Effects of gamma radiation in mycotoxin descontamination of Aloysia citrodora Paláu

The interest and demand for aromatic and medicinal plants have been growing due to their combined organoleptic and bioactive properties. However, in general these plants suffer natural contamination by fungi and associated toxins during growth as also in harvesting, storage and drying processes, which represents a threat to public health. The rigorous standards required by the industrial sector in terms of good quality of raw materials demand efficient decontamination procedures (1-3). Gamma radiation is assumed as an accredited methodology for the decontamination of medicinal and aromatic plants, with numerous advantages not only to the product itself but also to the consumer and the environment (4). In this study, efficient methods for detecting aflatoxins (AFB" AFB2, AFG1 and AFG2) and ocratoxin A (OTA), were optimized and validated, and afterwards, applied to spiked samples of Aloysia citrodora Pahiu submitted to gamma radiation treatment at different doses (I , 5 and I 0 kGy ), to evaluate the effectiveness of irradiation as a decontamination technique for dry plants. Mycotoxin levels were determined by reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection, after immunoaffinity column (lAC) cleanup. All the applied gamma radiation doses conducted to a degradation of the studied mycotoxins. In relation to the control sample (0 kGy), the reduction rates in the irradiated samples ranged from 4.9 and 5.2% in OTA, 5.3 and 9.6% in AFBt. 12.3 and 13.5 in AFB2, 16.4 and 23.6 in AFG1 and, finally, 52.6 and 62.7% in AFG2. The gamma radiation dose of 5 kGy stood out as the best decontamination dose for AFB1 and AFG1, which are the most significant aflatoxins naturally found in food commodities. For OTA, AFG2 and AFB2 there was no significant difference in decontamination between doses. In conclusion, the extraction and analysis methods proved to be suitable for detection of aflatoxins and ocratoxin A in A. citrodora. Gamma radiation seems to be an effective technique for reducing aflatoxins G in A. citrodora, and eventually oth~r medicinal and aromatic plants. On the other hand, aflatoxins B and OTA are less affected by this treatment.

Piezoelectric PVDF materials performance and operation limits in space environments

Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes. Dimensional adjustments of adaptive polymer films are achieved via charge deposition and require a detailed understanding of the piezoelectric material responses which are expected to suffer due to strong vacuum UV, gamma, X-ray, energetic particles and atomic oxygen under low earth orbit exposure conditions. The degradation of PVDF and its copolymers under various stress environments has been investigated. Initial radiation aging studies using gamma- and e-beam irradiation have shown complex material changes with significant crosslinking, lowered melting and Curie points (where observable), effects on crystallinity, but little influence on overall piezoelectric properties. Surprisingly, complex aging processes have also been observed in elevated temperature environments with annealing phenomena and cyclic stresses resulting in thermal depoling of domains. Overall materials performance appears to be governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and AO exposure is evident as depoling and surface erosion. Major differences between individual copolymers have been observed providing feedback on material selection strategies.

Gamma-tocotrienol as an effective agent in targeting prostate cancer stem cell-like population

Emerging evidence supports that prostate cancer originates from a rare sub-population of cells, namely prostate cancer stem cells (CSCs). Conventional therapies for prostate cancer are believed to mainly target the majority of differentiated tumor cells but spare CSCs, which may account for the subsequent disease relapse after treatment. Therefore, successful elimination of CSCs may be an effective strategy to achieve complete remission from this disease. Gamma-tocotrienols (-T3) is one of the vitamin-E constituents which have been shown to have anticancer effects against a wide-range of human cancers. Recently, we have reported that -T3 treatment not only inhibits prostate cancer cell invasion but also sensitizes the cells to docetaxel-induced apoptosis, suggesting that -T3 may be an effective therapeutic agent against advanced stage prostate cancer. Here, we demonstrate for the first time that -T3 can down-regulate the expression of prostate CSC markers (CD133/CD44) in androgen independent (AI) prostate cancer cell lines (PC-3 & DU145), as evident from western blotting analysis. Meanwhile, the spheroid formation ability of the prostate cancer cells was significantly hampered by -T3 treatment. In addition, pre-treatment of PC-3 cells with -T3 was found to suppress tumor initiation ability of the cells. More importantly, while CD133-enriched PC-3 cells were highly resistant to docetaxel treatment, these cells were as sensitive to -T3 treatment as the CD133-depleted population. Our data suggest that -T3 may be an effective agent in targeting prostate CSCs, which may account for its anticancer and chemosensitizing effects reported in previous studies.