Dietary fibre in processed murta (Ugni molinae Turcz) berries: bioactive components and antioxidant capacity

Antioxidant properties of phenolic extracts of murtilla pomace: First report on the importance of soluble and insoluble-bound compounds

Some native Chilean berries, including murtilla, have gained attention for their high phenolic content which renders them attractive for the beverage industry. However, phenolic-rich by-products are generated during the production of murtilla juice (murtilla pomace), and there has been no scientific consideration of this by-product as a source of different forms of phenolic compounds. The aim of this study was thus to obtain phenolic extracts from the soluble fraction (free, esterified, and etherified) of murtilla pomace as well from the counterpart that contains insoluble-bound compounds, and evaluate their antioxidant properties. The fraction obtained from the insoluble-bound form (insoluble-bound phenolic hydrolysates) showed the highest total phenolic content, reducing power and antioxidant capacity, as evaluated by the FRAP and ORAC assay, respectively. The results revealed the presence of different compounds in each fraction, highlighting important levels of phenolic acids (e.g., gallic acid) and flavonoids (e.g., quercetin and its derivatives) as evaluated by UPLC-ESI-MS/MS. The most prominent fraction (released from the insoluble-bound form) exhibited antioxidant activity (in concentrations as low as 0.0025 μM of total phenolic acids and 0.0002 μM of total flavonoids) in Caco-2 cells. The necessary concentration of quercetin to protect Caco-2 cells against the hydrogen peroxide-induced oxidative stress was twenty times lower than the concentration needed for gallic acid to exert the same level of antioxidant protection. We can therefore suggest that the quercetin concentration would be a better-quality control indicator for functional ingredients, food supplements, and/or nutraceutical products generated from the insoluble-bound phenolic fraction of murtilla pomace.

Differential Extraction and Preliminary Identification of Polyphenols from Ugni candollei (White Murta) Berries

Ugni candollei, commonly known as white murta, is a native Chilean berry with a polyphenol composition that has been underexplored. This study aimed to establish a comprehensive profile of white murta polyphenols using ultra-performance liquid chromatography electrospray ionization Orbitrap mass spectrometry (UPLC-ESI-ORBITRAP MS). Additionally, it compared the efficacy of conventional extraction methods with emerging techniques such as deep eutectic solvent (DES) extraction and hot pressurized water extraction (HPWE). The analysis tentatively identified 107 phenolic compounds (84 of them reported for the first time for this cultivar), including 25 phenolic acids, 37 anthocyanins, and 45 flavonoids. Among the prominent and previously unreported polyphenols are ellagic acid acetyl-xyloside, 3-p-coumaroylquinic acid, cyanidin 3-O-(6'-caffeoyl-glucoside, and phloretin 2'-O-xylosyl-glucoside. The study found HPWE to be a promising alternative to traditional extraction of hydroxybenzoic acids, while DES extraction was less effective across all categories. The findings reveal that white murta possesses diverse phenolic compounds, potentially linked to various biological activities.

Evaluation of the antioxidant, anti-inflammatory, and anti-tumoral properties of bioactive compounds extracted from murta berries (Ugni molinae T.) dried by different methods

This study evaluated the effects of different drying methods (freeze drying, vacuum drying, infrared drying, convective drying, and sun drying) on the biological properties of berries from the Chilean murta (Ugni molinae Turcz) shrub. Physical-chemical properties (proximal composition, dietary fiber, sugars) were determined. Total phenolic content through the method of Folin-Ciocalteau, the profile of phenol compounds was determined by HPLC, and antioxidant potential by DPPH and ORAC assays were also evaluated. The topic anti-inflammatory effect was evaluated by mice´s ear edema, and in vitro anti-tumoral activity was tested by MTT assay. The chemical properties of dried berries differed significantly based on the drying method: freeze-dried murta berries showed increased total phenolic content extracted over fresh and dried samples. In addition, this lyophilized extract stood out in its antioxidant potential, in both assays evaluated (DPPH and ORAC), compared to the other drying methods. Notwithstanding, vacuum- and infrared-dried murta also showed a higher ORAC value. Antioxidant potential was significantly associated with phenolic compounds catechin and pyrogallol, which were the most abundant phenolic compounds present in all samples. The anti-inflammatory activity was most effective under freeze-drying and vacuumdrying conditions. Moreover, vacuum drying and infrared drying best preserved the anti-tumoral effect on cancer cells.