Citrus sinensis (orange) by-products represent one of the most abundant citric residues from orange juice industrial production, and a promising source of health-promoting compounds like terpenes. In this work, different...

The neuroprotective potential of 32 natural extracts obtained from olive oil by-products was investigated. The online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption allowed the selective enrichment of olive leaves extracts in different terpenoids’ families. Seven commercial adsorbents based on silica gel, zeolite, aluminum oxide, and sea sand were used with SFE at three different extraction times to evaluate their selectivity towards different terpene families. Collected fractions were analyzed by gas chromatography coupled to quadrupole-time-of-flight mass spectrometry (GC-QTOF-MS) to quantify the recoveries of monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), and triterpenes (C30). A systematic analysis of the neuroprotective activity of the natural extracts was then carried out. Thus, a set of in vitro bioactivity assays including enzymatic (acetylcholinesterase (AChE), butyrylcholinesterase (BChE)), and anti-inflammatory (lipoxidase (LOX)), as well as antioxidant (ABTS), and reactive oxygen and nitrogen species (ROS and RNS, respectively) activity tests were applied to screen for the neuroprotective potential of these extracts. Statistical analysis showed that olive leaves adsorbates from SS exhibited the highest biological activity potential in terms of neuroprotective effect. Blood–brain barrier permeation and cytotoxicity in HK-2 cells and human THP-1 monocytes were studied for the selected olive leaves fraction corroborating its potential.

Natural carotenoids from microalgae have raised a huge interest for their potential health benefits. Among microalgae species with high carotenoid content, Dunaliella salina has been highlighted since it is able to accumulate relatively high amounts of β-carotene and other carotenoids of industrial interest when grown under specific conditions. In the present contribution, extractions based on carbon dioxide under sub-and supercritical conditions have been optimized to improve the recovery of carotenoids and extracts purity from D. salina. An experimental design was employed to investigate the effect of pressure and temperature variations ranging from 250 to 400 bar and from 15 to 45 °C, respectively. The chemical characterization of the carotenoids extracts was carried out by HPLC-DAD. Moreover, inhibition of the acetylcholinesterase activity of all the extracts was measured by using a recently developed in-vitro fluorescence methodology. High carotenoid yield and purity were obtained at 302-313 bar and 45 °C. Nine carotenoids were identified and three other compounds were recognized as carotenoids and quantified. Acetylcholinesterase activity inhibition could be satisfactorily explained by a partial least-square model (63% explained variance in cross-validation) built considering the chemical composition of the different extracts. The model indicates a positive effect of lutein, 15-cis-β-carotene and the negative effect of zeaxanthin, cryptoxanthin and the ratio 9-cis-β-carotene/all-trans-β-carotene and 9-cis-β-carotene/total carotenoids in the inhibition of acetylcholinesterase enzyme.

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Tamarillo (Cyphomandra betacea (Cav.) Sendt.), or tree tomato, is a tropical fruit from the Andean region of South America; it is highly rich in vitamins, minerals, and polyphenolic compounds. In this study, extracts from tamarillo epicarp (TE) were obtained by pressurized liquid extraction (PLE), and their in-vitro neuroprotective potential was assessed. A central composite design with response surface methodology was performed to optimize PLE as a function of solvent composition and temperature. Selected response variables were extraction yield, total phenolic content (TPC), total flavonoid content (TFC), total carotenoid content (TCC), antioxidant (ABTS), and anti-inflammatory (LOX) activities, and anti-acetylcholinesterase (AChE) inhibitory capacity. According to the desirability function, the optimal conditions were 100% ethanol and 180°C with a 0.87 desirability value. Next, the anti-butyrylcholinesterase enzyme (BChE), reactive oxygen species (ROS), and reactive nitrogen species (RNS) inhibition as well as cytotoxicity in HK-2, THP-1 monocytes, and SH-5YSY neuroblastoma cell lines were studied for the TE extract obtained under optimized conditions. The optimum TE extract provided the following results: extraction yield (36.25%), TPC (92.09 mg GAE/g extract), TFC (4.4 mg QE/g extract), TCC (107.15 mg CE/g extract), antioxidant capacity (ABTS, IC50 = 6.33 mg/ml extract), LOX (IC50 = 48.3 mg/ml extract), and AChE (IC50 = 97.46 mg/ml extract), and showed no toxicity at concentration up to 120 μg/ml extract for all the tested cell lines. Finally, chemical characterization by liquid chromatography-tandem mass spectrometry (UHPLC-q-TOF-MS/MS) of the optimum TE extract exhibited an important presence of hydroxycinnamic acid derivatives and other phenolic acids as well as quercetin hexoside and rutin, as main metabolites responsible for the observed biological properties. All these results suggested that TE, which represents between 8 and 15% of the total fruit, could become a promising natural by-product with a potential “multitarget” activity against Alzheimer's disease.

Plants and agri-food by-products represent a wide and renewable source of bioactive compounds with neuroprotective properties. In this research, various green extraction techniques were employed to recover bioactive molecules from Kalanchoe daigremontiana (kalanchoe), epicarp of Cyphomandra betacea (tamarillo), and cooperage woods from Robinia pseudoacacia (acacia) and Nothofagus pumilio (lenga), as well as a reference extract (positive control) from Rosmarinus officinalis L. (rosemary). The neuroprotective capacity of these plant extracts was evaluated in a set of in vitro assays, including enzymatic [acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and lipoxygenase (LOX)] and antioxidant [ABTS, and reactive oxygen and nitrogen species (ROS and RNS)] bioactivity tests. Extracts were also submitted to a parallel artificial membrane permeability assay mimicking the blood–brain barrier (PAMPA-BBB) and to two cell viability assays in HK-2 and SH-SY5Y cell lines. Comprehensive phytochemical profiling based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-Q-TOF-MS) analysis showed enriched content of phenolic and terpenoid compounds in the target extracts. Moreover, in vitro bioactivity tests showed promising neuroprotective capacity, particularly for supercritical-fluid extraction (SFE) extract from acacia (ABTS IC50 = 0.11 μg ml−1; ROS IC50 = 1.56 μg ml−1; AChE IC50 = 4.23 μg ml−1; BChE IC50 = 1.20 μg ml−1; and LOX IC50 = 4.37 μg ml−1), whereas PAMPA-BBB assays revealed high perfusion capacity of some representative compounds, such as phenolic acids or flavonoids. Regarding cytotoxic assays, tamarillo and rosemary SFE extracts can be considered as non-toxic, acacia SFE extract and lenga pressurized liquid extraction (PLE) extract as mild-cytotoxic, and kalanchoe as highly toxic extracts. The obtained results demonstrate the great potential of the studied biomass extracts to be transformed into valuable food additives, food supplements, or nutraceuticals with promising neuroprotective properties.

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Alzheimer’s disease (AD) is the most common form of dementia caused by a progressive loss of neurons from different regions of the brain. This multifactorial pathophysiology has been widely characterized by neuroinflammation, extensive oxidative damage, synaptic loss, and neuronal cell death. In this sense, the design of multi-target strategies to prevent or delay its progression is a challenging goal. In the present work, different in vitro assays including antioxidant, anti-inflammatory, and anti-cholinergic activities of a carotenoid-enriched extract from Dunaliella salina microalgae obtained by supercritical fluid extraction are studied. Moreover, its potential neuroprotective effect in the human neuron-like SH-SY5Y cell model against remarkable hallmarks of AD was also evaluated. In parallel, a comprehensive metabolomics study based on the use of charged-surface hybrid chromatography (CSH) and hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution tandem mass spectrometry (Q-TOF MS/MS) was applied to evaluate the effects of the extract on the metabolism of the treated cells. The use of advanced bioinformatics and statistical tools allowed the identification of more than 314 metabolites in SH-SY5Y cells, of which a great number of phosphatidylcholines, triacylglycerols, and fatty acids were significantly increased, while several phosphatidylglycerols were decreased, compared to controls. These lipidomic changes in cells along with the possible role exerted by carotenoids and other minor compounds on the cell membrane might explain the observed neuroprotective effect of the D. salina extract. However, future experiments using in vivo models to corroborate this hypothesis must be carried out. Graphical abstract