The fruit of the Morinda citrifolia species popularly known as "noni" has been widely used in folk medicine for diverse therapeutic purposes including in the treatment of infectious diseases. Given this, we tested the essential oil from M. citrifolia fruits obtained by hydrodistillation against fungi and bacteria. The oil was rich in short-chain fatty acids: octanoic acid (38.7%) and hexanoic acid (20.0%) were identified as the major constituents after analysis of oil by GC/MS. The oil showed antimicrobial activity against all the microorganisms tested, mainly against fungi Candida albicans and C. utilise with minimal inhibitory concentration of 39 and 78 μg.mL −1 , respectively. The antimicrobial potential of the oil was drastically reduced after it was subjected to the esterification reaction, indicating that the carboxyl group is responsible for the strong oil activity.

No abstract

Abstract. Fatty acid profiles and antimicrobial activity of ten oils from tropical fruit seeds were determined. The fatty acid composition of the oils was determined by GC-MS analysis that allowed identification of oleic, linoleic, palmitic, and stearic acids as major constituents.  Oil samples exhibited antimicrobial activity against fungus, yeast, Gram-positive and Gram-negative bacteria.  Eugenia uniflora seed oil was the most active for bacteria with Minimum Inhibitory Concentration (MIC) values ​​from 39.0 to 1250 μg mL-1. E. uniflora oil showed strong activity against bacteria Staphylococcus aureus, Enterococcus faecalis and Klebsiella pneumoniae as wells as for yeast Candida utilis with MIC of 312.5 μg mL-1. The carboxylic group of acids identified was associated with the antimicrobial activity considering that the esterified oils showed MIC greater than 2000 μg mL-1. Our study showed that the tropical fruit seeds have antimicrobial potential and their residues from the fruit juice industry can be used as a source of bioactive products. Keywords: Bacteria; seed oil; fatty acids; tropical fruits; fung.   Resumen. Se determinaron los perfiles de ácidos grasos y la actividad antimicrobiana de diez aceites de semillas de frutas tropicales. La composición de ácidos grasos de los aceites se determinó mediante análisis CG-EM que permitió identificar los ácidos oleico, linoleico, palmítico y esteárico como constituyentes mayoritarios. Las muestras de aceite exhibieron actividad antimicrobiana contra hongos, levadura, Gram-positivas y bacterias Gram-negativas. El aceite de semilla de Eugenia uniflora fue el más activo para bacterias con valores de Concentración Inhibitoria Mínima (CIM) de 39,0 a 1250 μg mL-1. El aceite de E. uniflora mostró una fuerte actividad contra las bacterias Staphylococcus aureus, Enterococcus faecalis y Klebsiella pneumoniae, así como contra la levadura Candida utilis con CIM de 312.5 μg mL-1. El grupo de ácidos carboxílicos identificado se asoció con la actividad antimicrobiana considerando que los aceites esterificados presentaron CIM major a 2000 μg mL-1. Nuestro estudio mostró que las semillas de frutas tropicales tienen potencial antimicrobiano y sus residuos de la industria de jugos de frutas pueden usarse como fuente de productos bioactivos. Palabras clave: Bacteria; aceite de semilla; ácidos grasos; frutas tropicales; hongo.