Alessandra Gomes Marques Pacheco

The Role of Flavonoids on Oxidative Stress in Epilepsy

Backgrounds. Oxidative stress can result from excessive free-radical production and it is likely implicated as a possible mechanism involved in the initiation and progression of epileptogenesis. Flavonoids can protect the brain from oxidative stress. In the central nervous system (CNS) several flavonoids bind to the benzodiazepine site on the GABAA-receptor resulting in anticonvulsive effects. Objective. This review provides an overview about the role of flavonoids in oxidative stress in epilepsy. The mechanism of action of flavonoids and its relation to the chemical structure is also discussed. Results/Conclusions. There is evidence that suggests that flavonoids have potential for neuroprotection in epilepsy.

Chemical composition, antioxidant and antibacterial activities and evaluation of cytotoxicity of the fractions obtained from Selaginella convoluta (Arn.) Spring (Selaginellaceae)

ABSTRACT The aim of this study was to evaluate the chemical composition, antioxidant and antibacterial activities and cytotoxicity of fractions from Selaginella convoluta, obtained by liquid–liquid extraction using hexane (Sc-Hex), chloroform (Sc-CHCl3) and ethyl acetate (Sc-AcOEt). The phenolic and flavonoid contents were measured by the Folin-Ciocalteu and aluminium chloride methods, respectively. Antioxidant activities were evaluated by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and β-carotene-linoleic acid bleaching test. The antibacterial effect was evaluated by the method of microdilution and the cytotoxicity analysis in HCT-116 (colon), OVCAR-8 (ovarian) and SF-295 (brain) cells were carried out for MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) test. The fractions were positive for the presence of anthracene derivatives, flavonoids, lignans, naphthoquinones, steroids and triterpenoids. The Sc-Hex and Sc-AcOEt showed good antioxidant activities. The fractions of S. convoluta demonstrated antibacterial activity and showed weak cytotoxicity. These activities were correlated with presence of phenolic compounds in active fractions.

Assessment of the antibacterial, cytotoxic and antioxidant activities of Morus nigra L. (Moraceae)

This study was carried out to assess the antibacterial, cytotoxic and antioxidant activities of extracts of Morus nigra L. HPLC was used to determine the fingerprint chromatogram of the crude ethanolic extract (Mn-EtOH). The antibacterial effect was assessed through the method of microdilution. The cytotoxicity was tested against human tumour cell lines using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The total phenolic and flavonoid contents were also assessed through the Folin-Ciocalteu and aluminum chloride methods, respectively. Antioxidant activities of the extracts were evaluated by using 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging and β-carotene-linoleic acid bleaching methods. The presence of phenolic compounds in Mn-EtOH was confirmed using HPLC. The extracts showed activity against most microorganisms tested. The extracts did not show any expressive antiproliferative effect in the assessment of cytotoxicity. The most significant total phenolic content was 153.00 ± 11.34 mg of gallic acid equivalent/g to the ethyl acetate extract (AcOEt). The total flavonoid content was 292.50 ± 70.34 mg of catechin equivalent/g to the AcOEt extract, which presented the best antioxidant activity (IC50 50.40 ± 1.16 μg/mL) for DPPH scavenging. We can conclude that this species shows strong antibacterial and antioxidant activities, as well as weak cytotoxic effects.

Antimicrobial activity and chemical analysis of Microlicia hatschbachii Wurdack (Melastomataceae) extract

Aerial parts of Microlicia hatschbachii were extracted with hexane, and the extract was evaluated for antimicrobial activity by a broth dilution method. After phytochemical procedures: GC-MS identified aliphatic alkanes, carboxylic acids and methyl esters of long-chain fatty acids; and two diterpenoids [labd-8(17)-en-15-oic acid and labd-8(17),13-dien-15-oic acid] were identified by 1H and 13C NMR. The antimicrobial activity of the hexane extract could be attributed to the presence of labdanes. This identification is the first reported occurrence of labdane diterpenes in the Melastomataceae family.