Alzheimer’s disease (AD), due to its spread, has become a global health priority, and is characterized by senile dementia and progressive disability. The main cause of AD and other neurodegenerations (Huntington, Parkinson, Amyotrophic Lateral Sclerosis) are aggregated protein accumulation and oxidative damage. Recent research on secondary metabolites of plants such as polyphenols demonstrated that they may slow the progression of AD. The flavonoids’ mechanism of action in AD involved the inhibition of acetylcholinesterase, butyrylcholinesterase, Tau protein aggregation, β-secretase, oxidative stress, inflammation, and apoptosis through modulation of signaling pathways which are implicated in cognitive and neuroprotective functions, such as ERK, PI3-kinase/Akt, NFKB, MAPKs, and endogenous antioxidant enzymatic systems. This review focuses on flavonoids and their role in AD, in terms of therapeutic potentiality for human health, antioxidant potential, and specific AD molecular targets.

Citrus spp. are among the most widespread plants cultivated worldwide and every year millions of tons of fruit, juices, or processed compounds are produced and consumed, representing one of the main sources of nutrients in human diet. Among these, the flavonoids play a key role in providing a wide range of health beneficial effects. Apigenin, diosmetin, luteolin, acacetin, chrysoeriol, and their respective glycosides, that occur in concentrations up to 60 mg/L, are the most common flavones found in Citrus fruits and juices. The unique characteristics of their basic skeleton and the nature and position of the substituents have attracted and stimulated vigorous investigations as a consequence of an enormous biological potential, that manifests itself as (among other properties) antioxidant, anti-inflammatory, antiviral, antimicrobial, and anticancer activities. This review analyzes the biochemical, pharmacological, and biological properties of Citrus flavones, emphasizing their occurrence in Citrus spp. fruits and juices, on their bioavailability, and their ability to modulate signal cascades and key metabolic enzymes both in vitro and in vivo. Electronic databases including PubMed, Scopus, Web of Science, and SciFinder were used to investigate recent published articles on Citrus spp. in terms of components and bioactivity potentials.

Flavonols are a subclass of natural flavonoids characterized by a remarkable number of biotechnological applications and health-promoting properties. They attract researchers’ attention due to many epidemiological studies supporting their usage. They are phytochemicals commonly present in our diet, being ubiquitous in the plant kingdom and, in particular, relatively very abundant in fruits and vegetables. All these aspects make flavonols candidates of choice for the valorization of products, based on the presence of a remarkable number of different chemical structures, each one characterized by specific chemical features capable of influencing biological targets inside the living organisms in very different manners. In this review, we analyzed the biochemical and physiological characteristics of flavonols focalizing our attention on the most promising compounds to shed some light on their increasing utilization in biotechnological applications in processing industries, as well as their suitable employment to improve the overall wellness of the humankind.

Although the chemical composition and biological properties of some species of the genus Pistacia has been investigated, studies on hull essential oil of Pistacia vera L. variety Bronte (HEO) are currently lacking. In this work, we have carried out an in-depth phytochemical profile elucidation by Gas Chromatography-Mass Spectrometry (GC-MS) analysis, and an evaluation of antioxidant scavenging properties of HEO, using several different in vitro methods, checking also its cytoprotective potential on lymphocytes treated with tert-butyl hydroperoxide. Moreover, the antimicrobial activity against Gram-positive and Gram-negative strains, both American Type Culture Collection (ATCC) and clinical isolates, was also investigated. GC-MS analysis highlighted the richness of this complex matrix, with the identification of 40 derivatives. The major components identified were 4-Carene (31.743%), α-Pinene (23.584%), d-Limonene (8.002%), and 3-Carene (7.731%). The HEO showed a strong iron chelating activity and was found to be markedly active against hydroxyl radical, while scarce effects were found against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Moreover, pre-treatment with HEO was observed to significantly increase the cell viability, decreasing the lactate dehydrogenase (LDH) release. HEO was bactericidal against all the tested strains at the concentration of 7.11 mg/mL, with the exception of Pseudomonas aeruginosa ATCC 9027. The obtained results demonstrate the strong free-radical scavenging activity of HEO along with remarkable cytoprotective and antimicrobial properties.

Recent studies on natural antioxidant compounds have highlighted their potentiality against various pathological conditions. The present review aims to selectively evaluate the benefits of catechins and their polymeric structure on metabolic syndrome, a common disorder characterized by a cluster of three main risk factors: obesity, hypertension, and hyperglycemia. Patients with metabolic syndrome suffer chronic low inflammation state and oxidative stress both conditions effectively countered by flavanols and their polymers. The mechanism behind the activity of these molecules has been highlighted and correlated with the characteristic features present on their basic flavonoidic skelethon, as well as the efficient doses needed to perform their activity in both in vitro and in vivo studies. The amount of evidence provided in this review offers a starting point for flavanol dietary supplementation as a potential strategy to counteract several metabolic targets associated with metabolic syndrome and suggests a key role of albumin as flavanol-delivery system to the different target of action inside the organism.

Lemon bottlebrush (Callistemon citrinus (Curtis) Skeels) is one of the most common ornamental plants, diffused worldwide, and characterized by the presence of flowers with an intense red/purple coloration. There is increasing interest in the use and application of anthocyanins for their unique structural/chemical features in both food and pharmaceutical applications. RP-HPLC-DAD-ESI-MS/MS analysis of an enriched fraction of acidified methanolic extract of C. citrinus flowers allow the possibility of identifying, for the first time, the presence of four anthocyanins: cyanidin-3,5-O-diglucoside (cyanin), peonidin-3,5-O-diglucoside (peonin), cyanidin-3-O-glucoside, and cyanidin-coumaroylglucoside-pyruvic acid. Moreover, the evaluation of antioxidant and biological potential showed a remarkable activity of this fraction, able to actively scavenge DPPH, AAPH, and ABTS radicals, and to counteract the β-carotene-bleaching. In addition, it protects human mononuclear cells from oxidative injuries and prevents angiogenesis (acting in the range of few μg/ml); furthermore, it does not show significant iron-chelating ability (up to 200 µg/mL). The easy way of cultivation, robustness, and adaptability to different environments make the flowers of this plant a useful source of anthocyanins, with remarkable health promoting properties.