ABSTRACT
The essential oils from leaves, twigs and trunk bark of Onychopetalum amazonicum R.E. Fr. (Annonaceae), obtained by hydrodistillation, were analysed by GC and GC-MS, and also were evaluated for in vitro antimicrobial activity. Forty-one compounds, which correspond to 75.0-92.2% of the oil components, were identified. Major compounds were sesquiterpenes, including (E)-caryophyllene, caryophyllene oxide, spathulenol, α-gurjunene, allo-aromadendrene and α-epi-cadinol. The oils were evaluated for antimicrobial activities against four bacteria strains and five pathogenic fungi. The oil of the trunk bark exhibited good activity against Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 10538 and Kocuria rhizophila ATCC 9341, with a minimal inhibitory concentration of 62.5 µg/mL. The essential oil composition and the antimicrobial evaluation are reported for the first time for the genus Onychopetalum.
Subject(s)
Annonaceae/chemistry , Anti-Infective Agents/isolation & purification , Oils, Volatile/chemistry , Oils, Volatile/pharmacology , Sesquiterpenes , Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Azulenes/isolation & purification , Escherichia coli/drug effects , Gas Chromatography-Mass Spectrometry , Microbial Sensitivity Tests , Oils, Volatile/isolation & purification , Plant Leaves/chemistry , Polycyclic Sesquiterpenes , Sesquiterpenes/analysis , Sesquiterpenes/isolation & purification , Staphylococcus epidermidis/drug effects , Terpenes/isolation & purificationABSTRACT
INTRODUCTION: The Annonaceae family is known as a promising abundant source of secondary metabolites, especially annonaceous acetogenins, terpenoids and isoquinoline-derived alkaloids. Although widely investigated from the phytochemical viewpoint, this family still presents some largely unexplored genera, e.g. the Bocageopsis. OBJECTIVE: To investigate the alkaloid content of Bocageopsis pleiosperma Maas using direct infusion electrospray ionisation ion trap tandem mass spectrometry (ESI-IT-MS(n)) analysis. METHODOLOGY: Dichloromethane extracts of aerial parts were subjected to acid-base partitioning to yield the alkaloidal fractions. These fractions were analysed by direct infusion into a (+)ESI-IT-MS(n) system. The alkaloidal fraction from the leaves was also obtained on a large scale and subjected to chromatographic separation. RESULTS: The tentative MS(n) -based identification of alkaloids in leaves, twigs and trunk bark showed that aporphine alkaloids were restricted to the leaves and twigs, tetrahydroprotoberberine alkaloids were only found in the twigs and trunk bark while benzylisoquinoline alkaloids were found in the leaves, twigs and trunk bark. Chromatographic separation of the leaf alkaloidal fraction yielded the aporphine alkaloids nornuciferine, asimilobine and isoboldine, the ß-carboline alkaloid tetrahydroharman and some mixtures containing benzylisoquinoline and aporphine alkaloids, all described for the first time in the Bocageopsis genus. Furthermore, tetrahydroharman has not previously been reported in the Magnoliales order. CONCLUSION: Direct infusion ESI-IT-MS(n) analysis of alkaloids allowed fast recognition of alkaloidal classes previously reported in the Annonaceae family, aiding the chromatographic step and allowing a selective isolation of compounds previously not identified in the Bocageopsis genus.
