Publications

Saffron is a valued herb, obtained from the stigmas of the C. sativus Linn (Iridaceae), with therapeutic effects. It has been described in pharmacopoeias to be variously acting, including as an anti-depressant, anti-carcinogen, and stimulant agent. The therapeutic effects of saffron are harbored in its bioactive molecules, notably crocins, the subject of this paper. Crocins have been demonstrated to act as a monoamine oxidase type A and B inhibitor. Furthermore, saffron petal extracts have experimentally been shown to impact contractile response in electrical field stimulation. Other research suggests that saffron also inhibits the reuptake of monoamines, exhibits N-methyl-d-aspartate antagonism, and improves brain-derived neurotrophic factor signaling. A host of experimental studies found saffron/crocin to be similarly effective as fluoxetine and imipramine in the treatment of depression disorders. Saffron and crocins propose a natural solution to combat depressive disorders. However, some hurdles, such as stability and delivery, need to be overcome.

Flavone (Fl), genistein (Gen) and kaempferol (Kol) were studied for their affinities towards human serum albumin (HSA) in the presence and absence of Pb2+,Cu2+,Zn2+,Mg2+ and Mn2+. The fluorescence intensities of HSA decreased with increasing concentration of the three flavonoids. Kaempferol resulted in a blue-shift of the ?em of HSA from 336 to 330 nm; flavone showed an obvious red-shift of the ?em of HSA from 336 to 342 nm; genistein did not cause an obvious blue-shift or red-shift of the ?em of HSA. However, the extents of ?em-shifts induced by the flavonoids in the presence of metal ions were much bigger than that in the absence of mental ions. Pb2+,Cu2+,Zn2+,Mg2+ and Mn2+ reduced the quenching constants of the flavonoids for HSA by 14.6% to 60.7% , 28% to 67.9%,3.5% to 59.4%, 23.2% to 63.7% and 14% to 65%, respectively. The affinities of flavone, genistein and kaempferol for HSA decreased about 10.84%, 10.05%and 3.56% in the presence of Pb2+, respectively. Cu2+ decreased the affinities of flavone, genistein and kaempferol for HSA about 14.04%, 5.14%and 8.89%, respectively. Zn2+ decreased the affinities of flavone, genistein and kaempferol for HSA about 3.79%, 0.55% and 3.58%, respectively. Mg2+ decreased the affinities of flavone, genistein and kaempferol for HSA about 16.94%, 2.94%and 7.04%, respectively. Mn2+ decreased the affinities of flavone, genistein and kaempferol for HSA about 14.24%, 3.66% and 4.78%, respectively.

The present work reports on a sensitive and affordable non-instrumental method for the determination of bromine species in environmental waters by combination of paper-based headspace sampling and smartphone-based fluorescence detection. The proposed approach takes advantage of the luminescence quenching of a probe (5-oxo-3,5-dihydro-2 H-thiazolo[3,2-a]pyridine-7-carboxylic acid, TPCA) derived from natural compounds, namely, citric acid and cysteamine, when exposed to molecular bromine. The decreased luminescence intensity of the probe was attributed to the formation of a dibrominated derivative of TPCA at the detection area of a paper-based analytical device (PAD). Remarkably, PADs modified with the luminescent probe showed excellent stability. Under optimal conditions, the proposed approach showed limits of detection of 5.4 µg L-1 and 0.9 µg L-1 for Br- and BrO3-, respectively, with a repeatability lower than 10% for both bromine species. The non-instrumental method was validated against two certified reference materials, namely BCR-611 and BCR-612 (low and high level Br- in groundwater), and successfully applied to the analysis of environmental water samples with recoveries in the range 93–106%.

A flow-through UV reactor has been implemented in an automated flow-injection/stopped-flow manifold, and used for on-line generation of Se volatile derivatives prior to detection by quartz furnace atomic absorption spectrometry. The presence of a low molecular weight organic acid (formic or acetic) in the carrier was a necessary requirement so that efficient vapour generation was achieved. Stopped-flow conditions were employed with the aim of increasing the time for which the sample zone was subjected to UV irradiation while it was transported to the detector. The simultaneous formation of H2 during the photochemical decomposition of formic acid facilitated the atomization of the Se derivatives in the quartz furnace, and therefore the addition of H2 to the carrier gas, which is necessary for efficient atomisation, could be eliminated. Nevertheless, the presence of H2 in the carrier gas (Ar) was required for efficient atomisation when using acetic acid as carrier. This manifold allowed a sample throughput of 26 h−1 with a detection limit of 0.5 ng mL−1 Se and a repeatability, expressed as relative standard deviation, of 4%. Effect of concomitants in the online generation of Se vapours with the new manifold was investigated. Chloride salts of alkaline and alkaline-earth elements did not interfere at concentrations up to 10 000 mg L−1, but nitrate salts caused a positive effect. Tolerance of typical hydride-forming elements such as As and Sn was much higher with UV vapour generation as compared to chemical hydride generation. The presence of Cu(II) was critical since interference effects are observed from 0.05 mg L−1, but tolerance of Ni(II) was greater with UV vapour generation.

This study investigated the behavior of pesticides commonly used on potato in a part of northwestern Spain with a large area devoted to this crop. Experimental potato plots were treated with commercial formulations of two insecticides, a nematicide, a herbicide, and a combination of two fungicides, and the concentrations of the active ingredients were monitored throughout the growing season in the 0-1 and 1-15 cm soil layers, in water dripping off the potato plants, and in the potatoes themselves. The technique used for pesticide determination was gas chromatography with mass selective detection. For potato analyses, pesticide extraction was optimized. The only pesticide ever detected in potato tubers was metalaxyl, the concentration of which never exceeded half the maximum residual limit even when it was applied several times more often than is officially recommended for potato crops. Metalaxyl was also the only pesticide detected in wash-off, apparently due to its being more soluble in water than the other pesticides applied to the growing plants. A mathematical model of pesticide transport in soil was fitted to the experimental data using the program HYDRUS-1D.

This study aimed to confirm the effects of Tibet kefir milk (TKM) on gut microbiota and metabolism. An obesity model was established by feeding a high-fat diet (HFD) to human-microbiota-associated rats. Next-generation sequencing and ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry were applied for gut microbiota and untargeted metabolomics, respectively. After 8 weeks of feeding, the enterotype in the HFD group was switched from ET1 (<i>Prevotella</i>/<i>Akkermansia</i>-dominant) to ET2 (<i>Bacteroides</i>/<i>Akkermansia</i>-dominant). Branched-chain amino-acids- and aromatic amino-acids-metabolism increased, and taurine-conjugated bile acids decreased in the HFD group. Compared with the HFD group, taurocholic acid increased in the TKM1 group, while l-threonine decreased, and equol, taurochenodeoxycholate, and taurodeoxycholic acid increased in the TKM2 group. The metabolite alteration suggested restorative bile acid metabolism, modified metabolic pattern of amino acids, and elevation of anti-obesity factors in the TKM-intervened animals. It can be deduced that changes by TKM intervention in the host gut metabolites are the major contributors to reducing fat deposition.