Tyrosols retrieved from traditionally brewed yeasts assist in tolerance against heavy metals and promote the growth of cells.

Heavy metals act as cofactors for several microbial enzymes and are required in low concentrations for the proper biological functioning of yeasts. Because concentrations beyond the permitted threshold can damage a cell's functionality and viability, metal tolerance in yeasts towards such heavy metals is therefore desirable during fermentation. Tyrosol, a quorum-sensing molecule in yeasts, protects yeasts from oxidative stress induced by various factors, but the performance of the molecule under heavy metal-induced stress is not known. In this investigation, the metal tolerance of four species of endemic yeasts from northeast India, Wickerhamomyces anomalus, Candida tropicalis, Saccharomyces cerevisiae and Candida glabrata, isolated from traditional starter culture cakes, was tested towards zinc (Zn+2), manganese (Mn+2), cobalt (Co+2) and copper (Cu+2) in the presence and absence of tyrosols retrieved from these isolates. The decreasing order of the tolerance of isolates was found to be Mn+2 > Zn+2 > Co+2 > Cu+2. Under the influence of tyrosols, isolates showed enhanced growth at their upper metal tolerance limit. Candida tropicalis showed enhanced growth (2-48-fold, P < 0.0001) in all the tested metal consisting medium (2 mM Zn+2, 5 mM Mn+2, 2 mM Co+2 and 1 mM Cu+2), while W. anomalus, C. glabrata and S. cerevisiae showed increased growth (3-17-fold, P < 0.0001) in Zn+2 (2 mM), Mn+2 (5 mM) and Cu+2 (1 mM) augmented medium. The overall result suggests that tyrosol exerts a protective effect under heavy metal-induced stress, which could be useful in enhancing the quality of fermented products.

Development of a Continuous System for 2-Phenylethanol Bioproduction by Yeast on Whey Permeate-Based Medium.

2-Phenylethanol (2-PE) is an alcohol with a rosy scent and antimicrobial activity, and therefore, it is widely used in the food and cosmetic industries as an aroma and preservative. This work was aimed to draw up a technology for 2-PE bioproduction on whey permeate, which is waste produced by the dairy industry, rich in lactase and proteins. Its composition makes it a harmful waste to dispose of; however, with a properly selected microorganism, it could be converted to a value-added product. Herein, two yeast Kluyveromyces marxianus strains and one Kluyveromyces lactis, isolated from dairy products, were tested for 2-PE production, firstly on standard media and then on whey permeate based media in batch cultures. Thereafter, the 2-PE bioproduction in a continuous system in a 4.8 L bioreactor was developed, and subsequently, the final product was recovered from culture broth. The results showed that the yield of 2-PE production increased by 60% in the continuous culture compared to batch culture. Together with a notable reduction of chemical oxygen demand for whey permeate, the present study reports a complete, effective, and environmentally friendly strategy for 2-PE bioproduction with a space-time yield of 57.5 mg L-1 h-1.

One-Step Extraction of Olive Phenols from Aqueous Solution Using ß-Cyclodextrin in the Solid State, a Simple Eco-Friendly Method Providing Photochemical Stability to the Extracts.

The extraction of phenolic compounds from olive mill wastes is important, not only to avoid environmental damages, but also because of the intrinsic value of those biophenols, well-known for their high antioxidant potential and health benefits. This study focuses on tyrosol (Tyr) and hydroxytyrosol (HT), two of the main phenolic compounds found in olive mill wastes. A new, simple, and eco-friendly extraction process for the removal of phenolic compounds from aqueous solutions using native ß-cyclodextrin (ß-CD) in the solid state has been developed. Several ß-CD/biophenol molar ratios and biophenol concentrations were investigated, in order to maintain ß-CD mostly in the solid state while optimizing the extraction yield and the loading capacity of the sorbent. The extraction efficiencies of Tyr and HT were up to 61%, with a total solid recovery higher than 90% using an initial concentration of 100 mM biophenol and 10 molar equivalents of ß-CD. The photochemical stability of the complexes thus obtained was estimated from ∆E*ab curve vs. illumination time. The results obtained showed that the phenols encapsulated into solid ß-CD are protected against photodegradation. The powder obtained could be directly developed as a safe-grade food supplement. This simple eco-friendly process could be used for extracting valuable biophenols from olive mill wastewater.

Hydroxytyrosol alleviate intestinal inflammation, oxidative stress and apoptosis resulted in ulcerative colitis.

Hydroxytyrosol (HYT) is one of the main alcoholic compounds of the olive leaves extract (OLE), which is known for its beneficial effects. This study aimed to investigate the effectiveness of olive leaves extract standardized with 25% hydroxytyrosol (OLES-25%HYT) in treatment of induced ulcerative colitis. Three groups of albino rats, were divided as following, group 1 (normal control), group 2 (induced ulcerative colitis and untreated) and group 3 (induced ulcerative colitis and treated with OLES-25%HYT). Colonic tissue samples were collected from all studied groups, the antioxidant activity for malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), myeloperoxidase (MPO) and nitric oxide (NO) were performed. The expression of pro-inflammatory cytokines, the apoptotic gene Bax and the anti-apoptotic gene Bcl2 was obtained in colon tissue to evaluate the OLES-25%HYT effect on ulcerative colitis. OLES-25%HYT showed effectiveness on reduction of mortality rate and disease activity index (DAI). Also, reduced oxidative stress and inflammation in colon tissue, OLES-25%HYT showed a significant reduction in colon MDA, MPO and NO levels and a significant elevation in SOD, CAT and GPX levels and cause down regulation of pro-inflammatory cytokines. Also, the apoptotic gene Bax downregulated and the anti-apoptotic gene Bcl2 upregulated as a result of the treatment compared to untreated induced ulcerative colitis group. OLES-25%HYT showed intestinal anti-inflammatory, antioxidants and anti-apoptotic effects in experimental models of ulcerative colitis.

Fatty Acid Analysis, Chemical Constituents, Biological Activity and Pesticide Residues Screening in Jordanian Propolis.

Propolis is a resinous natural product collected by honeybees (Apis mellifera and others) from tree exudates that has been widely used in folk medicine. The present study was carried out to investigate the fatty acid composition, chemical constituents, antioxidant, and xanthine oxidase (XO) inhibitory activity of Jordanian propolis, collected from Al-Ghour, Jordan. The hexane extract of Jordanian propolis contained different fatty acids, which are reported for the first time by using GC-FID. The HPLC was carried out to identify important chemical constituents such as fatty acids, polyphenols and α-tocopherol. The antioxidant and xanthine oxidase inhibitory activities were also monitored. The major fatty acid identified were palmitic acid (44.6%), oleic acid (18:1∆9cis, 24.6%), arachidic acid (7.4%), stearic acid (5.4%), linoleic acid (18:2∆9-12cis, 3.1%), caprylic acid (2.9%), lignoceric acid (2.6%), cis-11,14-eicosaldienoic acid (20:2∆11-14cis, 2.4%), palmitoleic acid (1.5%), cis-11-eicosenoic acid (1.2%), α-linolenic acid (18:3∆9-12-15cis, 1.1%), cis-13,16-docosadienoic acid (22:2∆13-16cis, 1.0%), along with other fatty acids. The major chemical constituents identified using gradient HPLC-PDA analysis were pinocembrin (2.82%), chrysin (1.83%), luteolin-7-O-glucoside (1.23%), caffeic acid (1.12%), caffeic acid phenethyl ester (CAPE, 0.79%), apigenin (0.54%), galangin (0.46%), and luteolin (0.30%); while the minor constituents were hesperidin, quercetin, rutin, and vanillic acid. The percentage of α-tocopherol was 2.01 µg/g of the lipid fraction of propolis. Antioxidant properties of the extracts were determined via DPPH radical scavenging. The DPPH radical scavenging activities (IC50) of different extracts ranged from 6.13 to 60.5 µg/mL compared to ascorbic acid (1.21 µg/mL). The xanthine oxidase inhibition (IC50) ranged from 75.11 to 250.74 µg/mL compared to allopurinol (0.38 µg/mL). The results indicate that the various flavonoids, phenolic compounds, α-tocopherol, and other constituents which are present in propolis are responsible for the antioxidant and xanthine oxidation inhibition activity. To evaluate the safety studies of propolis, the pesticide residues were also monitored by LC-MS-MS 4500 Q-Trap. Trace amounts of pesticide residue (ng/mL) were detected in the samples, which are far below the permissible limit as per international guidelines.

Effects of phenylethanol glycosides from Orobanche cernua Loefling on UVB-Induced skin photodamage: a comparative study.

Previous study has found that Orobanche cernua Loefling(OC) and its main ingredient, acteoside, possess excellently anti-photo-aging effect. In addition to acteoside, crenatoside, isoacteoside and 2'-acetylacteoside were also identified as the main phenylethanol glycosides (PhGs) in OC. To screen optimum effective substance and further clarify the photoprotective ingredients of OC, the effects of four major PhGs in OC were compared using UVB-irradiated HaCaT cells. Results indicated that acteoside, isoacteoside and 2'-acetylacteoside effectively decreased UVB-induced MMP-1 expression and stimulated type I procollagen synthesis through inhibition of MAPK/AP-1 and activation of TGF-ß/Smad pathway. Moreover, acteoside and 2'-acetylacteoside significantly reduced UVB-induced ROS and TARC secretion, which is involved in the inhibition of NF-κß/Iκßα and stimulation of Nrf2 antioxidant defense system. However, crenatoside did not show any effect on the regulation of signal cascades mentioned above. Together, our results suggested that 2'-acetylacteoside and isoacteoside also served as efficient agents against UV radiation-induced skin damage. Among them, acteoside and 2'-acetylacteoside showed a higher efficiency than that of isoacteoside, which possessed great potential in treating skin photo-damage.

Recent progresses in the pharmacological activities of caffeic acid phenethyl ester.

The past decades have seen a growing interest in natural products. Caffeic acid phenethyl ester (CAPE), a flavonoid isolated from honeybee propolis, has shown multiple pharmacological potentials, including anti-cancer, anti-inflammatory, antioxidant, antibacterial, antifungal, and protective effects on nervous systems and multiple organs, since it was found as a potent nuclear factor κB (NF-κB) inhibitor. This review summarizes the advances in these beneficial effects of CAPE, as well as the underlying mechanisms, and proposes that CAPE offers an opportunity for developing therapeutics in multiple diseases. However, clinical trials on CAPE are necessary and encouraged to obtain certain clinically relevant conclusions.

Antioxidant and Biological Activities of Hydroxytyrosol and Homovanillic Alcohol Obtained from Olive Mill Wastewaters of Extra-Virgin Olive Oil Production.

Some constituents of the Mediterranean diet, such as extra-virgin olive oil (EVOO) contain substances such as hydroxytyrosol (HT) and its metabolite homovanillic alcohol (HA). HT has aroused much interest due to its antioxidant activity as a radical scavenger, whereas only a few studies have been made on the HA molecule. Both chemical synthesis and extraction techniques have been developed to obtain these molecules, with each method having its advantages and drawbacks. In this study, we report the use of tyrosol from olive mill wastewaters as a starting molecule to synthesize HT and HA, using a sustainable procedure characterized by high efficiency and low cost. The effects of HT and HA were evaluated on two cell lines, THP-1 human leukemic monocytes and L-6 myoblasts from rat skeletal muscle, after treating the cells with a radical generator. Both HT and HA efficiently inhibited ROS production. In particular, HT inhibited the proliferation of the THP-1 leukemic monocytes, while HA protected L-6 myoblasts from cytotoxicity.

Comprehensive investigations of 2-phenylethanol production by high 2-phenylethanol tolerating Meyerozyma sp. strain YLG18.

2-Phenylethanol (2-PE) production through bio-synthesis method has become an appealing option owning to the mild conditions and high product selectivity. However, 2-PE is toxic to cells, which is an important limiting factor for the biosynthesis of 2-PE. In this study, a novel 2-PE generating Meyerozyma sp. strain YLG18 was first isolated, which could produce 2-PE through both Ehrlich and Shikimate pathways. Moreover, the indigenous high 2-PE tolerance makes it a promising candidate for high 2-PE production. Response surface methodology and in situ product recovery technology could improve the final 2-PE production to 3.20 g/L, representing the highest 2-PE production by using Meyerozyma sp. Furthermore, genes involved in 2-PE synthesis were identified and their expression levels between Shikimate pathway and Ehrlich pathway were compared. Based on the genomic and transcriptional analysis, a penta-functional enzyme AroM and an aspartate aminotransferase (AAT) with the potential to convert phenylalanine into phenylpyruvate were identified. These findings would help broaden our knowledge and add the pool of known 2-PE generating microbes and genes.

Green Route for the Isolation and Purification of Hyrdoxytyrosol, Tyrosol, Oleacein and Oleocanthal from Extra Virgin Olive Oil.

Extra virgin olive oil (EVOO) phenols represent a significant part of the intake of antioxidants and bioactive compounds in the Mediterranean diet. In particular, hydroxytyrosol (HTyr), tyrosol (Tyr), and the secoiridoids oleacein and oleocanthal play central roles as anti-inflammatory, neuro-protective and anti-cancer agents. These compounds cannot be easily obtained via chemical synthesis, and their isolation and purification from EVOO is cumbersome. Indeed, both processes involve the use of large volumes of organic solvents, hazardous reagents and several chromatographic steps. In this work we propose a novel optimized procedure for the green extraction, isolation and purification of HTyr, Tyr, oleacein and oleocanthal directly from EVOO, by using a Natural Deep Eutectic Solvent (NaDES) as an extracting phase, coupled with preparative high-performance liquid chromatography. This purification method allows the total recovery of the four components as single pure compounds directly from EVOO, in a rapid, economic and ecologically sustainable way, which utilizes biocompatible reagents and strongly limits the use or generation of hazardous substances.

Two new phenylethanoid glycosides from Ginkgo biloba leaves and their tyrosinase inhibitory activities.

Two undescribed phenylethanoid glycosides, Ginkgoside C (1) and D (2), together with ten known glycosides (3-12) were isolated from Ginkgo biloba leaves. Their structures were characterized by physical data analyses such as NMR, HRESIMS, as well as chemical hydrolysis. All compounds were tested for their tyrosinase inhibitory activities. At a concentration of 25 µM, compounds 2, 4, 5, 6, and 11 showed obvious mushroom tyrosinase inhibition activities, with %inhibition values of 19.12 ± 2.59%, 25.79 ± 1.83%, 16.07 ± 1.07%, 24.46 ± 1.10%, 18.64 ± 3.62%, respectively, with kojic acid used as the positive control (27.50 ± 2.72%).

Beer Phenolic Composition of Simple Phenols, Prenylated Flavonoids and Alkylresorcinols.

Beer is a fermented beverage with beneficial phenolic compounds and is widely consumed worldwide. The current study aimed to describe the content of three families of phenolic compounds with relevant biological activities: prenylated flavonoids (from hops), simple phenolic alcohols (from fermentation) and alkylresorcinols (from cereals) in a large sample of beers (n = 45). The prenylated flavonoids analyzed were xanthohumol, isoxanthohumol, 6- and 8-prenylnaringenin. The total prenylated flavonoids present in beer ranged from 0.0 to 9.5 mg/L. The simple phenolic alcohols analyzed were tyrosol and hydroxytyrosol, ranging from 0.2 to 44.4 and 0.0 to 0.1 mg/L, respectively. Our study describes, for the first time, the presence of low amounts of alkylresorcinols in beer, in concentrations ranging from 0.02 to 11.0 µg/L. The results in non-alcoholic beer and the differences observed in the phenolic composition among different beer types and styles highlight the importance of the starting materials and the brewing process (especially fermentation) on the final phenolic composition of beer. In conclusion, beer represents a source of phenolic compounds in the diet that could act synergistically, triggering beneficial health effects in the context of its moderate consumption.

Natural Deep Eutectic Solvents for the Extraction of Phenyletanes and Phenylpropanoids of Rhodiola rosea L.

The extraction of Rhodiola rosea rhizomes using natural deep eutectic solvent (NADES) consisting of lactic acid, glucose, fructose, and water was investigated. A two-level Plackett-Burman design with five variables, followed by the steepest ascent method, was undertaken to determine the optimal extraction conditions. Among the five parameters tested, particle size, extraction modulus, and water content were found to have the highest impact on the extrability of phenyletanes and phenylpropanoids. The concentration of active compounds was analyzed by HPLC. The predicted results showed that the extraction yield of the total phenyletanes and phenylpropanoids (25.62 mg/g) could be obtained under the following conditions: extraction time of 154 min, extraction temperature of 22 °C, extraction modulus of 40, molar water content of 5:1:11 (L-lactic acid:fructose:water, mol/mol), and a particle size of rhizomes of 0.5-1 mm. These predicted values were further verified by validation experiments in predicted conditions. The experimental yields of salidroside, tyrosol, rosavin, rosin, cinnamyl alcohol and total markers (sum of phenyletanes and phenylpropanoids in mg/g) were 11.90 ± 0.02, 0.36 ± 0.02, 12.23 ± 0.21, 1.41 ± 0.01, 0.20 ± 0.01, and 26.10 ± 0.27 mg/g, respectively, which corresponded well with the predicted values from the models.

A trisaccharide phenylethanoid glycoside from Scrophularia flava Grau with potential anti-type 2 diabetic properties by inhibiting α-glucosidase enzyme and decreasing oxidative stress.

The Scrophularia genus is a rich source of phenylethanoid glycosides, with diverse biological activities including anti-diabetic properties. This study investigated anti-type 2 diabetic potential and active component of Scrophularia flava Grau. A new phenylethanoid glycoside was isolated from aerial parts of the plant and identified as 2-(4-hydroxy-3-methoxyphenyl) ethyl 6-deoxy-3-O-[(2E)-3-(3 hydroxy-4-methoxyphenyl) prop-2-enoyl]-α-rhamnopyranosyl-(1 â†’ 3)-[α-rhamnopyranosyl-(1 â†’ 6)]-4-O-[(2E)-3-(4-hydroxy-3-methoxyphenyl) prop-2-enoyl]-ß-glucopyranoside. It was named flavaioside. The structure of flavaioside was identified based on 1H NMR, 13C NMR, DEPT-HSQC, COSY, HMBC, NOESY and LC-ESI-MS-MS. Total methanol extract, fractions (A-F) and specific main phenylethanoid glycoside (flavaioside), were assessed for inhibitory effects against the α-glucosidase enzyme (in vitro anti-type 2 diabetic assay). The antioxidant activities of methanol extracts, all fractions and isolated flavaioside were identified based on 2, 2'-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity, 2, 2'-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid radical cation (ABTS+) scavenging activity, phosphomolybdenum method, and metal chelating activity. In comparison to the other fractions, the best antioxidant result was observed in fraction E and its main compound, flavaioside, in DPPH (IC50 = 4.26, 2.57 µg/mL) and ABTS+ (EC50 = 55.45, 6.34 µg/mL) scavenging activities. Flavaioside showed significantly stronger activities than α-tocopherol and ascorbic acid in DPPH and ABTS+ assays. Furthermore, flavaioside showed a potent inhibitory activity on the α-glucosidase enzyme which was comparable with the known anti-type 2 diabetic drug, acarbose (91.85%, and 92.87%, respectively). Fraction E and flavaioside showed α-glucosidase inhibitory activities with IC50 values, 65.05 and 6.50 µg/mL. The plant and its isolated flavaioside can possess acceptable anti-type 2 diabetic potential and anti-oxidant activity.

Identification and occurrence of phenylethanoid and iridoid glycosides in six Polish broomrapes (Orobanche spp. and Phelipanche spp., Orobanchaceae).

There are about 200 holoparasitic broomrapes (Orobanchaceae) known worldwide, however, only several species have been so far investigated phytochemically. Among Orobanche s.l. are both rare and endangered species, as well as onerous crop pests. This study aims to give a phytochemical description, both qualitative and quantitative, of six broomrape species (Orobanche and Phelipanche taxa) growing in Poland, including species that have not been tested in detail (O. caryophyllacea, O. lutea, O. picridis, and P. arenaria). Sixteen metabolites, including 14 phenylethanoid glycosides (PhGs) and 2 iridoid glycosides (IrGs), were isolated and identified using NMR spectroscopy and hydrolysis, revealing the presence of two previously undescribed PhGs in P. ramosa, named ramoside A and 2'-acetylramoside A. In addition, in the example of O. caryophyllacea, we have reported as the first occurrence of IrGs in broomrapes. Concentrations of phenylethanoids, the main constituents of broomrapes, in the studied plant material (flowering shoots with haustoria) were determined using the UHPLC-PDA method. It was found that P. ramosa has been the richest source of PhGs. In addition, the differences between broomrapes have been visualized using principal component and cluster analysis. The results of the antiradical DPPH test of 13 PhGs confirmed previous findings on the relation of the antioxidant potential with the structure of phenolic moieties - phenolic acid and phenylethanoid unit.

Tyrosol from marine Fungi, a novel Quorum sensing inhibitor against Chromobacterium violaceum and Pseudomonas aeruginosa.

An ethyl acetate extracts isolated from a marine fungal strain, Penicillium chrysogenum DXY-1, obtained from marine sediments surrounding the East Sea, was found to exhibit anti-quorum sensing (anti-QS) activity. Interestingly, a novel active compound was identified as tyrosol by the purification and structural characterization. At a concentration of 0.5 mg/mL, tyrosol decreased QS-regulated violacein production in Chromobacterium violaceum CV026 by 53.5% and decreased QS-regulated pyocyanin production, elastase activity and proteolytic activity in Pseudomonas aeruginosa PA01 by 63.3%, 57.8% and 9.9%, respectively. SEM images showed that tyrosol inhibited biofilm formation in P. aeruginosa PA01 without having any effect on bacterial growth. Molecular docking results revealed that the natural signal molecule C6HSL and tyrosol bound to different receptor pockets of CviR, and tyrosol inhibited the QS activity of CviR in C. violaceum by binding to the DNA-binding domain and blocking pathogenic gene expression. All the data suggest that tyrosol may act as a potential inhibitor of the QS systems to solve the looming crisis of bacterial resistance. We believe that there are other active compounds with relatively high anti-QS activity or synergistic inhibitory effects on QS in the crude extract, which warrants further research.

Ultrasound-assisted aqueous extraction of total flavonoids and hydroxytyrosol from olive leaves optimized by response surface methodology.

Olive leaves were often extracted with methanol or ethanol at different proportions. In this study, ultrasound-assisted aqueous extraction was adopted for olive leaf extraction. The yields of total flavonoids (TF) and hydroxytyrosol (HT) were optimized by central composite experimental design. Two second-order polynomial equations were established to quantify the relationship between the responses and the processing parameters. Under the optimal condition of extracting at 60 °C for 60 min with the solvent-to-material ratio of 40, TF and HT amounted to 57.31 ± 0.35 and 1.80 ± 0.02 mg/g dry leaves (DL), respectively. The scavenging rate of all extracts against α, α-diphenyl-ß-picrylhydrazyl (DPPH) and hydroxyl free radicals was screened. The integrated scores, representing both active ingredients and antioxidant capacity of the extracts, were calculated by principle component analysis (PCA). The optimal extract gained the highest score in PCA. In addition, compared to the extracts from 80% methanol to 44% ethanol, the ultrasound-assisted aqueous extract was richer in TF, HT, and polyphenols, while it also presented stronger ferric reducing antioxidant power (FRAP), but poorer strength to quench hydroxyl radicals. The study indicated that the aqueous extract of olive leaves may present broad potential opportunities in health-care sector.

Chemical, physical and biotechnological approaches to the production of the potent antioxidant hydroxytyrosol.

Hydroxytyrosol (HT) is a polyphenol of interest to the food, feed, supplements and pharmaceutical sectors. It is one of the strongest known natural antioxidants and has been shown to confer other benefits such as anti-inflammatory and anti-carcinogenic properties, and it has the potential to act as a cardio- and neuroprotectant. It is known to be one of the compounds responsible for the health benefits of the Mediterranean diet. In nature, HT is found in the olive plant (Olea europaea) as part of the secoiridoid compound oleuropein, in its leaves, fruit, oil and oil production waste products. HT can be extracted from these olive sources, but it can also be produced by chemical synthesis or through the use of microorganisms. This review looks at the production of HT using plant extraction, chemical synthesis and biotechnological approaches.

Phenylethanoid glycosides from the Schnabelia nepetifolia (Benth.) P.D.Cantino promote the proliferation of osteoblasts.

An investigation of the n-BuOH fraction of Schnabelia nepetifolia (Benth.) P.D.Cantino led to the isolation and identification of 12 undescribed phenylethanoid glycosides (nepetifosides A-L) and one undescribed phenylmethanoid glycoside (nepetifoside M), together with 23 known compounds. The structures of these compounds were determined by spectroscopic analyses including two-dimensional nuclear-magnetic-resonance (2D-NMR) spectroscopy and chemical-hydrolysis methods. Nepetifoside F exhibited strong activity that significantly increased osteoblast proliferation at three concentrations of 0.1, 1, and 10 µM. Moreover, nepetifoside C and nepetifoside D exhibited moderate activities in promoting the proliferation of osteoblasts at medium and high concentrations of 1 µM and 10 µM, respectively.

An easy and green tool for olive oils labelling according to the contents of hydroxytyrosol and tyrosol derivatives: Extraction with a natural deep eutectic solvent and direct spectrophotometric analysis.

Natural deep eutectic solvents (NADES) are a green, promising class of solvents. Phenolic compounds are among the targets of NADES' use in foods. A health claim is admitted by European Regulations for olive oils (OOs) containing at least 250 mg kg-1 of selected polyphenols (hydroxytyrosol and its derivatives, included tyrosol, HTD), but their determination involves analytical issues that are being currently debated. A NADES based on glucose and lactic acid was here used to develop a green and rapid tool for correct labelling of OOs. 163 OOs were submitted to liquid/liquid extraction with the NADES. Regression and classification approaches were adopted to relate features of the UV spectra of extracts to HTD content. The models allowed to assess HTD content for screening purposes (R2prediction = 0.84, RMSEP = 35.5 mg kg-1). For labelling purposes, oils could be labelled according to health claim limits with an error of 0.6%.