Enhancing tellurite and selenite bioconversions by overexpressing a methyltransferase from Aromatoleum sp. CIB.

Pollution by metalloids, e.g., tellurite and selenite, is of serious environmental concern and, therefore, there is an increasing interest in searching for ecologically friendly solutions for their elimination. Some microorganisms are able to reduce toxic tellurite/selenite into less toxic elemental tellurium (Te) and selenium (Se). Here, we describe the use of the environmentally relevant ß-proteobacterium Aromatoleum sp. CIB as a platform for tellurite elimination. Aromatoleum sp. CIB was shown to tolerate 0.2 and 0.5 mM tellurite at aerobic and anaerobic conditions, respectively. Furthermore, the CIB strain was able to reduce tellurite into elemental Te producing rod-shaped Te nanoparticles (TeNPs) of around 200 nm length. A search in the genome of Aromatoleum sp. CIB revealed the presence of a gene, AzCIB_0135, which encodes a new methyltransferase that methylates tellurite and also selenite. AzCIB_0135 orthologs are widely distributed in bacterial genomes. The overexpression of the AzCIB_0135 gene both in Escherichia coli and Aromatoleum sp. CIB speeds up tellurite and selenite removal, and it enhances the production of rod-shaped TeNPs and spherical Se nanoparticles (SeNPs), respectively. Thus, the overexpression of a methylase becomes a new genetic strategy to optimize bacterial catalysts for tellurite/selenite bioremediation and for the programmed biosynthesis of metallic nanoparticles of biotechnological interest.

Inhibitory activity of aromatic plant extracts against dairy-related Clostridium species and their use to prevent the late blowing defect of cheese.

The aim of the present work was the selection of aromatic plant essential oils (EOs) and/or ethanolic extracts (EEs) to prevent the late blowing defect (LBD) of cheese caused by Clostridium spp. EEs resulted more effective than EOs to inhibit dairy-borne Clostridium spp. in vitro. Savory, hyssop, lavender and tarragon EEs, which showed the lowest minimal inhibitory concentration against Clostridium tyrobutyricum, were selected to study the prevention of LBD caused by this bacterium in cheese. Addition of savory and lavender EEs to cheese milk delayed LBD by 2 weeks, but at the end of ripening these cheeses showed similar clostridial vegetative cells counts, spoilage symptoms and propionic, and butyric acids levels than blown control cheese. Tarragon EE, with the highest content in caffeic acid, also delayed LBD by 2 weeks, but it was more effective to inhibit Clostridium, since cheese with tarragon EE showed minor LBD symptoms, lower vegetative cells count and lower concentrations of propionic and butyric acids than the rest of cheeses made with EEs. This fact could be also attributable to the greater number of antimicrobial terpenes (1,8-cineole, 4-terpineol, α-terpineol, isoelemicin, methyl eugenol, and methyl trans-isoeugenol) detected in this cheese. This is the first report on the application of EEs to control C. tyrobutyricum in cheese.

Stress, subjective wellbeing and self-knowledge in higher education teachers: A pilot study through bodyfulness approaches.

Work-related stress is a major cause of health problems worldwide. Faculty in educational institutions, including universities, also face high levels of stress, which undoubtedly affects their performance, level of personal satisfaction and wellbeing, and the relationship with students. Training interventions based on embodied learning can promote self-knowledge, emotional regulation and stress reduction, thereby increasing levels of psychological well-being. The present pilot study analyzed the impact of body awareness training in 31 university teachers using a controlled, randomized pre-post experimental design, with two experimental groups and a control group (n = 10). The two interventions were: Hatha Yoga (n = 11) and Dance Movement Therapy/Body Mind Centering (n = 10), which we have termed Body Movement Awareness. Variables related to body awareness, mindfulness, wellbeing, life satisfaction and stress were measured using self-perception tests. Cortisol levels, heart rate variability and sleep quality were also analyzed. Finally, participants' reflections were analyzed according to a qualitative approach. The results showed significant differences between the control group and the Hatha Yoga group in terms of stress reduction and wellbeing. The Body Movement Awareness group exhibited evidence of contributions on self-knowledge, communication and kinesthetic empathy, key elements in the educational field. Despite the inherent limitations of the study, the conclusions are encouraging and open new lines of research from embodied approaches that introduce creative movement and group experience as part of the process of emotional regulation and self-knowledge.

Comparative Genomics Provides Insights into the Taxonomy of Azoarcus and Reveals Separate Origins of Nif Genes in the Proposed Azoarcus and Aromatoleum Genera.

Among other attributes, the Betaproteobacterial genus Azoarcus has biotechnological importance for plant growth-promotion and remediation of petroleum waste-polluted water and soils. It comprises at least two phylogenetically distinct groups. The "plant-associated" group includes strains that are isolated from the rhizosphere or root interior of the C4 plant Kallar Grass, but also strains from soil and/or water; all are considered to be obligate aerobes and all are diazotrophic. The other group (now partly incorporated into the new genus Aromatoleum) comprises a diverse range of species and strains that live in water or soil that is contaminated with petroleum and/or aromatic compounds; all are facultative or obligate anaerobes. Some are diazotrophs. A comparative genome analysis of 32 genomes from 30 Azoarcus-Aromatoleum strains was performed in order to delineate generic boundaries more precisely than the single gene, 16S rRNA, that has been commonly used in bacterial taxonomy. The origin of diazotrophy in Azoarcus-Aromatoleum was also investigated by comparing full-length sequences of nif genes, and by physiological measurements of nitrogenase activity using the acetylene reduction assay. Based on average nucleotide identity (ANI) and whole genome analyses, three major groups could be discerned: (i) Azoarcus comprising Az. communis, Az. indigens and Az. olearius, and two unnamed species complexes, (ii) Aromatoleum Group 1 comprising Ar. anaerobium, Ar. aromaticum, Ar. bremense, and Ar. buckelii, and (iii) Aromatoleum Group 2 comprising Ar. diolicum, Ar. evansii, Ar. petrolei, Ar. toluclasticum, Ar. tolulyticum, Ar. toluolicum, and Ar. toluvorans. Single strain lineages such as Azoarcus sp. KH32C, Az. pumilus, and Az. taiwanensis were also revealed. Full length sequences of nif-cluster genes revealed two groups of diazotrophs in Azoarcus-Aromatoleum with nif being derived from Dechloromonas in Azoarcus sensu stricto (and two Thauera strains) and from Azospira in Aromatoleum Group 2. Diazotrophy was confirmed in several strains, and for the first time in Az. communis LMG5514, Azoarcus sp. TTM-91 and Ar. toluolicum TT. In terms of ecology, with the exception of a few plant-associated strains in Azoarcus (s.s.), across the group, most strains/species are found in soil and water (often contaminated with petroleum or related aromatic compounds), sewage sludge, and seawater. The possession of nar, nap, nir, nor, and nos genes by most Azoarcus-Aromatoleum strains suggests that they have the potential to derive energy through anaerobic nitrate respiration, so this ability cannot be usefully used as a phenotypic marker to distinguish genera. However, the possession of bzd genes indicating the ability to degrade benzoate anaerobically plus the type of diazotrophy (aerobic vs. anaerobic) could, after confirmation of their functionality, be considered as distinguishing phenotypes in any new generic delineations. The taxonomy of the Azoarcus-Aromatoleum group should be revisited; retaining the generic name Azoarcus for its entirety, or creating additional genera are both possible outcomes.

Effects of gastrointestinal digested polyphenolic enriched extracts of Chilean currants (Ribes magellanicum and Ribes punctatum) on in vitro fecal microbiota.

Chilean currants (Ribes magellanicum and Ribes punctatum) are wild polyphenol-rich berries with interesting bioactivities in several in vitro models. The aim of this study was to investigate the effects of the pre-digested PEE (polyphenol-enriched extract) in a simulated colon model. Fruits were extracted, submitted to simulated gastrointestinal digestion and further colonic fermentation with feces from healthy human donors. Samples were taken at 1, 4, 8 and 24 h of incubation, monitoring pH, ammonia, branched-chain fatty acids (BCFA), short-chain fatty acids (SCFA) and bacterial growth. FOS (fructooligosaccharides) and fecal slurry without treatments were positive and negative control, respectively. Both Ribes species reduced (p < 0.05) both BCFA and SCFA at 24 h. R. punctatum promoted the growth (p < 0.05) of beneficial bacteria such as Clostridium cluster XIVa, and Faecalibacterium prausnitzii; while a trend to increase Akkermansia muciniphila was observed. R. magellanicum increased (p < 0.05) Clostridium cluster XIVa population. Escherichia coli, Lactobacillus spp. and Bifidobacterium spp. remained unaffected. Our results suggest that polyphenols from R. punctatum and R. magellanicum may modulate both bacterial metabolism and some selected gut beneficial bacteria under simulated conditions. Therefore, Chilean currants might be useful as supplements to maintain a healthy colon; however, further in vivo studies are needed to confirm their effect and their mechanisms.

Impregnation of Curcumin into a Biodegradable (Poly-lactic-co-glycolic acid, PLGA) Support, to Transfer Its Well Known In Vitro Effect to an In Vivo Prostate Cancer Model.

Prostate cancer (PCa) is one of the most common cancers in older men and is associated with high mortality. Despite advances in screening for early detection of PCa, a large proportion of patients continue to be diagnosed with metastatic disease, with ~20% of men showing a high tumor grade and stage. Medicinal plant extracts have a great potential to prevent/treat PCa, as well as to reduce its incidence/prevalence and improve survival rates. One of the most promising extracts is curcumin, which is a major, nontoxic, bioactive compound of Curcuma longa. Curcumin has strong antitumor activity in vitro. However, its potential beneficial in vivo affects are limited by its low intestinal absorption and rapid metabolism. In this study, curcumin was impregnated into a biodegradable poly(lactic-co-glycolic) acid (PLGA) support and characterized by FTIR and DSC, and its release by UV spectrophotometry. PLGA-curcumin was tested in different subcutaneous PCa xenograft models (PC3, 22rv1, and DU145 PCa cell-lines), and its effects evaluated by tumor progression an immuno-histochemical analysis (Trichromic, Ki67 and TUNEL stainings), were compared with those of a commercial curcumin preparation. Our results indicate that curcumin-impregnated PLGA is significantly more active (~2-fold increase) with respect to oral curcumin, which supports its use for subcutaneous administration.

Synthesis of rigid polyurethane foams from phosphorylated biopolyols.

Renewable resources are playing a key role on the synthesis of biodegradable polyols. Moreover, the incorporation of covalently linked additives is increasing in importance in the polyurethane (PU) market. In this work, previously epoxidized grape seed oil and methyl oleate were transformed into phosphorylated biopolyols through an acid-catalyzed ring-opening hydrolysis in the presence of H3PO4. The formation of phosphate polyesters was confirmed by FT-IR and 31P-NMR. However, the synthesis of a high-quality PU rigid foam was not possible using exclusively these polyols attending to their low hydroxyl value. In that way, different rigid PU foams were prepared from the phosphorylated biopolyols and the commercial polyol Alcupol R4520. It was observed that phosphorylated biopolyols can be incorporated up to a 57 wt.% in the PU synthesis without significant structural changes with respect to the commercial foam. Finally, thermogravimetric and EDAX analyses revealed an improvement of thermal stability by the formation of a protective phosphorocarbonaceous char layer.

Effect of a Protein Supplement on the Gut Microbiota of Endurance Athletes: A Randomized, Controlled, Double-Blind Pilot Study.

Nutritional supplements are popular among athletes to improve performance and physical recovery. Protein supplements fulfill this function by improving performance and increasing muscle mass; however, their effect on other organs or systems is less well known. Diet alterations can induce gut microbiota imbalance, with beneficial or deleterious consequences for the host. To test this, we performed a randomized pilot study in cross-country runners whose diets were complemented with a protein supplement (whey isolate and beef hydrolysate) (n = 12) or maltodextrin (control) (n = 12) for 10 weeks. Microbiota, water content, pH, ammonia, and short-chain fatty acids (SCFAs) were analyzed in fecal samples, whereas malondialdehyde levels (oxidative stress marker) were determined in plasma and urine. Fecal pH, water content, ammonia, and SCFA concentrations did not change, indicating that protein supplementation did not increase the presence of these fermentation-derived metabolites. Similarly, it had no impact on plasma or urine malondialdehyde levels; however, it increased the abundance of the Bacteroidetes phylum and decreased the presence of health-related taxa including Roseburia, Blautia, and Bifidobacterium longum. Thus, long-term protein supplementation may have a negative impact on gut microbiota. Further research is needed to establish the impact of protein supplements on gut microbiota.

Speeding up bioproduction of selenium nanoparticles by using Vibrio natriegens as microbial factory.

Selenium and selenium nanoparticles (SeNPs) are extensively used in biomedicine, electronics and some other industrial applications. The bioproduction of SeNPs is gaining interest as a green method to manufacture these biotechnologically relevant products. Several microorganisms have been used for the production of SeNPs either under aerobic or anaerobic conditions. Vibrio natriegens is a non-pathogenic fast-growing bacterium, easily cultured in different carbon sources and that has recently been engineered for easy genetic manipulation in the laboratory. Here we report that V. natriegens was able to perfectly grow aerobically in the presence of selenite concentrations up to 15 mM with a significant survival still observed at concentrations as high as 100 mM selenite. Electron microscopy and X-ray spectroscopy analyses demonstrate that V. natriegens cells growing aerobically in selenite-containing LB medium at 30 °C produced spherical electron-dense SeNPs whose size ranged from 100-400 nm. Selenite reduction just started at the beginning of the exponential growth phase and the release of SeNPs was observed after cell lysis. Remarkably, V. natriegens produced SeNPs faster than other described microorganisms that were proposed as model bioreactors for SeNPs production. Thus, the fast-growing V. natriegens bacterium becomes a suitable biocatalyst for bioremediation of selenite and for speeding-up the eco-friendly synthesis of SeNPs.

Biosynthesis of selenium nanoparticles by Azoarcus sp. CIB.

BACKGROUND: Different bacteria have been reported so far that link selenite resistance to the production of metallic selenium nanoparticles (SeNPs). Although SeNPs have many biotechnological applications in diverse areas, the molecular mechanisms involved in their microbial genesis are not fully understood. The Azoarcus genus is a physiologically versatile group of beta-proteobacteria of great environmental relevance. Azoarcus sp. CIB is a facultative anaerobe that combines the ability to degrade under aerobic and/or anaerobic conditions a wide range of aromatic compounds, including some toxic hydrocarbons such as toluene and m-xylene, with an endophytic life style in the root of rice. We unravel here an additional physiological feature of the strain CIB that is related to its resistance to selenium oxyanions and the formation of SeNPs. RESULTS: This work is the first report of a member of the Azoarcus genus that is able to anaerobically grow in the presence of selenite. Electron microscopy preparations and X-ray spectroscopy analyses demonstrate the reduction of selenite to spherical electron-dense SeNPs whose average size was 123 ± 35 nm of diameter. Our data suggest that the main molecular mechanism of selenite resistance resides on an energy-dependent selenite exporter. Azoarcus cells trigger the synthesis of SeNPs when they reach the stationary-phase of growth, and either the exhaustion of electron donor or acceptor, both of which lead to starvation conditions, produce the reduction of selenite to red elemental selenium. Azoarcus becomes a promising biocatalyst, either as whole cells or cellular extracts, for the anaerobic and/or aerobic green synthesis of SeNPs. CONCLUSIONS: Azoarcus turns out to be a new eco-friendly system to reduce selenite and produce spherical SeNPs. Moreover, this is the first report of a rice endophyte able to produce SeNPs. Since Azoarcus is also able to degrade both aerobically and anaerobically toxic aromatic compounds of great environmental concern, it becomes a suitable candidate for a more sustainable agricultural practice and for bioremediation strategies.

Effects of Crocetin Esters and Crocetin from Crocus sativus L. on Aortic Contractility in Rat Genetic Hypertension.

BACKGROUND: Endothelial dysfunction, characterized by an enhancement in vasoconstriction, is clearly associated with hypertension. Saffron (Crocus sativus L.) bioactive compounds have been recognized to have hypotensive properties. Recently, we have reported that crocetin exhibits potent vasodilator effects on isolated aortic rings from hypertensive rats. In this work, we have aimed to analyze the anticontractile ability of crocetin or crocetin esters pool (crocins) isolated from saffron. Thus, we have studied the effects of saffron carotenoids on endothelium-dependent and -independent regulation of smooth muscle contractility in genetic hypertension. METHODS: We have measured the isometric responses of aortic segments with or without endothelium obtained from spontaneously hypertensive rats. The effects of carotenoids were studied by assessing the endothelial modulation of phenylephrine-induced contractions (10(-9)-10(-5) M) in the presence or absence of crocetin or crocins. The role of nitric oxide and prostanoids was analyzed by performing the experiments with L-NAME (NG-nitro-l-arginine methyl ester) or indomethacin (both 10(-5) M), respectively. RESULTS: Crocetin, and to a minor extent crocins, diminished the maximum contractility of phenylephrine in intact rings, while crocins, but not crocetin, increased this contractility in de-endothelizated vessels. In the intact vessels, the effect of crocetin on contractility was unaffected by indomethacin but was abolished by L-NAME. However, crocetin but not crocins, lowered the already increased contractility caused by L-NAME. CONCLUSIONS: Saffron compounds, but especially crocetin have endothelium-dependent prorelaxing actions. Crocins have procontractile actions that take place via smooth muscle cell mechanisms. These results suggest that crocetin and crocins activate different mechanisms involved in the vasoconstriction pathway in hypertension.

Dairy matrix effect on the transference of rosemary (Rosmarinus officinalis) essential oil compounds during cheese making.

BACKGROUND: The use of aromatic plant extracts as ingredients may be compromised owing to low transference and activity lack in food matrixes compared with in vitro trials. Rosemary essential oil (REO) was added to sheep milk to study the transference of its compounds during the cheese-making process and to determine how cheese antimicrobial activity is modified. RESULTS: The volatile characterization of dairy samples was performed using headspace stir bar sorptive extraction coupled to gas chromatography/mass spectrometry (HS-SBSE/GC/MS) so that fat matrix interferences were reduced. This method detected a decrease in volatile recovery concentration of 19.33% when REO was added to milk. A total recovery volatile yield of 62.51% was measured from the initial quantification of milk to cheese, with hydrocarbon volatiles being transferred in a higher ratio (64.88%) than oxygenated ones (58.74%). No effects were observed for REO in fortified cheese on the counts of native flora necessary for ripening processes, but the total inhibition of Clostridium spp. was provoked CONCLUSION: The study of active compound transference during cheese elaboration was achieved. The antimicrobial results in fortified cheeses with REO showed a preventive effect in the case of clostridial species, which are responsible for late cheese blowing.

Crocetin, a carotenoid derived from saffron (Crocus sativus L.), improves acetylcholine-induced vascular relaxation in hypertension.

BACKGROUND: Hypertension is associated with endothelial dysfunction characterized by decreased vasorelaxation. Crocetin, a bioactive compound of saffron, exhibits favorable cardiovascular properties. We analyze the vasomodulatory effects of crocetin in hypertension. METHODS: Myographical experiments were performed to compare the relaxation induced by acetylcholine (ACH) on aortic rings from normotensive (Wistar) and hypertensive (SHR) rats, incubated with or without crocetin or saffron extract and L-NAME or indomethacin. Extracts were also assayed in deendothelialized rings. UV-vis spectrophotometry and HPLC-DAD were used to characterize and quantify the saffron used. RESULTS: Crocetin enhanced the ACH relaxations in aorta from hypertensive (strongly) and normotensive rats (weakly). Saffron extract did not modify this. Crocetin plus L-NAME abolished the relaxant response in SHR but not in Wistar aorta. Crocetin plus indomethacin did not modify the indomethacin response in either SHR or Wistar aorta. Crocetin in rubbed segments did not modify the ACH responses. In contrast, saffron increased this response in rubbed segments from SHR but not Wistar rats. CONCLUSION: Crocetin exerts healthy vasomodulatory effects in hypertension, strongly improving endothelium-dependent ACH relaxations via endothelial nitric oxide but not the cyclooxygenase pathway. This work proposes that crocetin supplements are a possible complement in the therapy of hypertension.

Determination of saffron quality by high-performance liquid chromatography.

The aim of this work was to propose a high-performance liquid chromatography with diode array detection (HPLC-DAD) method for determining the three main compounds responsible for determining the quality of saffron (crocetin esters, picrocrocin, and safranal) by preparing an aqueous extract according to the ISO 3632 standard to solve the difficulty that this standard has for aroma and taste determination by ultraviolet-visible spectroscopy. Toward this aim, laboratory-isolated picrocrocin, a safranal standard with a purity of ≥ 88%, trans-crocetin di(ß-D-gentiobiosyl) ester (trans-4-GG) and trans-crocetin (ß-D-glucosyl)-(ß-D-gentiobiosyl) ester (trans-3-Gg) standards, both with a purity of ≥ 99%, and 50 different saffron spice samples from Italy, Iran, Greece, and Spain were used in the intralaboratory validation of the HPLC method. The analytical method proposed was adequate in terms of linearity, selectivity, sensitivity, and accuracy for determining the three foremost parameters that define the quality of saffron using only a saffron solution prepared according to the ISO 3632 standard.

Antitumor effects of saffron-derived carotenoids in prostate cancer cell models.

Crocus sativus L. extracts (saffron) are rich in carotenoids. Preclinical studies have shown that dietary intake of carotenoids has antitumor effects suggesting their potential preventive and/or therapeutic roles. We have recently reported that saffron (SE) and crocin (CR) exhibit anticancer activity by promoting cell cycle arrest in prostate cancer (PCa) cells. It has also been demonstrated that crocetin esters are produced after SE gastrointestinal digestion by CR hydrolysis. The aim of the present report was to investigate if SE, crocetin (CCT), and CR affected in vivo tumor growth of two aggressive PCa cell lines (PC3 and 22rv1) which were xenografted in male nude mice treated by oral gavage with SE, CR, and CCT. We demonstrated that the antitumor effects of CCT were higher when compared to CR and SE and treatments reverted the epithelial-mesenchymal transdifferentiation (EMT) as attested by the significant reduction of N-cadherin and beta-catenin expression and the increased expression of E-cadherin. Additionally, SE, CR, and CCT inhibited PCa cell invasion and migration through the downmodulation of metalloproteinase and urokinase expression/activity suggesting that these agents may affect metastatic processes. Our findings suggest that CR and CCT may be dietary phytochemicals with potential antitumor effects in biologically aggressive PCa cells.

Cytotoxic effect against 3T3 fibroblasts cells of saffron floral bio-residues extracts.

For every kilogram of saffron spice produced, about 63 kg of floral bio-residues (FB) (tepals, stamens and styles) are thrown away. Extracts of these bio-residues in water (W1), water:HCl (100:1, v/v) (W2), ethanol (E3), ethanol:HCl (100:1, v/v) (E4), dichloromethane (D5) and hexane (H6) were prepared. Their composition in flavonols and anthocyanins, and their effect on cell viability were determined. W1 was the richest in kaempferol 3-sophoroside (30.34 mg/g dry FB) and delphinidin 3,5-diglucoside (15.98 mg/g dry FB). The highest tested concentration (900 µg/ml) of W1, W2, E4, D5 and H6 did not significantly decrease the cell viability. Only E3 at that concentration caused a significant decrease of 38% in the cell viability. Therefore, all extracts studied are not cytotoxic at concentrations lower than 900 µg/ml, and W1 is proposed as the optimal for food applications due to its greater contribution of phenolic compounds.

Mycotoxicogenic fungal inhibition by innovative cheese cover with aromatic plants.

BACKGROUND: The use of aromatic plants and their extracts with antimicrobial properties may be compromised in the case of cheese, as some type of fungal starter is needed during its production. Penicillium verrucosum is considered a common cheese spoiler. The aim of this study was to evaluate the innovative use of certain aromatic plants as natural cheese covers in order to prevent mycotoxicogenic fungal growth (P. verrucosum). A collection of 12 essential oils (EOs) was obtained from various aromatic plants by solvent-free microwave extraction technology, and volatile characterisation of the EOs was carried out by gas chromatography/mass spectrometry. RESULTS: The most effective EOs against P. verrucosum were obtained from Anethum graveolens, Hyssopus officinalis and Chamaemelum nobile, yielding 50% inhibition of fungal growth at concentration values lower than 0.02 µL mL⁻¹. All EOs showed high volatile heterogeneity, with α-phellandrene, pinocamphone, isopinocamphone, α-pinene, camphene, 1,8-cineole, carvacrol and trans-anethole being found to be statistically significant in the antifungal model. CONCLUSION: The use of these aromatic plants as natural covers on cheese can satisfactorily inhibit the growth of some mycotoxicogenic fungal spoilers. Among the volatile compounds present, α- and ß-phellandrene were confirmed as the most relevant in the inhibition.

Picrocrocin kinetics in aqueous saffron spice extracts (Crocus sativus L.) upon thermal treatment.

The kinetics of picrocrocin degradation in aqueous extracts of saffron upon thermal treatment from 5 to 70 °C have been studied, together with the degradation of purified picrocrocin in water at 100 °C. The best fits to experimental data were found for a second-order kinetics model. Picrocrocin showed high stability with half-life periods (t(1/2)) ranging from >3400 h at 5 °C in saffron extracts to 9 h in the experiments with purified picrocrocin at 100 °C. In saffron extracts, the evolution of the rate constant (k) with temperature showed maximum values at 35 °C, and filtration of the extracts contributed to picrocrocin stability. In the case of purified picrocrocin, the generation of safranal in the first 5 h (yield up to 7.4%) was confirmed. Spectrometric parameters used in saffron quality control (E(1cm)(1%) 257 nm and ΔΕ(pic)) were not appropriate for documenting the evolution of picrocrocin.

Picrocrocin content and quality categories in different (345) worldwide samples of saffron ( Crocus sativus L.).

In this paper, 345 saffron samples were analyzed from different countries to study their picrocrocin content using different analytical techniques. The E1cm 1% of 257 nm results from all samples are inflated in comparison by the high-performance liquid chromatography (HPLC) data, because of the interferences with the crocetin ester pool and especially with those with a lower trans/cis relation. A picrocrocin range update is proposed for International Organization for Standardization (ISO) 3632 normative because category III should be incremented up to 50 units, while category II should be incremented up to 60 units. More accurate data are achieved when the deltaEpic measurement is carried out. Consequently, improvements to the ISO method are suggested. Fourier transform (FT)-near-infrared spectrometry analysis has also been carried out, showing excellent results from the calibration with HPLC data. This spectrophotometric technique could be used by saffron enterprises to obtain quick and more accurate data for picrocrocin determination.

Parabens as agents for improving crocetin esters' shelf-life in aqueous saffron extracts.

The effect of parabens on the shelf-life of crocetin esters and picrocrocin in aqueous saffron solutions was studied. Degradation of saffron crocetin esters fits a first-order kinetics model, and the results indicated that the crocetin (beta-D-glucosyl)-(beta-D-gentiobiosyl) esters were more stable than the crocetin di-(beta-D-gentiobiosyl) esters regardless of whether trans and cis isomers were considered. Under all tested conditions both parabens gave good results, especially propyl paraben that showed a greater influence on the degradation rate constant, except for cis-crocetin di-(beta-D-gentiobiosyl) ester and cis-crocetin (beta-D-glucosyl)-(beta-D-gentiobiosyl) ester. In presence of propyl paraben (200 mg/L), the half-life periods of trans-crocetin di-(beta-D-gentiobiosyl) esterimproved considerably, up to four-fold. Special attention has been paid to the effect of propyl paraben on 46 saffrons with different crocetin ester contents. No differences were observed in terms of picrocrocin. By analysis of variance, it is noteworthy that there were differences between the mean content of crocetin esters for all analysed saffron, except for trans-crocetin (beta-D-glucosyl)-(beta-D-gentiobiosyl) ester.