Montmorillonite with essential oils as antimicrobial agents, packaging, repellents, and insecticides: an overview.

Essential oils (EOs) are complex natural mixtures of secondary plant metabolites that function as biocides and therapeutic agents. They are extensively used in bactericidal, virucidal, fungicidal, antiparasitic, insecticidal, pharmaceutical, and cosmetic products. However, certain characteristics, such as the volatility of EOs, hinder their widespread use. To mitigate this limitation, several studies have investigated combinations of EOs with natural materials, including clay minerals. Clay minerals are abundant in nature, biocompatible, and non-toxic to the environment and humans. Clay minerals such as montmorillonite possess available sites where EO molecules can interact. The combination of EOs with clay minerals produces new materials for various applications including antibacterial, antifungal, insecticidal/repellent, and active packaging materials. Therefore, this review focuses on the immobilization of several types of EOs in raw and modified montmorillonites. The applications of the described systems were evaluated and demonstrated the synergism of the properties of the isolated components as a function of different EOs incorporated in the silicate matrix.

Modulation of the resistance to norfloxacin in Staphylococcus aureus by Bauhinia forficata link.

Microdilution assays were performed in order to evaluate the antimicrobial activity of the ethanoic extract from the leaves of Bauhinia forficate (EEBF) against different microorganisms. The extract did not present inner antimicrobial activities against the tested strains. However, EEBF was able to modulate the norfloxacin-resistance against Staphylococcus aureus SA1199-B that overproduce the NorA efflux pump, once sub-inhibitory concentrations of EEBF reduced the minimal inhibitory concentratio of the norfloxacin in 87.5%. This modulatory effect was also found when the antibiotic was replaced by ethidium bromide, suggesting that EEBF acts probably by inhibition of NorA, allowing the antibiotic accumulation intracellularly, and making the line more sensitive. These results point out the EEBF potential as a source of NorA inhibitors that could be used in combination with norfloxacin for treatment of infections caused by multidrug-resistant S. aureus.

Different susceptibilities of Aedes aegypti and Aedes albopictus larvae to plant-derived products.

INTRODUCTION: Aedes aegypti and Aedes albopictus are important vectors that transmit arboviruses to human populations. METHODS: Natural products were obtained and tested against larvae collected from the field in Fortaleza, capital of Ceará state. RESULTS: The essential oils of Syzygium aromaticum (Ae. aegypti LC50 = 32.7 ppm and Ae. albopictus LC50 = 138.1 ppm) and Croton nepetaefolius (Ae. aegypti LC50 = 81.7 ppm and Ae. albopictus LC50 = 76.1 ppm) showed the most intense larvicidal activity. CONCLUSIONS: The essential oils and methyl esters showed greater larvicidal activity than did the ethanol extracts.

Different susceptibilities of Aedes aegypti and Aedes albopictus larvae to plant-derived products

Abstract INTRODUCTION: Aedes aegypti and Aedes albopictus are important vectors that transmit arboviruses to human populations. METHODS: Natural products were obtained and tested against larvae collected from the field in Fortaleza, capital of Ceará state. RESULTS: The essential oils of Syzygium aromaticum (Ae. aegypti LC50 = 32.7 ppm and Ae. albopictus LC50 = 138.1 ppm) and Croton nepetaefolius (Ae. aegypti LC50 = 81.7 ppm and Ae. albopictus LC50 = 76.1 ppm) showed the most intense larvicidal activity. CONCLUSIONS: The essential oils and methyl esters showed greater larvicidal activity than did the ethanol extracts.

Chemical composition of the essential oils from two subspecies of Protium heptaphyllum / Composição química do óleo essencial de duas subespécies do Protium heptaphyllum

Qualitative and quantitative analyses of the volatile constituents from resin of Protium heptaphyllum (Aubl.) Marchand subsp. ulei (Swat) Daly (PHU), and Protium heptaphyllum (Aubl.) Marchand subsp. heptaphyllum (PHH), Burseraceae were performed using GC-MS and GC-FID. The resins were collected around the city of Cruzeiro do Sul, state of Acre, Brazil. Essential oils from the two subspecies were extracted by hydrodistillation with a yield of 8.6 percent (PHU) and 11.3 percent (PHH); the main components were terpinolene (42.31 percent) and p-cymene (39.93 percent) for subspecies ulei (PHU) and heptaphyllum (PHH), respectively.

As análises qualitativa e quantitativa dos óleos essenciais obtidos das resinas das espécies Protium heptaphyllum (Aubl.) Marchand subespécie ulei (Swat) Daly (PHU) e Protium heptaphyllum (Aubl.) Marchand subespécie heptaphyllum (PHH), Burseraceae, foram realizadas utilizando cromatografia em fase gasosa acoplado a um espectrômetro de massa (CG-EM) e cromatografia a gás com detector de chama (CG-DIC). As resinas foram coletadas no Município de Cruzeiro do Sul, Acre, Brasil. O óleo essencial das oleoresinas foi extraído por hidrodestilação fornecendo rendimento 8,6 por cento para PHU e 11,3 por cento para PHH. Os monoterpenos terpinoleno (42.31 por cento) e p-cimeno (39.93 por cento) foram os constituintes principais para PHU e PHH, respectivamente.