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The present study aims to determine the antioxidant capacity of the ethanolic extracts of husk fiber of four coconut (Cocos nucifera L.) varieties (yellow dwarf, green dwarf, giant and hybrid) and to evaluate the electrochemical behavior of these extracts on a glassy carbon electrode and on a modified glassy carbon electrode. The highest values of total phenolic content were obtained for the hybrid (531 ± 24 mg GAE g(-1) dry extract) and yellow dwarf (501 ± 29 mg GAE g(-1) dry extract) varieties and the lowest was for the green dwarf variety with 58 ± 9 mg GAE g(-1) dry extract. The ability of the extracts to scavenge DPPH˙ radicals was in the order of giant > yellow dwarf > hybrid > green dwarf and the IC50 values varied from 8.6 to 55.9 μg mL(-1). All varieties showed reducing potential by the use of FRAP and CUPRAC methods, with the lowest performance obtained for the green dwarf variety. Additionally, through the use of mimetic biomembranes, ethanolic extracts of coconut husk were shown to protect lipids against oxidative damage independent of the variety. The main antioxidants identified in the extract of yellow dwarf variety by UPLC-MS were quercetin and catechin. Cyclic voltammetric studies of the ethanolic extracts on glassy carbon electrode confirmed the presence of easily oxidized compounds, and the high antioxidant capacity of the varieties. This capacity was expressed as mg quercetin equivalents g(-1) dry extract and ranged from 25.9 up to 53.5 mg QE g(-1). A poly-xanthurenic acid (poly-Xa)/multi-walled carbon nanotube (MWCNT) / glassy carbon modified electrode (poly-Xa/MWCNT/GCE) was used for this purpose. Our findings suggest that these extracts are potentially important antioxidant supplements for the everyday human diet, pharmaceutical and cosmetic industries, thereby aggregating value to the enormous amount of waste from the coconut industry, mostly used for burning purposes.

The antispasmodic effect of 4'-methylepigallocatechin (MEC), which was isolated from Maytenus rigida Mart (Celestraceae), was investigated in vitro in guinea pig intestinal segments. In the isolated ileum, MEC (1 nM-100 μM) did not modify the ileal spontaneous tonus or the electrically elicited contractions. MEC (8 μM) significantly (p<0.01) reduced the submaximal contractions induced by histamine (2 μM), carbachol (100 μM) and BaCl₂ (0.03 M). An additive relaxing action (p<0.001) was observed by co-incubation of verapamil (10 nM) and MEC (8 μM). Although MEC (1 nM-100 μM) did not modify the contractions elicited by 60 mM KCl, it significantly reduced the CaCl₂ contractile response without changing the EC₅₀ (effective concentration of CaCl₂ causing 50% of maximum response). In brief, these results show that MEC has a potent ileal spasmolytic effect and blocks spasms induced by specific and nonspecific stimuli. Importantly, the spasmolytic effects were attained at low concentrations and might be related to the symptomatic relief of abdominal pain that is obtained from the use of the M. rigida stem bark., (Copyright © 2012 Elsevier B.V. All rights reserved.)

As part of an ongoing project to identify plant natural products as resistance-modifying agents, bioassay-guided fractionation of an extract of Jatropha elliptica (Pohl) Muell Arg. led to the isolation of a penta-substituted pyridine, namely 2,6-dimethyl-4-phenyl-pyridine-3,5-dicarboxylic acid diethyl ester (8). The structure was established by spectroscopic methods. This known compound was assayed for in vitro antibacterial and resistance-modifying activities against strains of Staphylococcus aureus possessing the MsrA and NorA resistance efflux mechanisms. Antibiotic efflux studies indicated that (8) acts as an inhibitor of the NorA efflux pump and restores the level of intracellular drug concentration.

Abstract: Ethanol extracts of powdered genipap (Genipa americana L.), umbu (Spondia tuberosa A.) and siriguela (Spondia purpurea L.) prepared from separate pulp, seeds and peel were investigated for their (i) antioxidant capacity, which was evaluated by various known methods; (ii) acetylcholinesterase (AChE) inhibitory activity; and (iii) cytotoxic effect on corneal epithelial cells of sheep. The highest values of total phenolic content were obtained with peel and seed extracts. Siriguela and umbu (seeds and peel) extracts displayed the highest antioxidant activities. Lipid peroxidation assays using mimetic biomembranes and mouse liver homogenates indicated that genipap pulp is a promising antioxidant. The investigation of phenols and organic acid contents revealed the presence of quercetin, citric and quinic acids, chlorogenic acid derivatives, among others, in several extracts, with the highest amount found in siriguela seeds. Genipap pulp and siriguela seed ethanol extracts presented an AChE inhibition zone similar to that of the positive control, carbachol. AChE inhibition assay with chlorogenic acid, one of the main constituents of siriguela seeds, revealed that this acid showed activity similar to that of the control physostigmine. These data suggest that these extracts are potentially important antioxidant supplements for the everyday human diet, pharmaceutical and cosmetic industries. [Copyright &y& Elsevier]

Abstract: Extracts from various organs of 25 plants of Brazilian traditional medicine were assayed with respect to their anti-bacterial activities against Escherichia coli, a susceptible strain of Staphylococcus aureus and two resistant strains of Staphylococcus aureus harbouring the efflux pumps NorA and MsrA. Amongst the 49 extracts studied, 14 presented anti-bacterial activity against Staphylococcus aureus, including the ethanolic extracts from the rhizome of Jatropha elliptica, from the stem barks of Schinus terebinthifolius and Erythrina mulungu, from the stems and leaves of Caesalpinia pyramidalis and Serjania lethalis, and from the stem bark and leaves of Lafoensia pacari. The classes of compounds present in the active extracts were determined as a preliminary step towards their bioactivity-guided separation. No extracts were active against Escherichia coli. [Copyright &y& Elsevier]