: Skin ageing is a natural process caused by both intrinsic and extrinsic factors, such as exposure to solar radiation, smoking, environmental pollution, improper skin care, improper lifestyle, ...stress and lack of sleep. These factors accelerate the ageing process of the skin by impairing and limiting many of its functions. In order to protect the skin against the harmful effects of ultraviolet radiation, photoprotective preparations and antioxidants are used, which neutralize the action of free radicals affecting the abnormal homeostasis of the body. Antioxidants are the main group of ingredients used in anti-ageing prophylaxis. Many raw materials of natural origin are rich in these ingredients. The aim of the study was to assess the antioxidant activity of the aloe vera extracts and to evaluate extraction conditions including the effect of solvent used as an extractant on the observed antioxidant potential and the ability to absorb solar radiation by aloe vera (
).
: The material for the study consisted of alcoholic extracts prepared from the peel and flesh of aloe vera. Extracts in 40%, 70% or concentrated ethanol, methanol, n-propanol and isopropanol were used. Extracts were obtained after 15, 30 or 60 min of ultrasound-assisted extraction. Antioxidant activity was determined spectrophotometrically using the DPPH and ABTS methods, while the Folin–Ciocalteu method was used to determine total polyphenol content. Absorption spectra of the prepared extracts were taken to evaluate the absorption capacity.
: The highest average antioxidant activity was shown by aloe leaf peel extract in 40% methanol, subjected to a 60 min extraction and determined by the DPPH method. For aloe vera leaf peel extracts tested by the DPPH and ABTS methods, the best solvent seems to be 40% methanol, while in the Folin–Ciocalteu method it was 96% ethanol. For aloe vera flesh extracts evaluated by the DPPH method, the best solvents were undiluted alcohols, while for those evaluated by the ABTS method, it was 40% methanol, and for the determination of total polyphenol content, it was 96% ethanol. If compared to the evaluated parts of the plant studied, aloe leaf peel showed the most favourable antioxidant properties of the raw materials used. The UV-VIS spectra of the majority of extracts show an absorption maximum at a wavelength of about 300 nm, which corresponds to the UVB range.
: Aloe vera is a valuable source of antioxidant components. Ultrasound-assisted extraction is a useful method to isolate antioxidant substances from plant material. The antioxidant potential is influenced by the extraction time of the raw material and the solvent used. Aloe vera leaf peel extracts showed higher antioxidant activity than extracts prepared from its flesh. It can be successfully used as a raw material in anti-ageing prevention and as a potential photoprotective ingredient.
There is currently an upsurge of interest in phytochemicals as new sources of natural antioxidants. The aim is to use them in foods and pharmaceutical preparations in order to replace synthetic ...antioxidants, which are being restricted due to their potential health risks and toxicity. The relative levels of antioxidant activity and the total phenolic content of aqueous and methanolic extracts of a total of 51 plant species of Jordanian origin have been determined using the improved ABTS
+
method and the Folin–Ciocalteu colorimetric method. The total phenolic content of aqueous and methanolic extracts of the investigated plant species ranged from 2.8 to 70.3 and from 2.6 to 59.6
mg GAE/g dry weight, respectively, while the total antioxidant capacity ranged from 12.9 to 731 and from 10.1 to 720
μmol TE/g dry weight, respectively. Based on our results, a number of plant species, namely,
Arbutus andrachne,
Hypericum triquetrifolium and
Rosmarinus officinalis, were identified as among the best sources of free radical-scavenging compounds. There was positive linear correlation between antioxidant activity and total phenolic content for aqueous and methanolic extracts. Thus, it was concluded that phenolic compounds were the predominant antioxidant components in the investigated plant species.
Total antioxidant capacity (TAC) of humic acid (HA) samples was determined using CUPRAC (CUPric Reducing Antioxidant Capacity), FC (Folin–Ciocalteu), QUENCHER-CUPRAC, QUENCHER-FC, Ag-NP (Silver ...nanoparticle)‒ and Au-NP (Gold nanoparticle)‒based methods. Conventional FC and modified FC (MFC) methods were applied to solid samples. Because of decreased solubility of Folin–Ciocalteu's phenol reagent in organic solvents, solvent effect on TAC measurement was investigated using QUENCHER-CUPRAC assay by using ethanol:distilled water and dimethyl sulfoxide:distilled water with varying ratios. To see the combined effect of solubilization (leaching) and TAC measurement of humic acids simultaneously, QUENCHER experiments were performed at 25°C and 50°C; QUENCHER-CUPRAC and QUENCHER-FC methods agreed well and had similar precision in F-statistics. Although the Gibbs free energy change (ΔG°) of the oxidation of HA dihydroxy phenols with the test reagents were negative, the ΔG° was positive only for the reaction of CUPRAC reagent with isolated monohydric phenols, showing CUPRAC selectivity toward polyphenolic antioxidants. This is the first work on the antioxidant capacity measurement of HA having a sparingly soluble matrix where enhanced solubilization of bound phenolics is achieved with coupled oxidation by TAC reagents.
Display omitted
•Humic acid antioxidant capacity (TAC) was determined by CUPRAC, FC, and nanoparticle methods.•QUENCHER extraction involving oxidation-coupled solubilization was effective for TAC measurement.•QUENCHER-FC and QUENCHER-CUPRAC methods agreed well and had similar precision.•Highest TAC in QUENCHER-CUPRAC was achieved by mixing DMSO or MeOH with 3-fold water.•This is the first report on simultaneous solubilization and TAC assay of insoluble humic matrix.
The Folin-Ciocalteu (FC) method is the most common method used for total phenolic content (TPC) determination, but in recent years, a more specific method that does not detect non-phenolic reducing ...compounds has been developed, the Fast Blue BB (FBBB) assay. In this study, the reference spectrophotometric methods have been adapted to a rising, simple, fast and low-cost technique (Digital Image Analysis, (DIA)) based assay while studying if the reaction time of both methods could be reduced and applied for the determination of TPC in food samples. Moreover, the interaction of ascorbic acid (AA) and fructose (F), with both reagents, has been observed.
Two linear methods were obtained by DIA with R2 values of 0.997 and 0.995, low detection limits (LOD), a precision and accuracy below 10%, and no statistically significant differences (p > 0.05) with the spectrophotometer. The reaction times were 60 and 30 min for FC and FBBB, respectively. The FC method required lower concentrations of AA and F to observe interactions in contrast to the FBBB, which did not exhibit any interactions with F. DIA has successfully been applied with both methods on a variety of drink samples, with results ranging from 10 to 600 mg GAE/g sample.
•The Fast Blue BB assay is better than Folin-Ciocalteu for polyphenol determination.•A combination of assays is useful for a better perspective on antioxidant capacity.•Digital Image Analysis (DIA), an alternative technique to UV–Vis spectrophotometry.•DIA shows major advantages regarding operation time and waste production.•Green and black tea, along with grape juice, have the highest phenolic content.
Chronic inflammation is associated with noncommunicable diseases, including obesity, metabolic syndrome (MetS), and CVDs. The Mediterranean diet has been shown to have strong anti-inflammatory ...effects, attributed in part to the polyphenol richness of many of its components.
This study aimed to assess the value of polyphenols as a urinary biomarker of an anti-inflammatory diet and their influence on MetS status.
A longitudinal analysis was performed in Spain considering 543 participants with high CVD risk in a PREDIMED study. Approximately 52% of the participants were women and 48% were men with a mean age of 67.5 (5.9) y. Total polyphenol excretion (TPE) in urine was determined at baseline and 5 y of intervention using a validated Folin–Ciocalteu spectrophotometric method, and the dietary inflammatory index (DII) was calculated from a validated 137-item food-frequency questionnaire. Three categories were built according to tertiles of change in the DII score. Multivariable linear regression analyses were performed to assess the association of changes in TPE with changes in the DII scores and with MetS status at 5 y.
Tertiles 2 and 3 compared with tertile 1 presented a lower anti-inflammatory potential of the diet and were inversely associated with TPE in women −0.30 mg gallic acid equivalent (GAE)/g creatinine; 95% CI: −0.46, −0.15; P value = 0.006 and −0.29 mg GAE/g creatinine; 95% CI: −0.43, −0.15; P value = 0.005, respectively. The mean changes in TPE were 7.9 (56.1) mg GAE/g creatinine in women and 7.7 (48.2) mg GAE/g creatinine in men. In addition, TPE was inversely associated with changes in MetS status −0.06 (−0.09; −0.02), P value = 0.009 in both men and women.
Urinary polyphenols may be a potential biomarker of anti-inflammatory diet consumption in women and are prospectively associated with improvement in MetS.
Polyphenols are natural phytochemicals recognized as one of the largest and most widespread classes of plant constituents occurring throughout the plant kingdom. Over the years, polyphenols have ...attracted the attention of the scientific community due to their potential health-promoting effects. Owing to their several interesting properties, polyphenols have aroused considerable interest, shedding light on their chemistry, reactivity, biological properties and their beneficial effects on both plants and humans. As a result of these investigations, a huge number of research works have been reported on polyphenols. However, despite the voluminous literature studying polyphenols and their impact on human health, there are still many issues waiting to be explored in order to explain and elucidate the positive effects of polyphenols on human health. This Special Issue was intended to gather up-to-date knowledge related to the cutting-edge research in the broad scientific area of polyphenols, providing an opportunity to show the latest advances in the exploration of polyphenols and their health beneficial effects. The special issue was a great success with more than 50 published manuscripts covering various aspects related to polyphenols and their role in human health. We are confident that this Special Issue will be of great interest to the scientific community, and will contribute to the improvement of knowledge regarding the area of polyphenols, leading to a better understanding of their role in human health.
Measuring the total phenolic content in wine is important in estimating the taste and health benefits of wine. We developed an automatic Folin–Ciocalteu (F‐C) method to reduce processing times ...(3 min), human errors and waste volume as compared it to the manual method. The gallic acid standard responded linearly up to 5000 μg mL⁻¹, and the wine dilution series responded linearly between four‐ and sixteenfold dilutions. Anthocyanins showed slower reaction rate compared with wine, gallic acid and quercetin, while ascorbic acid showed the fastest rate. Fructose and glucose at the 10% level showed approximately 8% interference in port wines, and the interference was thought to be negligible in most dry wines containing <1% sugar. Total phenolic contents ranged between 1600 and 3300 μg mL⁻¹ by the automatic method and were approximately 20% less than those by the manual method, except in pink wines which was nearly identical. The regression analysis of the phenolic contents showed a very linear relationship between the methods (r² = 0.97***). This automatic method was thought to be efficiently adopted in wine testing laboratories as a fast and reproducible assay.
The widely used methodology to quantify polyphenols—the Folin-Ciocalteu (FC) method—cannot be applied indiscriminately since different matrices may impair the assay’s accuracy. Thus, this study aimed ...to adapt the FC method for the açaí seed extract, a tannin-rich extract with potential applications for various therapies. Firstly, a pre-method standardization was established to determine parameters such as reading wavelength (765 nm), reaction time (30 min), and the reference substance (pyrogallol). In the validation step, the adapted method responded linearly to the analyte (R
2
= 0.9910), ensuring its selectivity (linearity and selectivity curves statistically parallel) and accuracy (99.18–101.43%). Furthermore, the method proved to be precise (RSD ≤ 2.63%) at the two levels assessed (repeatability and intermediate precision) and robust (RSD ≤ 4.45%) concerning variation on the Na
2
CO
3
concentration and the reaction time. The limits of detection and quantification were also calculated (9.9 µg/mL and 33.1 µg/mL, respectively). An additional step for tannins quantification based on its reported selective precipitation by complexing agents was also evaluated; however, unspecific precipitation was observed, reducing the results’ accuracy. Our work successfully adapted and validated a method for total phenolics quantification of açaí seed extract, resulting in 38 g of pyrogallol equivalent/100 g of extract.
Graphic abstract
•The work give insight to the literature about the antioxidant and phenolic contents of Tilia cordata fruit extracts.•The efficiency of traditional hot water infusion was compared to the ...ultrasound-assisted extraction technique.•Fruit extracts of Tilia cordata were screened for their total phenolic contents and total antioxidant capacities.•Individual phenolic compounds were determined quantitatively by LC–MS/MS in Tilia cordata fruit extracts.
Herbal infusions are a common practice among people. Making a hot water infusion is the simplest way to extract the medicinal properties of a plant. One of the most frequently used plants for this purpose is linden. Antioxidants (especially phenolic compounds) may also enhance the immune system and reduce the risk of cancer and infections such as colds, a frequent medicinal use for this species. In this work, ultrasound-assisted extraction (UAE) method and infusion extraction (IE) technique using only water as the extractant were carried out comparatively for the extraction of phenolic compounds from Tilia cordata fruits to evaluate the efficiency of the hot water infusion technique. Both extracts obtained with IE and UAE techniques were initially screened for their total phenolic contents (TPCs) and total antioxidant capacities (TACs) via Folin-Ciocalteu and CUPRAC methods, respectively. TPCs of the extracts obtained with IE and UAE were found as 58.86 ± 21.51 and 111.84 ± 13.99 mg gallic acid equivalent (GAE)/g dry sample, respectively. Furthermore, TACs of the extracts obtained with IE and UAE were calculated as 82.99 ± 13.13 and 197.52 ± 12.69 mg trolox equivalent (TE)/g dry sample, respectively. Subsequently, 31 phenolic compounds in the same extracts were scanned by liquid chromatography-electrospray tandem mass spectrometry (LC–MS/MS) method. Among phenolics, 24 compounds were quantitatively determined with protocatechuic acid as the dominant one (1723.1–2183.5 μg/g dry sample). Consequently, the traditional hot water infusion which can be easily applied at home was considered to be a comparatively effective method for the extraction of phenolic compounds from Tilia cordata fruits.
Edible insects have the potential to become one of the major future foods. In fact, they can be considered cheap, highly nutritious, and healthy food sources. International agencies, such as the Food ...and Agriculture Organization (FAO), have focused their attention on the consumption of edible insects, in particular, regarding their nutritional value and possible biological, toxicological, and allergenic risks, wishing the development of analytical methods to verify the authenticity, quality, and safety of insect-based products. Edible insects are rich in proteins, fats, fiber, vitamins, and minerals but also seem to contain large amounts of polyphenols able to have a key role in specific bioactivities. Therefore, this review is an overview of the potential of edible insects as a source of bioactive compounds, such as polyphenols, that can be a function of diet but also related to insect chemical defense. Currently, insect phenolic compounds have mostly been assayed for their antioxidant bioactivity; however, they also exert other activities, such as anti-inflammatory and anticancer activity, antityrosinase, antigenotoxic, and pancreatic lipase inhibitory activities.
