Hossein Rastegar

Removal of chlorophenolic derivatives by soil isolated ascomycete of Paraconiothyrium variabile and studying the role of its extracellular laccase

The ability of Paraconiothyrium variabile, a laccase producing ascomycete recently isolated from soil, was studied to eliminate chlorophenol derivatives in submerged culture medium. Among the tested compounds, ρ-chlorophenol (ρ-CP) and pentachlorophenol (PCP) were found to have minimum and maximum toxic effects, respectively, on the growth of the microorganism and at the same time high and low bioelimination percentages. The fungal strain was able to remove 86% of ρ-CP (with initial concentration of 40 mg l(-1)) and 56% of 2,4-dichlorophenol (2,4-DCP; with same concentration as ρ-CP) after 9 days of incubation while no elimination was observed in the presence of 2,4,6-trichlorophenol (2,4,6-TCP) and PCP. Monitoring of laccase production level in the fermentation broth together with pollutant removal confirmed the key role of this copper-containing oxidase in chlorophenol derivatives elimination. The type of laccase inducer (guaiacol) and its final concentration (250 μM) and also initial pH of the fermentation broth (pH=5.5) in the elimination of ρ-CP increased the final removal yield from 86% to 94.3%.

Monitoring of some pesticides residue in consumed tea in Tehran market

Tea is an agricultural product of the leaves, leaf buds, and internodes of various cultivars and sub-varieties of the Camellia sinensis plant, processed and vulcanized using various methods. Tea is a main beverage in Iranian food basket so should be free from toxic elements such as pesticides residue. There is no data bank on the residue of pesticides in the consumed black tea in Iran. The present study is the first attempt for monitoring of 25 pesticide residues from different chemical groups in tea samples obtained from local markets in Tehran, I.R. Iran during the period 2011. A reliable and accurate method based on spiked calibration curve and QuEChERS sample preparation was developed for determination of pesticide residues in tea by gas chromatography–mass spectrometry (GC/MS). The using of spiked calibration standards for constructing the calibration curve substantially reduced adverse matrix-related effects and negative recovery affected by GCB on pesticides. The recovery of pesticides at 3 concentration levels (n = 3) was in range of 81.4 - 99.4%. The method was proved to be repeatable with RSDr lower than 20%. The limits of quantification for all pesticides were ≤20 ng/g. 53 samples from 17 imported and manufactured brand were analyzed. Detectable pesticides residues were found in 28.3% (15 samples) of the samples. All of the positive samples were contaminated with unregulated pesticides (Endosulfan Sulfate or Bifenthrin) which are established by ISIRI. None of the samples had contamination higher than maximum residue limit set by EU and India.

Simultaneous analysis of mycotoxins in corn flour using LC/MS-MS combined with a modified QuEChERS procedure

Abstract The present study was developed to simultaneously quantify different mycotoxins including zearalenone (ZEA), T2-toxin, aflatoxin B1 (AFB1), deoxynivalenol (DON), and ochratoxin A (OTA) in 30 and 10 corn flour samples collected from local gristmill corn in Ardabil province and local markets in Tehran, respectively. A modified method QuEChERS (quick, easy, cheap, effective, rugged, and safe) in combination with an LC-MS/MS technique was used for sample preparation and measuring the levels of mycotoxins, respectively. Spiked calibration curves based on external and internal standards were used to overcome matrix effects and were reported as linear between 2 and 50 ng g−1 for aflatoxin B1, T-2 toxin, ochratoxin A; 50 and 1250 ng g−1 for zearalenone; and 75 and 1800 ng g−1 for deoxynivalenol. With the aid of spike calibration curves and acidic condition, the absorption of OTA by primary, secondary amine was reduced, and consequently, the percentage of recoveries was improved (in the range of 92.98–103.8). AFB1, OTA, and ZEA were detected and quantified in 23 (76.6%), 6 (20%), and 14 (46%) of 30 samples, with average contamination of 154.1 ng g−1, 25 ng g−1, and 358.7 ng g−1, respectively. The co-occurrence of AFB1 + ZEA and AFB1 + OTA + ZEA was noted in 20% and 23% of corn samples, respectively. The measured level of contamination for DON and T-2 toxin of corn flour samples did not exceed the maximum tolerated level. Moreover, the estimation of dietary intake of AFB1, OTA, ZER, DON, and T2-toxin were 5.8, 1.1, 32.1, 5.58, and 0.06 ng per kg body weight per day, respectively.

The concentration and probabilistic health risk assessment of pesticide residues in commercially available olive oils in Iran

This study was undertaken to analyze 29 pesticides residues in 37 commercially olive oil collected samples from Irans markets using Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) approach along with acetonitrile for the extraction, surface adsorbents for clean-up procedure, following with a gas chromatography-mass spectroscopy (GC-MS). In order to eliminate the matrix effect, the calibration curves were drawn using spiked samples with the Area under curve (AUC) portion calculation of pesticide residue to AUC internal standard (Triphenyl Methane (TPM)). Moreover, the probabilistic health risk assessment includes non-carcinogenic and carcinogenic risk were estimated by target hazard quotient (THQ), total target hazard quotient (TTHQ) and cancer risk (CR) using the Monte Carlo Simulation (MCS) method. The calibration curves were linear in the range of 10-1500 ng/g, and R2 was higher than 0.994. All pesticides recoveries as average were in the range of 77.97-112.65%. The respective numbers attributed to LOD and LOQ were 3-5 ng/g and 8-15 ng/g. Results showed that 29.7% of samples were contaminated by pesticides which according to Iranian regulation, while in 7 cases banned pesticides were detected. Only 4 samples are noncompliant with EU regulation. The rank order of pesticides based on THQ was Heptachlor > DDT > Pretilachlor. Also, TTHQ for adults was 0.139; and children 0.467. The rank order of pesticides based on CR was Heptachlor > DDT. Consumers (adults and children) are not at non-carcinogenic risk due to ingestion of oil olive content (THQ and TTHQ < 1 value) but are at considerable carcinogenic (CR > 1E-6). According to the observed profile of pesticide in olive oil samples, which are mostly banned according to Iranian regulation, further improvements in agriculture procedures of cultivated olive in Iran, as well as required assessments of imported olive oil, was recommended.

Effect of Iranian traditional cooking on fate of pesticides in white rice

Abstract In the current study, the reduction in the level of 42 pesticides from different chemical groups in white rice by means of traditional cooking was evaluated. A gas chromatography-mass spectrometry (GC/MS) system in combination with the modified QuEChERS technique as the base of sample preparation method was employed. The spiked rice samples (at 3 levels of 25, 100, and 500 ng/g) were analyzed to determine the reduction percentage of pesticide. Processing factor for each pesticide excepted for one of them was lower than 1. The introduced sample preparation and identification methods showed a precision as well as accuracy. The recovery of pesticides at three concentration levels was in the range of 84.08–105.95%. The highest and lowest percentages of pesticides reduction were reported as 99.8% and 15.6% for dichlorvos and metalaxyl, respectively. Regarding the different chemical groups, the most reduction is belong organophosphorus pesticides and the less reduction can be correlated to organochlorine pesticides. The results demonstrated that the Iranian traditional rice cooking, which involves long boiling times, significantly could reduce the concentrations of pesticide residues in white rice.

Preventing Aggregation of Recombinant Interferon beta-1b in Solution by Additives: Approach to an Albumin-Free Formulation

PURPOSE Aggregation suppressing additives have been used to stabilize proteins during manufacturing and storage. Interferonβ-1b is prone to aggregation because of being non-glycosylated. Aggregation behavior of albumin-free formulations of recombinant IFNβ-1b was explored using additives such as n-dodecyl-β-D-maltoside, Tween 20, arginine, glycine, trehalose and sucrose at different pH. METHODS Fractional factorial design was applied to select major factors affecting aggregation in solutions. Box-Behnken technique was used to optimize the best concentration of additives and protein. RESULTS Quadratic model was the best fitted model for particle size, OD350 and OD280/OD260. The optimal conditions of 0.2% n-Dodecyl-β-D-maltoside, 70 mM arginine, 189 mM trehalose and protein concentration of 0.50 mg/ml at pH 4 were achieved. A potency value of 91% ± 5% was obtained for the optimized formulation. CONCLUSION This study shows that the combination of n-Dodecyl-β-D-maltoside, arginine and trehalose would demonstrate a significant stabilizing and anti-aggregating effect on the liquid formulation of interferonβ-1b. It can not only reduce the manufacturing costs but will also ease patient compliance.

Design and synthesis of novel quinazolinone-1,2,3-triazole hybrids as new anti-diabetic agents: In vitro α-glucosidase inhibition, kinetic, and docking study

A novel series of quinazolinone-1,2,3-triazole hybrids 10a-p were designed, synthesized, and evaluated for their in vitro α-glucosidase inhibitory activity leading to efficient anti-diabetic agents. All synthesized compounds exhibited good inhibitory activity against yeast α-glucosidase (IC50 values in the range of 181.0-474.5 µM) even much more potent than standard drug acarbose (IC50 = 750.0). Among them, quinazolinone-1,2,3-triazoles possessing 4-bromobenzyl moiety connected to 1,2,3-triazole ring (10g and 10p) demonstrated the most potent inhibitory activity towards α-glucosidase. Compound 10g inhibited α-glucosidase in a competitive manner with Ki value of 117 µM. Furthermore, the binding modes of the most potent compounds 10g and 10p in the α-glucosidase active site was studied through in silico docking studies. Also, lack of cytotoxicity of compounds 10g and 10p was confirmed via MTT assay.