César Cornélio Andrei

Antimicrobial activity and chemical investigation of Brazilian Drosera

The antimicrobial activity of three different extracts (hexanic, ethyl acetate, methanol) obtained from Brazilian Drosera species (D. communis, D. montana var. montana, D. brevifolia, D. villosa var. graomogolensis, D. villosa var. villosa, Drosera sp. 1, and Drosera sp. 2 ) were tested against Staphylococcus aureus (ATCC 25923), Enterococcus faecium (ATCC23212), Pseudomonas aeruginosa (ATCC27853), Escherichia coli (ATCC11229), Salmonella choleraesuis (ATCC10708), Klebsiella pneumoniae (ATCC13883), and Candida albicans (a human isolate). Better antimicrobial activity was observed with D. communis and D. montana var. montana ethyl acetate extracts. Phytochemical analyses from D. communis, D. montana var. montana and D. brevifolia yielded 5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin); long chain aliphatic hydrocarbons were isolated from D. communis and from D. villosa var. villosa, a mixture of long chain aliphatic alcohols and carboxylic acids, was isolated from D. communis and 3b-O-acetylaleuritolic acid from D. villosa var. villosa.

Allylphenols from Ocotea cymbarum

Abstract An ethanol extract of Ocotea cymbarum wood was shown to contain apiol, dillapiol, 4-hydroxy-2,3,5-trimethoxyallylbenzene, apiolglycol and lyoniresinol.

Analysis of Rotenoids by High Temperature High Resolution Gas Chromatography-Mass Spectrometry

A short glass capillary column coated with PS-090 (20% phenyl–80% methylpolysiloxane, of 10 m × 0.30 mm i.d.; with 0.1 μm film thickness) was used to analyze samples from Tephrosia candida; eighteen rotenoids were separated and identified without derivatization by HT-HRGC and HT-HRGC-MS. The mass spectra show the typical fragmentation pattern for rotenoids, with the base peaks either at M+, or originating from RDA (Retro Diels-Alder) rearrangements. HT-HRGC and HT-HRGC-MS were shown to be extremely valuable and neglected techniques for structural studies as well as the routine analysis of rotenoids in crude extracts. Possible applications to other classes of aromatic natural products, e.g. flavonoids, are envisaged.

Alcalóides de flores e folhas de Erythrina speciosa Andrews

In vitro bioassays with leave extracts of Erythrina speciosa showed promising activity against Trypanosoma cruzi. From the flowers of E. speciosa two alkaloids were isolated: erysotrine and erythartine. The leaves furnished one alkaloid, nororientaline. The structures were determined on the basis of spectroscopic evidence. This is the first report about the investigation of alkaloids in flowers and leaves of this species, as well the first report of nororientaline occurrence in this plant.

Antibacterial activity of honey from stingless bees Scaptotrigona bipunctata Lepeletier, 1836 and S. postica Latreille, 1807 (Hymenoptera: Apidae: Meliponinae) against methicillin-resistant Staphylococcus aureus (MRSA)

The antibacterial activity of honey produced by the stingless bees Scaptotrigona postica (H6) and Scaptotrigona bipunctata (H7) was evaluated against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains. Fifty-three MRSA strains in the bacterial collection of the hospital of Londrina State University, three standard MRSA strains and two standard MSSA strains were used. Evaluation of the antibacterial activity of honey samples was determined by agar well diffusion assay, calculation of minimum inhibitory concentrations (MICs), and construction of growth and viability curves. The inhibition zones generated by the honey samples ranged from 20 to 27 mm for H6 and 20 to 24 mm for H7, while MIC values ranged from 0.62 to 1.25% for H6 and 1.25 to 2.5% for H7. According to the growth curves, the growth of all MRSA and MSSA strains was completely inhibited. Honey cytotoxicity was evaluated by dimethylthiazol diphenyl tetrazolium bromide (MTT) assay, and the CC50 values were found to be 13% for H6 and 7.3% for H7, which were significantly higher when compared to the MIC values. The honey of both the stingless bees S. bipunctata and S. postica can thus be utilized as antibacterial substances against MSSA and MRSA strains, and this action is probably due to a synergistic action of different components such as hydrogen peroxide, sugars, and other compounds not identified in this study. The application of natural products is important for the control of MRSA infections. Further studies are warranted to demonstrate that the antimicrobial activity of the honey examined here could be used in clinical applications for the prevention of MRSA infections.