Solid-phase adsorption methodologies of naturally occurring anthraquinones: A review.

INTRODUCTION: Solid-phase extraction applied to plant matrices is nowadays a well-validated technique allowing to concentrate and purify different secondary metabolites. Several classes of phytochemicals have been selectively extracted by this methodology. During the last decade attention has been focused on biologically active anthraquinones from numerous sources like edible, healthy, and medicinal plants. OBJECTIVES: The aim of this review is to provide a detailed literature survey of the solid-phase adsorption methodologies for the extraction of natural anthraquinones reported so far and to discuss and propose future directions in this field of research. MATERIALS AND METHODS: Substructure search was performed in the SciFinder Scholar, PubMed, Medline, and Scopus databases. RESULTS: The first report about application of solid-phase adsorption for the purification of anthraquinones appeared in the literature in 2002. From this date, and in particular during recent years, the most notable examples included the use of chitin- and chitosan-based polymers, of molecularly imprinted polymers, of coated magnetic nanoparticles, of miniaturized matrix solid-phase dispersion, of functionalized resins, of differently structured lamellar solids, and finally of vortex-synchronized matrix solid-phase dispersion. CONCLUSIONS: The herein detailed solid-phase adsorption methodologies are powerful tools to selectively extract natural anthraquinones and/or provide anthraquinone-enriched phytopreparations. Nevertheless, many other important methods have been applied to synthetic anthraquinones (e.g., azo dyes). These could be conveniently employed also for natural anthranoids. Studies in this field are discussed in this review article.

Cognitive and biological effects of citrus phytochemicals in subjective cognitive decline: a 36-week, randomized, placebo-controlled trial.

BACKGROUND: Auraptene (AUR) and naringenin (NAR) are citrus-derived phytochemicals that influence several biological mechanisms associated with cognitive decline, including neuronal damage, oxidative stress and inflammation. Clinical evidence of the efficacy of a nutraceutical with the potential to enhance cognitive function in cohorts at risk of cognitive decline would be of great value from a preventive perspective. The primary aim of this study is to determine the cognitive effects of a 36-week treatment with citrus peel extract standardized in levels of AUR and NAR in older adults experiencing subjective cognitive decline (SCD). The secondary aim is to determine the effects of these phytochemicals on blood-based biomarkers indicative of neuronal damage, oxidative stress, and inflammation. METHODS: Eighty older persons with SCD will be recruited and randomly assigned to receive the active treatment (400 mg of citrus peel extract containing 0.1 mg of AUR and 3 mg of NAR) or the placebo at a 1:1 ratio for 36 weeks. The primary endpoint is a change in the Repeatable Battery for the Assessment of Neuropsychological Status score from baseline to weeks 18 and 36. Other cognitive outcomes will include changes in verbal and nonverbal memory, attention, executive and visuospatial functions. Blood samples will be collected from a consecutive subsample of 60 participants. The secondary endpoint is a change in interleukin-8 levels over the 36-week period. Other biological outcomes include changes in markers of neuronal damage, oxidative stress, and pro- and anti-inflammatory cytokines. CONCLUSION: This study will evaluate whether an intervention with citrus peel extract standardized in levels of AUR and NAR has cognitive and biological effects in older adults with SCD, facilitating the establishment of nutrition intervention in people at risk of cognitive decline. TRIAL REGISTRATION: The trial is registered with the United States National Library of Medicine at the National Institutes of Health Registry of Clinical Trials under the code NCT04744922 on February 9th, 2021 ( https://www. CLINICALTRIALS: gov/ct2/show/NCT04744922 ).

A novel and efficient concentration of pomegranate juice with enhanced antioxidant activity.

In the present study we investigated the performance of a panel of 13 solid sorbents comprising layered double hydroxides, zirconium phosphate-based materials, and phyllosilicates as heterogeneous supports for the concentration of pomegranate (Punica granatum L.) juice. Mg-containing clays exhibited an almost complete bleaching capacityof pomegranate juice and more interestingly provided blends with an increased antioxidant capacity (around 1.5-fold) respect to the parent juice when assayed for the Trolox equivalent antioxidant capacity (TEAC) coupled to ABTS decolorization test. Such an activity remained practically unaltered after 4 days during which the pomegranate concentrated preparations remained supported on clays. The approach investigated herein and used for the concentration of pomegranate juice and the discovery of the preservation for long periods of the antioxidant activities of pomegranate extracts when supported on solid sorbents have been reported herein for the first time in the literature to the best of our knowledge.

7-Isopentenyloxycoumarin: What Is New across the Last Decade.

7-Isopentenyloxycoumarin is among the most widespread naturally occurring prenyloxy umbelliferone derivatives. This secondary metabolite of mixed biosynthetic origin has been typically isolated from plants belonging to several genera of the Rutaceae and Apiaceae families, comprising widely used medicinal plants and in general plants with beneficial effects on human welfare, as well as edible fruits and vegetables. Although known for quite a long time (more than 50 years), only in the last two decades has this natural compound been revealed to exert powerful and promising pharmacological properties, such as active cancer chemopreventive, antibacterial, antiprotozoal, antifungal, anti-inflammatory, neuroprotective, and antioxidant properties, among the activities best outlined in the recent literature. The aim of this comprehensive miniature review article is to detail the novel natural sources and the effects described during the last decade for 7-isopentenyloxycoumarin and what has been reported on the mechanisms of action underlying the observed biological activities of this oxyprenylated secondary metabolite. In view of the herein described data, suggestions on how to address future research on the abovementioned natural product and structurally related derivatives in the best ways according to the authors will be also provided.

Solid phase adsorption of anthraquinones from plant extracts by lamellar solids.

Solid phase extraction is nowadays a well validated and powerful technique applicable to complex matrices like plant extracts and phytocomplexes. This process provides concentration and/or purification of selected secondary metabolites from these matrices for subsequent analysis and isolation. In this research article sixteen lamellar solids, comprising layered structures (hydrotalcites, zirconium phosphates, magnesium hydroxide), magnesium oxide, and the phyllosilicates talc and bentonite were investigated for their capacity and performance to selectively adsorb five naturally occurring and widespread anthraquinones (aloe, aloe-emodin, rhein, chrysophanol, and physcion) contained in three ethanolic extracts of well known plants with purgative effects (frangula, senna, and rhubarb). Ethanolic solutions of extracts from these species were vigorously magnetically stirred with fixed quantities of each solid support at room temperature for 1 h. Subsequent HPLC analysis, coupled to photodiode array detection, revealed that, among the solids tested, the hydrotalcite zinc aluminum oleate and magnesium aluminum azelate and magnesium oxide were largely the most effective to this concern allowing to recover anthraquinones (all or some) in good to excellent percentages. Another interesting result was the selective and total removal of rhein by some sorbents from senna and rhubarb extracts. Sorbents were also recyclable and could be re-used to accomplish additional steps without appreciable loss of adsorption capacity. The application of the title solid inorganic and mixed inorganic/organic supports for the selective adsorption and concentration in the solid phase of anthraquinones from commonly used laxative plant species is reported herein for the first time.

Solid phase adsorption of emodin on hydrotalcites and inorganic oxides: A preliminary study.

Solid phase extraction applied to plant matrices is nowadays a well validated technique allowing the concentration and purification of selected secondary metabolites for subsequent analysis. In this short communication we screened the efficiency of 16 selected solid supports including layered structures (hydrotalcites and zirconium phosphate), magnesium oxide and hydroxide, and finally the phyllosilicates talc and bentonite for the selective concentration of the anthraquinone emodin from raw solid extracts of Polygonum cuspidatum Siebold & Zucc. (sin. Reynoutria japonica Houtt.) (Polygonaceae), commonly known as "Japanese knotweed". An ethanolic solution of sample extract from this plant was vigorously mixed with fixed quantities of each solid support. Subsequent HPLC analysis, coupled to photodiode array detection, revealed that, among the solid supports assayed, the hydrotalcite zinc aluminum oleate and magnesium oxide were largely the most effective to this concern. Both were able to extract emodin from the raw extract in percentages of 81.5 % and 92.4 %, respectively. The application of the title supports for the extraction and concentration in the solid phase of anthraquinones from raw plant extracts have been reported herein for the first time.

Umbelliprenin as a novel component of the phytochemical pool from Artemisia spp.

Plants belonging to Artemisia spp. are known to biosynthesize a wide panel of 3,3-dimethylallyl- and sesquiterpenyl- substituted coumarins. In this short communication we applied a novel extraction methodology based on the use of subcritical butane under a counter-current mode to further characterize the presence of selected biologically active oxyprenylated phenylpropanoids, namely coumarins and ferulic acid derivatives, in extracts deriving from aerial parts of Artemisia vulgaris L. (commonly known as "common mugwort") (Asteraceae). In the mean time, we assessed the efficiency of the above mentioned extractive methodology with other routes like maceration and ultrasounds and microwaves-based methods using absolute EtOH as the solvents. UHPLC analysis coupled to UV/Vis detection revealed that, among the 5 pure chemical standard assayed, only umbelliprenin (7-farnesyloxycoumarin) was recorded, while boropinic acid, 4'-geranyloxyferulic acid, 7-isopentenyloxycoumarin, and auraptene were not detected. The best extractive yield (0.18 %) was obtained after extaction with subcritical butane. The presence of umbelliprenin in Artemisia plant species has been reported herein for the first time. This coumarin may represent the biosynthetic precursors of sesquiterpenyloxycoumarins with more complex structures typically found in this genus.