Scavenging capacity of strawberry tree (Arbutus unedo L.) leaves on free radicals

Despite strawberry tree (Arbutus unedo L.) leaves had a long use in traditional medicine due to its antiseptic, diuretic, astringent and depurative properties, the potential of their antioxidant activity are still lacking. Our study goals to assess the antioxidant and free radical scavenging potential of water, ethanol, methanol and diethyl ether extracts of A. unedo leaves. Total phenols content was achieved spectrophotometrically using Folin–Ciocalteau reagent with gallic acid as standard. Antioxidant activity was evaluated using three different methods: reducing power of iron (III)/ferricyanide complex assay, scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and scavenging effect on superoxide radicals by using the PMS–NADH–nitroblue tetrazolium system. Ethanol extracts of A. unedo leaves were the highest in reducing power (IC₅₀ 232.7 μg/mL) and DPPH scavenging effect (IC₅₀ 63.2 μg/mL) followed by water extracts (with IC₅₀ of 287.7 and 73.7 μg/mL, respectively); whereas diethyl ether extracts were the lowest. In the scavenging on superoxide radical assay, methanol extracts obtained the best results (IC₅₀ 6.9 μg/mL). For all the methods tested the antioxidant activity was concentration dependent. In accordance with antioxidant activity, highest total phenols content were found in ethanol, followed by water, methanol and diethyl ether extract. The results indicated that A. unedo leaves are a potential source of natural antioxidants.     

Valorisation of Salicornia ramosissima biowaste by a green approach – An optimizing study using response surface methodology

The purpose of this study was to optimize the extraction of antioxidants from Salicornia ramosissima by-product through Response Surface Methodology (RSM). The impacts of time (10–60 min) and temperature (40–80 °C) in total phenolic content (TPC) and antioxidant/antiradical activity were assessed. The optimal extract was attained at the binomial 80 °C/10 min and characterized regarding phenolic composition, pigments quantification, radicals quenching capacity, anti-acetylcholinesterase (AChE) activity, and cell viability effects. The optimal extract was characterized by low carotenoids content (8.15 μg/g on dry weight (dw)) and high amounts of hydroxycinnamic acid derivatives (23.12 mg/g dw). A remarkable scavenging efficiency was observed, particularly for HOCl (IC₅₀ = 27.61 μg/mL) and ONOO^? (IC₅₀ = 47.32 μg/mL). No adverse effects were detected on HaCaT and HFF-1 viability up to 1000 μg/mL. Additionally, the neuroprotective properties of the optimal extract were demonstrated by AChE inhibition (32.34% at 1000 μg/mL). This study encourages the sustainable recovery of antioxidants from the undervalued biowaste of S. ramosissima as a new raw material for different industries.     

Allicin from garlic neutralizes the hemolytic activity of intra- and extra-cellular pneumolysin O in vitro

Pneumolysin (PLY) is a key virulence factor contributes to the pathogenesis of Streptococcus pneumoniae. In this study we investigated the effect of allicin and aqueous garlic extracts on hemolytic activity of PLY both in prelysed and intact cells. Additionally the antimicrobial activity of allicin was tested against the bacteria. All tested materials potently inhibited the PLY hemolytic activity. Allicin neutralizes PLY in a concentration- and time-dependent manner. Twenty five minute incubation of PLY (2 HU/mL) with 0.61 μM/mL concentration of allicin, totally inhibited hemolytic activity of PLY (IC50 = 0.28 μM/mL). The inhibitory activity of old extract of garlic was similar to pure allicin (IC50 = 50.46 μL/mL; 0.31 μM/mL; P < 0.05). In contrast fresh extract of garlic inhibits the PLY hemolytic activity at lower concentrations (IC50 = 13.96 μL/mL; 0.08 μM/mL allicin). Exposure of intact cells to allicin (1.8 μM) completely inhibited hemolytic activity of PLY inside bacterial cells. The inhibitory effect of the allicin was restored by addition of reducing agent DTT at 5 mM, proposing that allicin likely inhibits the PLY by binding to cysteinyl residue in the binding site. The MIC value of allicin was determined to be 512 μg/mL (3.15 μM/mL). These results indicate that PLY is a novel target for allicin and may provide a new line of investigation on pneumococcal diseases in the future.     

Development,pharmacological and toxicological evaluation of a new tablet formulation based on Cassia grandis fruit extract

The treatment of Diabetes mellitus (DM) involves drugs for controlling the blood glucose level, and for treating concomitant disorders such as obesity. Based on the potent antioxidant activity, the α-glycosidase and lipase inhibitory effect, and the potent hypoglycemic effect of the fruit extract of Cassia grandis Lf (CgE), in this work it was developed a novel tablet formulation (CgET) using CgE as the active ingredient. The excipients proportion was optimized by using a D-optimal mixture design. The effect of the compaction force (10, 13, 16, 19, and 22 kN) on the technological properties of tablets was evaluated. The optimized granules formulation was compressed at 16 kN, for producing tablets with excellent technological properties. Tablets showed a potent antioxidant effect (IC₅₀ = 1.45 μg/mL), and α-glycosidase inhibitory activity (IC₅₀ = 34.96 μg/mL) more potent than Acarbose (IC₅₀ = 63.25 μg/mL). Tablets exhibited a strong antiglycant effect by the oxidative (IC₅₀ = 22.45 ± 1.80 μg/mL) and non-oxidative (IC₅₀ = 25.49 ± 1.80 μg/mL) pathways, and produced (at 100 mg/kg) a hypoglycemic effect statistically equal to glibenclamide (25 mg/kg). CgET did not show oral acute toxicity (LC₅₀ > 2000 mg/kg), framed as a non-toxic products. Fruits of the Cassia grandis L f, an underutilized species from the Cuban’ eastern region; allow developing a novel tablet formulation that could be used for the treatment of diabetic patients.     

Rubus rosifolius (Rosaceae) stem extract induces cell injury and apoptosis in human hepatoma cell line

Rubus rosifolius, popularly known as “red mulberry”, is a common medicinal plant in southern Brazil and is used as an antidiarrheal, analgesic, antimicrobial and antihypertensive, and to treat stomach diseases. The aim of this study was to analyze the R. rosifolius stem extract (RrSE) for possible in vitro cytotoxic and genotoxic effects, using the comet assay and the micronucleus test to assess genotoxicity, and flow cytometry to assess the impact on the cell cycle and apoptosis in HepG2/C3A cells, in addition to evaluating the expression of genes linked to the induction of DNA damage, cell cycle, apoptosis and metabolism of xenobiotics. The MTT assay observed no cytotoxic effects at concentrations between 0.01 and 100 μg/mL of the extract. However, genotoxic effects occurred in treatments with the extract from a 1 μg/mL concentration. Flow cytometry analysis revealed a significant increase in cells in the G2/M phase after treatment with 10 μg/mL, a decrease in cells in the G0/G1 phase in the treatment with 100 μg/mL, and a significant increase in total apoptotic cells. In the gene expression analysis, an increase in the CYP1A2 xenobiotics metabolizing gene expression was observed. Despite the promising pharmacological effects of R. rosifolius, the results revealed that the RrSE has genotoxic effect and induces apoptosis in HepG2/C3A cells, indicating danger in using this plant extract by humans.     

Leaf extracts from Teucrium ramosissimum protect against DNA damage in human lymphoblast cell K562 and enhance antioxidant,antigenotoxic and antiproliferative activity

The in vitro antioxidant, antigenotoxic and antiproliferative activities of Teucrium ramosissimum extracts were investigated. The antioxidant activities of the tested extracts were evaluated through three chemical assays: The Cupric reducing antioxidant capacity, the reducing power and the ferric reducing antioxidant power. TR1 fraction from methanol extract showed the best antioxidant activity evaluated by the CUPRAC, RP and FRAP assays with TEAC values of 4.04, 1.77 and 1.48 μM respectively compared to control. Yet, TR2 fraction exhibited the lowest antioxidant effect with a TEAC values of 1.97, 0.408 and 0.35 μM respectively. All the tested extracts were also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals. Furthermore, the effects of T. ramosissimum extracts on cell proliferation were also examined. The cytotoxic study revealed that methanol extract significantly inhibited the proliferation of K562 cells (IC50 = 150 μg/mL). The antigenotoxic properties of these extracts were investigated by assessing the induction and inhibition of the genotoxicity induced by the direct-acting mutagen, hydrogen peroxide (H₂O₂), using an eukaryotic system; the “Comet assay.” The results showed that all the extracts inhibited the genotoxicity induced by H₂O₂, and particularly TR2 fraction (96.99%) and methanol extract (96.64%).The present study has demonstrated that T. ramosissimum extract possess potent antioxidant, antiproliferative and antigenotoxic activities, which could be derived from compounds such as flavonoids and polyphenols.     

Assessment of anti-inflammatory effect of 5β-hydroxypalisadin B isolated from red seaweed Laurencia snackeyi in zebrafish embryo in vivo model

5β-Hydroxypalisadin B, a halogenated secondary metabolite isolated from red seaweed Laurencia snackeyi was evaluated for its anti-inflammatory activity in lipopolysaccharide (LPS)-induced zebrafish embryo. Preliminary studies suggested the effective concentrations of the compound as 0.25, 0.5, 1 μg/mL for further in vivo experiments. 5β-Hydroxypalisadin B, exhibited profound protective effect in the zebrafish embryo as confirmed by survival rate, heart beat rate, and yolk sac edema size. The compound acts as an effective agent against reactive oxygen species (ROS) formation induced by LPS and tail cut. Moreover, 5β-hydroxypalisadin B effectively inhibited the LPS-induced nitric oxide (NO) production in zebrafish embryo. All the tested protective effects of 5β-hydroxypalisadin B were comparable to the well-known anti-inflammatory agent dexamethasone. According to the results obtained, 5β-hydroxypalisadin B isolated from red seaweed L. snackeyi could be considered as an effective anti-inflammatory agent which might be further developed as a functional ingredient.     

Extraction of water-soluble polysaccharide and the antioxidant activity from Semen cassiae

Water-soluble polysaccharide was isolated from Semen cassiae using water for extraction and ethanol for deposition. The optimized conditions for polysaccharide isolation by orthogonal experiments were a sample to liquid ratio of 1:30 at 80°C for 3.5 hours; the yield of polysaccharide from Semen cassiae under these conditions was 5.46%. Different polysaccharides (SCPW-1, SCPW-2, SCPW-3, SCPW-4, SCPW-5, SCPS-1, SCPS-2) were obtained from the extract (i.e., crude polysaccharide) by DEAE-cellulose column chromatography. The polysaccharides obtained showed different structures by Fourier transform infrared therein the five elected from the seven kinds separated. The antioxidant activities of the extract were evaluated. The scavenging rates of the present extract on hydroxyl and superoxide were 43.32% and 64.97%, respectively, at a concentration of polysaccharide of 94.03 μg/mL, which was better than vitamin C at the same concentration. The scavenging rate of the present extract on 1,1-diphenyl-2-picrylhydrazyl was 13.33% at a polysaccharide concentration of 94.03 μg/mL, which was less than vitamin C at the same concentration.     

Pharmacological and computer-aided studies provide new insights into Millettia peguensis Ali (Fabaceae)

Millettia peguensis, popular for its ethnopharmacological uses, was employed to evaluate its different pharmacological properties in this study. The analgesic studies of the plant have been performed by acetic acid-induced writhing and formalin-induced licking tests respectively, whereas the antidiarrheal experiment was done by castor oil-induced diarrheal test. Besides, antioxidant, cytotoxic, antimicrobial, thrombolytic evaluations were performed by DPPH scavenging with phenol content determination, brine shrimp lethality, disc diffusion and clot lysis methods respectively. Moreover, in silico study of the phytoconstituents was carried out by molecular docking and ADME/T analysis.The methanol extract of Millettia peguensis (MEMP) revealed significant biological activity in the analgesic and antidiarrheal test (p < 0.001) compared to the standards. Antioxidant assay displayed promising IC₅₀ values (15.96 μg/mL) with the total phenol content (65.27 ± 1.24 mg GAE/g). In the cytotoxicity study, the LC₅₀ value was found to be 1.094 μg/mL. Besides, MEMP was highly sensitive to the bacteria but less liable to clot lysis. Furthermore, phytoconstituents exposed potential binding affinity towards the selected receptors, whereas the ADME/T properties indicated the drug likeliness of the plant. The outcomes of these findings suggest the therapeutic potential of this plant against pain, diarrhea, inflammation, and tissue toxicity.     

Phenolic composition and biological activities of Juniperus drupacea Labill. berries from Turkey

The present study was designed to define the phenolic profile and the biological potential of berries methanol extract of Juniperus drupacea Labill. from Turkey.The total phenolic content (Folin-Ciocalteau assay) was 48.06 ± 0.99 mg GAE/g extract. The HPLC-DAD-ESI-MS analysis allowed the determination of the complete phenolic profile of J. drupacea berries. Phenolic acids represented more than 60% of the total phenolics, and tyrosol was the major one (1324 ± 0.64 μg/g extract); within the flavonoids amentoflavone was detected as the main constituent (927 ± 0.35 μg/g extract).The extract exhibited good antioxidant properties, as determined by different in vitro models: DPPH test (IC₅₀ 0.38 ± 0.02 mg/mL), reducing power (12.63 ± 0.14 ASE/mL), Fe²⁺ chelating ability (IC₅₀ 2.26 ± 0.06 mg/mL), and TBA test (IC₅₀ 2.47 ± 1.13 μg/mL).Cytotoxicity against Artemia salina was highlighted (LC₅₀ 489.47 ± 27.8 μg/mL), and a significant decrease (p ? 0.05; p ? 0.01) in HepG2 cells viability was observed at the higher concentrations (5-10 μg/mL).The extract displayed good antibacterial activity towards Gram-positive bacteria and in particular Staphylococcus aureus was the most susceptible strain (MIC 78.12 μg/mL).     

Optimization of fermentation process of Cordyceps militaris and antitumor activities of polysaccharides in vitro

The influence of medium composition and cultural conditions on simultaneous yield of mycelia, intracellular polysaccharide, adenosine, and mannitol by Cordyceps militaris CGMCC 2909 was investigated with desirability functions in this study. An optimization strategy based on the desirability function approach, together with response surface methodology (RSM) has been used to optimize medium composition, and the optimal medium was obtained via the desirability as follows: yeast extract 10.33 g/L, sucrose 27.24 g/L, KH₂PO₄ 5.60 g/L and the optimal culture conditions are initial pH 6, 25°C, rotation speed 150 r/minute, inoculum size 4%(v/v), and medium capacity 40 mL/250 mL. Under these conditions, the yield of mycelia, intracellular polysaccharide, adenosine and mannitol reached 12.19 g/L, 0.6 g/L, 61.84 mg/L, and 1.38 g/L, respectively, and the D value was 0.77. Furthermore, the polysaccharides showed significant antitumor activities against HeLa and HepG2 in vitro in a dose-dependent manner in 72 hours. At a concentration of 1000 mg/mL, the inhibition rate of polysaccharides was 92.38% and 98.79%. The IC50 for HeLa and HepG2 were 70.91 μg/mL and 97.63 μg/mL, respectively.     

Genotoxicity and antileishmanial activity evaluation of Physalis angulata concentrated ethanolic extract

Antileishmanial in vitro tests, as well as Ames and micronucleus assays were performed with a concentrated ethanolic extract of Physalis angulata (EEPA)ResultsEEPA did not present mutagenic effect in Salmonella typhimurium strains at concentration reaching 3000 μg/plate and did not induce mutagenic effects after two oral administrations with a 24 h interval at a dose level of 2000 mg/kg. EEPA presented antileishmanial activity and presented an IC₅₀ value of 5.35 ± 2.50 μg/mL and 4.50 ± 1.17 μg/mL against Leishmania amazonensis and Leishmania braziliensis promastigotes, respectively. In the cytotoxicity test against macrophages, the EEPA had a LC₅₀ of 6.14 ± 0.59 μg/mL. Importantly, the IC₅₀ against L. amazonensis intracellular amastigotes was 1.23 ± 0.11 μg/mL.ConclusionEEPA extract is non-mutagenic and presented a promising pharmacological effect against Leishmania parasites.     

Extraction of bioactive compounds from buriti (Mauritia flexuosa L.) fruit by eco-friendly solvents: Chemical and functional characterization

Buriti (Mauritia flexuosa L.) is a palm tree found in several regions of Latin America. Buriti fruit is a rich source of bioactive compounds such as carotenoids and phenolic compounds. Thus, the aim of this study was to extract bioactive compounds from buriti fruit by ethanol and a supramolecular solvent system (SUPRAS) formed by octanoic acid aggregates. The extracts were evaluated for total carotenoids, β-carotene, phenolic compounds and antioxidant capacity. Additionally, SUPRAS extracts were characterized for antibacterial activity and modulating effect. The extraction of β-carotene with SUPRAS showed a yield of 5.82 ± 0.05 mg/g for the peel and 26.7 ± 0.02 mg/g for the pulp. In relation to total phenolic compounds, the yields were 32.1 ± 1.2 μg GAE/g for the peel and 24.53 ± 4.9 μg GAE/g for the pulp. The presence of gallic acid, quercetin and catechin stand out regarding the phenolics identified. The extracts showed antioxidant activity, with an emphasis on the extracts obtained by SUPRAS, which presented EC₅₀ (concentration required to obtain a 50% antioxidant effect) for the ABTS radical sequestration of 3.00 μg/mL for the peel and 0.84 μg/mL for the pulp. When combined with norfloxacin and gentamicin antibiotics, the extracts also showed a synergistic action against multi-resistant strains of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. Thus, the extraction of bioactive compounds from buriti fruit using a safe, biocompatible, biodegradable and environmentally friendly solvent such as SUPRAS represents potential for developing new pharmaceuticals, cosmetics and functional foods.     

Characterization of metabolite profiles from the leaves of green perilla (Perilla frutescens) by ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry and screening for their antioxidant properties

The objective of this research was to access the determination of metabolite profiles and antioxidant properties in the leaves of green perilla (Perilla frutescens), where these are considered functional and nutraceutical substances in Korea. A total of 25 compositions were confirmed as six phenolic acids, two triterpenoids, eight flavonoids, seven fatty acids, and two glucosides using an ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) technique from the methanol extract of this species. The individual and total compositions exhibited significant differences, especially rosmarinic acid (10), and linolenic acids (22 and 23) were detected as the predominant metabolites. Interestingly, rosmarinic acid (10) was observed to have considerable differences with various concentrations in three samples (Doryong, 6.38 μg/g; Sinseong, 317.60 μg/g; Bongmyeong, 903.53 μg/g) by UPLC analysis at 330 nm. The scavenging properties against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals also showed potent effects with remarkable differences at a concentration of 100 μg/mL, and their abilities were as follows: Sinseong (DPPH, 86%; ABTS, 90%) > Bongmyeong (71% and 84%, respectively) > Doryong (63% and 73%, respectively). Our results suggest that the antioxidant activities of green perilla leaves are correlated with metabolite contents, especially the five major compositions 10 and 22–25. Moreover, this study may be useful in evaluating the relationship between metabolite composition and antioxidant activity.     

The antioxidant and cytoprotective activity of Ocimum gratissimum extracts against hydrogen peroxide-induced toxicity in human HepG2 cells

Ocimum gratissimum is used as a traditional folk medicine in many countries. The objective of this study was to evaluate the antioxidant activities of an aqueous O. gratissimum extract (OGE) and to evaluate its cytoprotective activity against hydrogen peroxide-induced toxicity in human HepG2 cells. The results revealed that the total phenolic content of the OGE reached 20%. In the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the OGE reduced up to 80% of the free radicals at a plateau concentration of 66.7 μg/mL. This indicates that OGE contains considerable free radical scavenging activity. In a dose-dependent manner, OGE pretreatment counteracted the decrease in cell viability in H₂O₂-treated HepG2 cells (p < 0.05), and at a concentration of 20–80 μg/mL, it effectively reduced thiobarbituric acid reactive substance (TBARS) formation. These findings indicated that the aqueous extract of O. gratissimum has an antioxidant capacity and protective effect on oxidative stress in HepG2 cells. This makes OGE a promising therapeutic agent in liver diseases.     

Antimalarial and free radical scavenging activities of rhizomes of Polygonatum verticillatum supported by isolated metabolites

Antimalarial activity of the crude extract of Polygonatum verticillatum rhizomes and its sequentially partitioned fractions were investigated against Plasmodium falciparum. The crude extract possessed notable activity (IC₅₀: 21.67?μg/mL) that enhanced reasonably upon fractionation. The antiparasitic potency of the n-hexane fraction was maximum (IC₅₀: 2.33?μg/mL) followed by chloroform (IC₅₀: 4.62?μg/mL). However, the remaining fractions showed insignificant activity in the assay. The extracts of the plant showed marked scavenging activity on stable free radical, DDPH. The most potent antioxidant was the chloroform fraction (IC₅₀: 90?μg/mL) followed by ethyl acetate (IC₅₀: 93?μg/mL) and n-butanol (IC₅₀: 95?μg/mL) fractions. In the brine shrimps lethality test, the extracts were found nontoxic with the exception of ethyl acetate fraction (LD₅₀: 492.846?μg/mL). The bioactivity-guided isolation resulted into 5-hydroxymethyl-2-furaldehyde (HMF) and diosgenin which strongly supports the present experimental findings.     

The effect of tramadol hydrochloride on early life stages of fish

The aim of this study was to perform the fish embryo acute toxicity test (FET) on zebrafish (Danio rerio) and the early-life stage toxicity test on common carp (Cyprinus carpio) with tramadol hydrochloride. The FET was performed using the method inspired by the OECD guideline 236. Newly fertilized zebrafish eggs were exposed to tramadol hydrochloride at concentrations of 10; 50; 100 and 200 μg/l for a period of 144 h. An embryo-larval toxicity test on C. carpio was performed according to OECD guideline 210 also with tramadol hydrochloride at concentrations 10; 50; 100 and 200 μg/l for a period of 32 days.Hatching was significantly influenced in both acute and subchronic toxicity assays. Subchronic exposure also influenced early ontogeny, both morphometric and condition characteristics and caused changes in antioxidant enzyme activity. The LOEC value was found to be 10 μg/l tramadol hydrochloride.     

Mutagenic,antimutagenic and antioxidant potency of leaf extracts from Nitraria retusa

Four extracts were prepared from the leaves of Nitraria retusa; methanol, ethyl acetate, chloroform and hexane extracts. An assay for the ability of these extracts to prevent mutations induced by various oxidants in Salmonella typhimurium TA102 and TA 104 strains was conducted. These extracts from leaf parts of N. retusa showed no mutagenicity either with or without the metabolic enzyme preparation (microsome fraction). The highest protection against methylmethanesulfonate induced mutagenicity was observed with chloroform and methanol extracts with inhibition percentages of 44.93% (at 50 μg/plate in the presence of TA102 strain) and 38% (at 10 μg/plate in the presence of TA104 strain), respectively. Whereas Hexane and chloroform extracts reduced the mutagenicity induced by 2-aminoanthracene by 83.4% (using the S. typhimurium TA104 assay system) and 65.3% (using the S. typhimurium TA 102 assay system), respectively. Antioxidant activity of N. retusa extracts was determined by the ability of each extract to protect plasmid DNA against strand scission induced by hydroxyl radicals. Chloroform extract exhibited the highest ability to protect plasmid DNA against hydroxyl radical induced DNA damages and exhibited the highest antioxidant capacity, with 0.95 mM trolox equivalent when tested by the ferric reducing/antioxidant method.     

A phenolic extract from grape by-products and its main hydroxybenzoic acids protect Caco-2 cells against pro-oxidant induced toxicity

Grape/wine industry produces large amounts of by-products, however knowledge on their health-promoting qualities is limited. This study investigated the effects of a grape phenolic extract (GPE) and its phenolic compounds, gallic acid (GA) and syringic acid (SA) on human intestinal Caco-2 cells, directly or after cytotoxicity induced by tert-butylhydroperoxide (t-BOOH). Direct treatment with 0.1–10 μg/mL GPE, or 0.1–10 μM GA and SA produced no major cytotoxic effect, either changes in antioxidant defences (glutathione content, glutathione peroxidase and reductase activities) or protein damage (carbonyl groups). However, 10 μg/mL GPE, 1 and 10 μM GA and 10 μM SA decreased reactive oxygen species (ROS) production.Pre-treatment with GPE, SA and GA at the same concentrations for 20 h showed that 10 μg/mL GPE and 10 μM GA or SA significantly counteracted ROS increase induced by t-BOOH. 10 μg/mL GPE and 1–10 μM GA or 10 μM of SA significantly reduced pro-oxidant-induced cytotoxicity. 1–10 μg/mL GPE, 1–10 μM GA and 10 μM SA significantly recovered both depleted glutathione and enhanced glutathione reductase and peroxidase activities, and reduced protein oxidative damage. Therefore, treatment with realistic concentrations of GPE and its main hydroxybenzoic acids protected Caco-2 cells against induced oxidative stress.