Ociel Muñoz

Total and inorganic arsenic concentrations in different species of economically important algae harvested from coastal zones of Chile.

Chile is one of the major producers of phytocolloids extracted from seaweed. Multicellular algae are considered to be primary accumulators of arsenic. We analyzed 14 species of algae belonging to the groups Rhodophyceae (10), Phaeophyceae (3) and Chlorophyceae (1) from different coastal zones of Chile in 2003-2004. Dry ashing mineralization (for total As) and acid digestion (for inorganic As) together with quantification by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) were employed. In general, total arsenic concentrations varied between 3.0 and 68 mg kg(-1), whereas inorganic arsenic concentrations ranged between 0.15 and 1.06 mg kg(-1). The algal species Durvillaea antarctica and Porphyra columbina, used for direct human consumption, did not have inorganic arsenic levels that represent a health risk to consumers. Among species used for phytocolloids production, such as Macrocystis piryfera, Gracilaria chilensis and Gigartina skottsbergii, observed levels of inorganic arsenic were greater than 1 mg kg(-1), the limit value established by the regulations of some countries. Among the 14 species of algae tested, inorganic arsenic levels were between 0.8% and 13% of the total arsenic concentrations; that is, arsenic present in these algae was found primarily as organic arsenic.

Honey as a bioindicator of arsenic contamination due to volcanic and mining activities in Chile

The content of heavy metals in honey is indicative of natural or anthropogenic pollution and has therefore been proposed as a feasible bioindicator for arsenic contamination in different regions of Chile. Total arsenic (t-As) and inorganic As (i-As) concentrations were determined in 227 samples of honey harvested during the years 2007, 2008, and 2009 in the areas of San Pedro de Atacama, Atacama, Chiloe, and Futaleufu, with the last town located 156 km from the Chaiten Volcano (latest eruption in 2008). These analyses were conducted using an atomic absorption spectrophotometer coupled with a hydride generator. In the honey samples, the concentrations of t-As ranged from 2.2 to 171.9 μg kg-1, and the i-As concentrations ranged from none detected (ND) to 24.6 μg kg-1, with the area of San Pedro de Atacama having the highest As concentrations. The samples of honey from Futaleufu showed higher As concentrations after the eruption of the Chaiten Volcano in 2008. This study demonstrates that As pollution in honey may originate from both natural and anthropogenic sources. The results indicate that it is appropriate to use honey as a bioindicator of environmental pollution. In addition, the consumption of the honey studied herein does not pose any health hazards to the consumer due to its As content.

Optimization of secoisolariciresinol diglucoside extraction from flaxseed (Linum usitatissimum L.) and isolation by a simple HPLC-UV method

This research was conducted to develop and optimize a methodology to quantify the content of secoisolariciresinol diglucoside (SDG), the main vegetable lignan present in flaxseed. However, at the time of this work, commercial SDG was not available for standard use. Therefore, an effective method to obtain purified SDG from flaxseed was developed using chromatographic techniques. The SDG obtained was of approximately 97% purity. The methanol extraction time, alkali concentrations, and reaction temperature were optimized through a response surface methodology (RSM), and the optimal conditions established for the extractions were 47°C, 58 mmol L−1 sodium methoxide, and 24 h. This methodology was then applied to study the variation of SDG content in flaxseed from different cultivars. The SDG content in different varieties of flaxseed ranged from 10.8 to 17.9 mg g−1 in defatted flaxseed flour and from 6.0 to 10.9 mg g−1 in whole flaxseed.

Bioaccessibility of lignans from flaxseed (Linum usitatissimum L.) determined by single‐batch in vitro simulation of the digestive process

BACKGROUND Flaxseed is an important source of lignan secoisolariciresinol diglucoside (SDG) and its aglycone, secoisolariciresinol (SECO). These phenolic compounds can be metabolized to the mammalian lignans enterodiol (ED) and enterolactone (EL) by human intestinal microflora. Flaxseed lignans are known for their potential health benefits, which are attributed to their antioxidant and phytoestrogenic properties. The focus of this study was to determine the bioaccessibility of plant and mammalian lignans in whole flaxseed (WF) and flaxseed flour (FF) throughout the entire digestive process. Moreover, the metabolic activity of intestinal microflora was evaluated. RESULTS A single-batch in vitro simulation of the digestive process was performed, including fermentation by the intestinal microflora in the colon. Bioaccessibility was calculated as (free lignan)/(total lignan). In digested WF, the bioaccessibility values of SECO, ED and EL were 0.75%, 1.56% and 1.23%, respectively. Conversely, in digested FF, the bioaccessibility values of SDG, ED and EL were 2.06%, 2.72% and 1.04%, respectively. The anaerobic count and short-chain fatty acids indicate that bacteria survival and carbohydrate fermentation occurred. CONCLUSION The contents of both SDG and ED were significantly higher in digested FF than in digested WF. FF facilitated the action of intestinal bacteria to release SDG and metabolize ED.