Minor compounds in the phenolic fraction of virgin olive oils

Chemical Profile of Lipophilic Fractions of Different Parts of Zizyphus lotus L. by GC-MS and Evaluation of Their Antiproliferative and Antibacterial Activities

Zizyphus lotus L. is a perennial shrub particularly used in Algerian folk medicine, but little is known concerning the lipophilic compounds in the most frequently used parts, namely, root bark, pulp, leaves and seeds, which are associated with health benefits. In this vein, the lipophilic fractions of these morphological parts of Z. lotus from Morocco were studied by gas chromatography-mass spectrometry (GC-MS), and their antiproliferative and antimicrobial activities were evaluated. GC-MS analysis allowed the identification and quantification of 99 lipophilic compounds, including fatty acids, long-chain aliphatic alcohols, pentacyclic triterpenic compounds, sterols, monoglycerides, aromatic compounds and other minor components. Lipophilic extracts of pulp, leaves and seeds were revealed to be mainly composed of fatty acids, representing 54.3-88.6% of the total compounds detected. The leaves and seeds were particularly rich in unsaturated fatty acids, namely, (9Z,12Z)-octadeca-9,12-dienoic acid (2431 mg kg^-1 of dry weight) and (9Z)-octadec-9-enoic acid (6255 mg kg^-1 of dry weight). In contrast, root bark contained a high content of pentacyclic triterpenic compounds, particularly betulinic acid, accounting for 9838 mg kg^-1 of dry weight. Root bark extract showed promising antiproliferative activity against a triple-negative breast cancer cell line, MDA-MB-231, with a half-maximal inhibitory concentration (IC₅₀) = 4.23 ± 0.18 µg mL^-1 of extract. Leaf extract displayed interesting antimicrobial activity against Escherichia coli, methicillin-sensitive Staphylococcus aureus and Staphylococcus epidermis, presenting minimum inhibitory concentration (MIC) values from 1024 to 2048 µg mL^-1 of extract. Our results demonstrate that Zizyphus lotus L. is a source of promising bioactive components, which can be exploited as natural ingredients in pharmaceutical formulations.

Chemical analysis, biological and therapeutic activities of Olea europaea L. extracts

The Olea europaea L. is a very well-known and widely used plant, especially for its nutritional qualities. Its extracts from leaves and fruits are widely used in contrasting and preventing various pathologies. In this review, the collected data highlight important chemical analyses and biological effects of this plant extracts. It exhibits cholesterol-lowering, hypoglycemic, cytotoxic, antibacterial, neuroprotective, antioxidant, anti-inflammatory and hypotensive activities. The results show that extracts from O. europaea could be used as a food additive in the supplementary treatment of many diseases.

LC-DAD-ESI-MS/MS-based phenolic profiling and antioxidant activity in Turkish cv. Nizip Yaglik olive oils from different maturity olives

The current study was designed to find out how olive maturity indices (2.5, 3.5, and 4.5) affect the individual phenolic compounds and antioxidant potencies of olive oils produced from cv. Nizip Yaglik olives. Liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry in multiple reaction monitoring mode was utilized for the determination of phenolic composition qualitatively and quantitatively. Findings asserted a quite similar phenolic profile (14 phenols) depending on the various phenolic groups in all oils, while the concentration of total and individual phenolic compounds revealed significant differences between the samples statistically (p < 0.05). Among the individual phenolic classes in all samples, secoiridoids were the most prevailing group and their total content showed a clear significant decline as the olive fruits get ripened. Antioxidant potency values showed a clear diminution attitude during the maturation of the olives. The principal component analysis revealed that oils were discriminated from each other according to phenolic compounds and antioxidant potencies. Moreover, oils obtained from the unripe and medium-ripe fruits possessed a very good quality marked by their elevated phenolic levels.

4-(Hydroxymethyl)catechol Extracted From Fungi in Marine Sponges Attenuates Rheumatoid Arthritis by Inhibiting PI3K/Akt/NF-κB Signaling

Rheumatoid arthritis (RA) is a progressive autoimmune disease specific to synovial joints; it causes joint damage and other systemic abnormalities, thereby leading to physical disability and early mortality. Marine sponge-derived fungi, Pestalotiopsis sp., secrete immunosuppressive compounds in the culture broth. In the present study, we isolated 4-(hydroxymethyl)catechol (4-HMC) from these fungal species, and evaluated its anti-RA effects using a murine collagen-induced arthritis model and tumor necrosis factor-α-stimulated human RA synovial fibroblasts. Oral 4-HMC administration decreased the clinical arthritis score, paw thickness, histologic and radiologic changes, and serum IgG1 and IgG2a levels. It prevented the proliferation of helper T (Th) 1/Th17 CD4⁺ lymphocytes isolated from inguinal lymph nodes, thereby reducing inflammatory cytokine production in CIA mice. It decreased the expression of inflammatory mediators, including cytokines and matrix metalloproteinases (MMPs), both in vitro and in vivo. We observed that 4-HMC suppresses Th immune responses and MMP expression to inhibit inflammatory cytokine production in human RA synovial fibroblasts by modulating the PI3K/Akt/NF-κB pathway. These results verify the anti-RA potential of 4-HMC.

Modulation of intestinal epithelium homeostasis by extra virgin olive oil phenolic compounds

Extra virgin olive oil polyphenols concentrate at the intestinal level and, by modulating the microbiota, oxidative status and inflammation, contribute to prevent the onset or delay the progression of inflammatory/degenerative diseases.

A Straightforward Access to New Families of Lipophilic Polyphenols by Using Lipolytic Bacteria

The chemical synthesis of new lipophilic polyphenols with improved properties presents technical difficulties. Here we describe the selection, isolation and identification of lipolytic bacteria from food-processing industrial wastes, and their use for tailoring a new set of compounds with great interest in the food industry. These bacteria were employed to produce lipolytic supernatants, which were applied without further purification as biocatalysts in the chemoselective and regioselective synthesis of lipophilic partially acetylated phenolic compounds derived from olive polyphenols. The chemoselectivity of polyphenols acylation/deacylation was analyzed, revealing the preference of the lipases for phenolic hydroxyl groups and phenolic esters. In addition, the alcoholysis of peracetylated 3,4-dihydroxyphenylglycol resulted in a series of lipophilic 2-alkoxy-2-(3,4-dihydroxyphenyl)ethyl acetate through an unexpected lipase-mediated etherification at the benzylic position. These new compounds are more lipophilic and retained their antioxidant properties. This approach can provide access to unprecedented derivatives of 3,4-dihydroxyphenylglycol with improved properties.

Determination of eight polyphenols and pantothenic acid in extra-virgin olive oil samples by a simple, fast, high-throughput and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method

A new ultra high performance liquid chromatography coupled with tandem mass spectrometry method for a fast and sensitive determination of eight polyphenols (hydroxytyrosol, catechin, epicatechin, epigallocatechin gallate, oleuropein, quercetin, rutin, tyrosol) and panthotenic acid in extra-virgin olive oil was developed. The method does not require long sample pre-treatment and presents the lowest limit of detection and limit of quantitation values present in literature. Inter- and intra-day variability, linear dynamic range of the calibration curve, recovery and matrix effect were also determined and investigated. The method was applied to several oil samples of different type and origin. Given its accuracy, precision and rapidity, the method is characterized by an interestingly high throughput, reliability, and sensitivity.

Analysis of phenolic and cyclic compounds in plants using derivatization techniques in combination with GC-MS-based metabolite profiling

Metabolite profiling has been established as a modern technology platform for the description of complex chemical matrices and compound identification in biological samples. Gas chromatography coupled with mass spectrometry (GC-MS) in particular is a fast and accurate method widely applied in diagnostics, functional genomics and for screening purposes. Following solvent extraction and derivatization, hundreds of metabolites from different chemical groups can be characterized in one analytical run. Besides sugars, acids, and polyols, diverse phenolic and other cyclic metabolites can be efficiently detected by metabolite profiling. The review describes own results from plant research to exemplify the applicability of GC-MS profiling and concurrent detection and identification of phenolics and other cyclic structures.

Dynamic changes in composition of extracts of natural products as monitored by in situ NMR

The direct in situ NMR observation and quantification, based on the aldehyde -CH chemical shift region, of the inter-conversion of secoiridoid derivatives due to temperature and solvent effects is demonstrated in complex extracts of natural products without prior isolation of the individual components. The equilibrium between the aldehyde hydrate form and the dialdehyde form of the oleuropein aglycon of an olive leaf aqueous extract in D(2)O was shown to be temperature dependent. The resulting thermodynamic values of the Van't Hoff plot with ΔH(o)  = -26.34 ± 1.00 kJ mol(-1) and TΔS° (298 K) = -24.70 ± 1.00 kJ mol(-1) demonstrate a significant entropy term which nearly compensates the effect of enthalpy at room temperature. The equilibrium between the two diastereomeric hemiacetal forms and the dialdehyde form of the oleuropein 6-O-β-d-glucopyranoside aglycon of an olive leaf aqueous extract in CD(3) OD was also shown to be strongly temperature dependent again because of the significant entropy term (TΔS° (298 K) = -26.50 ± 1.39 kJ mol(-1)) compared with that of the enthalpy term (ΔH(o)  = -36.64 ± 1.46 kJ mol(-1)). This is the first demonstration of the significant role of the entropy parameter in determining the equilibrium of chemical transformations in complex mixtures of natural products due to solvent and temperature effects.

Evaluating prodrug strategies for esterase-triggered release of alcohols

Prodrugs are effective tools in overcoming drawbacks typically associated with drug formulation and delivery. Those employing esterase-triggered functional groups are frequently utilized to mask polar carboxylic acids and phenols, increasing drug-like properties such as lipophilicity. Herein we detail a comprehensive assessment for strategies that effectively release hydroxy and phenolic moieties in the presence of an esterase. Matrix metalloproteinases (MMPs) serve as our proof-of-concept target. Three distinct ester-responsive protecting groups are incorporated into MMP proinhibitors containing hydroxy moieties. Analytical evaluation of the proinhibitors demonstrates that the use of a benzyl ether group appended to the esterase trigger leads to considerably faster kinetics of conversion and enhanced aqueous stability when compared with more conventional approaches where the trigger is directly attached to the inhibitor. Biological assays confirm that all protecting groups effectively cleave in the presence of esterase to generate the active inhibitor. The superior reaction-based prodrug strategies presented here should serve as a platform for esterase-responsive prodrug design in the future.

Lipophilic extracts of Cynara cardunculus L. var. altilis (DC): a source of valuable bioactive terpenic compounds

Lipophilic extracts of Cynara cardunculus L. var. altilis (DC) from the south of Portugal (Baixo Alentejo) were studied by gas chromatography-mass spectrometry. One sesquiterpene lactone, four pentacyclic triterpenes, and four sterols were reported for the first time as cultivated cardoon components, namely, deacylcynaropicrin, β- and α-amyrin, lupenyl and ψ-taraxasteryl acetates, stigmasterol, 24-methylenecholesterol, campesterol, and Δ(5)-avenasterol. In addition, other new compounds were identified: ten fatty acids, eight long-chain aliphatic alcohols, and six aromatic compounds. Four triterpenyl fatty acid esters were also detected. Sesquiterpene lactones and pentacyclic triterpenes were the major lipophilic families, representing respectively 2-46% and 10-89% of the detected compounds. Cynaropicrin was the most abundant sesquiterpene lactone, while taraxasteryl acetate was the main pentacyclic triterpene. Fatty acids and sterols, mainly hexadecanoic acid and β-sitosterol, were present at lower amounts (1-20% and 1-11% of the detected compounds). Long-chain aliphatic alcohols and aromatic compounds were detected at reduced abundances (1-6% of the detected compounds).

Natural antioxidant dihydroxybenzyl alcohol blocks ritonavir-induced endothelial dysfunction in porcine pulmonary arteries and human endothelial cells

Background

Patients with HIV have an increased incidence of pulmonary artery hypertension. This study was designed to determine if the naturally occurring antioxidant dihydroxybenzyl alcohol (DHBA) could counteract the deleterious effects of ritonavir (RTV), an HIV-protease inhibitor known to impair endothelial function and increase oxidative stress.

Material/Methods

Antioxidant assays were performed on DHBA in a cell free system. Glutathione (GSH) levels were measured in human pulmonary artery endothelial cells (HPAEC) to determine the effect of DHBA on the level of oxidative stress in cells treated with RTV. Myograph analysis was performed on porcine pulmonary artery (PA) rings after treatment with RTV and/or DHBA. Likewise, reactive oxygen species (ROS) production was assessed in porcine PA rings after RTV +/− DHBA using a lucigenin reaction. Immunohistochemical staining for endothelial nitric oxide synthase (eNOS) was also performed in porcine PAs treated as above.

Results

DHBA demonstrated significant antioxidant activity in a cell free system that surpassed that of vitamin C. Also, treatment with DHBA reduced RTV-induced reduction in endothelium-dependent vasorelaxation and eNOS staining and increased superoxide anion levels. Meanwhile, there was a reversal in RTV-induced oxidative stress leading to reduced GSH levels in HPAECs after treatment with DHBA.

Conclusions

These findings suggest that the naturally occurring antioxidant DHBA reduces the impairment of vasomotor functions caused by RTV in porcine PAs and reduces oxidative stress caused by RTV in HPAEC and porcine PA rings. This study indicates that DHBA may have clinical applications in the prevention or treatment of antiretroviral drugs-associated vascular complications in patients with HIV.

Characterisation and quantification of phenolic compounds of extra-virgin olive oils according to their geographical origin by a rapid and resolutive LC-ESI-TOF MS method

The phenolic compounds present in seven samples of olive fruits were analysed by a rapid and resolutive LC-ESI-TOF MS method. All samples were collected during the normal picking period for olive oil production, in central and south Tunisia, and were obtained from the Oueslati variety cultivated in different olive growing areas. In the Tunisian samples, 22 compounds have been characterised by LC-ESI-TOF MS analysis. Results showed no qualitative differences in the phenolic fractions between virgin olive oils from different geographical region. However, significant quantitative differences were observed in a wide number of phenolic compounds. These results permit to use the phenolic fractions as an indicator of each region.

Prediction of extra virgin olive oil varieties through their phenolic profile. Potential cytotoxic activity against human breast cancer cells

The aim of this work was to develop a rapid resolution liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (RRLC-ESI-TOF-MS) method followed by tetrazolium salt (MTT)-based cell viability assays for qualitative and quantitative classification of extra virgin olive oil (EVOO) varieties by phenolic and other polar compound contents as well as for rapid characterization of putative cytotoxic activities against human cancer cells. Five different Spanish EVOO varieties were analyzed, and RRLC-ESI-TOF-MS method was applied for qualitative and quantitative identification of most important phenolic compounds. We finally employed MTT-based cell viability protocol to assess the effects of crude EVOO phenolic extracts (PEs) on the metabolic status of cultured SKBR3 human breast cancer cells. MTT-based cell viability assays revealed a wide range of breast cancer cytotoxic potencies among individual crude PE obtained from EVOO monovarietals. Remarkably, breast cancer cell sensitivity to crude EVOO-PEs was up to 12 times higher in secoiridoids enriched-PE than in secoiridoids-low/null EVOO-PE.

Characterization of isomers of oleuropein aglycon in olive oils by rapid-resolution liquid chromatography coupled to electrospray time-of-flight and ion trap tandem mass spectrometry

In this work, rapid-resolution liquid chromatography (RRLC) coupled to electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) and ion trap multiple mass spectrometry (IT-MS(n)) has been applied to separate and characterize eleven isomers of oleuropein aglycon in fourteen Spanish extra-virgin olive oils. After the extra-virgin olive oil sample had been dissolved in hexane and cleaned up by a diol-bonded phase solid-phase extraction (SPE) cartridge, the eluting extract was resolved in methanol and analyzed on an Angilent 1200 system with a 4.6 x 150 mm, 1.8 microm Zorbax Eclipse plus C18 column. Mass spectrometry was carried out on a Bruker Daltonics microTOF mass spectrometer and a Bruker Daltonics ion trap mass spectrometer. The characterization of isomers of oleuropein aglycon was based on accurate mass data and the isotope function of characteristic fragment ions in the studied compounds by TOF-MS, and the fragment ions were further confirmed by IT-MS(n). The fragmentation pathway of oleuropein aglycon was successfully elucidated and all possible transformations among isomers of oleuropein aglycon were suggested.