Antimicrobial diterpene from the brazilian termite nasutitermes macrocephalus (Isoptera: Termitidae: Natutitermitinae)

Abstract

Termites are insects with a complex social organization on castes among which soldiers are the only responsible for the colony defense. The soldiers of the Nasutitermes genus use chemical defense, which comprises a mixture of mono, sesqui and mainly diterpenes. The new diterpene 2b,3a-dihydroxy-trinervita-1(15),11-diene, found in Nasutitermes macrocephalus, was isolated using preparative high performance liquid chromatography (HPLC) and identified by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) techniques. The absolute stereochemistry determined was supported by ab initio calculations and by comparison of the experimental circular dichroism data with the theoretical results. The isolated diterpene was evaluated against the bacteria Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), and the fungi Candida albicans and Aspergillus brasiliensis. The isolated diterpene presented minimal inhibitory concentrations of 62.5 and 62.5 µg mL-1 against S. aureus and C. albicans, respectively.