σ-Hole intermolecular interactions between carbon oxides and dihalogens: Ab-initio investigations.

Recently, halogen bonding (XB) has received increased attention as a new type of non-covalent interaction widely present in nature. In this work, quantum chemical calculations at DFT level have been carried out to investigate halogen bonding interactions between COn (n = 1 or 2) and dihalogen molecules XY (X = F, Cl, Br, I and Y = Cl, Br, I). Highly accurate all-electron data, estimated by CCSD(T) calculations, were used to benchmark the different levels of computational methods with the objective of finding the best accuracy/computational cost. Molecular electrostatic potential, interaction energy values, charge transfer, UV spectra, and natural bond orbital (NBO) analysis were determined to better understand the nature of the XB interaction. Density of states (DOS) and projected DOS were also computed. Hence, according to these results, the magnitude of the halogen bonding is affected by the halogen polarizability and electronegativity, where for the more polarizable and less electronegative halogen atoms, the σ-hole is bigger. Furthermore, for the halogen-bonded complexes involving CO and XY, the OC∙∙∙XY interaction is stronger than the CO∙∙∙XY interaction. Thus, the results presented here can establish fundamental characteristics of halogen bonding in media, which would be very helpful for applying this noncovalent interaction for the sustainable capture of carbon oxides.

Extraction and characterisation of type I collagen from the skin offcuts generated at the commercial fish processing centres.

Effective use of underutilised fish processing by-products could open avenues for new industries if they are used to extract high-valued bioactive compounds. Therefore, discarded skin offcuts of three main commercial fish species of Sri Lanka were used to extract collagen with acetic acid and the extracted collagen was evaluated for industrial suitability. The yields of acid-soluble collagens from Yellowfin tuna (Thunnus albacares), Seer fish (Scomberomorus commerson) and Asian sea bass (Lates calcarifer) were 61.26%, 58.21% and 59.31%, respectively on a dry-weight basis. Fourier Transform Infra-Red spectra and X-ray Diffraction spectra confirmed that all collagens were in type I and preserved the native triple-helical structure during extraction. The UV absorption spectra confirmed a high collagen purity in all species. These results confirm that the extracted collagen consists of the characteristics required for collagen-based industries such as food, pharmaceutical, and biomedical. The high availability of skin offcuts from the processing industry and the higher collagen yields revealed in this study confirm the possibility of using discarded skin offcuts of the three fish species as a potential source of type I collagen for industrial purposes.

Investigation of the influence of clathrate hydrate crystals on the structuring of homeopathic high dilutions

High dilutions (HD) of drugs used in homeopathy are mostly too dilute to contain original drug molecules. But evidences support their specific biological and therapeutic effects. The reason behind this is thought to be water structure characteristic of the original drug. Spectroscopic studies indicate that the specific water structure in HDs can be resolved into free water molecules, hydrogen bonding strength of water hydroxyl, number of hydrogen bonds and clathrate hydrate crystals (CHC). HDs are prepared in EtOH water solution by serial dilution and mechanical agitation, and are called potencies. The objective of the present study is to further confirm the presence of CHCs in the two potencies of three drugs. Electronic spectra of the HDs of the potencies indicate two broad peaks and marked difference in intensities of absorption. Furior Transform Infrared (FT-IR) spectra of the test potencies and their control show difference in intensity shift and contour shape of OH stretching and bending bands. All the experimental data indicate the presence of CHCs in varying amounts in the test potencies.

Multi-wavelength UV-based PAT tool for measuring protein concentration.

Process chromatography is commonly used for purification of therapeutic proteins. Most chromatography skids that are used in such operations utilize single ultraviolet (UV) absorbance for monitoring and quantification of protein content. While the signal from such UV measurement is linear with respect to protein concentration at low values of protein concentrations, as the concentration increases across an eluting product peak, it goes manifold over the linear range, resulting in saturation of the UV signal and as a result incomplete quantification of the protein concentration. This can hamper our ability to decide on where to pool the process chromatography peak. It is evident that a simple, fast, and cost-effective methodology for on-line estimation of protein concentration is the need of the hour. In this paper, a multi-wavelength UV-based approach has been proposed for dilution-free on-line concentration estimation in the range of 0.8-100 g/L. Stable absorbance regions are picked up in the proposed approach from the multi-wavelength UV spectra, thereby offering a solution to the problem of saturation and non-linearity of the UV signal that is otherwise observed at higher concentrations. Further, using chemometrics tools such as principal component analysis (PCA) and partial least squares (PLS), the model has been validated for rapid quantification of protein concentration from the spectra. The predictions from the model were comparable to values measured using an existing UV-based offline method with an R2 of>98%. The proposed process analytical technology (PAT) tool was successfully tested online and exhibited<8% variability and could effectively be used from capture to formulation to enable dilution-free online concentration measurement of IgG. The proposed tool is a simple, low-cost alternative to other methods and could enable integrated/continuous operations throughout the downstream train.

High dilutions of a drug of COVID-19 origin show difference in ranks

High dilutions (HDs) of drugs, used in Homeopathy, are prepared in aqueous EtOH (ethanol) through serial dilution accompanying mechanical agitation or succussion, and are called potencies. The potencies from the rank 12 onwards are too dilute to contain any original drug molecules. Do the potency ranks show any difference from each other? Do serial dilution and succussion contribute to the difference in potency ranks? This study aims to address these two questions. The throat swab of a Covid-19 patient was preserved and diluted with aqueous EtOH 90% to prepare the mother tincture (MT) and five different potencies of Covid named Covidinum. These potencies and their solvent media were analysed by electronic and vibrational spectroscopy. Charge transfer (CT) and proton transfer interactions occur during preparation of the potencies. The FT-IR spectra of all the test samples after normalization show difference from each other with respect to O-H stretching and bending (v2) bands. Serial dilution and succussion contribute to the observed difference in ranks and CT interactions.

Evaluation of quality the pumpkin, wild plum, pear, cabbage traditional homemade vinegars using the spectroscopy and rheology methods.

In this study, the quality evaluation of homemade pumpkin, pear, wild plum and cabbage vinegar produced by traditional methods was carried out using the ultraviolet (UV) spectroscopy, rheology technique and Fourier transform infrared (FTIR) spectroscopy method. The measurement of UV spectra, flow behaviours and infrared spectral fingerprints of all the vinegars were performed in the wavelength range of 190 nm to 600 nm, shear rate of 10-3 s-1 to 102 s-1 and wavenumber of 4200 c-1 to 400 cm-1 at room temperature, respectively. The quality of homemade vinegars was correlated with the UV spectra peaks, which took values with acetic acid and phenolic compound concentrations. It was determined that the absorption coefficient and optical energy gaps (Eg) which were caused by the release time, depends on the organic acids content. It was observed that the UV spectra and forbidden energy gaps of all the vinegars compatible with the Lambert-Beer-Bouguer and Tauc laws, respectively. The flow behaviour of homemade vinegars was consistent with the non-Newtonian flow, which is the signature behaviour of the dilatant (thickening) and pseudo-plastic (thinning) liquids. Moreover, it was determined that the spectral fingerprint peaks obtained from FTIR spectroscopy were caused by the mixture of acetic acid and water forming the structure of the vinegar. As a result of spectroscopy and rheological analyses, which yields compatible results with commercial tests, it is predicted that it can be safely used as health test.

Pork Liver Pâté Enriched with Persimmon Coproducts: Effect of In Vitro Gastrointestinal Digestion on Its Fatty Acid and Polyphenol Profile Stability.

Agrofood coproducts are used to enrich meat products to reduce harmful compounds and contribute to fiber and polyphenol enrichment. Pork liver pâtés with added persimmon coproducts (3 and 6%; PR-3 and PR-6, respectively) were developed. Therefore, the aim was to study the effect of their in vitro gastrointestinal digestion on: the free and bound polyphenol profile (HPLC) and their colon-available index; the lipid oxidation (TBARs); and the stability of the fatty acid profile (GC). Furthermore, the effect of lipolysis was investigated using two pancreatins with different lipase activity. Forty-two polyphenols were detected in persimmon flour, which were revealed as a good source of bound polyphenols in pâtés, especially gallic acid (164.3 µg/g d.w. in PR-3 and 631.8 µg/g d.w. in PR-6). After gastrointestinal digestion, the colon-available index in enriched pâté ranged from 88.73 to 195.78%. The different lipase activity in the intestinal phase caused significant differences in bound polyphenols' stability, contributing to increased lipid oxidation. The fatty acids profile in pâté samples was stable, and surprisingly their PUFA content was raised. In conclusion, rich fatty foods, such as pâté, are excellent vehicles to preserve bound polyphenols, which can reach the colon intact and be metabolized by the intestinal microbiome.

Fast and accurate procedure to perform SCF or DFT calculation for large molecules.

The roadblock on the way to perform the quantum mechanical calculation as the "SCF or DFT" method for some molecules such as drugs, biological molecules, and so on is that these molecules are too large to study. They need a computer with a large amount of system memory and a very fast CPU. Therefore, we are looking for an entirely quantum-mechanical procedure to study the electronic properties of a large molecule with considerable saving computational time and acceptable accuracy. This procedure is based on searching for the active parts of a molecule, which are essentially HOMO and LUMO parts and their surroundings, and is called truncated molecule (TM) in this manuscript. To this end, at first, this procedure is inspected for Mn-complex, due to the availability of its experimental UV spectra. The calculation of the UV spectrum for TM part of Mn-complex shows λmax = 355.64 nm, while experimental UV spectra is λmax = 334.31 nm, and the corresponding theoretical value for the original molecule reveals λmax = 346.99 nm. The CPU time for the original molecule is 448,045 s that is reduced to 101,555 s for TM with acceptable accuracy (the CPU ratio is 4.41). Furthermore, this procedure is also tested for one of the sequences of A-chain of insulin, Docetaxel (drug molecule), and Taxol (drug molecule); the acceptable resemblance between UV spectra of the original and TM molecule is obtained. The computational time is reduced with a ratio of 3.59, 2.44, and 1.69, respectively.

Rapid screening for natural lipase inhibitors from Alisma orientale combining high-performance thin-layer chromatography-bioautography with mass spectrometry.

Lipase inhibitors are an attractive class of hypolipidemic compounds, which inhibit the activity of human pancreatic lipase, thereby preventing the absorption of triglycerides in vivo. As a library of promising lead compounds for drug development, traditional Chinese medicine (TCM) has gained growing attention in quick discovery and identification of enzyme inhibitors of natural-origin. The purpose of this work was to discover unknown lipase inhibitors from Alisma orientale by the activity oriented analysis method thin-layer chromatography-bioautography, then use electrospray ionization mass spectrometry technology via the elution based TLC-MS interface to identify their structures. As a result, eleven natural lipase inhibitors from Alisma orientale extracts were identified based on molecular mass and fragment ions obtained by HPTLC-MS, and further confirmed by a series of complementary means including UV spectra, 1H NMR characteristic proton signals and polarity of compounds, eleven lipase inhibitors were tentatively assigned as triterpenoids: alisol B (m/z 495.50 [M + Na]+), alisol B 23-acetate (m/z 537.58 [M + Na]+), 11-deoxy-alisol B (m/z 479.50 [M + Na]+), 11-deoxy-alisol B 23-acetate (m/z 521.50 [M + Na]+), alisol A/epialisol A (m/z 513.50 [M + Na]+), 16-oxo-11-deoxy-alisol A (m/z 511.50 [M + Na]+), 16-oxo-alisol A (527.50 [M + Na] +), alisol C (m/z 509.58 [M + Na]+), alisol C 23-acetate (m/z 551.50 [M + Na]+), alisol M 23-acetate (m/z 567.50 [M + Na]+), and alismanol Q/neoalisol (m/z 493.42 [M + Na]+). The integrated approach is an efficient method for rapid screening lipase inhibitors from complex plant extracts and provides a reasonable and favorable basis for the identification and separation of other enzymatic system and other important compounds with therapeutic values.

UV spectrophotometric methods for quantitative determination of masitinib; extraction of qualitative information.

Masitinib is an orally administered selective tyrosine kinase inhibitor. It has emerged as a promising drug for multiple diseases including cancer and inflammation in either human or veterinary medicine. Five new and simple UV spectrophotometric methods were developed for its determination in bulk and in pharmaceutical tablets. These methods are based on measuring the absorbance of masitinib in either zero order or first, second, third or fourth derivative spectra. Measurements are optimized so as to minimize excipients' interferences. The methods are suitable for micro-analysis of masitinib. The proposed methods were validated according to the ICH-Q2(R1) guidelines and was successfully applied for determination of masitinib in laboratory prepared tablet. The presented methods are simple, fast, cost-effective and suitable for routine pharmaceutical analysis. Moreover, two derivative spectrophotometric-based methods were developed for identification of masitinib, the derivative ratio method and log-A derivative method. The impact of the developed methods on the environment was assessed by both analytical Eco-Sale and the Green Analytical Procedure Index (GAPI). The present work proves how derivative spectrophotometry could greatly extract qualitative and quantitative information from UV spectra.

Multicopper oxidase laccases with distinguished spectral properties: A new outlook.

Multicopper oxidases (MCOs) has a unique feature of having the presence of four Cu atoms arranged into three (Type I, II and III) spectral classification. MCOs laccase due to its broad range of substrate specificity has numerous biotechnological applications. The two types of laccases include the typical blue and the atypical white, yellow laccases which have been isolated from diverse geographical locations globally. In the present study laccases were identified using Liquid Chromatograph Mass Spectrometer Studies (LCMS) study where blue laccase exhibited homology with Trametes villosa Q99044 and Q99046 and white, yellow laccase exhibited homology with Myrothecium verrucaria OX = 1859699; Q12737 and Trametes versicolor Q12717 respectively. The spectral comparison between laccases were determined via spectroscopic analysis where UV-spectra of blue laccase from Trametes versicolor had a peak at 605 nm (Type I Cu atom) whereas in case of white and yellow laccases the peak was absent and in addition had an absorption peak at 400nm. It was followed by X-Ray Diffraction (XRD) analysis of proteins where α-helix (10°) and ß-sheet (22°) structure were observed in case of all the three laccases. However, the intensity of α-helix in white and yellow laccase was stronger as compared to the blue laccase whereas the intensity of ß-sheet was stronger in case of blue laccase as compared to other two laccases. Further, Fourier-transform infrared spectroscopy (FTIR) analysis was performed which enabled the analysis of proteins where α-helix (1650-1658 cm-1), ß-sheets (1620-1640 cm-1), amide I (1700-1600 cm-1) amide II (bands at under 1400 cm-1) and amide A, B (bands above 3000 cm-1).

Three-way analysis of pH-UV absorbance dataset for the determination of paracetamol and its pKa value in presence of excipients.

A three-way analysis method, parallel factor analysis (PARAFAC) model was applied to the pH-absorbance dataset for the simultaneous determination of paracetamol and its acid-base dissociation constant in presence of excipient interference in a syrup formulation without using chemical pretreatment or chromatographic separation step. The UV spectroscopic data matrices of calibration set, validation and unknown samples were obtained from the absorbance measurements at the five different pH media, considering conjugate acid/base properties of the related drug. Their pH-absorbance data matrices were arranged as a cubic data array (wavelength x sample x pH) (425x52x5). Three-way array of pH-absorbance dataset was decomposed into a trilinear set of spectral, pH and relative concentration profiles of paracetamol and excipients in the commercial syrup using PARAFAC model. In the PARAFAC implementation, paracetamol in the commercial syrup formulation and its pKa value were simultaneously predicted from the relative concentration and pH profiles, respectively. In the method validation step of this study, the performance of PARAFAC model was checked by analyzing the validation samples in terms of selectivity, sensitivity, accuracy and precision of the method. The determination results of paracetamol and its pKa value provided from PARAFAC application were compared to those obtained by a newly developed ultra-performance liquid chromatography (UPLC) method, in terms of simplicity, applicability, interpretability with low cost and short analysis time.

Bromide counterion as a spectroscopic sensor at the interface of cetyltrimethylammonium micelles.

The strong UV absorption of the bromide in aqueous solution undergoes a remarkable red shift of more than 10 nm induced by the addition of the salts that constitute a saline buffer. The maximum absorption wavelength of the bromide is displaced from approximately 194 nm in ultrapure water to wavelengths above 200 nm, depending on the composition of the solution. The bromide spectrum as counterion of the cetyltrimethylammonium in the surfactant CTAB also shows sensitivity to the aggregation behavior of the tensioactive, being able to detect intermolecular interactions even at concentrations lower than the critical micelle concentration. And, when the micelles are assembled, the bromide absorption detects the interfacial rearrangements caused by the incorporation of ions. To know more about those interfacial features, the pyrene molecular probe was used, taking advantage of the extensive knowledge of its spectroscopy. Pyrene verifies the existence of changes in the interfacial organization which confirm that the sensitivity of the bromide spectrum is based on the ability of the ion to detect its microenvironment, and therefore reaffirms that its absorption spectrum can be used as a local sensor. The present work encourages the use of bromide as a sensor ion in the UV region between 190 and 210 nm, which would avoid the introduction of external molecular probes that could disturb the system.

Effect of UV-B radiation on the content of UV-B absorbing compounds and photosynthetic parameters in Parmotrema austrosinense from two contrasting habitats.

We studied the resistance of Parmotrema austrosinense to UV-B stress. We focused on the effects of a high dose UV-B radiation on the content of chlorophylls, carotenoids and UV-B screening compounds. Photosynthetic parameters were measured by chlorophyll fluorescence (potential and effective quantum yields, photochemical and non-photochemical quenching) and evaluated in control and UV-B-treated lichens. Lichens from two different locations in Cordoba, Argentina, were selected: (i) high altitude and dry plots at (Los Gigantes) and (ii) lowland high salinity plots (Salinas Grandes). UV-B treatment led to a decrease in the content of photosynthetic pigments and UV-B screens (absorbance decrease in 220-350 nm) in the samples from Salinas Grandes, while in Los Gigantes samples, an increase in UV-B screen content was observed. Chlorophyll fluorescence parameters showed a UV-B-induced decline in FV /FM , ΦPSII and qP indicating limitation of primary photosynthetic processes in photosystem II (PSII) of symbiotic alga, more pronounced in Salinas Grandes samples. Protective mechanism of PSII were activated by the UV-B treatment to a higher extent in samples from Salinas Grandes (NPQ 0.48) than in Los Gigantes samples (NPQ 0.26). We concluded that site-related characteristics, and in particular different UV-B radiation regimen, had a strong effect on resistance of the photosynthetic apparatus of P. austrosinense to UV-B radiation.

Molecular level investigation of the role of peptide interactions in the glyphosate analytics.

The detection of the herbicide glyphosate (GLP) in environmental samples is most often conducted after derivatizing the target molecule with the chromophore 9-fluorenylmethyloxycarbonyl chloride (FMOC-Cl). However, this method is sensitive to all primary and secondary amines, which can occur in the sample matrix as well. In order to quantify the interference of primary and secondary amines on GLP detection, we have used well-defined peptides such as pentaglycine (PG) and albumin as well as mixtures of peptides such as peptone. These peptides have been added to the derivatization solution of GLP at different constant concentration levels and UV extinction coefficients have been determined. Data analysis supported by quantum chemical modeling of the GLP-peptide, FMOC-GLP, and FMOC-peptide complexation reactions facilitated the identification of two interfering impacts of peptide on GLP derivatization: (i) increase of the signal due to reaction with FMOC-Cl leading to an overestimation of GLP concentration and (ii) decrease of GLP recovery due to complex formation and therefore inhibition of GLP derivatization, which leads to an underestimation. Specifically, our results indicated that the GLP-peptide- and peptide-FMOC-interactions are mainly affected by type of interfering peptides as well as concentration of each peptide and GLP in the environmental samples.

Determination of the Deacetylation Degree of Chitooligosaccharides.

The methods for determination of chitosan content recommended in the Chinese Pharmacopoeia and the European Pharmacopoeia are not applicable for evaluation of the extent of deacetylation (deacetylation degree, DD) in chitooligosaccharides (COS). This study explores two different methods for assessment of DD in COS having relatively high and low molecular weights: an acid-base titration with bromocresol green indicator and a first order derivative UV spectrophotometric method for assessment of DD in COS. The accuracy of both methods as a function of molecular weight was also investigated and compared to results obtained using ¹H NMR spectroscopy. Our study demonstrates two simple, fast, widely adaptable, highly precise, accurate, and inexpensive methods for the effective determination of DD in COS, which have the potential for widespread commercial applications in developing country.

Crystal structure and UV spectra of a 1,2-disubstituted benzimidazolium chloride.

1-(2-Hy-droxy-benz-yl)-2-(2-hy-droxy-phen-yl)-1H-benzimidazol-3-ium chloride, C20H17N2O2+·Cl-, was prepared by reaction of salicyl-aldehyde with o-phenyl-enedi-amine in the presence of tri-methyl-silyl chloride acting as a source of HCl. As a result of steric hindrance, the cation in the crystal is far from planar: the benzimidazole ring system makes dihedral angles of 55.49 (9) and 81.36 (8)° with the planes of the phenolic groups. The crystal packing is dominated by O-H⋯Cl and N-H⋯Cl hydrogen bonds, which link the cations and anions into four-membered rings and then into chains along [100]. The title compound exhibits two transitions in the UV region, which are revealed in the solid state and solution spectra as an absorption maximum at 280 nm and a shoulder at 320 nm. According to the results of TD-DFT calculation, both transitions have a π-π* nature and the mol-ecular orbitals involved in these transitions are mostly localized on the benzimidazole ring system and on the phenyl ring attached to it at the 2-position.

DFT and TD-DFT study of isomeric 5-(pyridyl)-1,3,4-oxadiazol-2-thiones and 2-methylthio-5-(pyridyl)-1,3,4-oxadiazoles.

Internal rotations of pyridine fragment around single bond of isomeric 5-(2', 3' and 4'-pyridyl)-1,3,4-oxadiazol-2-thiones and 2-methylthio-5-(2', 3' and 4'-pyridyl)-1,3,4-oxadiazoles have been performed by DFT (B3LYP) and MP2 methods with RHF/6-31G(d,p) basis set. It was found that the MP2 barrier height lies a few below than DFT barrier heights for all studied compounds. In the molecule of 2-methylthio-5-(2'-pyridyl)-1,3,4-oxadiazole an anomeric effect detected due to a lone pair-lone pair interaction of pyridine and N4 oxadiazole nitrogen atoms. But it not found in the molecule of 5-(2'-pyridyl)-1,3,4-oxadiazol-2-thione. Furthermore, theoretical UV spectra of the compounds were studied using TD-DFT/6-31G(d,p) method. Theoretical transitions located about 10nm in the long-wavelength region relatively to the experimental bands field. Whereas, the theoretical transitions of 2-methylthio-5-(2', 3' and 4'-pyridyl)-1,3,4-oxadiazoles have very good agreement with the position of experimental bands. The longest wavelength band in both of experimental and theoretical spectra of the investigated compounds have been observed for 5-(4'-pyridyl)-1,3,4-oxadiazole-2-thione and 2-methylthio-5-(2'-pyridyl)-1,3,4-oxadiazole. Furthermore, the longest-wavelength experimental band's position are in good agreement with (r2=0.95) the HOMO-LUMO energetic gaps of studied compounds.

Synthesis, electronic, and spectral properties of novel geranylated chalcone derivatives: a theoretical and experimental study.

Novel chalcone derivatives with different substituents attached to A and B-rings: hydroxyl, methoxyl, geranyl, and prenyl groups were synthesized. The obtained compounds were characterized by NMR, HRMS, UV-Vis, IR, and MS. The theoretical analysis was carried out in all the compounds using density functional theory (DFT) with the B3LYP, PBE0, and M06-2X functionals in combination with the 6-311G(d,p) Pople-type basis set. The excited state properties were calculated by time dependent density functional theory (TD-DFT) using the same methodology applied for the ground state properties. The calculated vertical absorption wavelengths (λmax) in gas phase and in ethanol as a solvent are consistent with the experimental ones, being the TD-DFT:B3LYP/6-311G(d,p) and PCM-TD-DFT:PBE0/6-311G(d,p) the best methodologies for these calculations with good approximation to the experimental values. The calculated reorganization energies indicated that, the four chalcone derivatives present an electron transfer character due to the smaller registered values. From these parameters it is proposed that these show an n-type semiconductor character. The localization of the frontier orbitals (HOMO and LUMO) shows that only the compound containing a hydroxyl group on the A-ring displays a marked delocalization favoring the charge-transfer process in this system. The HOMO-LUMO gap energies indicate that the inclusion of different donor groups in the rings does not improve the obtained values for this property. Graphical Abstract Relationship between spectroscopic and geometrical properties of chalcones were carried out using quantum-chemical calculations and compared with experimental values.

Towards green analysis of virgin olive oil phenolic compounds: Extraction by a natural deep eutectic solvent and direct spectrophotometric detection.

The determination of phenolic compounds in extra virgin olive oils (EVOO) by means of rapid, low-cost, environment-free methods would be a desirable achievement. A natural deep eutectic solvent (DES) based on glucose and lactic acid was considered as extraction solvent for phenolic compounds in EVOO. DESs are green solvents characterized by high availability, biodegradability, safety, and low cost. The spectrophotometric characteristics of DES extracts of 65 EVOO samples were related to the total phenolic content of the oils, assessed by methanol-water extraction coupled to the Folin-Ciocalteu assay. A regression model (ncalibration=45, nvalidation=20), including the absorbance at two wavelengths (257, 324nm), was obtained, with an adjusted R(2)=0.762. Therefore the DES could provide a promising and viable approach for a green screening method of phenolic compounds in EVOO, by means of simple spectrophotometric measurements of extracts, even for on-field analysis (for example in olive mills).