ABSTRACT
The current trend toward using natural food additives, cosmetics, and medicines has motivated industries to substitute synthetic compounds for natural products. Essential oils (EOs) from medicinal plants are a well-known source of chemical compounds that display several interesting biological activities, including antimicrobial action. In this study, we investigated the antibacterial activity of EOs extracted from three Piperaceae species collected in the Brazilian Amazon region against a representative panel of cariogenic bacteria. The minimum inhibitory concentration (MIC) of the essential oils extracted from Peperomia pellucida (PP-EO), Piper marginatum (PM-EO), and Piper callosum (PC-EO) was determined against Streptococcus mutans, S. mitis, S. sanguinis, S. salivarius, S. sobrinus, Enterococcus faecalis, and Lactobacillus casei by using the microplate microdilution method. PM-EO, PC-EO, and PP-EO displayed antibacterial activity against all the tested cariogenic bacteria. PM-EO displayed the best inhibitory activity, with MIC values ranging from 50 to 500 µg/mL. The lowest MIC values were obtained for PM-EO against S. mitis (MIC = 75 µg/mL), Lactobacillus casei (MIC = 50 µg/mL), and S. mutans (MIC = 50 µg/mL). Gas chromatography mass spectrometry (GC-MS) analysis allowed the chemical composition of all the EOs to be identified. The main constituents of PM-EO, PC-EO, and PP-EO were 3,4-(methylenedioxy)propiophenone, α-pinene, and dillapiole, respectively. Finally, the compounds that were exclusively detected in PM-EO are highlighted. Our results suggest that PM-EO may be used in products for treating dental caries and periodontal diseases.
ABSTRACT
During grain storage, a considerable amount of product is lost because of insects, such as Zabrotes subfasciatus. Currently, to mitigate these risks, studies are searching for plants with potential for the control of agricultural pests, also known as botanical insecticides. In this study, the fumigant toxicity of the essential oils of Piper callosum (PC-EO), Piper marginatum (PM-EO) and Vitex agnus-castus (VA-EO) against Zabrotes subfasciatus was investigated. The essential oils of PC-EO, PM-EO and VA-EO were analysed by gas chromatography (GC-MS), and the major components were 3,4-methylenedioxypropiophenone (10.4%), bicyclogermacrene (10.1%) and germacrene D (9.9%) for PM-EO; safrol (29.3%) for PC-EO; and 1,8-cineol (23.8%) for VA-EO. In fumigation tests, VA-EO killed 100% Zabrotes subfasciatus at a concentration of 0.004 µL/L air after 24 h of treatment, whereas PC-EO and PM-EO at 0.01 µL/L air caused 100% Z. subfasciatus mortality after 48 h. The VA-EO sample provided the lowest LD50 after 24 h (0.17 µL/L air), followed by PC-EO (0.78 µL/L air) and PM-EO (1.17 µL/L air). These results demonstrate that the essential oils of these species can be an alternative to control pests in stored products. This is the first report of the fumigant potential of these species against Z. subfasciatus.
