Claudia Fuentealba

Potential of Chilean native corn (Zea mays L.) accessions as natural sources of phenolic antioxidants and in vitro bioactivity for hyperglycemia and hypertension management.

Thirty-three Chilean corn accessions were screened for the first time regarding their phenolic profiles, total phenolic contents (TPC), antioxidant capacity (DPPH and ABTS), and in vitro inhibition against key enzymes relevant for hyperglycemia (α-amylase and α-glucosidase) and hypertension (angiotensin I-converting enzyme, ACE-I) in both free and cell wall-bound fractions. TPC varied from 132.2 to 262.5 mg of gallic acid equivalents/100g dry weight (DW), and around 88% of TPC and antioxidant capacity were found in the bound form. Vanillin, vanillic, protocatechuic, ferulic, and p-coumaric acids were detected by HPLC in free fractions, whereas ferulic and p-coumaric acids were found in the bound form. Pisankalla accession (red kernel) had the highest ferulic acid content (269.5 mg/100g DW). No α-amylase and ACE-I inhibition were found; however, all free fractions inhibited α-glucosidase (10.8-72.5%). Principal component analysis revealed that darker samples (free fraction) showed higher TPC and antioxidant capacity, while α-glucosidase inhibition was related to yellow-colored samples.

Colour and in vitro quality attributes of walnuts from different growing conditions correlate with key precursors of primary and secondary metabolism

Walnuts (Juglans regia L.) are well known for their flavour, nutritional and health properties. The light colour of walnuts is a quality attribute that leads to consumer preference. The aim of this study was to correlate attributes such as colour and antioxidant capacity with the precursors of primary and secondary metabolism. Two growing areas and four different colours of walnuts cv. Chandler from the central region of Chile were evaluated. Walnuts grown in the zone with Andes Mountains influence showed higher (p<0.05) sugar and unsaturated fatty acid contents, which could be attributed to lower minimum temperatures during seed filling. Extra light walnuts had higher (p<0.05) total phenolic compounds, antioxidant capacity and arbutin levels than amber walnuts. To the best of our knowledge, this is the first time that arbutin has been reported in walnuts and could provide the first insight into how enzymatic browning is prevented in the Chandler cultivar.

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.

Optimized methodology for the extraction of free and bound phenolic acids from Chilean Cristalino corn (Zea mays L.) accession

ABSTRACT The aim of this study was to optimize the extraction of free and bound phenolic acids from Chilean Cristalino corn by response surface methodology based on the total phenolic contents (TPCs) and the 2,2-diphenyl-1-picrylhydrazyl scavenging-linked antioxidant capacity (AC) as response variables. Central Composite 22 + axial points experimental designs were applied. The best extraction conditions for the free and bound phenolic fraction were acetone 69% in water for 63 min and a hydrolysis with 3 M NaOH for 90 min, respectively. Under these conditions, TPCs in free and bound forms were 59.9 ± 0.7 and 172.9 ± 1.1 mg gallic acid equivalents/100 g, respectively. Further, AC found in free and bound fractions was 186 ± 3 and 694.5 ± 3.3 µmol Trolox equivalents/100 g, respectively. The experimental and predicted values of TPC and AC were similar in case of free phenolic fraction indicating that the model was adequate and reproducible. Major phenolic acids were found in the bound fraction and were ferulic and p-coumaric acids.