Chemical composition and potentiating action of Norfloxacin mediated by the essential oil of Piper caldense C.D.C. against Staphylococcus aureus strains overexpressing efflux pump genes.

Infectious diseases caused by multidrug-resistant microorganisms has increased in the last years. Piper species have been reported as a natural source of phytochemicals that can help in combating fungal and bacterial infections. This study had as objectives characterize the chemical composition of the essential oil from Piper caldense (EOPC), evaluate its potential antimicrobial activity, and investigate the synergistic effect with Norfloxacin against multidrug-resistant S. aureus overproducing efflux pumps, as well as, verify the EOPC ability to inhibit the Candida albicans filamentation. EOPC was extracted by hydrodistillation, and the chemical constituents were identified by gas chromatography, allowing the identification of 24 compounds (91.9%) classified as hydrocarbon sesquiterpenes (49.6%) and oxygenated sesquiterpenes (39.5%). Antimicrobial tests were performed using a 96-well plate microdilution method against C. albicans ATCC 10231, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 standard strains, as well as against multidrug-resistant strains S. aureus SA1199B (overexpressing norA gene), S. aureus K2068 (overexpressing mepA gene) and S. aureus K4100 (overexpressing qacC gene). The oil showed activity against C. albicans ATCC 10231 (≥ 512 µg/mL) and was able to inhibit hyphae formation, an important mechanism of virulence of C. albicans. On the other hand, EOPC was inactive against all bacterial strains tested (≤ 1,024 µg mL). However, when combined with Norfloxacin at subinhibitory concentration EOPC reduced the Norfloxacin and Ethidium bromide MIC values against S. aureus strains SA1199B, K2068 and K4100. These results indicate that EOPC is a source of phytochemicals acting as NorA, MepA and QacC inhibitors.

The Anticholinesterase Properties of Plants from the Northeast of Brazil Selected by an Ethnopharmacological Study for Disorders Relating to the Nervous System.

BACKGROUND: Various factors may trigger Alzheimer's disease and the cholinergic hypothesis, which is one of the most widely accepted, argues damage to the brain nuclei, may reduce the production of the choline acetyltransferase enzyme, and cause a decline in the synthesis of acetylcholine (ACh). Studies have thus focused on discovering molecules that are capable of inhibiting the action of cholinesterase enzymes that degrade ACh, thereby preventing the evolution of the disease. OBJECTIVE: The aim of the present study is to assess the anticholinesterase properties of extracts of medicinal plants in a semi-arid region of Northeast of Brazil. MATERIALS AND METHODS: The species were selected by way of an ethnobotanical study and were collected if there were some indications that they are related to the nervous system. The plant samples were extracted using hexane, ethyl acetate, and methanol. Anticholinesterase activity in vitro was assessed by way of bioautography in thin layer chromatography and microassays in 96-well plates. RESULTS: Twenty-three species of plant were collected, and 75 extracts were analyzed. The bioautography revealed that 26.7% of the samples showed inhibitory activity against the acetylcholinesterase (AChE) enzyme. After the test for false positives, 8% of the samples were found to inhibit AChE. Thirty samples were analyzed by microassay (500 µg/mL), on which 86.7% showed moderate to powerful anticholinesterase activity. CONCLUSION: Of the extracts tested, Citrus limonum, Ricinus communis, and Senna occidentalis stand out as was the most promising in terms of anticholinesterase activity and may serve as a guide for the discovery and development of new substances for the treatment of AD. SUMMARY: The bioautography revealed that 26.7% of the samples showed inhibitory activity against the acetylcholinesterase enzymeSamples were analyzed by microassay (500 µg/mL), upon which 86.7% showed moderate to powerful anticholinesterase activityCitrus limonum, Ricinus communis, and Senna occidentalis stand out as being the most promising in terms of anticholinesterase activityC. limonum, R. communis, and S. occidentalis may serve as a guide for the discovery and development of new substances for the treatment of Alzheimer's disease. Abbreviations used: AChE: Acetilcolinesterase.