Marine ecosystems cover more than 70% of the globe’s surface. These habitats are occupied by a great diversity of marine organisms that produce highly structural diverse metabolites as a defense mechanism. In the last decades, these metabolites have been extracted and isolated in order to test them in different bioassays and assess their potential to fight human diseases. Since traditional extraction techniques are both solvent- and time-consuming, this review emphasizes alternative extraction techniques, such as supercritical fluid extraction, pressurized solvent extraction, microwave-assisted extraction, ultrasound-assisted extraction, pulsed electric field-assisted extraction, enzyme-assisted extraction, and extraction with switchable solvents and ionic liquids, applied in the search for marine compounds. Only studies published in the 21st century are considered.
The antioxidant and enzyme inhibitory properties of methanolic extracts from four aromatic plants used in traditional medicine and food [ (L.) Savi subsp. , subsp. Franco, L. and subsp. (Hoffmanns. & Link) Bonnier & Layens] were evaluated. The extract from exhibited the strongest DPPH (IC of 4.65 ± 0.12 µg/ml) and ABTS (1479.56 ± 12.29 µmol/g) scavenging capacities, as well as the largest ferric reducing ability (1746.76 ± 45.11 µmol/g). This extract also showed the highest total phenolic content (1597.20 ± 24.10 µmol/g) and although HPLC-DAD analysis revealed rosmarinic acid as the main compound of the extract, other compounds seem to be involved in the antioxidant activity. Furthermore, the extract from , which was found to be rich in caffeoylquinic and dicaffeoylquinic acids and in pinocembrin, showed the highest inhibitory potential against acetylcholinesterase, tyrosinase and α-glucosidase. Overall, the results obtained validate the usefulness of the studied plants as valuable sources of natural agents beneficial for human health.
Neurodegenerative, neurological and psychiatric diseases are a group of pathologies with huge social and economic impacts. Since brain disorders continue to be pathological conditions for which corrective surgery cannot be widely used, treatments are based on drugs that only alleviate the symptoms. Despite all efforts in finding more efficient therapeutic agents, the requirement for neuroprotective drugs able to cross the blood-brain barrier (BBB) has been a hard challenge to overcome. Flavonoids are known by their antioxidant activities thus preventing oxidative stress, which is believe to be one of the causes of disorders affecting the central nervous system. Moreover, they can also modulate both enzymes and receptors activities, being regarded as multi-target botanical therapeutics or drugs. This review will give emphasis to the benefits of flavonoids found in the diet in the treatment of Alzheimer's disease, Parkinson's disease, epilepsy, depression, and schizophrenia. The antioxidant effect of several flavonoids, as well as their effects not related with antioxidant activity, in the above mentioned diseases will be reviewed. Aspects concerning structure-activity relationships, but also the bioavailability of these compounds in the brain will be referred.
The use of mass spectrometry (MS) coupled to liquid chromatography (LC) as working tool for the study of the C-glycosyl flavones acylated with aliphatic and aromatic acids has allowed the tentative characterization of these compounds in Spergularia rubra and the establishment of the position of the acylation on the sugar moiety of the C-glycosylation by use of MS data. The combination of retention time (Rt), ultraviolet (UV) and MS(n) data of the compounds revealed their C-glycosyl flavone nature, being luteolin, apigenin and chrysoeriol derivatives. Ten non-acylated flavones were identified, from which six are described for the first time (one 7-O-glycosyl-6,8-diC-glycosyl flavone, four 6,8-diC-glycosyl flavones and one 2"-O-glycosyl-6-C-glycosyl flavone). Twenty-six acylated derivatives were also found for the first time. These compounds are grouped in three classes, namely, C-glycosyl flavones acylated with aliphatic acids, with aromatic acids or with a mixed acylation. The first group is characterized by the presence of one 6,8-diC-(acetyl)glycosyl flavone, four 6,8-diC-(malonyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(malonyl)glycosyl flavones, while in the second one twelve 6,8-diC-(acyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(acyl)glycosyl flavones are described. The last class contained five 6,8-diC-(malonyl,acyl)glycosyl flavones. No previous work has described the presence of C-glycosyl flavones acylated with aliphatic acids in this genus.
Supercritical fluid extraction (SEE) of the volatile oil from Thymus vulgaris L. aerial flowering parts was performed under different conditions of pressure, temperature, mean particle size and CO2 flow rate and the correspondent yield and composition were compared with those of the essential oil isolated by hydrodistillation (HD). Both the oils were analyzed by GC and GC-MS and 52 components were identified. The main volatile components obtained were p-cymene (10.0-42.6% for SFE and 28.9-34.8% for HD), gamma-terpinene (0.8-6.9% for SFE and 5.1-7.0% for HD), linalool (2.3-5.3% for SFE and 2.8-3.1% for HD), thymol (19.5-40.8% for SFE and 35.4-41.6% for HD), and carvacrol (1.4-3.1% for SFE and 2.6-3.1% for HD). The main difference was found to be the relative percentage of thymoquinone (not found in the essential oil) and carvacryl methyl ether (1.0-1.2% for HD versus t-0.4 for SFE) which can explain the higher antioxidant activity, assessed by Rancimat test, of the SFE volatiles when compared with HD. Thymoquinone is considered a strong antioxidant compound.
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