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This study provides a novel quantitative analysis of metformin hydrochloride (MET-HCl) solvation behavior in binary solvents mixtures of methyl alcohol and water, as well as ethyl alcohol and water, addressing critical gaps in understanding its solubility mechanisms for pharmaceutical formulation. We employed the inverse Kirkwood-Buff integrals (IKBI) method to extract key parameters from the solution thermodynamic properties of MET.HCl, yielding valuable insights into its behavior. The findings reveal that MET.HCl is sensitive to solvation effects, with the values of δx1,MET-HCl exhibiting a non-linear relationship with the proportion of solvent (1) in the two solvent mixtures. Specifically, in both the methyl alcohol/water and ethyl alcohol/water systems, all alcoholic aqueous mixture compositions exhibit negative δx1,MET-HCl values. Overall, our results reveal that MET-HCl exhibits preferential solvation by water, with a significantly greater magnitude of preferential solvation observed in ethyl alcohol /water mixtures compared to methyl alcohol /water mixtures. This enhanced solvation by water may be attributed to the disordered structure of the alcohol molecules surrounding the polar regions of MET-HCl. The influence of solvent composition on the molar fraction solubility of MET-HCl was investigated using the Kamlet-Taft linear solvation energy relationship model. The KAT-LSER model revealed that solvent polarity (π*) and ability to accept hydrogen bonds (α) were key factors in MET-HCl dissolution in methyl alcohol and water, as well as ethyl alcohol and water.

The main objective of this research was to understand the effect of different solvents (ethanol, ethyl acetate, and hexane) on the extraction of bioactive compounds in addition to the antioxidant activity of eight Tunisian and Algerian olive leaf (Olea europaea L) cultivars. The different extracts were evaluated for their content of total phenols, flavonoids, and condensed tannins. The antioxidant capacity was determined by ABTS (2,2-azinobis (3 ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1 picrylhydrazyl) methods. In addition, qualitative and quantitative analyses of phenolic compounds by HPLC were performed. In terms of phenolic content, ethanol was found to be the best solvent to extract phenolic compounds with antioxidant capacity. The ethanolic extract of Sigoise and Rougette varieties were the richest in total phenols 161.54 ± 0.99, and 160.53 ± 1.17 mg GAE/g DE respectively. The highest levels of flavonoids were detected in ethyl acetate extracts of Rougette (87.58 ± 6.99 mg QE/g DE) and Verdal varieties (86.77 ± 1.75 mg QE/g DE), whereas the hexanolic extracts of Gerboui, Sofiana, and Chemlali exhibited the higher amount of tannins (67.99 ± 5.41, 65.52 ± 1.94, 64.64 ± 1.51 mg CE/g DE, respectively). Furthermore, in the DPPH radical scavenging activity assay, the Sofiana extract exhibited the highest antioxidant activity (23.85 ± 0.58 mg/L). In another case, for the ABTS radical scavenging assay, the Verdal extract showed high antioxidant potential (30.22 ± 1.35 mg/L). HPLC analysis of ethanolic extracts of the different varieties allowed the identification of 19 organic compounds, with oleuropein (2604.01–7991.14 mg/100g DM) being the most abundant, followed by hydroxytyrosol (250.74–687.54 mg/100g DM) and verbascoside (216.12–672.64 mg/100g DM) being the major compounds in the olive leaves in all studied ethanolic extracts, with concentrations varying significantly according to the cultivars and geographical origin. Principal component analysis (PCA) performed on phenolic profiles and antioxidant activities revealed the influence of bioactive compounds on antioxidant activity, with high concentrations of phenols and flavonoids in olive leaf extracts having a strong antioxidant activity.

Organic cocrystals, which are assembled by noncovalent intermolecular interactions, have garnered intense interest due to their remarkable chemicophysical properties and practical applications. One notable feature, namely, the charge transfer (CT) interactions within the cocrystals, not only facilitates the formation of an ordered supramolecular network but also endows them with desirable semiconductor characteristics. Here, we present the intriguing ambipolar CT properties exhibited by nanosheets composed of single cocrystals of C70/ferrocene (C70/Fc). When heated to 150 °C, the initially ambipolar monoclinic C70/Fc nanosheet-based field-effect transistors (FETs) were transformed into n-type face-centered cubic (fcc) C70 nanosheet-based FETs owing to the elimination of Fc. This thermally induced alteration in the crystal structure was accompanied by an irreversible switching of the semiconducting behavior of the device; thus, the device transitions from ambipolar to unipolar. Importantly, the C70/Fc nanosheet-based FETs were also found to be much more thermally stable than the previously reported C60/Fc nanosheet-based FETs. Furthermore, we conducted visible/near-infrared diffuse reflectance and photoemission yield spectroscopies to investigate the crucial role played by Fc in modulating the CT characteristics. This study provides valuable insights into the overall functionality of these nanosheet structures.

Abstract Background The in vitro activity of the brown seaweed Dictyota spiralis against both Leishmania amazonensis and Trypanosoma cruzi was evaluated in a previous study. Processing by bio-guided fractionation resulted in the isolation of three active compounds, classified as diterpenes. In the present study, we performed several assays to detect clinical features associated to cell death in L. amazonensis and T. cruzi with the aim to elucidate the mechanism of action of these compounds on parasitic cells. Methods The aims of the experiments were to detect and evaluate specific events involved in apoptosis-like cell death in the kinetoplastid, including DNA condensation, accumulation of reactive oxygen species and changes in ATP concentration, cell permeability and mitochondrial membrane potential, respectively, in treated cells. Results The results demonstrated that the three isolated diterpenes could inhibit the tested parasites by inducing an apoptosis-like cell death. Conclusions These results encourage further investigation on the isolated compounds as potential drug candidates against both L. amazonensis and T. cruzi. Graphic abstract

Propolis is a resinous substance collected by bees from plants with a complex and variable chemical composition. Propolis and its fractions possess multiple biological activities. This study focused on a chemical and statistical comparison between four Tunisian Propolis Essential Oils (PEO) and its antioxidant activities. Volatile oils were extracted by hydrodistillation and analyzed by GC-MS. Essential oil yield varied from 0.095% to 0.324%. A total of 59 volatile components were identified mainly dominated by sesquiterpenes and diterpenes hydrocarbons. Six major components were found in all samples collected from the four different locations α-Cedrol, Manoyl Oxide, Manool, Totarol, Tricosane, and Eicosane. The antioxidant activities of Tunisian propolis essential oils have been evaluated using two methods: β-carotene-linoleic acid bleaching and DPPH radical scavenging assays and the results were compared with the standard antioxidant (Triolox). PEO from Bizerte region presented a lower IC50 value (30.5 mg/mL) than that of the standard antioxidant Trolox (IC50 = 40.05 mg/mL) indicating high antioxidant capacity using DPPH assay but for the b-carotene-linoleic acid bleaching assay, PEO from Zouarine region had the lowest value of (IC50 = 26.5 mg/mL) compared to standard (IC50 = 31.25 mg/mL). Our findings demonstrated that Propolis Essential Oil (PEO) possess high antioxidant activities and may be suggested as a new potential source of natural antioxidant.

Essential oils (EOs) that have antifungal activity and mycotoxin reduction ability are candidates to develop bioactive alternatives and environmentally friendly treatment against Fusarium species in cereals. However, their practical use is facing limitations such as high volatility, UV sensitivity, and fast oxidation. Encapsulation techniques are supposed to provide protection to the EOs and control their release into the environment. Ammoides pusilla essential oil (AP-EO) proved to be an efficient inhibitor of Fusarium avenaceum growth and its enniatins (ENNs) production. In the present work, AP-EO was encapsulated, using the impregnation method, into mesoporous silica particles (MSPs) with narrow slit pores (average diameter = 3.1 nm) and coated with chitosan. In contact assays using an agar medium, the antifungal activity of AP-EO at 0.1 µL mL−1 improved by three times when encapsulated into MSPs without chitosan and the ENNs production was significantly inhibited both in coated and non-coated MSPs. Controls of MSPs also inhibited the ENNs production without affecting the mycelial growth. In fumigation experiments assessing the activity of the EO volatile compounds, encapsulation into MSPs improved significantly both the antifungal activity and ENNs inhibition. Moreover, coating with chitosan stopped the release of EO. Thus, encapsulation of an EO into MSPs improving its antifungal and antimycotoxin properties is a promising tool for the formulation of a natural fungicide that could be used in the agriculture or food industry to protect plant or food products from the contamination by toxigenic fungi such as Fusarium sp. and their potential mycotoxins.

The extended application fields of the essential oils keep them a subject of interest. In this study, we investigated the aerial part essential oil and the fruit essential oil of the wild plant Ziziphus lotus, collected from the southern region of Tunisia. These essential oils obtained by hydrodistillation using a Clevenger-type apparatus showed an extraction yield of 0.013% and 0.0046% respectively. The qualitative and quantitative analysis of the samples using GC-MS/GC-FID revealed two distinct compositions. Apocarotenoid derivatives characterized the essential oil of the aerial part; the major compound was hexahydrofarnesyl acetone (23.2%) followed by geranylacetone (12.5%) and cis-hexenyl-3-benzoate (11.1%). While the abundance of fatty acid marked the fruit essential oil. The noticed major compounds were 2-pentadecanone (16.9%), dodecanoic acid ethyl ester (14.5%) and n-hexadecanoic acid (13.0%). Such chemical composition may explain the traditional use of Ziziphus lotus as a drug to treat various pathologies. DOI: http://dx.doi.org/10.5281/zenodo.5552960

‘Maltaise demi sanguine’ cultivars are usually grafted on sour orange rootstock. Nonetheless, this rootstock is highly susceptible to Citrus tristeza virus (CTV). A trial was set up in order to present new rootstocks as an alternative to sour orange. The effects of eight citrus rootstocks upon the volatile flavor components of the “Maltaise demi sanguine” peel were investigated in both healthy plants and those inoculated with Citrus exocortis viroid (CEVd) and Hop stunt viroid (HSVd). Rootstocks and viroid infection had no significant effect on essential oil yields. Oil components were analyzed by GC-MS. Total of 69 compounds were identified, representing 99% of the total oil. Limonene was the major component in all samples (59.53–95.34%). Principal components and hierarchical cluster analyses revealed that essential oils from plants grafted on Alemow and Carrizo citrange showed the most variable compositions in cases of healthy plants and those inoculated with CEVd. For those plants infected by HSVd, Cleopatra mandarin seemed to be the most affected. Overall, the combined effect of CEVd infection and the use of rootstocks Alemow, Carrizo citrange, and Volkamer lemon had the most pronounced chemical variability.

This study aimed to evaluate the effects of thyme (Thymus vulgaris L.), rosemary (Rosmarinus officinalis L.), and ammoides (Ammoidespusilla L.) aqueous extracts supplementation on the quality of heat-treated (55, 65, and 75 °C) raw milk (sample lots: A, B, and C) and cold-stored pasteurized milk (lot D). The three herbs have shown rich polyphenol contents (32.65–104.23 mgGAE/g), relevant antioxidant capacity, and high caffeic and rosmarinic acids and catechin contents. A significant reduction in psychrotrophic and total viable bacteria counts (PC and TVC) was attained following milk extract supplementation in both experiments. Monitoring PC and TVC counts in sample lots (A, B, and C) has revealed a significant improvement in extracts’ effectiveness in reducing the TVC count with the increment of temperature. The highest reductions of PC and TVC counts were achieved, respectively, in samples treated with thyme and rosemary in (lots: A, B, and C) and in samples treated with ammoides and thyme in (lot D). Thyme extract showed the highest milk serum DPPH scavenging activity (74.84% at 0.1 mg/mL) and induced a significant Listeria monocytogenes growth inhibition (>1 Log cycle). The sensory evaluation of supplemented milk has shown good consumer acceptability of ammoides-supplemented milk, quite similar to the control sample.

Fusarium Head Blight (FHB), caused by multiple species of Fusarium in small grain cereals, is a significant and long-standing problem anywhere in the world. Knowing regional Fusarium spp. present on non-symptomatic grains and their potential for mycotoxin production is of concern for identifying novel actions for FHB and mycotoxin management, such as treatments with essential oils. Analyzing the mycotoxin content of grains from non-symptomatic ears of different wheat varieties cultivated in Tunisia, we isolated Fusaria specimens identified as F. culmorum and F. acuminatum using analysis of the partial DNA sequence of the β-tubulin gene and ITS region. Two isolates of the latter species, uncommon in cereal grains in this region until now, were shown to be effective producers of enniatins in vitro, with 1390 and 3089 µg g−1 mycelial biomass (dry) in 11-day-old cultures. The susceptibility of an isolate of F. acuminatum to the fungistatic and antimycotoxin effects of eight essential oils was measured. Essential oils from Ammoides pusilla and Thymus capitatus used at 0.1 µL mL−1 in an agar culture medium, affected the mycelial growth by 55% and 79%, respectively and reduced the accumulation of enniatins per unit of mycelial colony by 26% and 52%, respectively. Finally, F. acuminatum was shown to be a contaminant of wheat grains in Tunisia and it may contribute to the contamination in enniatins. Two essential oils of Tunisian plants could be used for developing a biofungicide limiting both its mycelial growth and its accumulation of mycotoxins in grains.

The Tunisian Ziziphus lotus plant was investigated to determine its phytoconstituents and evaluate its biological activities. In particular, the GC/MS technique was used to describe the chemical composition of Z. lotus active extracts and fractions. Among the obtained extracts, the yields of the dried root methanolic extract (29.80%) and the fruit aqueous extract (48.00%) were the highest ones. The dried root methanolic extract exhibited the highest amount in the total phenolics (186.44 ± 0.26 mg GAE/g DW), total flavonoids (102.50 ± 3.53 mg QE/g DW), and tannins (60.714 ± 2.2 mg catechin/g DW). The root aqueous extracts revealed the highest antioxidant activity with an IC50 of 8.96 ± 0.38 mg/L and 16.46 ± 0.60 mg/L for the ABTS•+ and DPPH• assays, respectively. The total antioxidant capacity was accorded to the methanolic extract of the dried roots with a value of 304.07 ± 1.11 µg AAE/mg. The drying process was found to improve the qualitative and quantitative properties of the Z. lotus extracts. The evaluation of the cytotoxic activity against the SH-SY5Y cell line was carried out using MTT assay. The petroleum ether and dichloromethane extracts of the dried roots showed relevant cytotoxic activities. The thin layer chromatography and the GC-MS/GC-FID analysis led to the identification of the 13-epimanool as a potent cytotoxic compound.

Enniatins are mycotoxins produced by Fusarium species contaminating cereals and various agricultural commodities. The co-occurrence of these mycotoxins in large quantities with other mycotoxins such as trichothecenes and the possible synergies in toxicity could lead to serious food safety problems. Using the agar dilution method, Ammoides pusilla was selected among eight Tunisian plants for the antifungal potential of its essential oil (EO) on Fusarium avenaceum mycelial growth and its production of enniatins. Two EO batches were produced and analyzed by GC/MS-MS. Their activities were measured using both contact assays and fumigant tests (estimated IC50 were 0.1 µL·mL−1 and 7.6 µL·L−1, respectively). The A. pusilla EOs and their volatiles inhibited the germination of spores and the mycelial growth, showing a fungistatic but not fungicidal activity. The accumulation of enniatins was also significantly reduced (estimated IC50 were 0.05 µL·mL−1 for the contact assays and 4.2 µL·L−1 for the fumigation assays). The most active batch of EO was richer in thymol, the main volatile compound found. Thymol used as fumigant showed a potent fungistatic activity but not a significant antimycotoxigenic activity. Overall, our data demonstrated the bioactivity of A. pusilla EO and its high potential to control F. avenaceum and its enniatins production in agricultural commodities.

The antioxidant and antifungal activities of crude hydro-ethanolic extract from Capparis spinosa L. (Capparidaceae) leaves and their fractions, obtained by liquid-liquid extraction (LLE) using solvents with increasing polarity (hexane, diethyl ether, ethyl acetate, butanol, and water), were investigated. The crude extract and the obtained fractions were characterized by colorimetric analysis, pyrolysis-gas chromatography (GC)-mass spectroscopy (MS), Fourier Transform Infrared Spectroscopy, and their antioxidant and antifungal capacity were determined. It was observed that the ethyl acetate fraction was enriched in polyphenols, the butanol fraction resulted in purified from proteins and the residual aqueous fraction contains more hydrophobic compounds. The evaluation of the antioxidant activity revealed that the ethyl acetate fraction possesses an interesting capacity 1,1-diphenyl-2-picrylhydrazyl(DPPH) radical scavenging with a percentage of inhibition of 84.02% at a concentration of 2 mg/mL and better ferric reducing antioxidant power (FRAP) 4.275 ± 0.011 mmol/g of dry sample than the other fractions tested. Regarding the antifungal activity, the diethyl ether fraction showed the highest activity against Aspergillus niger with 58.78% of inhibition. The results obtained in this work showed the relevance of the valorization of the leaves of Capparis spinosa L., given its richness in bioactive molecules can be regarded as a natural source of antioxidant and antifungal and may be considered in the future to replace synthetic preservatives in food, pharmaceutic products and cosmetic.

Since the early nineties, countless publications have been devoted to the study of possible uses of [60] fullerene (C60) and its derivatives in the fields of materials and nano-biomedical sciences. However, in spite of the importance of conformers notably from the pharmacological point of view, the cis/trans isomerization of C60 mono-adducts has been rarely seldom investigated. Here we present the results of DFT calculations of the structural, vibrational and NMR properties of both cis and trans isomers of fulleropyrrolidine mono-adduct obtained by photo-addition of glycine methyl ester to C60. Taken together, our results have shown that the cis isomer is more stable than the trans one. For the cis conformation, the simulated vibrational spectrum shows a more intense peak at 1298 cm-1. While 13C spectra revealed no significant differences between the two isomers as compared to experimental results, the calculated 1H chemical shifts show a significant difference between the two conformers in both the gas phase and in solution. The trans isomer presents a proton at 5.86 ppm, which is more deshielded than the proton of the cis conformer (5.24 ppm).

The main concern of this work was to find a new biological antisprouting product for potatoes during storage. Ruta chalepensis L. essential oil (RCEO) was for the first time used as a potential sprouting inhibitor for potatoes. To confirm RCEO antisprouting effect, evolution of sprout length and weight loss of potato tubers was determined during a storage period of six weeks under three RCEO different treatments (2%, 4%, and 6%). Sprout final weight was also computed. Then, a screening of RCEO chemical composition was performed. An outstanding antisprouting effect of 6% emulsions concentrations was observed as compared to 2% and 4% emulsions concentrations. Final sprout weight (SW) of untreated samples was 4.66%, while 6% treated samples scored 0.98%. These results were endorsed by high Pearson correlation coefficients (>0.9). Indeed, increasing treatment concentration enhanced the sprout growth inhibition. Identification of RCEO major components showed that 2-undecanone represented 87.18% of total identified components suggesting that this component is the possible active agent of RCEO against potatoes sprouting.

In this study, Carum carvi L. essential oil (CEO) and Origanum majorana L. essential oil (MEO) was steam-distillated under reduced pressure. We henceforth obtained three fractions for each essential oil: CF1, CF2, CF3, MF1, MF2, and MF3. Then, these fractions were characterized using the gas chromatography−mass spectrometry (GC-MS) technique. The results indicated that some fractions were rich in oxygenated compounds (i.e., CF2, CF3, MF2, and MF3) with concentrations ranging from 79.21% to 98.56%. Therefore, the influence of the chemical composition of the essential oils on their antifungal activity was studied. For this purpose, three food spoilage fungi were isolated, identified, and inoculated in vitro, in order to measure the antifungal activity of CEO, MEO, and their fractions. The results showed that stronger fungi growth inhibitions (FGI) (above 95%) were found in fractions with higher percentages of oxygenated compounds, especially with (−)-carvone and terpin-4-ol as the major components. Firstly, this work reveals that the free-terpenes hydrocarbons fractions obtained from MEO present higher antifungal activity than the raw essential oil against two families of fungi. Then, it suggests that the isolation of (−)-carvone (97.15 ± 5.97%) from CEO via vacuum distillation can be employed successfully to improve antifungal activity by killing fungi (FGI = 100%). This study highlights that separation under reduced pressure is a simple green method to obtain fractions or to isolate compounds with higher biological activity useful for pharmaceutical products or natural additives in formulations.

Therapy against Acanthamoeba infections such as Granulomatous Amoebic Encephalitis (GAE) and Acanthamoeba Keratitis (AK), remains as an issue to be solved due to the existence of a cyst stage which is highly resistant to most chemical and physical agents. Recently, the activity of Olive Leaf Extracts (OLE) was demonstrated against Acanthamoeba species. However, the molecules involved in this activity were not identified and/or evaluated. Therefore, the aim of this study was to evaluate the activity of the main molecules which are present in OLE and secondly to study their mechanism of action in Acanthamoeba. Among the tested molecules, the observed activities ranged from an IC50 of 6.59 in the case of apigenine to an IC50 > 100 μg/ml for other molecules. After that, elucidation of the mechanism of action of these molecules was evaluated by the detection of changes in the phosphatidylserine (PS) exposure, the permeability of the plasma membrane, the mitochondrial membrane potential and the ATP levels in the treated cells. Vanillic, syringic and ursolic acids induced the higher permeabilization of the plasma membrane. Nevertheless, the mitochondrial membrane was altered by all tested molecules which were also able to decrease the ATP levels to less than 50% in IC90 treated cells after 24 h. Therefore, all the molecules tested in this study could be considered as a future therapeutic alternative against Acanthamoeba spp. Further studies are needed in order to establish the true potential of these molecules against these emerging opportunistic pathogenic protozoa.

In this study, essential oil and various extracts (hexane, petroleum ether, acetone, ethanol, methanol and water) of Eucalyptus gilii were screened for their chemical composition, antimicrobial and antioxidant activities. The essential oil chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID), respectively. Thirty four compounds were identified, corresponding to 99.5% of the total essential oil. Tannins [104.9–251.3 g catechin equivalent (CE)/Kg dry mass], flavonoids [3.3–34.3 g quercetin equivalent (QE)/Kg dry mass], phenolics [4.7–216.6 g gallic acid equivalent (GAE)/Kg dry mass] and anthocyannins [1.2–45.3 mg cyanidin-3-glucoside equivalent (C3GE)/Kg dry mass] of various extracts were investigated. Free radical scavenging capacity of all samples was determinedt. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the IC50 of essential oil was 163.5 ± 10.7 mg/L and in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS) assay, it was 94.7 ± 7.1 mg/L. Among the various extracts, the water extract showed the best result (IC50 = 11.4 ± 0.6 mg/L) in the DPPH assay which was comparable to vitamin C (IC50 = 4.4 ± 0.2 mg/L). The antimicrobial activities were evaluated against different bacterial and fungal strains. Gram positive bacteria were found to be more sensitive to the essential oil and extracts than Gram negative ones. Anthocyanins seem to have a major effect on the growth of Bacillus subtilis (R2 = 0.79). A significant antifungal activity was observed against the yeast and fungi. Correlations between chemical composition and antioxidant activities were studied and R2 values were about 0.96 for the effect of phenolics on the DPPH assay.

Bioassay-guided fractionation of the antikinetoplastid extract of the brown alga Dictyota spiralis has led to the isolation of spiralyde A (1), a new dolabellane aldehyde, along with other five known related diterpenes (2–6). Their structures were determined by HRESIMS, 1D and 2D NMR spectroscopy, and comparison with data reported in the literature. The antiparasitic activity of all compounds was evaluated. Spiralyde A (1) and the known compound 3,4-epoxy-7,18-dolabelladiene (2) were the most active compounds against Leishmania amazonensis and Trypanosoma cruzi. Spiralyde A (1) was the most potent compound, comparable to benznidazole, the reference drug for trypanocidal activity.

Melaleuca styphelioides, known as the prickly-leaf tea tree, contains a variety of bioactive compounds. The purposes of this study were to characterize the polyphenols extracted from Melaleuca styphelioides leaves and assess their potential antioxidant and anti-inflammatory effects. The polyphenol extracts were prepared by maceration with solvents of increasing polarity. The LC/MS-MS technique was used to identify and quantify the phenolic compounds. An assessment of the radical scavenging activity of all extracts was performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS+), and ferric reducing antioxidant power (FRAP) assays. The anti-inflammatory activity was determined on interferon gamma (IFN-γ)/histamine (H)-stimulated human NCTC 2544 keratinocytes by Western blot and RT-PCR. Compared to other solvents, methanolic extract presented the highest level of phenolic contents. The most frequent phenolic compounds were quercetin, followed by gallic acid and ellagic acid. DPPH, ABTS+, and FRAP assays showed that methanolic extract exhibits strong concentration-dependent antioxidant activity. IFN-γ/H treatment of human NCTC 2544 keratinocytes induced the secretion of high levels of the pro-inflammatory mediator inter-cellular adhesion molecule-1 (ICAM-1), nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nuclear factor kappa B (NF-κB), which were inhibited by extract. In conclusion, the extract of Melaleuca styphelioides leaves is rich in flavonoids, and presents antioxidant and anti-inflammatory proprieties. It can be proposed as a useful compound to treat inflammatory skin diseases.