Bioadhesive Polymeric Films Based on Red Onion Skins Extract for Wound Treatment: An Innovative and Eco-Friendly Formulation.

The onion non-edible outside layers represent a widely available waste material deriving from its processing and consumption. As onion is a vegetable showing many beneficial properties for human health, a study aiming to evaluate the use of extract deriving from the non-edible outside layers was planned. An eco-friendly extraction method was optimized using a hydroalcoholic solution as solvent. The obtained extract was deeply characterized by in vitro methods and then formulated in autoadhesive, biocompatible and pain-free hydrogel polymeric films. The extract, very soluble in water, showed antioxidant, radical scavenging, antibacterial and anti-inflammatory activities, suggesting a potential dermal application for wounds treatment. In vitro studies showed a sustained release of the extract from the hydrogel polymeric film suitable to reach concentrations necessary for both antibacterial and anti-inflammatory activities. Test performed on human keratinocytes showed that the formulation is safe suggesting that the projected formulation could be a valuable tool for wound treatment.

λ5-Phosphorus-Containing α-Diazo Compounds: A Valuable Tool for Accessing Phosphorus-Functionalized Molecules.

The compounds characterized by the presence of a λ5-phosphorus functionality at the α-position with respect to the diazo moiety, here referred to as λ5-phosphorus-containing α-diazo compounds (PCDCs), represent a vast class of extremely versatile reagents in organic chemistry and are particularly useful in the preparation of phosphonate- and phosphinoxide-functionalized molecules. Indeed, thanks to the high reactivity of the diazo moiety, PCDCs can be induced to undergo a wide variety of chemical transformations. Among them are carbon-hydrogen, as well as heteroatom-hydrogen insertion reactions, cyclopropanation, ylide formation, Wolff rearrangement, and cycloaddition reactions. PCDCs can be easily prepared from readily accessible precursors by a variety of different methods, such as diazotization, Bamford-Stevens-type elimination, and diazo transfer reactions. This evidence along with their relative stability and manageability make them appealing tools in organic synthesis. This Review aims to demonstrate the ongoing utility of PCDCs in the modern preparation of different classes of phosphorus-containing compounds, phosphonates, in particular. Furthermore, to address the lack of precedent collective papers, this Review also summarizes the methods for PCDCs preparation.

Hydrophobic Amino Acid Content in Onions as Potential Fingerprints of Geographical Origin: The Case of Rossa da Inverno sel. Rojo Duro.

In this study, we were interested in comparing the amino acid profile in a specific variety of onion, Rossa da inverno sel. Rojo Duro, produced in two different Italian sites: the Cannara (Umbria region) and Imola (Emilia Romagna region) sites. Onions were cultivated in a comparable manner, mostly in terms of the mineral fertilization, seeding, and harvesting stages, as well as good weed control. Furthermore, in both regions, the plants were irrigated by the water sprinkler method and subjected to similar temperature and weather conditions. A further group of Cannara onions that were grown by micro-irrigation was also evaluated. After the extraction of the free amino acid mixture, an ion-pairing reversed-phase (IP-RP) HPLC method allowed for the separation and the evaporative light scattering detection of almost all the standard proteinogenic amino acids. However, only the peaks corresponding to leucine (Leu), phenylalanine (Phe), and tryptophan (Trp), were present in all the investigated samples and they were unaffected from the matrix interfering peaks. The use of the beeswarm/box plots revealed that the content of Leu and Phe were markedly influenced by the geographical origin of the onions (with *** p.

Antioxidant activity of phenolic extracts from different cultivars of Italian onion (Allium cepa) and relative human immune cell proliferative induction.

CONTEXT: The total antioxidant activity (TAC) may vary considerably between onion cultivars. Immunological effects of onion phenolic compounds are still underestimated. OBJECTIVE: The objective of this study is to determine the total phenol content (TPC) and the relative TAC of three Allium cepa L. (Liliaceae) onion cultivars cultivated in Cannara (Italy): Rossa di Toscana, Borettana di Rovato, and Dorata di Parma, and to evaluate the phenol extracts ability to induce human immune cell proliferation. MATERIALS AND METHODS: TPC was determined by the Folin-Ciocalteu method, TAC with FRAP, TEAC/ABTS, and DPPH methods. Peripheral blood mononuclear cells from healthy human donors were incubated for 24 h at 37 °C with 1 ng/mL of phenolic extract in PBS, immunostained, and then analyzed by 4-color flow cytometry for the phenotypic characterization of T helper cells (CD4+ cells), cytotoxic T lymphocytes (CD8+ cells), T regulatory cells (CD25high CD4+ cells), and natural killer cells/monocytes (CD16+ cells). RESULTS: Rossa di Toscana displayed the highest TPC (6.61 ± 0.87 mg GA equivalents/g onion bulb DW) and the highest TAC with the experienced methods: FRAP, 9.19 ± 2.54 µmol Trolox equivalents/g onion bulb DW; TEAC/ABTS, 21.31 ± 0.41 µmol Trolox equivalents/g onion bulb DW; DPPH, 22.90 ± 0.01 µmol Trolox equivalents/g onion bulb DW. Incubation with Rossa di Toscana extract determined an increase in the frequency of the antitumor/anti-infection NK CD16+ immune cells (23.0 ± 0.4%). DISCUSSION AND CONCLUSIONS: Content of health-promoting phenols and the deriving antioxidant and immunostimulating activity vary considerably among the investigated cultivars. Rossa di Toscana can be considered as a potential functional food.

The effect of mobile phase composition in the enantioseparation of pharmaceutically relevant compounds with polysaccharide-based stationary phases.

Mobile phase variables have a deep influence on the chromatographic behavior with polysaccharide-based chiral stationary phases. Basic additives are generally used to minimize peak broadening arising from unwanted interactions between polar solutes and underivatized silanols. However, basic additives can improve enantioselectivity through disruption of hydrogen bonds and modification of the polymer morphology. Acidic additives are incorporated into the mobile phase during the analysis of acidic compounds as efficiency enhancers. Acidic additives can also improve enantioselectivity by minimizing within the chiral recognition site nonenantioselective retention. Peak shape without acidic additive in the eluent could be severely distorted during the analysis of salified compounds. Concentration and type of alcohol modifier can have an effect on the morphology of the polymer. The different winding of the chiral selector, caused by alcohol modifiers of different size/shape, ultimately results in different stereo environment of the chiral cavities in the polymer chain. Trace amounts of water in normal-phase eluents can affect retention time, tailing, and resolution. Deliberate addition of water to the eluent can improve peak resolution and save analysis time and solvent needs. Immobilized-type polysaccharide-derived chiral stationary phases offer new selectivity profiles and often improved enantioselectivity.

Asymmetric synthesis of the four diastereoisomers of a novel non-steroidal farnesoid X receptor (FXR) agonist: role of the chirality on the biological activity.

An asymmetric synthetic strategy was designed for the preparation of the four possible diastereoisomers of 3,6-dimethyl-1-(2-methylphenyl)-4-(4-phenoxyphenyl)-4,8-dihydro-1H-pyrazolo[3,4-e][1,4]thiazepin-7-one, a non-steroidal FXR agonist, we recently discovered following a virtual screening approach. The results obtained from an AlphaScreen assay clearly demonstrated that only the isomer endowed with 4R,6S absolute configuration is responsible for the biological activity. A deep investigation of the different putative binding modes adopted by these enantiomerically pure ligands using computational modeling studies confirmed the enantioselectivity of FXR towards this class of molecules.

Simultaneous diastereo- and enantioseparation of farnesoid X receptor (FXR) agonists with a quinine carbamate-based chiral stationary phase.

In the frame of a project aimed at finding non-steroidal farnesoid X receptor (FXR) agonists, we identified 4-(2,4-dimethoxyphenyl)-3,6-dimethyl-1-(2-tolyl)-4,8-dihydro-1H-pyrazole[3,4-e][1,4]thiazepin-7-one (1) as a hit endowed with FXR activity. Most of the compounds synthesised during the hit-to-lead optimisation work were characterised by the presence of two chiral centres and were therefore obtained as mixtures of anti(±)- and syn(±)-diastereoisomers. A restricted sub-set of species harboured with a carboxylic acid group on the distal phenyl ring of the biphenyl (a(±)5 (A1) and s(±)5 (S1)) or the phenoxyphenyl (a(±)6 (A2) and s(±)6 (S2)) moiety at C-4 position of the pyrazole[3,4-e][1,4]thiazepin-7-one core, resulted in suitable diastereo- and enantioresolution with a quinine (QN) carbamate-derived chiral stationary phase (CSP). Differently from the compounds usually analysed with QN-based CSPs, the couples A1/S1 and A2/S2 were atypical selectands, in which the two chiral carbon atoms reside at a remote position with respect to the carboxylic function, the main "point of attack" to the CSP. We produced evidence that the scarcely employed normal-phase (NP) eluent systems represent the elective choice for achieving the simultaneous diastereo- and enantioseparation of this class of compounds over the usually preferred reversed-phase (RP) and polar-organic (PO) modes of elution. Indeed, after the optimisation of the eluent composition, NP conditions allowed to obtain profitable enantioselectivity profiles, along with excellent diastereoselectivity levels (α(A1) = 1.07, R (S)(A1) = 1.15; α(S1) = 1.09, R (S)(S1) = 1.47; α(A2) = 1.08, R (S)(A2) = 1.31; and α(S2) = 1.06, R (S)(S2) = 1.18). The optimised NP methods are suitable for simultaneously providing information on the diastereo- and enantiopurity of the investigated compounds.

Identification of oxysterol synthetic analogs as a novel class of late-stage inhibitors of herpes simplex virus 2 replication.

Genital herpes, most frequently caused by herpes simplex virus 2 (HSV-2) infection, is one of the most prevalent sexually transmitted infections. The current rationale for the treatment of HSV-2 infection involves nucleoside analogs (e.g. acyclovir) to suppress reactivation. Enzymatic oxysterols are endogenous 27-carbon atoms molecules produced by enzymatic cholesterol oxidation, and recently emerged as a broad-spectrum host targeting antivirals. In this study, we screened selected members of an in-house synthesized library of oxysterol analogs for their activity against HSV-2, identifying three compounds, named PFM064, PFM067, and PFM069, endowed with 50% effective concentrations (EC50) in the micromolar range, without exerting any apparent cytotoxicity. Moreover, the results obtained showed the ability of the novel derivatives to inhibit both cell-to-cell fusion induced by HSV-2, and the production of an intracellular viral progeny. Further experiments performed with PFM067 (which was selected for more-in-depth studies as the most effective synthetic analog) showed that these molecules act in a late stage of HSV-2 replicative cycle, by sequestering viral glycoproteins in the Golgi compartment, and likely inhibiting the nuclear egress of neo-synthetized viral capsids. Taken together, these results point to PFM067 as a promising chemical scaffold for the development of novel herpetic antivirals.

Harnessing the reverse cholesterol transport pathway to favor differentiation of monocyte-derived APCs and antitumor responses.

Lipid and cholesterol metabolism play a crucial role in tumor cell behavior and in shaping the tumor microenvironment. In particular, enzymatic and non-enzymatic cholesterol metabolism, and derived metabolites control dendritic cell (DC) functions, ultimately impacting tumor antigen presentation within and outside the tumor mass, dampening tumor immunity and immunotherapeutic attempts. The mechanisms accounting for such events remain largely to be defined. Here we perturbed (oxy)sterol metabolism genetically and pharmacologically and analyzed the tumor lipidome landscape in relation to the tumor-infiltrating immune cells. We report that perturbing the lipidome of tumor microenvironment by the expression of sulfotransferase 2B1b crucial in cholesterol and oxysterol sulfate synthesis, favored intratumoral representation of monocyte-derived antigen-presenting cells, including monocyte-DCs. We also found that treating mice with a newly developed antagonist of the oxysterol receptors Liver X Receptors (LXRs), promoted intratumoral monocyte-DC differentiation, delayed tumor growth and synergized with anti-PD-1 immunotherapy and adoptive T cell therapy. Of note, looking at LXR/cholesterol gene signature in melanoma patients treated with anti-PD-1-based immunotherapy predicted diverse clinical outcomes. Indeed, patients whose tumors were poorly infiltrated by monocytes/macrophages expressing LXR target genes showed improved survival over the course of therapy. Thus, our data support a role for (oxy)sterol metabolism in shaping monocyte-to-DC differentiation, and in tumor antigen presentation critical for responsiveness to immunotherapy. The identification of a new LXR antagonist opens new treatment avenues for cancer patients.

Pyrazole[3,4-e][1,4]thiazepin-7-one derivatives as a novel class of Farnesoid X Receptor (FXR) agonists.

A virtual screening procedure was applied to the discovery of structurally diverse non-steroidal Farnesoid X Receptor (FXR) agonists. From 117 compounds selected by virtual screening, a total of 47 compounds were found to be FXR agonists, with 34 of them showing activity below a concentration of 20 µM. 1H-Pyrazole[3,4-e][1,4]thiazepin-7-one-based hit compound 7 was chosen for hit-to-lead optimization. A large number of 1H-pyrazole[3,4-e][1,4]thiazepin-7-one derivatives was designed, synthesized, and evaluated by a cell-based luciferase transactivation assay for their agonistic activity against FXR. Most of them exhibited low micromolar range of potency and very high efficacy.

Exploring the synthetic versatility of the Lewis acid induced decomposition reaction of α-diazo-ß-hydroxy esters. The case of ethyl diazo(3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)acetate.

Ethyl diazo(3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)acetate was prepared by aldol-type condensation of ethyl diazoacetate with isatin. A systematic and mechanistic study on the Lewis acid induced decomposition reaction of this valuable diazo precursor was carried out with the aim to gain new insights into the mechanistic aspects of the reaction as well as to further understand the factors and experimental conditions which affect the relative product distribution. The reaction, which may proceed via cationic and noncationic mechanisms, was found to be significantly influenced by the reaction environment determined by the characteristics of the Lewis acid employed, by the ability of the Lewis acid to form a complex with the alcohol functionality of the α-diazo-ß-hydroxy ester, and by the polarity and nucleophilicity of the solvent used.

Shedding light on the roles of liver X receptors in cancer by using chemical probes.

Nuclear receptors, liver X receptor-α (LXRα; NR1H3) and liver X receptor-ß (LXRß; NR1H2), are considered master regulators of lipid homeostasis. During the last couple of decades, their pivotal roles in several physiological and pathological processes ranging from energy supply, immunity, cardiovascular, neurodegenerative disorders and cancer have been highlighted. In this review, the main results achieved during more recent years about our understanding of the LXR involvement in cancer has been mainly obtained using small-molecule chemical probes. Remarkably, all these probes, albeit having different structure and biological properties, have a well demonstrated anti-tumoral activity arising from LXR modulation, indicating a high potential of LXR targeting for the treatment of cancer. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

In search for novel liver X receptors modulators by extending the structure-activity relationships of cholenamide derivatives.

N,N-Dimethyl 3ß-hydroxychol-5-en-24-amide (DMHCA, 3) is the prototype of cholenamides, a class of steroidal LXR modulators characterized by the nucleus of Δ5-cholen-3ß-ol and the presence of an amide moiety at C-24. DMHCA (3) has been reported to act as a gene-selective modulator able to fully induce ABCA1 expression whilst poorly up-regulate the expression of FASN and SREBP-1α genes. With the aim to widen the limited structure-activity relationships of DMHCA (3), herein we describe the synthesis and the biological evaluation of nine novel derivatives, resulting from a) the homologation of DMHCA's side-chain to give N,N-dimethyl 3ß-hydroxy-24a-homochol-5-en-24a-amide (4); b) the distal branching of the side-chain of 3 and 4 by introducing an ethyl group at C-23 and C-24, respectively; c) the replacement of the dimethyl amide moiety of all the derivatives with a carboxylic acid function. While broadening the structure-activity relationships of the class of cholenamides, we were successful in the discovery of (24R)-N,N-dimethyl-24-ethyl-3ß-hydroxy-24a-homochol-5-en-24a-amide (6) as a novel LXR agonist with improved profile in term of selective gene modulation respect to the prototype DMHCA (3); indeed, 6 was able to up-regulate the expression of ABCA1 more than DMHCA (3), without to induce SREBP-1c, differently from DMHCA (3). Moreover, 6 induced the expression of FASN less than 3 and interestingly was a negative modulator towards SCD1 in contrast to DMHCA (3), which instead weakly induced the expression of this gene.

Rojo Duro Red Onion Extract Loaded Spray Thermogel as a Sustainable Platform for the Treatment of Oral Mucosa Lesions.

The urgent need for new green and sustainable models is ground for the current demand of innovative renewable resource based pharmaceutical products. We propose a Rojo Duro skin onion extract loaded poloxamer/chitosan spray mucoadhesive thermogel aimed at solving current limitations in oral mucosits treatment. Being among the main side effects of radio- and chemotherapy, effective treatment of buccal lesions still represents an unmet medical need. The obtained thermogel combined optimal gelling capacity, release behavior, sprayability, mucoadhesion properties, while maintaining the extract antioxidant and antimicrobial properties. The product preserved all properties when stored for 1 month as a freeze-dried powder at 4 °C. This potential new product is highly translational, as it combines a recognized safety to administration/application advantages, as well as simplicity and sustainability.

Cholesterol and oxysterol sulfates: Pathophysiological roles and analytical challenges.

Cholesterol and oxysterol sulfates are important regulators of lipid metabolism, inflammation, cell apoptosis, and cell survival. Among the sulfate-based lipids, cholesterol sulfate (CS) is the most studied lipid both quantitatively and functionally. Despite the importance, very few studies have analysed and linked the actions of oxysterol sulfates to their physiological and pathophysiological roles. Overexpression of sulfotransferases confirmed the formation of a range of oxysterol sulfates and their antagonistic effects on liver X receptors (LXRs) prompting further investigations how are the changes to oxysterol/oxysterol sulfate homeostasis can contribute to LXR activity in the physiological milieu. Here, we aim to bring together for novel roles of oxysterol sulfates, the available techniques and the challenges associated with their analysis. Understanding the oxysterol/oxysterol sulfate levels and their pathophysiological mechanisms could lead to new therapeutic targets for metabolic diseases. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Chiral ligand-exchange separation and resolution of extremely rigid glutamate analogs: 1-aminospiro[2.2]pentyl-1,4-dicarboxylic acids.

Owing to their chelation ability, a series of fully constrained L-Glu analogs formed by the spiro-union of two cyclopropane rings (1-aminospiro[2.2]pentyl-1,4-dicarboxylic acids, ASPED A-D), was submitted to chiral ligand-exchange chromatographic (CLEC) analysis. As the initial step, two methodologically different chiral devices were evaluated. A chiral stationary phase (CSP) obtained by dynamic coating of C(18) chains with the S-trityl-(R)-cysteine ((R)-STC) was used first with this objective. The lack of separation of the enantiomers of ASPED C and D prompted us to utilize the chiral mobile phase (CMP) prepared from O-benzyl-(S)-serine ((S)-OBS). The latter afforded complete separation of the four pairs of enantiomers. For all the pairs, quantum mechanical investigations shed light on the main features responsible for the different enantiomer recognition mechanism with (S)-OBS. The validated analytical method was then fruitfully adopted for semi-preparative-scale isolation of the enantiomers of ASPED C.

Design, synthesis and biological evaluation of novel bicyclo[1.1.1]pentane-based omega-acidic amino acids as glutamate receptors ligands.

A novel series of bicyclo[1.1.1]pentane-based omega-acidic amino acids, including (2S)- and (2R)-3-(3'-carboxybicyclo[1.1.1]pentyl)alanines (8 and 9), (2S)- and (2R)-2-(3'-carboxymethylbicyclo[1.1.1]pentyl)glycines (10 and 11), and (2S)- and (2R)-3-(3'-phosphonomethylbicyclo[1.1.1]pentyl)glycines (12 and 13), were synthesized and evaluated as glutamate receptor ligands. Among them, (2R)-3-(3'-phosphonomethylbicyclo[1.1.1]pentyl)glycine (13) showed relatively high affinity and selectivity at the NMDA receptor. The results are also discussed in light of pharmacophoric modelling studies of NMDA agonists and antagonists.

C24-hydroxylated stigmastane derivatives as Liver X Receptor agonists.

Phytosterols are stucturally correlated to the endogenous ligands of Liver X Receptor (LXR), a ligand-activated nuclear receptor that has emerged as an attractive drug target due to its ability to integrate metabolic and inflammatory signaling. Natural and semi-synthetic phytosterol derivatives characterized by the presence of side-chain oxygenated functions have shown to be able to modulate LXR activity. Here, we describe the efficient synthesis of four stigmastane derivatives, endowed with a hydroxyl group at C24 position, namely (24R)- and (24S)-stigmasta-5,28-diene-3ß,24-ols (also referred to as saringosterols, 10a and 10b) and (24R)- and (24S)-stigmasta-5-ene-3ß,24-ols (11a and 11b), starting from the readily available stigmasterol. Thanks to X-ray crystallography the absolute configuration of the newly created chiral centers was definitively assigned for all the four compounds. The subsequent luciferase assays with GAL-4 chimeric receptors evidenced the ability of the two 24(S)-epimers, 10b and 11b, to interact with LXRs, showing the same degree of affinity as (22R)-hydroxycholesterol (1). With regard to the isoform selectivity both the derivatives 10b and 11b showed a preference for LXRß, up to 4-fold in terms of efficacy for 11b. The gene expression profiling of (24S)-stigmasta-5,28-diene-3ß,24-ol (10a) and (24S)-stigmasta-5-ene-3ß,24-ol (11a) demonstrated the capability of both the compounds to induce the expression of four well-known LXR target genes, such as ABCA1, SREBP1c, FASN, and SCD1 in U937 monocytic cell line, thus supporting the hypothesis they were LXR positive modulators.

Synthesis, molecular modeling studies, and preliminary pharmacological characterization of all possible 2-(2'-sulfonocyclopropyl)glycine stereoisomers as conformationally constrained L-homocysteic acid analogs.

Bioisosteric replacements of the distal acidic group of L-glutamic acid (L-Glu, 1) and conformational constraining of its carbon skeleton, have been widely exploited to discover competitive modulators of glutamate receptors. Noteworthy, L-homocysteic acid (L-HCA, 18), a neurotransmitter belonging to the class of excitatory sulfur-containing amino acids, may be considered an endogenous occurring bioisoster of L-Glu (1). L-HCA (18) has been reported to mediate signaling between glial cells and postsynaptic neurons through the activation of glutamate receptors and others hitherto not well-characterized receptors. As a continuation of our work in the preparation of conformationally constrained glutamate analogs, we report the synthesis and the preliminary pharmacological characterization at iGluRs and mGluRs of all eight stereoisomers of 2-(2'-sulfonocyclopropyl)glycine (SCGs, 8-15). Among the reported compounds, S-SCG-4 (15) showed to be a potent and relatively selective AMPA ligand. Docking experiments coupled to molecular electrostatic potential calculations allowed insight into the molecular basis of the activity of this compound to be gained. The library of SCGs (8-15), while providing a novel source of modulators of the glutamate receptors, represents a valuable chemical tool to better characterize L-HCA pathways in the CNS.

Laboratory-Scale Preparative Enantioseparations of Pharmaceutically Relevant Compounds on Commercially Available Chiral Stationary Phases for HPLC.

In response to the outburst of research in the field of synthetic medicinal chemistry, enantioselective chromatography methods based on the use of chiral stationary phases (CSPs) found immediate acceptance as the elective choice for the analytical determinations of the enantiomeric purity of synthetic compounds. In contrast to an initial scepticism, also the preparative-scale applications are gaining increasing recognition as a powerful alternative to enantioselective synthesis for the supply of pure enantiomers of bioactive compounds. The increasing success of liquid chromatography methods has been made possible thanks to the development of highly efficient CSPs allowing the enantioresolution of practically all the chemical classes of chiral compounds. However, only few CSPs are really suitable for preparative- scale applications, being the loading capacity is the major concern for preparativescale enantioseparations. The cellulose- and amylose-based CSPs present the highest loading capacity and enantiodiscrimination power, which makes these CSPs the most versatile and applicable for preparative-scale applications in all the applicable elution modes (reversedphase, normal-phase, and with polar-organic or polar-ionic eluents). However, also other types of CSPs have been successfully employed at this regard (brush-type phases, polyacrylamide and cross-linked di-allyltartardiamide phases as well as cyclodextrin, and glycopeptide containing phases). Several instrumental methods exist for the determination of the absolute configuration of organic compounds in absence of known enantiopure reference standards. The most widely known are X-ray crystallography, followed by chirooptical methods [e.g., electronic and vibrational circular dichroism (ECD and VCD, respectively)] and nuclear magnetic resonance (NMR) spectroscopy. All these aspects will be treated in the review.