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.

ABSTRACT Abnormal multiplication of oral bacteria causes dental caries and dental plaque. These diseases continue to be major public health concerns worldwide, mainly in developing countries. In this study, the chemical composition and antimicrobial activity of the essential oil of Vitex agnus-castus leaves (VAC‒EO) collected in the North of Brazil against a representative panel of cariogenic bacteria were investigated. The antimicrobial activity of VAC-EO was evaluated in terms of its minimum inhibitory concentration (MIC) values by using the broth microdilution method in 96-well microplates. The chemical constituents of VAC-EO were identified by gas chromatography (GC‒FID) and gas chromatography‒mass spectrometry (GC‒MS). VAC‒EO displayed some activity against all the investigated oral pathogens; MIC values ranged from 15.6 to 200 μg/mL. VAC-EO had promising activity against Streptococcus mutans (MIC= 15.6 μg/mL), Lactobacillus casei (MIC= 15.6 μg/mL), and Streptococcus mitis (MIC= 31.2 μg/mL). The compounds 1,8-cineole (23.8%), (E)-β-farnesene (14.6%), (E)-caryophyllene (12.5%), sabinene (11.4%), and α-terpinyl acetate (7.7%) were the major chemical constituents of VAC‒EO. VAC-EO displays antimicrobial activity against cariogenic bacteria. The efficacy of VAC-EO against S. mutans is noteworthy and should be further investigated.

The Acanthaceae family is an important source of therapeutic drugs, and the ethnopharmacological knowledge of this family requires urgent documentation as several of its species are near extinction. Justicia is the largest genus of Acanthaceae, with approximately 600 species. The present work provides a review addressing the chemistry and pharmacology of the genus Justicia. In addition, the biological activities of compounds isolated from the genus are also covered. The chemical and pharmacological information in the present work may inspire new biomedical applications for the species of Justicia, considering atom economy, the synthesis of environmentally benign products without producing toxic by-products, the use of renewable sources of raw materials, and the search for processes with maximal efficiency of energy.