Molecular networking for the study of antimicrobial activity of Calophyllum inophyllum L. oil resin

Calophyllum inophyllum L. (Calophyllaceae) is a tropical tree traditionally used in folk medicine as anti-inflammatory, fungicidal, healing agent and antimicrobial agent. Its properties are explained by a high content in coumarins, xanthones and triterpenes [1]. Particularly, tamanu oil is a traditional Tahitian medicine. This oil is extracted from dried fruits (picture below) and contains a resinous fraction [2] possessing antimicrobial properties. The aim of our study was to investigate the molecular content-activity relationships of the resinous fraction from tamanu oil by aims of molecular networks. Molecular networking is a recent approach which allows to represent LC-MS² data according to similarities between fragmentation pathways [3] [4]. First of all, five major known specific markers were isolated and identified from the resin: inophyllum E, inophyllum J, tamanolid, inophyllum P and (E)-5-methoxy-2,2-dimethyl-6-(2-methylbut-2-enoyl)-10-propyl-2H,8H-pyrano[2,3-f]chromen-8-one [5], allowing the further annotation of specific clusters in molecular networks. Then, the antimicrobial activity of the crude oil-resin and fractions thereof was evaluated against seventeen bacteria strains and the minimal inhibitory concentration (MIC) measured. Finally, the molecular content of the tested samples including resin and its fractions was explored by UHPLC-HRMS² analysis and a molecular network using a “fraction layout” was built. The relationship between antimicrobial activity of fractions and the presence of coumarins and acid chromanones will be discussed.

Fig. 1 Picture of dried tamanu fruits (J.B Friday)

• References

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