Effect of olive leaf phytochemicals on the anti-acetylcholinesterase, anti-cyclooxygenase-2 and ferric reducing antioxidant capacity.

In this study, the phytochemical profile of fifty olive leaves (OL) extracts from Spain, Italy, Greece, Portugal, and Morocco was characterized and their anti-cholinergic, anti-inflammatory, and antioxidant activities were evaluated. Luteolin-7-O-glucoside, isoharmnentin, and apigenin were involved in the acetylcholinesterase (AChE) inhibitory activity, while oleuropein and hydroxytyrosol showed noteworthy potential. Secoiridoids contributed to the cyclooxygenase-2 inhibitory activity and antioxidant capacity. Compounds such as oleuropein, ligstroside and luteolin-7-O-glucoside, may exert an important role in the ferric reducing antioxidant capacity. It should be also highlighted the role of hydroxytyrosol, hydroxycoumarins, and verbascoside concerning the antioxidant activity. This research provides valuable insights and confirms that specific compounds within OL extracts contribute to distinct anti-cholinergic, anti-inflammatory, and anti-oxidative effects.

Exploring the Antioxidant, Neuroprotective, and Anti-Inflammatory Potential of Olive Leaf Extracts from Spain, Portugal, Greece, and Italy.

The leaves of the olive tree (Olea europaea L.) are one of the major solid wastes from the olive industry. Globally, the European Union is the largest producer of olive by-products, with Spain, Italy, Greece, and Portugal accounting for almost the entire production. Many questions remain to be solved concerning olive leaves (OL), including those related to possible differences in composition and/or biological activities depending on their geographical origin. In the present work, OL from Spain, Italy, Greece, and Portugal have been characterized according to their phytochemical profile, antioxidant capacity, neuroprotective activity, and anti-inflammatory effects. The Spanish and Italian OL samples presented the highest antioxidant and neuroprotective activities, while the Greek OL showed the lowest. These results were strongly associated with the content of oleoside methyl ester and p-hydroxybenzoic acid for the Spanish and Italian samples, respectively, whereas the content of decarboxymethyl elenolic acid dialdehyde form (hydrated) was negatively associated with the mentioned biological activities of the Greek samples. No country-related effect was observed in the anti-inflammatory activity of OL. Comprehensively, this work could provide a useful tool for manufacturers and R&D departments in making environmentally friendly decisions on how OL can be used to generate nutraceutical products based on the composition and origin of this by-product.

Ethanol and xylitol production by fermentation of acid hydrolysate from olive pruning with Candida tropicalis NBRC 0618.

Olive tree pruning biomass has been pretreated with pressurized steam, hydrolysed with hydrochloric acid, conditioned and afterwards fermented using the non-traditional yeast Candida tropicalis NBRC 0618. The main aim of this study was to analyse the influence of acid concentration on the hydrolysis process and its effect on the subsequent fermentation to produce ethanol and xylitol. From the results, it could be deduced that both total sugars and d-glucose recovery were enhanced by increasing the acid concentration tested; almost the whole hemicellulose fraction was hydrolysed when 3.77% was used. It has been observed a sequential production first of ethanol, from d-glucose, and then xylitol from d-xylose. The overall ethanol and xylitol yields ranged from 0.27 to 0.38kgkg(-1), and 0.12 to 0.23kgkg(-1) respectively, reaching the highest values in the fermentation of the hydrolysates obtained with hydrochloric acid 2.61% and 1.11%, respectively.

Monomeric carbohydrates production from olive tree pruning biomass: modeling of dilute acid hydrolysis.

Statistical modeling and optimization of dilute sulfuric acid hydrolysis of olive tree pruning biomass has been performed using response surface methodology. Central composite rotatable design was applied to assess the effect of acid concentration, reaction time and temperature on efficiency and selectivity of hemicellulosic monomeric carbohydrates to d-xylose. Second-order polynomial model was fitted to experimental data to find the optimum reaction conditions by multiple regression analysis. The monomeric d-xylose recovery 85% (as predicted by the model) was achieved under optimized hydrolysis conditions (1.27% acid concentration, 96.5°C and 138 min), confirming the high validity of the developed model. The content of d-glucose (8.3%) and monosaccharide degradation products (0.1% furfural and 0.04% 5-hydroxymethylfurfural) provided a high quality subtract, ready for subsequent biochemical conversion to value-added products.

Oligosaccharides and monomeric carbohydrates production from olive tree pruning biomass.

Using the severity factor, it has been possible to study cellulose and hemicellulose fractional conversion, sugar yields change and oligosaccharides variation through olive tree pruning biomass pretreatments with acid or liquid hot water under pressure. The temperatures tested were in the range 180-230°C, operation time varying between 0 and 30min and acid concentration used did not exceed 0.05M. Complete hemicellulose solubilization in autohydrolysis was achieved using severity factors (logR0) close to 3.9 (most sugars are like oligomers), while if sulfuric acid 0.025M is employed, this parameter could be smaller (≥3.4). With these treatments, we have obtained cellulose conversions between 30 and 42% from liquid hot water experiments, 40-51% with sulfuric acid 0.025M and 42-57% when the acid concentration was 0.05M. The best results in terms of maximum yield in total sugars, d-glucose and d-xylose, with a low amount of acetic acid and hydroxymethylfurfural, was obtained at 200°C, 0min (what means that there is no time of temperature maintenance, only heating and cooling) and H2SO4 0.025M.