Volatile Secondary Metabolites from Colombian Croton malambo (Karst) by Different Extraction Methods and Repellent Activity of its Essential Oil

Abstract

Croton malambo (Karst), is a small tree that grows in the northern Colombian coast and eastern Venezuela. Hydrodistillation (HD), microwave-assisted hydrodistillation (MWHD), simultaneous distillation-solvent extraction (SDE) and supercritical fluid (CO₂) extraction (SFE), were employed to isolate volatile secondary metabolites from Colombian C. malambo (Karst) barks. The essential oil and extracts were analyzed by GC-MS. More than 20 individual components in the various extracts were identified. Methyl eugenol was the main component found in the HD and MWHD essential oils (63.5, 74.6 %), SDE and SFE extracts (67.1 and ca. 67.9 %<, respectively), followed by linalool (5.6, 3.4, 4.0 %), trans-β-caryophyllene (2.5, 2.6, 2.1 and 6.5 %) and trans-methyl isoeugenol (1.5, 1.9, 3.2 and 4.2 %). The oil obtained by HD presented a mean lethal concentration (LC₅₀) against Artemia franciscana of 15.32 µg/mL and 2.20 µg/mL after 24 and 48 h exposition, respectively. These results show that C. malambo essential oil is an excellent source of methyl eugenol, but it is moderately cytotoxic. In addition, was evaluated the repellent activity of C. malambo essential oils against an important stored-product insect pest: Tribolium castaneum Herbst. These oils had high repellent effects on T. castaneum (92 % ± 3) at 0.2 µL/cm² after 4 h of exposure.

Key words:

• Croton malambo
• essential oils
• volatiles
• extraction
• GC-MS
• Tribolium castaneum Herbst

Acknowledgements

University of Cartagena, CENIVAM-University of Santander and COLCIENCIAS (Contract RC 432 – 2004).