Comparative polyphenolic profiling of five ethnomedicinal plants and their applicative potential in the treatment of type 2 diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

The medicinal plants Salvia officinalis, Trifolium pratense, Agrimonia eupatoria, Cichorium intybus and Vinca minor are traditionally used for the prevention and treatment of numerous diseases, including diabetes.

AIM OF THE STUDY

Type 2 diabetes (T2D) is one of the most common diseases nowadays, often accompanied by oxidative stress and microbial infections. The aim of our work was to examine the antidiabetic, antioxidant, and antimicrobial properties of ethanol extracts of five medicinal plants for the purpose of their possible use in the treatment of T2D.

MATERIALS AND METHODS

The polyphenolic profile of the plant extracts was analyzed by Ultra-High Performance Liquid Chromatography with a diode array detector configured with a triple quadrupole mass spectrometer (UHPLC/DAD/(-)HESI-MS2). In vitro antidiabetic activity of extracts was determined by measuring the percentage of α-amylase and α-glucosidase inhibition. The antioxidant activity of the extract was determined by different spectrophotometric methods, while the antimicrobial activity was determined by agar dilution and disc diffusion methods.

RESULTS

A. eupatoria extract contains the highest percentage of flavonoids (94%, with isoquercetin, vitexin, and rutin as the most abundant) in relation to the concentration of total phenolic compounds and exhibits excellent antidiabetic, antioxidant, and antimicrobial activity. S. officinalis extract contains 60% flavonoids (predominately cirsimaritin and epigallocatechin gallate) and 40% phenolic acids (with rosmarinic acid being the most abundant from this group) and exhibits weak antidiabetic activity, significant antioxidant activity, and excellent antibacterial activity. A 45% percentage of flavonoids (with isoquercetin as the most abundant one) and 55% of phenolic acids (with ferulic acid as the most abundant) were measured in the extract of T. pratense, which had excellent antidiabetic activity but weaker antioxidant and antimicrobial activity. A similar percentage of flavonoids (52%, with epigallocatechin gallate in the highest concentration) and phenolic acids (48%, with chlorogenic acid as the most abundant) was measured in the extract of C. intybus which showed moderate antidiabetic, antioxidant, and antimicrobial properties. The extract of V. minor was the richest in phenolic acids (80%, with the most abundant chlorogenic acid), which resulted in weaker antidiabetic and antioxidant activities (except for Fe2+ chelating ability) and antimicrobial activity.

CONCLUSION

The results indicate that specific phenolic compounds are responsible for the different biological activities of the plant extracts. Among the investigated plants, the extract of A. eupatoria has the greatest potential for applications in the treatment of T2D.

Mead fermentation parameters: Optimization by response surface methodology

Introduction. This article presents the development of mathematical models related to the effect of the initial content of dry matter, yeast, and yeast energizer on the fermentation rate, the alcohol content, and the dry matter content in the finished product – mead. Study objects and methods. The mathematical models were developed by using the response surface methodology (RSM). The effect of yeast, dry matter, and yeast energizer contents were tested in concentration ranges of 150–600 mg/L, 16.3–24.4%, and 140–500 mg/L, respectively. The starting substrates used were honeydew honey and 10% apple juice. Yeast was rehydrated and added in different amounts to obtain required concentrations. Initial dry matter concentrations were measured by a refractometer. At the end of fermentation, oenological parameters of mead, namely dry matter content, pH, and ethanol yield, were determined according to standard methods. Results and discussion. The statistical estimation of the developed models and the individual model parameters showed that the initial dry matter content had a significant effect on the content of alcohol and dry matter in the final product. While, the initial content of yeast and yeast energizer did not have a significant effect in the tested concentration ranges. In addition, it was proved that the initial content of dry matter and yeast energizer had a significant effect on the fermentation rate, i.e. on the course of fermentation, which was described by a second-degree polynomial. Conclusion. We determined the optimum content of dry matter (24.4%), amount of yeast (150 mg/L), and concentration of yeast energizer (140 mg/L) in the initial raw material which provided the maximum alcohol yield at a consistent fermentation rate.

Changes in the physicochemical, antioxidant and antibacterial properties of honeydew honey subjected to heat and ultrasound pretreatments

The objective of this study was to examine the effect of different treatments on the physicochemical, antioxidant, and antibacterial properties of honeydew honey. Honeydew honey was subjected to heat treatment and 9 different ultrasound treatments. Our results showed that the following parameters were significantly changed: water content, pH, electrical conductivity, diastase activity, HMF content and water activity. The ultrasound resulted in an increase in the total phenol content and the antioxidant capacity (DPPH, FRAP, and ABTS tests) in comparison with the conventional thermal technique. In most cases, the samples subjected to ultrasound improved the antibacterial activity; the heat treatment resulted in a significant reduction of the antibacterial activity, and sample 4 (ultrasound 30 °C, 5 min) showed the best antibacterial activity. The ultrasound treatment, especially at lower temperatures, represents a technique that enables the preservation and improvement of the biological properties of honeydew honey.

Influence of blackberry juice addition on mead fermentation and quality

Introduction. Mead, one of the oldest alcoholic beverages that man consumed is obtained by fermentation of honey solution, and contains from 8 to 18% vol. ethanol. Honey can be considered as an excellent source of carbohydrates for the fermentation process, but low concentrations of other substances in the honey can slow down the process. Blackberry (Rubus fruticosus L.) contains dietary fibers, vitamin C (ascorbic acid), vitamin A, vitamin E, potassium and calcium, along with the phenolic metabolites that are a source of possible health benefits. Study objects and methods. In this study was investigated the influence of blackberry juice addition on mead fermentation process, chemical composition and antioxidative activity. Dynamics of the fermentation process were controlled based on weighing the flasks in time on a scale every 24 h throughout the alcoholic fermentation. At the end of fermentations, oenological parameters of mead: dry matter content, pH, volatile acidity and ethanol content and reducing sugars. For the determination of antioxidative capacity the content of total phenolics, total flavonoids and total flavonols were measured and two tests were performed: DPPH and ABTS. Results and discussion. Addition of blackberry juice had a positive effect on fermentation dynamics (almost 25% higher rate of fermentation than in control samples), and improved all physicochemical characteristics and composition of resultant meads. Also, meads with the addition of blackberry juice had a significantly higher concentration of total phenolics, total flavonoids and total flavonols and significantly stronger antioxidative properties compared to the control meads without juice addition. The highest total phenolics, total flavonoids and total flavonols content was determined in the mead with the maximum addition of blackberry juice (B20W): it reached 490.88, 50.34 and 62.57 μgQE.mL–1, respectively, and was 6-fold higher for total phenolics and total flavonoids content, and 10-fold higher for total flavonols content than in the mead without juice addition (CW). The strongest antioxidative activity was determined in the B10W mead; it accounted for 6.98 μgTE.mL–1 (DPPH assay) and 0.65 μgTE.mL–1 (ABTS assay), what was 1.5-fold and 3-fold higher, respectively, than in the mead without juice addition (CW). Conclusion. The conducted study demonstrated that the use of blackberry juice influenced the course of fermentation of meads as well as their physicochemical and antioxidative properties (positive effect on fermentation dynamics – almost 25% higher rate of fermentation than in control samples, and improvement of all physicochemical characteristics and composition of resultant meads).

Effects of non-meat proteins on the quality of fermented sausages

Introduction. Non-meat proteins are widely used in meat processing. In our study, we analyzed the effects of whey and soy protein isolates on the physicochemical and sensory properties of domestic fermented sausage. Study objects and methods. Five groups of sausages were traditionally fermented under industrial conditions. The sausage group without the additives was labelled the control, while other sausages were manufactured with the addition of 0.5% and 1.5% protein isolates of whey and soybean. Using a quantitative descriptive test, we assessed the sensory characteristics of the sausages and instrumentally determined their color, hardness, water activity (aw), and pH. Results and discussion. The proteins added to fermented sausages improved emulsification, texture, as well as water and fat binding capacity, which was confirmed by the results for hardness. Using a 0.5% soy protein isolate resulted in a firmer product. The additives had a minor effect on the color: the samples with the additives had a slightly lower L* value, and those with a soy protein had higher yellowness (b*). Conclusion. Using the additives did not have a significant effect on the chemical composition and overall sensory quality of all tested samples (P > 0.05).