6-ones were trans-selectively intercepted with electrophiles. This alkylation was subsequently optimized for a one-pot dialkylation to form 5,5-disubstituted oxazinanones. The initial 5-monomethylated compounds could be enolized and then diastereoselectively intercepted with different electrophiles to form differentially 5,5-disubstituted products. The 5,5-dialkylated ox- azinanones were then transformed to N-methyl b 2,2,3 -substituted amino acids by reductive cleavage. Hydrolysis or solvolysis of the oxazinanones afforded b 2,2,3 -substituted amino acids or esters, re- spectively. The chemistry thus provides access to a range of symmetrical and stereopure b 2,2,3

Highly stereoselective consecutive or tandem Michael (MIMI) reactions are reported. A variety of initial nucleophiles react with chiral acylated 1,3-oxazolidin-2-ones to generate a reactive enolate. The enolate then reacts stereoselectively with a second equivalent of the acylated 1,3-oxazolidin-2-one to afford ‘dimeric’ adducts. The adducts have three new contiguous stereogenic centers formed with a high level of control. Single crystal X-ray crystallographic analysis confirmed this controlled formation of novel tandem acyclic conjugate addition or MIMI products in several examples.

We report the crystal structures of two galactosylacetylenes: 3,7-anhydro-4,5,6,8-tetra-O-benzyl-1,1,2,2-tetradehydro-1,2-dideoxy-1-C-(trimethylsilyl)-D-glycero-L-mannooctitol (7) and 3,7-anhydro-4,5,6,8-tetra-O-benzyl-1,1,2,2-tetradehydro-1,2-D-glycero-L-mannooctitol (8). A short overview of the synthetic chemistry used to obtain these targets is mentioned.

We report on the discovery of 3-alkylthio-1,2,4-triazine dimers that are potently toxic to Plasmodium falciparum, with single digit nanomolar activity, and up to several thousand-fold lower toxicity to mammalian cells. They are equipotent against chloroquine-resistant strains of P. falciparum.

β-Amino acids might be regarded as the building blocks that nature overlooked. Although seldom used in nature, scientists have recognized the importance of β-amino acids in the design of many molec...

N-But-3-enyl-α- and β-amino acids can be prepared by cleaving 1,3-oxazolidin-5-ones and 1,3-oxazinan-6-ones in the presence of allylsilanes and boron trifluoride etherate at room temperature in good to excellent yields.

1,3-Oxazolidin-5-ones and 1,3-oxazinan-6-ones have been shown to be useful precursors for the synthesis of N-methyl α- and β-amino acids, respectively. The methodology has now been expanded to allow for the synthesis of N-alkyl-β-amino acids.

Apical membrane antigen-1 is a protein found in the merozoite stage of the malaria parasite Plasmodium falciparum and has been shown to be critical in the invasion of host erythrocytes. Using a random peptide library displayed on the surface of phage, a 20-residue peptide, R1 (VFAEFLPLFSKFGSRMHILK), was identified which specifically recognized and bound to P. falciparum AMA-1. Moreover, the peptide was found to competitively inhibit parasite invasion of red blood cells (RBC). In this study we report the synthesis and properties of the R1 peptide modified by comprehensive N-methyl scanning along the backbone of the peptide. The native R1 and eighteen R1 analogues containing single N-methyl substitutions were synthesized by manual solid-phase Fmoc peptide chemistry. The set of N-methylated peptides was assessed for relative binding affinity with Pf AMA-1 and RBC invasion inhibitory ability. N-methylation in positions 1, 8, and 14 in the R1 peptide produced analogues exhibiting stronger binding characteristics to Pf AMA-1. A tri N-methylated peptide was more than 10 times more active in the inhibition of RBC invasion assay. This peptide also exhibited enhanced serum stability which may be partially responsible for the increase in binding and bioactivity. We have therefore shown that modifications to a biologically active peptide can dramatically enhance activity and potentially provide a lead to a peptide therapeutic molecule with optimized pharmacokinetic properties.

Marine microorganisms and fungi are sources of cyclopeptides and cyclodepsipeptides that have numerous biological activities including antifungal, immunosuppressive, and anticancer. Some have been through clinical trials including didemnin B discussed in this review. These interesting properties of cyclopeptides and cyclodepsipeptides have resulted in a huge increase in research activity in the last few years. In this review, discussion of four families and some miscellaneous cyclopeptides and cyclodepsipeptides is presented. Aureobasidins (Abs) are the first group discussed. The isolation protocol of the Abs from the yeast-like fungus, Aureobasidium pullulans, structural characterization, and synthetic efforts, particularly for the most active antifungal derivative, AbA, is outlined. In addition to this, the biological activities of Abs including their mode of action are considered explaining the importance of the unnatural amino acids including β-OHMeVal, largely responsible for their antifungal activity. The second part of the review discusses the cyclosporin cyclopeptide family. The review on this family covers the isolation of the compounds, the classification, the structural assignments, the biological activities, and also the synthetic attempts concerned with cyclosporins. Cyclosporins from Tolypocladium inflatum are a family of cycloundecapeptide with hindered N-methylated residues similar to the Abs with an unusual amino acid, MeBmt, found as a characteristic feature of the cyclosporin structure. This family has a narrow antifungal activity and an excellent immunosuppressive property accounting for its use in the clinic. Its immunosuppressant properties are unique with narrow therapeutic actions that make this group most interesting. Dolastatins are a family of compounds isolated from the sea hare Dollabella auricularia consisting of various natural products including unusual peptides, depsipeptides, cyclopeptides, and also cyclodepsipeptides. In this review, the discussion is limited to the cyclopeptides and the cyclodepsipeptides of the dolastatin family, which possess cytotoxic, antineoplastic, and anticancer properties. Efforts toward the preparation of the cyclic dolastatins, as well as structural characteristics of the cyclic dolastatins, are highlighted that are important for biological activity. The last group discussed is the cyclohexadepsipeptidic didemnins. This section also discusses the isolation, classification, characterization, biological activity, and synthesis of the didemnins. Didemnins are a family of cyclodepsipeptides with a side-chain structural feature that has raised a lot of interest particularly in the case of didemnin B having been the first marine secondary metabolite entering clinical trials as an anticancer agent. Syntheses of didemnins are discussed. The presence of side chain in the didemnins makes the synthetic attempts an interesting discussion point not to mention the impressive biological activities of the didemnins. The discussion on Abs, cyclosporins, dolastatins, and the didemnins shows the importance of the cyclopeptides and the cyclodepsipeptide as sources of biologically active secondary metabolites. Access to these compounds and their analogs may help in the design of more powerful or potent natural products as candidates for drug development.

N-Methyl β-amino acids are generally required for application in the synthesis of potentially bioactive modified peptides and other oligomers. Previous work highlighted the reductive cleavage of 1,3-oxazolidin-5-ones to synthesise N-methyl α-amino acids. Starting from α-amino acids, two approaches were used to prepare the corresponding N-methyl β-amino acids. First, α-amino acids were converted to N-methyl α-amino acids by the so-called ‘1,3-oxazolidin-5-one strategy’, and these were then homologated by the Arndt–Eistert procedure to afford N-protected N-methyl β-amino acids derived from the 20 common α-amino acids. These compounds were prepared in yields of 23–57% (relative to N-methyl α-amino acid). In a second approach, twelve N-protected α-amino acids could be directly homologated by the Arndt–Eistert procedure, and the resulting β-amino acids were converted to the 1,3-oxazinan-6-ones in 30–45% yield. Finally, reductive cleavage afforded the desired N-methyl β-amino acids in 41–63% yield. One sterically congested β-amino acid, 3-methyl-3-aminobutanoic acid, did give a high yield (95%) of the 1,3-oxazinan-6-one (65), and subsequent reductive cleavage gave the corresponding AIBN-derived N-methyl β-amino acid 61 in 71% yield (Scheme 2). Thus, our protocols allow the ready preparation of all N-methyl β-amino acids derived from the 20 proteinogenic α-amino acids.

A series of orthogonally protected 1,4-disubstituted-1,2,3-triazoles were prepared from the corresponding alkynols and trialkylsilyl-propargyl azides via 1,3-dipolar cycloaddition. These cycloadducts were selectively deprotected and extended in a stepwise fashion via further ‘click’ reactions to form oligomeric peptidomimetic compounds. This methodology gives access to triazole-based peptidomimetics in a controlled fashion and lays the foundation for a fragment-based approach to drug discovery.

Protonated threonine and its allo diastereomer exhibit different proportions of collisionally activated dissociation (CAD) product ions. N-Methylation attenuates these differences. Water loss from protonated allo-threonine gives protonated trans-3-methylaziridinecarboxylic acid via an internal S(N)2 pathway, rather than protonated vinylglycine.

A water-soluble oxonol dye containing a reactive hydroxysuccinimidyl ester suitable for reaction with biomolecules has been prepared. This fluorescent compound has 631 nm, eabs 147,000 M−1 cm−1, 659 nm, and quantum yield 0.30.

[2S,3S-Hmp]-Aureobasidin L 2 has been successfully synthesised through a combination of solution- and solid-phase peptide synthesis. All of the Fmoc-protected residues including a depsidipeptide, Fmoc-MeVal-Hmp-OH, were prepared in solution phase. Chain elongation on chlorotrityl resin was undertaken using selected coupling reagents including HBTU/HOBt, HATU/HOAt and BTC/collidine. Cleavage of the linear depsinonapeptide was followed by cyclisation to give the desired cyclodepsipeptide.

The far red region of the spectrum is increasingly being utilised in many applications in the biosciences. However, apart from the cyanine group of dyes, there are relatively few far red fluorescent probes available which are of practical use. We have synthesised and characterised a new class of far red fluorescent probes based on the perylene dione chromophore. The 2,10 di-substituted perylene diones possess broad absorption spectra (>90 nm bandwidths), large Stokes shifts (>60 nm) and quantum yields of up to 0.5 with a maximum absorption at 610–640 nm in organic solvents or in solutions of non-ionic detergents. A number of derivatives have been synthesised that can be used as membrane probes, as chromogenic substrates for alkaline phosphatase, and for the labelling of macromolecules such as proteins and DNA. These novel far red fluorophores have potential applications in diagnostic and research applications.

We report on novel 3-arylamino-6-benzylamino-1,2,4,5-tetrazines with potent activity against Plasmodium falciparum.

A novel trypsin inhibitor was extracted from the seeds of Cassia fistula by a process successively involving soaking seeds in water, extraction of the seeds in methanol, and extraction of the cell wall material at high ionic strength. The protease inhibitor (PI) was subsequently purified by chromatography on carboxymethylcellulose, gel filtration and reversed phase HPLC (RP-HPLC). Electrospray ionization mass spectrometry (ESMS) of the oxidized from of the PI yielded an average molecular mass of 5458.6±0.8 Da. Edman sequencing of the PI yielded a full-length 50 amino acid sequence inferred to contain eight cysteines and with a calculated average molecular mass (fully oxidized form) of 5459.3 Da, in agreement with the observed mass. The C. fistula seed PI is homologous to the family of plant defensins (γ-thionins), which have four disulfide linkages at highly conserved locations. The C. fistula PI inhibits trypsin (IC 50 2 μM), and is the first known example of a plant defensin with protease inhibitory activity, suggesting a possible additional function for some members of this class of plant defensive proteins. C. fistula seeds also contain a 9378 Da lipid transfer protein (LTP) homologue, other LTPs, a 7117 Da protein copurifying with PI activity and a 5144 Da defensin which does not inhibit trypsin. The complete sequence of the 5144 Da defensin was determined by Edman sequencing, yielding a calculated average molecular mass (oxidized form) of 5144.1 Da, in agreement with the mass observed by ESMS. The likely trypsin inhibitory residue on the 5459 Da defensin is Lysine-25, the corresponding amino acid being Tyrosine-25 in the homologous 5144 Da defensin that is not a trypsin inhibitor.

The synthesis of fluorescent 2,10-derivatives of the title chromophore are described. The substituents contain amino-reactive N-hydroxysuccinimde ester and thiol-reactive iodoacetamide groups for attachment to biomolecules. A phosphate derivative was also prepared as an enzyme substrate.

The nitronate and nitrovinyl methods to synthesize indole glucosinolates (GLs) have been investigated. The results were applied to generally the most prevalent natural indole glucosinolates to synthesize 4-methoxyglucobrassicin (MGB) and neo-glucobrassicin (NGB) in moderate overall yield for the first time. The anti-inflammatory activity of the synthetic indole GLs was determined by inhibition of TNF-α secretion in LPS-stimulated THP-1 cells. The data showed that glucobrassicin (GB) exhibited higher activity than other synthetic indolyl GLs.

The approach to the synthetically important chiral β-amino ketones involves diastereoselective acylation of 1,3-oxazinan-6-ones followed by acidic decarboxylation.

α-Amino acids (I) and (VII) are converted into chiral γ-amino nitroalkanes of type (V) in a three-step sequence.

Aromatic GLs are important members of the glucosinolate family of compounds because of their potential biological activity and medicinal properties. This study has shown success in the high yielding synthesis of some important aromatic GLs as well as the results of testing for anti-inflammatory properties of the synthetic GLs. 3,4-Dimethoxyphenylglucosinolate was found to be the most active anti-inflammatory of the seven glucosinolates assayed.

The enantioselective preparation of both enantiomers of a C2-symmetric diphenyl-bi-dihydropyran 3 and 4 is described. The application of enantiopure bi-dihydropyrans 1 – 4 towards the simultaneous enantioselective differentiation and regioselective protection of a range of cyclic and acyclic symmetrical polyols (23, 37, 43, 45, 54, 61 and 66) is investigated. Several deprotections utilising trifluoroacetic acid (TFA) and a transketalisation with acidic glycerol are presented.

The title compound, C38H35NO4, was isolated as one of two diastereoisomeric products. The mol­ecule was found to have trans-configured n-nonyl and methyl substituents on the 5-oxazolidinone ring, the S configuration being assigned to C4 with reference to l-alanine. The n-nonyl group is fully extended and the oxazolidinone ring adopts a half-chair conformation.

Oxazinan-6-ones were used to generate substituted b 2,2,3 -substituted amino acid derivatives. The enolates of 1,3-oxazinan-6-ones were trans-selectively intercepted with electrophiles. This alkylation was subsequently optimized for a one-pot dialkylation to form 5,5-disubstituted oxazinanones. The initial 5-monomethylated compounds could be enolized and then diastereoselectively intercepted with different electrophiles to form differentially 5,5-disubstituted products. The 5,5-dialkylated ox- azinanones were then transformed to N-methyl b 2,2,3 -substituted amino acids by reductive cleavage. Hydrolysis or solvolysis of the oxazinanones afforded b 2,2,3 -substituted amino acids or esters, re- spectively. The chemistry thus provides access to a range of symmetrical and stereopure b 2,2,3

This study analyzed repeated methylphenidate (MPH) administration and its effects on brain-derived neurotrophic factor (BDNF) in the dorsal striatum and nucleus accumbens of male and female adolescent rats. In Experiment 1, rats were administered intraperitoneal (ip) saline, 1, 3, or 5 mg/kg dose of MPH every second day from postnatal day (P)33–P49. Locomotor activity was analyzed for 10 min after each administration. Results revealed that the 1 mg/kg dose of MPH produced locomotor suppression, however, the 5 mg/kg dose of MPH produced locomotor sensitization and robust behavioral activation in females as compared to males. In Experiment 2, animals were administered ip saline or the 5 mg/kg dose of MPH using an identical regimen but a 30 min behavioral test was employed. Dorsal striatum and nucleus accumbens tissue was assayed for BDNF at P50. Females demonstrated sensitization to MPH and increased locomotor activation compared to males. Interestingly, females given MPH demonstrated a significant 42% decrease of striatal BDNF whereas males administered MPH demonstrated a significant 50.4% increase of striatal BDNF compared to controls. There were no effects on accumbal BDNF. This report demonstrates robust sex differences in the behavioral response, but sex-dependent changes in striatal BDNF in response to MPH in adolescence.

Various parameters in the reaction of ethyl bromobenzoate with HOMSi reagents (II) are optimized.

The formation of 1,8,13,16-tetraoxadispiro[5.0.5.4]hexadecanes (dispiroketals) of various D-glucopyranosyl substrates is described.

A new process for the efficient regioselective formation of 1,8,13,16-tetraoxadispiro[5.0.5.4]hexadecanes (dispiroketals) of various D-glucopyranosyl substrates by the chiral recognition of enantiomeric trans 1,2-diol relationships is described. This was achieved using the novel enantiomerically pure 2,2′-disubstituted 3,3′,4,4′-tetrahydro-6,6′-bi-2 H -pyrans 1 , 2 and 11 . New conditions for the removal of dispiroketal protecting groups are presented.

[reaction: see text] N-Methyl amino acid residues in peptides modify several pharmacologically useful parameters, but synthesis of alkylated peptides is hampered by unavailability of N-methylated monomers. The syntheses of four N-methyl amino acids with basic side chains are presented. The side chains of these basic amino acids needed to be specially protected or constructed. This completes the set of 20 common L-amino acid N-methyl derivatives prepared via 5-oxazolidinone intermediates by our group.

We report the synthesis of a series of bivalent 1,2,3-triazole linked galactopyranosides as potential inhibitors of cholera toxin (CT). The inhibitory activity of the bivalent series was examined (ELISA) and the series showed low inhibitory activity (millimolar IC(50)s). Conversely, the monomeric galactotriazole analogues were strong inhibitors of cholera toxin (IC(50) = 71-75 μM).

We report the solid-phase total synthesis of the antifungal highly modified cyclic depsipeptide petriellin A. The synthesis confirms earlier reports on the absolute configuration of the natural product. The solid-phase approach resulted in a protected linear precursor, which was cleaved from the solid support prior to cyclization and final deprotection. Use of advanced coupling agents for several hindered amides was a feature of the synthesis. The natural product was prepared in overall 5% yield.

The new azides (IX) and alcohols such as (X) are coupled by Huisgen 1,3-dipolar cycloaddition to give chiral 1,4-disubstituted triazole derivatives.

Whereas the oxidative cleavage of bicyclic isoxazolidines 5 (2-phenylperhydroisoxazolo[2,3-a]pyridine) and 9 (6-(2-benzyloxyethyl)- 8 -(3-phenylsulfonylpropyl)-7 -oxa-1-azabicyclo-[3.2.1]octane) with magnesium monoperoxyphthalate (MMPP) significantly favours the formation of the more substituted tetrahydropyridine N-oxides, 3-chloroperoxybenzoic acid (mCPBA) is shown to favour the less substituted nitrone 10 in reaction with the more substituted isoxazolidine 9.