Chemical fingerprinting and bioactivity of Amazonian Ecuador Croton lechleri Müll. Arg. (Euphorbiaceae) stem bark essential oil: A new functional food ingredient?

• Published in: Food chemistry 2011-06, Vol.126 (3), p.837-848
• Main Authors: Rossi, Damiano, Guerrini, Alessandra, Maietti, Silvia, Bruni, Renato, Paganetto, Guglielmo, Poli, Ferruccio, Scalvenzi, Laura, Radice, Matteo, Saro, Katia, Sacchetti, Gianni
• Format: Article
• Language: English
• Subjects: (HP)TLC-bioautography; Anti-mutagenic activity; antibacterial properties; Antimicrobial activity; antimutagenic activity; Antioxidant activity; Aroma and flavouring agent industries; bark; bioactive properties; Biological and medical sciences; chemical constituents of plants; chemical structure; Croton lechleri; Cytotoxicity; Escherichia coli; Essential oil; essential oils; Food industries; Food microbiology; free radical scavengers; Fundamental and applied biological sciences. Psychology; GC–MS; microbial growth; monoterpenoids; Mutagenic activity; mutagenicity; NMR; plant extracts; Pseudomonas aeruginosa; sesquiterpenoids
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2010.11.042

► Chemistry and bioactivities of C. lechleri bark essential oil have been investigated. ► Combined GC, GCMS and NMR showed sesquiterpenes as the most abundant compounds. ► TLC-bioautography evidenced calacorenes and sesquicineole as the most bioactive. ► Antimutagenic properties of the whole essential oil were particularly relevant. ► The data suggest possible uses of C. lechleri bark essential oil as food ingredient. Croton lechleri essential oil has been obtained by steam distillation of fresh stem bark from Amazonian Ecuador adult plants (yield: 0.61ml/kg [0.061%]; density: 1.01g/ml), and then chemically characterised by GC (Gas Chromatography) and GC–MS (gas chromatography–mass spectrometry). Seventy-four chemicals were detected and identified; the most abundant in descending order, were the sesquiterpenes sesquicineole (17.29%), α-calacorene (11.29%), 1,10-di-epi-cubenol (4.75%), β-calacorene (4.34%) and epi-cedrol (4.09%). Monoterpenes checked with a relative peak area higher than 2.0% were α-pinene (2.01%), p-cymene (2.61%), limonene (4.20%) and borneol (2.67%). The structure of the main chemicals were confirmed by GC–MS and 1H NMR analyses. Spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) and DPPH-(high performance) thin layer chromatography (DPPH-(HP)TLC) bioautographic assays showed a lower radical scavenging capacity (IC50) with respect to commercial thyme essential oil and BHA (butylated hydroxyl anisole), pointing out, however, that the C. lechleri essential oil fraction, characterised by α-calacorene, β-calacorene and δ-cadalene, was the most involved in the bioactivity. Similar results were obtained with β-carotene bleaching assay, where the IC50 values were 0.291±0.024mg/ml for C. lechleri essential oil, 0.164±0.013 and 1.34×10−4±10−5mg/ml for thyme essential oil and BHA, respectively. (HP)TLC-bioautographic assay performed with Gram positive and Gram negative bacteria revealed a minimum inhibitory concentration (MIC) values comprised between 0.10mg/ml (Escherichia coli) and 10.10mg/ml (for e.g. Pseudomonas aeruginosa), and the fraction mainly characterised by sesquicineole (97.38%) as the most involved in antibacterial capacity. Ames test employing Salmonella typhimurium TA98 and TA100 with and without a metabolic activation mixture (S9 mix) demonstrated the absence of mutagenicity of the C. lechleri essential oil between a concentration range of 10−2 and 100mg/plate. The same results were achieved by Saccharomyces cerevisiae D7 str