Elixabet Díaz-de-Cerio

Use of HPLC- and GC-QTOF to determine hydrophilic and lipophilic phenols in mango fruit (Mangifera indica L.) and its by-products

Mango industry processing generates high quantities of mango by-products such as peels and seeds (35%-60% of the fruit). Indeed, it is known that mango and its by-products contain different families of bioactive compounds that possess several health benefits. Thus, the aim of this study has been the determination of different families of phenolic derivatives (free and bound phenolic compounds and alk(en)ylresorcinols (ARs)) in mango edible part and its by-products (peel, seed and seed husk) from three different cultivars. This is the first study that evaluates the phenolic compounds and ARs in the four fractions of mango of three different cultivars. Special attention has been paid to the determination of anthocyanins and ARs, because these families of compounds had not been studied in depth in mango. In fact, petunidin rutinoside-(p-coumaric acid) gallate was found in mango pulp, peel, seed and seed husk of the three cultivars and, it had never been described in mango before. It is also important to highlight that this is the first time that the identification and quantification of ARs have been performed in mango seed and seed husk; besides, four and five out of eleven alk(en)ylresorcinols detected in peel and pulp, respectively, were identified for the first time in these mango fractions. Furthermore, antioxidant activity was measured by ABTS and FRAP assays. Seed free and bound phenolic extracts showed the highest antioxidant capacity.

Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.

The hypoglycemic effects of guava leaf (Psidium guajava L.) extract are associated with improving endothelial dysfunction in mice with diet-induced obesity

Obesity is associated with a low-grade inflammatory status that affects vascular function. Previous studies have reported the beneficial effects of Psidium guajava L. (guava) on diabetes. Here we evaluate the how guava leaf extract at the dose of 5 mg/kg, affects vascular dysfunction in obese mice fed a high-fat diet for 7 weeks. Extract intake did not alter weight over time, although it reduced glycemia and insulin resistance, improving the serum lipid profile in obese mice. Additionally, guava leaf extract reversed the endothelial dysfunction found in obese mice in terms of endothelium- and NO (nitric oxide)-dependent vasodilatation induced by acetylcholine in aortic rings. In conclusion, the beneficial effects of guava leaf extract in obese mice were associated with improved vascular functions altered by obesity, probably due to its phenolic content.

Health Effects of Psidium guajava L. Leaves: An Overview of the Last Decade

Today, there is increasing interest in discovering new bioactive compounds derived from ethnomedicine. Preparations of guava (Psidium guajava L.) leaves have traditionally been used to manage several diseases. The pharmacological research in vitro as well as in vivo has been widely used to demonstrate the potential of the extracts from the leaves for the co-treatment of different ailments with high prevalence worldwide, upholding the traditional medicine in cases such as diabetes mellitus, cardiovascular diseases, cancer, and parasitic infections. Moreover, the biological activity has been attributed to the bioactive composition of the leaves, to some specific phytochemical subclasses, or even to individual compounds. Phenolic compounds in guava leaves have been credited with regulating blood-glucose levels. Thus, the aim of the present review was to compile results from in vitro and in vivo studies carried out with guava leaves over the last decade, relating the effects to their clinical applications in order to focus further research for finding individual bioactive compounds. Some food applications (guava tea and supplementary feed for aquaculture) and some clinical, in vitro, and in vivo outcomes are also included.

Determination of Polar Compounds in Guava Leaves Infusions and Ultrasound Aqueous Extract by HPLC-ESI-MS

Literature lacks publications about polar compounds content in infusion or guava leaves tea. Because of that, a comparison between different times of infusion and a conventional ultrasound aqueous extract was carried out. Several polar compounds have been identified by HPLC-ESI-MS and their antioxidant activity was evaluated by FRAP and ABTS assays. Four different classes of phenolic compounds (gallic and ellagic acid derivatives, flavonols, flavanones, and flavan-3-ols) and some benzophenones were determined. The quantification results reported that the order, in terms of concentration of the classes of polar compounds in all samples, was flavonols > flavan-3-ols > gallic and ellagic acid derivatives > benzophenones > flavanones. As expected, the aqueous extract obtained by sonication showed the highest content in the compounds studied. Significative differences were noticed about the different times of infusion and five minutes was the optimal time to obtain the highest content in polar compounds using this culinary method. All the identified compounds, except HHDP isomers and naringenin, were positively correlated with antioxidant activity.

Psidium guajava L. leaves as source of proanthocyanidins: Optimization of the extraction method by RSM and study of the degree of polymerization by NP-HPLC-FLD-ESI-MS.

HIGHLIGHTSUltrasound extraction of proanthocyanidins from Psidium guajava was established.Best conditions: 50% acetone/water (v/v), 48 °C, 30 min, and 0% acetic acid (v/v).Low oxidized guava leaves reported the greatest procyanidin content by NP‐HPLC‐FLD.High degree of polymerization (DP1‐DP13) has been found in guava leaves. ABSTRACT Due to the importance of the proanthocyanidins (PAs) bioactivity and its relationship with the PAs degree of polymerization (DP), an experimental design was carried out to establish the best extraction conditions in order to evaluate the proanthocyanidins content and their degree of polymerization in Psidium guajava leaves at different oxidation state. Optimal conditions achieved by response surface methodology were 50% acetone/water (v/v), 48 °C, 30 min, and 0% acetic acid (v/v). The highest DP has been found in the low oxidized state (DP 13 plus the polymers). Medium and high oxidized state leaves reported a DP 11 plus the polymers. The total amounts of proanthocyanidins (sum of PAs by HPLC‐FLD‐ESI‐MS) decreased when oxidation state of leaves increased (15.8 ± 0.4, 12.6 ± 0.4, and 10.5 ± 0.3 mg/g leaf dry weight (d.w.) in low, medium and high oxidized state leaves, respectively). Guava leaves present an interesting source of low DP‐PAs.

Establishment of ultrasound-assisted extraction of phenolic compounds from industrial potato by-products using response surface methodology

Potato processing generates large amounts of by-products, which include potato peels and the outer layers of flesh, which contain phenolic compounds. The purpose of this study was to establish an extraction method for phenolic compounds from industrial potato by-products by using response surface methodology (RSM). Box-Behnken design (BBD) was performed to optimize the extraction conditions of phenolic compounds considering different extraction temperature, ratios of ethanol/water, time of extraction and sample/solvent ratio. The optimum extraction conditions were obtained with ethanol/water 55/45 (v/v) by ultrasound bath during 35 min at 35 °C and 1/10 sample/solvent ratio. The best conditions were applied to determine the phenolic content in five potato by-products. The analyses by HPLC-DAD-ESI-MS showed that chlorogenic acid accounted for a 49.3-61% of the total phenolic compounds. Positive Pearson correlations between HPLC data and antioxidant activity confirmed that the phenolic compounds had significant antioxidant properties.