Chemical Profile of the Volatile Constituents and Antimicrobial Activity of the Essential Oils from Croton adipatus, Croton thurifer, and Croton collinus

The aim of this study was to determine the volatile phytochemical constituents and evaluate the antimicrobial activity of the essential oils of the leaves from Croton adipatus, Croton thurifer, and Croton collinus. Essential oils were extracted by hydro-distillation using the Clevenger extractor and the phytochemical analysis was determined by Gas chromatography-Mass Spectrometry (GC-MS). The antimicrobial activity was assessed using the agar diffusion and colorimetric broth microdilution methods against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 9027, and Candida albicans ATCC The essential oils from C. adipatus, C. thurifer, and C collinus had 46, 38, and 35 volatile constituents respectively. The main compounds determined in C. adipatus were β-myrcene (18.34%), while in C. collinus was β-caryophyllene (44.7%), and in C. thurifer was an unknown component (C10H16: 22.38%). Essential oil of C. adipatus showed a MIC against B. subtilis (286.4 µg/mL) and C. albicans (572.8 ± 0 µg/mL); C. thurifer against S. aureus (296.1 ± 0 µg/mL) and B. subtilis (148 ± 0 µg/mL); and C. collinus against B. subtilis (72 ± 0 µg/mL) and C. albicans (576.2 ± 0 µg/mL). The three essential oils of Croton species demonstrated in vitro antimicrobial activity against a strain of bacteria or fungi.

Evaluation of volatile constituents, exudation of resin and occurrence of galls of Protium aracouchini (Aubl.) Marchand

Protium aracouchini (Aubl.) Marchand [sin Icica aracouchini Aubl.], which occurs in the Adolpho Ducke Forest Reserve, in the Brazilian Amazon, was evaluated for the presence of galls, for resin exudation and the composition of the essential oils from the aerial parts and the resin. The experiment to stimulate the exudation of resin from the trunk was conducted using a 2-chloroethylphosphonic acid solution. The resin produced after 40 days and the aerial parts had their essential oils extracted in a Clevenger apparatus and the volatile chemical constituents were analyzed using GC/MS. The non-oxygenated sesquiterpenes α-copaene (21.15%) and α-gurjunene (13.69%), in addition to the oxygenated sesquiterpene spathulenol (10.32%), were detected as the majority constituents of the essential oil of the leaves, and a concentration similar to that of α-gurjunene was found in the branches (13.28%). The resin essential oil showed a high concentration of hydrocarbon monoterpenes (76.49%) with a predominance of α-pinene (17.57%) and limonene (46.11%). Four gall morphotypes were found associated with this species. The present study reports for the first time information on the volatile constituents and the resinous potential of P. aracouchini, and registers the morphotypes of the galls that help in the taxonomy of the species.