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The article presents a spectroscopic characterization and in vitro assay of porphyrin derivatives in human blood, focusing on meso-tetrakis(4-carboxyphenyl) porphyrin (TPPC)-Jeff and ZnTPPC-Jeff porphyrin derivatives. It explores the hemolytic effect of the two different types of porphyrin derivatives and suggests that visible irradiation does not affect the effectiveness of the compounds in inducing hemolysis.

The interaction of a series of metal derivatives of 5, 10, 15, 20- tetrakis (4-sulfonato-phenyl)porphyrin (MTPPS 4 , M = Cu(II), Pt(II), Ni(II), Zn(II) and Co(II)), including the metal free porphyrin (TPPS 4 ), with the aromatic amino acids L-tryptophan (L-Trp), L-and D-phenylalanine (L-and D-Phe) and L-histidine (L-His) have been investigated through UV/Vis spectroscopy. The amino acid L-serine (L-Ser) has been included as reference compound. The spectroscopic changes induced by adding the amino acids have been exploited to evaluate the extent of interaction between the molecular components in the supramolecular adducts. The binding constants have been estimated for most of the investigated systems, assuming a simple 1:1 equilibrium. The bathochromic shifts of the B-bands, the extent of hypochromicity and the binding constants have been analyzed through two chemical descriptors. All the data point to the important role played by the steric hindrance introduced by axial ligands coordinated to the metal ions and to the degree of hydrophobicity and size of the aromatic moiety in the amino acids.

The cationic platinum(II) organometallic complex [Pt(terpy)Me] + (terpy = 2,2':6',2″-terpyridine) at mild acidic pH interacts with poly(L-glutamic acid) (L-PGA) in its α-helix conformation, affording chiral supramolecular adducts. Their kinetics of formation have been investigated in detail as a function of the concentrations of both reagents and changing pH, ionic strength, the length of the polymeric scaffold and temperature. After a very fast early stage, the kinetic traces have been analyzed as three consecutive steps, suggesting a mechanism based on the electrostatic fast formation of a not-organized aggregate that subsequently evolves through different rearrangements to form the eventual supramolecular adduct. A model for this species has been proposed based on (i) the attractive electrostatic interaction of the cationic platinum(II) complexes and the polyelectrolyte and (ii) the π-stacking interactions acting among the [Pt(terpy)Me] + units.

The self-assembly of porphyrins onto polyelectrolytes could lead to interesting changes in their reactivity with respect to the bulk solution. Here, we investigated the kinetics of Zn 2+ incorporation into tetra-cationic water-soluble 5,10,15,20-tetrakis-(N-methylpyridinium-4-yl)porphyrin (TMpyP(4)) in the presence of poly(L-glutamic acid) (PGA) in a pH range from 4 to 6.5. Under these conditions, the porphyrin electrostatically interacted with the polymer, which gradually switched from an α-helical to a random coil structure. The profile of the logarithm of the observed rate constant ( k obs ) versus the pH was sigmoidal with an inflection point close to the pH of the conformation transition for PGA. At a pH of 5.4, when PGA was in its highly charged random coil conformation, an almost 1000-fold increase in the reaction rates was observed. An increase in the ionic strength of the bulk solution led to a decrease in the metal insertion rates. The role of the charged matrix was explained in terms of its ability to assemble both reagents in proximity, in agreement with the theory of counter-ion condensation around polyelectrolytes in an aqueous solution.

The highly distorted water-soluble 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (Br 8 TPPS 4 4- ) is readily protonated under acidic pH, forming the diacid H 2 Br 8 TPPS 4 2- and subsequently the zwitterionic H 4 Br 8 TPPS 4 , which eventually evolves into J-aggregates. These latter species exhibit a relevant bathochromic shift with respect to the monomer with a quite sharp band due to motional narrowing. The depolarization ratio measured in resonant light scattering spectra allows estimating a tilt angle of ~20° of the porphyrins in the J-aggregate. The kinetic parameters are obtained by applying a model based on the initial slow nucleation step, leading to a nucleus containing m monomers, followed by fast autocatalytic growth. The k c values for this latter step increase on decreasing the acid concentration and on increasing the porphyrin concentration, with a strong power-law dependence. No spontaneous symmetry breaking or transfer of chirality from chiral inducers is observed. Both Atomic Force Microscopy (AFM) and Dynamic Light Scattering (DLS) point to the presence, in both the solid and solution phases, of globular-shaped aggregates with sizes close to 130 nm. Density functional theory (DFT) calculations performed on simplified models show that (i) upon protonation, the saddled conformation of the porphyrin ring is slightly altered, and a further rotation of the aryl rings occurs, and (ii) the diacid species is more stable than the parent unprotonated porphyrin. Time-dependent DFT analysis allows comparing the UV/Vis spectra for the two species, showing a consistent red shift upon protonation, even if larger than the experimental one. The simulated Raman spectrum agrees with the experimental spectrum acquired on solid samples.

Developing new broad-spectrum antimicrobial strategies, as alternatives to antibiotics and being able to efficiently inactivate pathogens without inducing resistance, is one of the main objectives in public health. Antimicrobial photodynamic therapy (aPDT), based on the light-induced production of reactive oxygen species from photosensitizers (PS), is attracting growing interest in the context of infection treatment, also including biofilm destruction. Due to the limited photostability of free PS, delivery systems are increasingly needed in order to decrease PS photodegradation, thus improving the therapeutic efficacy, as well as to reduce collateral effects on unaffected tissues. In this study, we propose a photosensitizing nanosystem based on the cationic porphyrin 5,10,15,20-tetrakis (N-methyl- 4-pyridyl)-21H,23H-porphyrin (TMPyP), complexed with the commerical sulfobutylether-beta-cyclodextrin (CAPTISOL ® ), at a 1:50 molar ratio (CAPTISOL ® /TMPyP) 50_1 . Nanoassemblies based on (CAPTISOL ® /TMPyP) 50_1 with photodynamic features exhibited photo-antimicrobial activity against Gram-negative and Gram-positive bacteria. Moreover, results from P. aeruginosa reveal that CAPTISOL ® alone inhibits pyocyanin (PYO) production, also affecting bacterial biofilm formation. Finally, we obtained a synergistic effect of inhibition and destruction of P. aeruginosa biofilm by using the combination of CAPTISOL ® and TMPyP.

The self-assembling kinetics of the 5,10,15,20- tetrakis (4-sulfonato-phenyl)porphyrin (TPPS 4 ) into nano-tubular J-aggregates under strong acidic condition and in the presence of amino acids as templating chiral reagents have been investigated through UV/Vis spectroscopy. The ability of the chiral species to transfer its chiral information to the final J-aggregate has been measured through circular dichroism (CD) spectroscopy and compared to the spontaneous symmetry breaking process usually observed in these nano-aggregates. Under the experimental conditions here selected, including mixing protocol, we have observed a large difference in the observed aggregation rates for the various amino acids, those with a positively charged side group being the most effective. On the contrary, these species are less efficient in transferring their chirality, exhibiting a quite low or modest enhancement in the observed dissymmetry g-factors. On the other side, hydrophobic and some hydrophilic amino acids are revealed to be very active in inducing chirality with a discrete increase of intensity of the detected CD bands with respect to the spontaneous symmetry breaking.

Levofloxacin (LVF) is an antibacterial drug approved for the treatment of ocular infections. However, due to the low ocular bioavailability, high doses are needed, causing bacterial resistance. Polymeric nanospheres (NPs) loading antibiotic drugs represent the most promising approach to eradicate ocular infections and to treat pathogen resistance. In this study, we have developed chitosan NPs based on sulfobutyl-ether- β -cyclodextrin (CH/SBE- β -CD NPs) for ocular delivery of LVF. CH/SBE- β -CD NPs loading LVF were characterized in terms of encapsulation parameters, morphology, and sizes, in comparison to NPs produced without the macrocycle. Nuclear magnetic resonance and UV-vis spectroscopy studies demonstrated that SBE- β -CD is able to complex LVF and to influence encapsulation parameters of NPs, producing high encapsulation efficiency and LVF loading. The NPs were homogenous in size, with a hydrodynamic radius between 80 and 170 nm and positive zeta potential (ζ) values. This surface property could promote the interaction of NPs with the negatively charged ocular tissue, increasing their residence time and, consequently, LVF efficacy. In vitro, antibacterial activity against Gram-positive and Gram-negative bacteria showed a double higher activity of CH/SBE- β -CD NPs loading LVF compared to the free drug, suggesting that chitosan NPs based on SBE- β -CD could be a useful system for the treatment of ocular infections.

The hierarchical self-assembling kinetics of the porphyrin 5,10,15,20- tetrakis (4-sulfonatophenyl)porphyrin (H 2 TPPS 4 4- ) into J-aggregates at high ionic strength under acidic conditions and eventually in the presence of an added chiral templating agent (tartrate) were investigated through UV/Vis spectroscopy, resonance light scattering, and circular dichroism (CD). The effect of changing the mixing order of the various components in the solution on the kinetic parameters and the expression of chirality on the final J-aggregates was evaluated. In this latter case, only when the chiral tartrate anion is premixed with the porphyrin, the resulting nano-architectures exhibit CD spectra that reflect the handedness of the chiral inducer. We discuss a general mechanistic scheme, with the involvement of ion pairs or dimers that offer an alternative pathway to the aggregation process.

Under moderate acidic conditions, the cationic (+3) complexes ions tris(1,10-phenanthroline)cobalt(III), [Co( phen ) 3 ] 3+ , and hexamminecobalt(III), [Co(NH 3 ) 6 ] 3+ , efficiently promote the self-assembling process of the diacid 5,10,15,20- tetrakis (4-sulfonatophenyl)porphyrin (H 2 TPPS 4 ) into J-aggregates. The growth kinetics have been analyzed according to a well-established autocatalytic model, in which the rate determining step is the initial formation of a nucleus containing m porphyrin units (in the range 2-3), followed by a stage whose rate constant k c evolves as a power of time. The observed catalytic rate constants and the extent of J-aggregation increase on increasing the metal complex concentration, with the phen complex being the less active. The UV/Vis extinction spectra display quite broad envelops at the J-band, especially for the amino-complex, suggesting that electronic dipolar coupling between chromophores is operative in these species. The occurrence of spontaneous symmetry breaking has been revealed by circular dichroism and the measured dissymmetry g -factor decreases on increasing the aggregation rates. The role of these metal complexes on the growth and stabilization of porphyrin nano-assemblies is discussed in terms of the different degree of hydrophilicity and hydrogen bonding ability of the ligands present in the coordination sphere around the metal center.

Under mild acidic conditions, various metal derivatives of tetrakis(4- N -methylpyridinium)porphyrin (gold(III), AuT 4 ; cobalt(III), CoT 4 ; manganese(III), MnT 4 and zinc(II), ZnT 4 ) catalytically promote the supramolecular assembling process of the diacid 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H 2 TPPS 4 ) into J-aggregates. The aggregation kinetics have been treated according to a well-established model that involves the initial formation of a critical nucleus containing m porphyrin units, followed by autocatalytic growth, in which the rate evolves as a power of time. An analysis of the extinction time traces allows to obtain the rate constants for the auto-catalyzed pathway, k c , and the number of porphyrins involved in the initial seeding. The aggregation kinetics have been investigated at fixed H 2 TPPS 4 concentration as a function of the added metal derivatives MT 4 . The derived rate constants, k c , obey a rate law that is first order in [MT 4 ] and depend on the specific nature of the catalyst in the order AuT 4 > CoT 4 > MnT 4 > ZnT 4 . Both resonance light scattering (RLS) intensity and extinction in the aggregated samples increase on increasing [MT 4 ]. With the exception of AuT 4 , the final aggregated samples obtained at the highest catalyst concentration exhibit a negative Cotton effect in the J-band region, evidencing the occurrence of spontaneous symmetry breaking. The role of the nature of the metal derivative in terms of overall charge and presence of axial groups will be discussed.

Background: Almond kernels contain phytochemicals with positive health effects in relation to heart disease, diabetes and obesity. Several studies have previously highlighted that almond cell wall encapsulation during digestion and particle size are factors associated with these benefits. In the present study, we have characterized almond oleosomes, natural oil droplets abundant in plants, and we have investigated their integrity during simulated gastrointestinal digestion., Methods: Oleosomes were visualized on the almond seed surface by imaging mass spectrometry analysis, and then characterized in terms of droplet size distribution by dynamic light scattering and protein profile by liquid chromatography high-resolution tandem mass spectrometry analysis., Results: The almond oleosomes' distribution remained monomodal after in vitro mastication, whereas gastric and duodenal digestion led to a bimodal distribution, albeit characterized mainly by a prevalent population with a droplet size decrease related to a rearrangement of the protein profile. Oleosins, structural proteins found in plant oil bodies, persisted unchanged during simulated mastication, with the appearance of new prunin isoforms after gastric and duodenal digestion., Conclusions: The rearrangement of the protein profile could limit lipid bioaccessibility. The data improve our understanding of the behavior of almond lipids during gastrointestinal digestion, and may have implications for energy intake and satiety imparted by almonds.

Injectable nanobioplatforms capable of locally fighting the inflammation in osteoarticular diseases, by reducing the number of administrations and prolonging the therapeutic effect is highly challenging. -Cyclodextrin cationic polymers are promising cartilage-penetrating candidates by intra-articular injection due to the high biocompatibility and ability to entrap multiple therapeutic and diagnostic agents, thus monitoring and mitigating inflammation. In this study, nanoassemblies based on poly--amino-cyclodextrin (PolyCD) loaded with the non-steroidal anti-inflammatory drug diclofenac (DCF) and linked by supramolecular interactions with a fluorescent probe (adamantanyl-Rhodamine conjugate, Ada-Rhod) were developed to manage inflammation in osteoarticular diseases. PolyCD@Ada-Rhod/DCF supramolecular nanoassemblies were characterized by complementary spectroscopic techniques including UV-Vis, steady-state and time-resolved fluorescence, DLS and ζ-potential measurement. Stability and DCF release kinetics were investigated in medium mimicking the physiological conditions to ensure control over time and efficacy. Biological experiments evidenced the efficient cellular internalization of PolyCD@Ada-Rhod/DCF (within two hours) without significant cytotoxicity in primary human bone marrow-derived mesenchymal stromal cells (hMSCs). Finally, polyCD@Ada-Rhod/DCF significantly suppressed IL-1 production in hMSCs, revealing the anti-inflammatory properties of these nanoassemblies. With these premises, this study might open novel routes to exploit original CD-based nanobiomaterials for the treatment of osteoarticular diseases., Competing Interests: The authors declare no conflict of interest.

The graphene road in nanomedicine still seems very long and winding because the current knowledge about graphene/cell interactions and the safety issues are not yet sufficiently clarified. Specifically, the impact of graphene exposure on gene expression is a largely unexplored concern. Herein, we investigated the intracellular fate of graphene (G) decorated with cyclodextrins (CD) and loaded with doxorubicin (DOX) and the modulation of genes involved in cancer-associated canonical pathways. Intracellular fate of GCD@DOX, tracked by FLIM, Raman mapping and fluorescence microscopy, evidenced the efficient cellular uptake of GCD@DOX and the presence of DOX in the nucleus, without graphene carrier. The NanoString nCounter™ platform provided evidence for 34 (out of 700) differentially expressed cancer-related genes in HEp-2 cells treated with GCD@DOX (25 µg/mL) compared with untreated cells. Cells treated with GCD alone (25 µg/mL) showed modification for 16 genes. Overall, 14 common genes were differentially expressed in both GCD and GCD@DOX treated cells and 4 of these genes with an opposite trend. The modification of cancer related genes also at sub-cytotoxic G concentration should be taken in consideration for the rational design of safe and effective G-based drug/gene delivery systems. The reliable advantages provided by NanoString ® technology, such as sensibility and the direct RNA measurements, could be the cornerstone in this field.

Under acidic conditions and at high ionic strength, the zinc cation is removed from its metal complex with 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS 4 ) thus leading to the diacid free porphyrin, that subsequently self-organize into J-aggregates. The kinetics of the demetallation step and the successive supramolecular assembly formation have been investigated as a function of pH and ionic strength (controlled by adding ZnSO 4 ). The demetallation kinetics obey to a rate law that is first order in [ZnTPPS 4 ] and second order in [H + ], according to literature, with k 2 = 5.5 ± 0.4 M -2 s -1 at 298 K (IS = 0.6 M, ZnSO 4 ). The aggregation process has been modeled according to an autocatalytic growth, where after the formation of a starting seed containing m porphyrin units, the rate evolves as a power of time. A complete analysis of the extinction time traces at various wavelengths allows extraction of the relevant kinetic parameters, showing that a trimer or tetramer should be involved in the rate-determining step of the aggregation. The extinction spectra of the J-aggregates evidence quite broad bands, suggesting an electronic coupling mechanism different to the usual Frenkel exciton coupling. Resonance light scattering intensity in the aggregated samples increases with increasing both [H + ] and [ZnSO 4 ]. Symmetry breaking occurs in these samples and the J-aggregates show circular dichroism spectra with unusual bands. The asymmetry g-factor decreases in its absolute value with increasing the catalytic rate k c , nulling and eventually switching the Cotton effect from negative to positive. Some inferences on the role exerted by zinc cations on the kinetics and structural features of these nanostructures have been discussed., Competing Interests: The authors declare no conflict of interest.

The ability of multiwalled carbon nanotubes (MWCNTs) covalently functionalized with polyamine chains of different length (ethylenediamine, EDA and tetraethylenepentamine, EPA) to induce the J-aggregation of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) was investigated in different experimental conditions. Under mild acidic conditions, protonated amino groups allow for the assembly by electrostatic interaction with the diacid form of TPPS, leading to hybrid nanomaterials. The presence of only one pendant amino group for a chain in EDA does not lead to any aggregation, whereas EPA (with four amine groups for chain) is effective in inducing J-aggregation using different mixing protocols. These nanohybrids have been characterized through UV/Vis extinction, fluorescence emission, resonance light scattering, and circular dichroism spectroscopy. Their morphology and chemical composition have been elucidated through transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). TEM and STEM analysis evidence single or bundles of MWCNTs in contact with TPPS J-aggregates nanotubes. The nanohybrids are quite stable for days, even in aqueous solutions mimicking physiological medium (NaCl 0.15 M). This property, together with their peculiar optical features in the therapeutic window of visible spectrum, make them potentially useful for biomedical applications.

Background: Candida sp. represent the most common cause of fungal infections worldwide. In the present work, we have evaluated the activity of an essential oil extracted from pistachio hulls against a number of standard and clinical strains of Candida sp., Methods: C. albicans ATCC 64550, C. parapsilosis ATCC 22019, 4 clinical strains of C. albicans, 3 clinical strains of C. parapsilosis and 3 clinical strains of C. glabrata were used. All clinical isolates were identified by species-specific PCR-based methods. Susceptibility studies were performed using pistachio hull essential oil alone or in combination with antifungal compounds. The interactions between pistachio hull essential oil and selected antifungal compounds were also evaluated using the checkerboard method and the mechanisms of interaction investigated by droplet size distribution., Results: Pistachio hull essential oil was fungicidal at the concentrations between 2.50 and 5.0 mg/ml. D-limonene and 3-Carene were the components with major activity. An antagonistic effect was observed with all combinations tested., Conclusion: The antifungal activity of pistachio hull essential oil could be used to help control resistance in Candida species. More studies need to be performed to elucidate the mechanisms responsible for the activity of pistachio hull essential oil.

J-aggregates of anionic meso -tetrakis(4-sulfonatophenyl)porphyrin form at intermediate pH (2.3-3.1) in the presence of NiSO 4 or ZnSO 4 (ionic strength, I.S. = 3.2 M). These aggregates convert to monomeric porphyrin units via metallation with copper(II) ions. The kinetics for the disassembly process, as monitored by UV/vis spectroscopy, exhibits zeroth-order behavior. The observed zeroth-order rate constants show a two-term dependence on copper(II) ion concentrations: linear and second order. Also observed is an inverse dependence on hydrogen ion concentration. Activation parameters have been determined for the disassembly process leading to Δ H ≠ = (+163 ± 15) kJ·mol -1 and Δ S ≠ = (+136 ± 11) J·K -1 . A mechanism is proposed in which copper(II) cation is in pre-equilibrium with a reactive site at the rim of the J-aggregate. An intermediate copper species is thus formed that eventually leads to the final metallated porphyrin either through an assisted attack of a second metal ion or through a direct insertion of the metal cation into the macrocycle core., Competing Interests: The authors declare no competing financial interest.

The potential of pyrene-1-sulfonate to act as an emitting anion for the development of ionic liquids is explored here. Amphiphilic trimethylpropylammonium hepta(isooctyl)octasilsesquioxane and conventional imidazolium, namely, 1-vinyl-3-hexyl-, 1-vinyl-3-decyl-, and 1-methyl-3-decyl-imidazolium, featuring moderate alkyl chain length substituents, have been chosen as countercations. The new species have been synthesized via simple metathesis reactions involving pyrene-1-sulfonate sodium salt and the appropriate halide cation precursors. Their thermal behavior has been investigated by thermogravimetric and differential scanning calorimetry at different scanning rates. According to this latter technique, only the trimethylpropylammonium hepta(isooctyl)octasilsesquioxane pyrenesulfonate adduct, displaying a reversible glass transition at -4.2 °C, may be classified as an ionic liquid. All pyrene-1-sulfonate imidazolium-based ion pairs are crystalline solids with the melting point just above 100 °C that produce very complex, nonreversible, and scanning rate-dependent thermograms, very likely arising from polymorphism phenomena. Such a behavior may be attributed to the pyrene-1-sulfonate polycyclic system, which in solution, as confirmed through spectroscopic characterization, displays a general attitude in promoting supramolecular structures via cation interactions. Emission lifetime measurements on the emitting fluorophore reveal that there are at least two different active species, whereas light scattering measurements show the presence of aggregates with hydrodynamic radii depending on the medium and adduct concentration. Tests aimed at investigating the potential of these novel pyrene-1-sulfonate salts in functionalization/exfoliation of graphite flakes are also reported here., Competing Interests: The authors declare no competing financial interest.

Functionalized carbon nanotubes (CNTs) have been proposed in the last years as vectors for delivery of biomolecules, proteins and DNA into various cells. In this study, a new multiwalled carbon nanotube β-cyclodextrin platform (MWCNT-CD) modified with branched polyethylenimine (PEI) and doped with Rhodamine (Rhod), MWCNT-CD-PEI-Rhod, was designed and investigated as drug delivery system. The drug binding abilities of MWCNT-CD-PEI-Rhod towards Cidofovir (Cid) and DNA plasmid encoding enhanced green fluorescence protein (pCMS-EGFP) were investigated by complementary spectroscopic techniques. MWCNT-CD-PEI-Rhod showed no significative cytotoxicity and an excellent ability to entrap and delivery Cid. The present study broadens the spectrum of biological evaluation by investigating platform-treatment induced cellular response such as antiviral activity, transfection properties, cellular uptake, internalization mechanisms and cellular localization. The mechanism of cellular uptake was elucidated monitoring the dependence of intracellular red fluorescence from the assembly concentration, time and presence of specific uptake inhibitors. The biological results indicated that MWCNT-CD-PEI-Rhod loaded with Cid and/or pCMS-EGFP crossed the cell membrane via clathrin-dependent pathway and co-localized in lysosomal compartment. However, no green fluorescent protein expression of pCMS-EGFP was detected, whereas the efficient escape of Cid from lysosome and the release close to nuclear region prompted the antiviral activity., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: Obesity is widely acknowledged as a critical risk factor for metabolic complications. Among obese subjects, there is a phenotype of metabolically healthy but obese (MHO) individuals that shows a favorable cardiometabolic risk profile. We aimed to evaluate the potential mechanisms underlying the metabolic profile of this subset, including alpha and beta cell function and entero-insular axis., Design and Methods: One hundred twenty-nine obese and 24 nonobese subjects were studied. Obese participants were defined as MHO or at-risk obese, according to the homeostasis model of assessment-insulin resistance (HOMA-IR) index (MHO: lower tertile of HOMA-IR, n = 43; at-risk: upper tertile of HOMA-IR index, n = 41). Insulin, glucagon, and incretin responses after a 120' oral glucose tolerance test (75-g OGTT) were investigated., Results: During OGTT, MHO individuals showed in comparison with at-risk subjects: lower fasting and afterloads plasma levels of glucose, insulin, and C-peptide; higher disposition index; lower fasting (P = 0.004) and at 30' (P = 0.01) plasma glucose-dependent insulinotropic polypeptide (GIP) levels; lower area under the curve (AUC) (0-30) for GIP (P = 0.008); higher glucagon-like peptide-1 (GLP-1) plasma levels at 90' (P = 0.02) and 120' (P = 0.02); lower glucagon plasma levels at baseline (P = 0.04) and at 30' (P = 0.03); and appropriate glucagon suppression after the oral glucose load., Conclusions: MHO subjects show, as well as normal-weight individuals, a lower diabetogenic profile by virtue of higher disposition index and unaffected entero-insular axis. At-risk obese individuals present increased GIP levels that might play a role in determining increased glucagon secretion and inappropriate glucagon responses after glucose load, thus contributing to impaired glucose homeostasis., (Copyright © 2012 The Obesity Society.)