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A hydroxytyrosol (HTyr)-enriched fraction containing HTyr 6% w/w, derived from Olea europaea L. byproducts and obtained using an environmentally and economically sustainable technology, was lipophilized under green chemistry conditions. The effects of three fractions containing hydroxytyrosyl butanoate, octanoate, and oleate, named, respectively, lipophilic fractions 5, 6, and 7, and unreacted HTyr on the human colon cancer cell line HCT8-β8 engineered to overexpress estrogen receptor β (ERβ) were evaluated and compared to those of pure HTyr. The experimental data demonstrated that HTyr and all fractions showed an antiproliferative effect, as had been observed by the evaluation of the cellular doubling time under these different conditions (mean control, 32 ± 4 h; HTyr 1, 65 ± 9 h; fraction 5, 64 ± 11 h; fraction 6, 62 ± 14 h; fraction 7, 133 ± 30 h). As evidenced, fraction 7 containing hydroxytyrosyl oleate showed the highest activity. These results were related to the link with ER-β, which was assessed through simultaneous treatment with an inhibitor of ERβ.

Polyphenols are widespread in vegetables and fruits. They can play an important role in human diet and health, and they influence the sensorial properties of many foods, and act as natural antioxidants. This study was conducted using HPLC/DAD, tyrosinase biosensor, and differential pulse voltammetry (DPV) analyses to detect polyphenolic compounds in natural complex matrices. The analyses were applied to a series of both standards and natural extracts derived from grape, olives, and green tea. The pure compounds include phenolic acids, flavones, flavonols, catechins, tannins, and oleuropein. HPLC/DAD, DPV, and the biosensor approach were used as independent analytical techniques. Bare graphite screen-printed electrodes were employed in DPV and in the biosensor analysis. The most accurate data were obtained by HPLC/DAD analysis, while the DPV approach using screen-printed electrodes could represent a quick screening method for the determination of polyphenols in natural extracts. Use of the biosensor for the analysis of complex matrices needs further study in order to improve its performance.

Anthocyanins (Anths) in olive (Olea europaea L.) fruits at different degrees of pigmentation were assessed nondestructively by measuring chlorophyll fluorescence (ChlF). The method is based on the comparison of the ChlF excitation spectra from olives with different pigmentation from green to green-red, reddish-purple, and purple. The logarithm of the ratio between the fluorescence excitation spectra (logFER) from two different colored zones gave the difference in the absorption spectrum between them. The absorbance spectrum derived from the logFER between a red olive and the same olive devoid of the skin showed the typical Anth green band (at 550 nm). It matched that recorded by microspectrophotometry on a single pulp cell and the in vitro absorbance spectrum of the olive skin extract. As expected, the in vivo Anths absorption maximum increased in intensity going from less to more mature olives and was higher in the sun-exposed olive side with respect to the sun-shaded side. Absolute quantitative nondestructive determination of Anths for each olive sample was obtained by the logFER calculated for two excitation wavelengths, 550 and 625 nm, of ChlF at 740 nm. Going from green to purple skin colors, the Log[ChlF(625)/ChlF(550)] was fairly well-correlated to the extract Anths concentration. Finally, the relationship between the Anths and the other main phenolics present in the olives analyzed by high-performance liquid chromatography was evaluated. The main result was a net increase of verbascoside with increasing Anths content. On the basis of our results, the development of a new rapid and noninvasive method for the monitoring of olive development and ripening can be envisaged.

The production of olive oil yields a considerable amount of waste water, which is a powerful pollutant and is currently discarded. Polyphenols and other natural antioxidants, extracted from olives during oil extraction process, partially end up in the waste waters. Experimental and commercial olive oil waste waters from four Mediterranean countries were analyzed for a possible recovering of these biologically interesting constituents. Identification and quantitation of the main polyphenols were carried out by applying HPLC-DAD and HPLC-MS methods. Representative samples of ripe olives were also analyzed at the same time to correlate, if possible, their polyphenolic profiles with those of the corresponding olive oil waste waters. The results demonstrate that Italian commercial olive oil waste waters were the richest in total polyphenolic compounds with amounts between 150 and 400 mg/100 mL of waste waters. These raw, as yet unused, matrices could represent an interesting and alternative source of biologically active polyphenols.

In this study polyphenolic compounds extracted from olive fruits of five registered cultivars were analyzed. A solid-liquid extraction (LSE) procedure with Extrelut cartridge (diatomaceous earth) using different eluents was developed to obtain polyphenolic compounds. HPLC-DAD and HPLC-MS methods were applied for the quali-quantitative analysis of each fraction obtained from LSE. The results of this work show that the LSE procedure with diatomaceous earth cartridge supplies a rapid and reproducible fractioning method able to obtain a quantitative recovery of all compounds and to collect fractions directly analyzed by HPLC. A comparison among different cultivars shows significant quantitative differences in some polyphenols, such as verbascoside, anthocyanic compounds, and oleuropein derivatives.