In vitro assessment of the mutagenic and genotoxic potential of a pure stilbene extract

Novel and safe debranched starch-zinc complexes with endoconcave structure as zinc supplements

Zinc deficiency is a serious risk to human health and growth, especially in children. The development of zinc supplements can effectively reduce this harm. Here, a series of debranched starch‑zinc complexes (DS-Zn) were prepared, whose zinc complexation was inversely proportional to the amylopectin content in the debranched starch (DS). The physicochemical properties of DS-Zn were characterized using the conductivity, XRD, iodine staining and thermogravimetry. Combined with XPS, solid-state 13C NMR and IR, it was elucidated that the structure of DS-Zn is endoconcave structure with 2-O and 3-O of DS on the inner side and 6-O of DS on the outer side, where zinc is located. The DS-Zn exhibits good biosafety including blood, cellular and mutagenicity. In vitro simulations of digestion and zinc-deficient cellular models showed that DS-Zn was more tolerant to the gastrointestinal environment and more effective in zinc supplementation (increased by 33 %) than inorganic zinc supplements. Utilizing the compressibility of starch, DS-Zn was prepared as a more palatable oral cartoon tablet for children. This study will provide important support to advance the development and application of novel starch-based zinc nutritional supplements.

Efficient encapsulation of fat-soluble food-derived biofunctional substances (curcumin as an example) in dual-modified starch-based nanoparticles containing large conjugated systems

Acid-ethanol hydrolysis and subsequent cinnamic acid (CA) esterification were employed to prepare a series of dual-modified starches efficiently loaded with curcumin (Cur) utilizing large conjugation systems provided by CA. Structures of the dual-modified starches were confirmed by IR and NMR, and their physicochemical properties were characterized by SEM, XRD and TGA. The nanoparticles fabricated from the dual-modified starch have perfect spherical shape (250.7-448.5 nm, polydispersity index <0.3), excellent biosafety (no hematotoxicity, no cytotoxicity, no mutagenicity) and high loading of Cur (up to 26.7 % loading). By XPS analysis, this high loading is believed to be supported by the synergistic effect of hydrogen bonding (provided by hydroxyl groups) and π-π interactions (provided by large conjugation system). In addition, the encapsulation of dual-modified starch nanoparticles effectively enhanced the water solubility (18-fold) and physical stability (6-8-fold) of free Cur. In vitro gastrointestinal release showed that Cur-encapsulated dual-modified starch nanoparticles were released more preferably than free Cur and that the Korsmeyer-Peppas model was the most suitable release model. These studies suggest that dual-modified starches containing large conjugation systems would be a better alternative for encapsulating fat-soluble food-derived biofunctional substances in functional food and pharmaceutical applications.

Genotoxicity evaluation of graphene derivatives by a battery of in vitro assays

The interest of graphene materials has increased markedly in the recent years for their promising applications in many fields as food packing. These new applications have caused some concern regarding their safety for consumers since the intake of these materials may increase. In this sense, a battery of in vitro test is required before its use as a food contact material. Then, the aim of this study was to assess the potential mutagenicity and genotoxicity of graphene oxide (GO) and reduced-graphene oxide (rGO) following the recommendations of the European Food Safety Authority (EFSA). Thus, the mouse lymphoma assay (MLA) and the micronucleus test (MN) were performed in L5178YTk ± cells, and the Caco-2 cells were used for the standard and modified comet assays. The results indicated that GO (0-250 μg/mL) was not mutagenic in the MLA. However, rGO revealed mutagenic activity from 250 μg/mL and 125 μg/mL after 4h and 24h of exposure, respectively. In the MN test, negative results were obtained for both compounds at the concentrations assayed (0-250 μg/mL) for GO/rGO. Moreover, no DNA strand breaks, or oxidative DNA damage were detected in Caco-2 cells exposed to GO (0-250 μg/mL) and rGO (0-176.3 μg/mL for 24h and 0-166.5 μg/mL for 48h). Considering the mutagenic potential of rGO observed further investigation is needed to describe its toxic profile.

Isolation of oligostilbenes from Iris lactea Pall. var. chinensis (Fisch.) Koidz and their anti-inflammatory activities

Iris lactea Pall. var. chinensis (Fisch.) Koidz (Iris lactea) is an herbaceous perennial widely distributed in China, India, and South Korea. Iris lactea has been extensively used in traditional Chinese medicine. The present study isolated a new oligostilbene (compound 1), together with three known oligostilbenes (compounds 2, 3 and 4) from the seeds of Iris lactea. The structures of these compounds were elucidated by HRESIMS, NMR, and chemical analyses. The network-based pharmacologic analysis platform was used to predict the target proteins related to inflammation of isolated compounds. Furthermore, the isolated compounds were tested for their anti-inflammatory effects in LPS-stimulated RAW 264.7 cells. In this network, 138 candidate targets of compounds related to its therapeutic effect on inflammation were identified. In addition, compounds 1, 2, 3 and 4 significantly decreased NO content and the IL-6 levels as well as the expression of COX-2 in LPS-stimulated RAW 264.7 cells.

In Vivo Genotoxicity Evaluation of a Stilbene Extract Prior to Its Use as a Natural Additive: A Combination of the Micronucleus Test and the Comet Assay

Genotoxic data of substances that could be used as food additives are required by the European Food Safety Authority. In this sense, the use of an extract from grapevine shoots containing a stilbene richness of 99% (ST-99), due to its antioxidant and antibacterial activities, has been proposed as an alternative to sulfur dioxide in wine. The aim of this work was to study, for the first time, the in vivo genotoxic effects produced in rats orally exposed to 90, 180, or 360 mg ST-99/kg body weight at 0, 24, and 45 h. The combination of micronucleus assay in bone marrow (OECD 474) and standard (OECD 489) and enzyme-modified comet assay was used to determine the genotoxicity on cells isolated from stomach, liver, and blood of exposed animals. The ST-99 revealed no in vivo genotoxicity. These results were corroborated by analytical studies that confirm the presence of stilbenes and their metabolites in plasma and tissues. Moreover, to complete these findings, a histopathological study was performed under light microscopy in liver and stomach showing only slight modifications in both organs at the highest concentration used. The present work confirms that this extract is not genotoxic presenting a good profile for its potential application as a preservative in the wine industry.