Optimization extraction study for the isolation of a bioactive diterpene from Plectranthuns ornatus Codd.

Tuberculosis (TB) infects thousands of people every year and is a serious public health problem worldwide. The causative agent, Mycobacterium tuberculosis, is a bacterium that has elaborated survival mechanisms in the host.

The discovery of new antibiotics is essential for reducing TB deaths and natural products offer an excellent starting point for the discovery of these compounds due to their structural and functional diversity.

The genus Plectranthus belonging to the Lamiaceae family, such as mint and sage, exhibit a wide range of ethnobotanical uses. The P.ornatus species has diuretic, antipyretic, analgesic, antibiotic and anti-inflammatory properties and is used to relieve stomach and liver disorders.

Halimane's backbone diterpene (11R*-acetoxy-halima-5,13E-dien-15-oic acid) was previously isolated for the first time from an acetone extract of P.ornatus. This compound is described due to its antimicrobial, namely antitubercular activity. Thus, in this work, for a large-scale of the compound isolation, we optimized its extraction. Moreover, an acetonic ultrasound extraction was performed (extraction yield 7.082% (w / w)). Chromatographic isolation of 5.3 mg of pure diterpene, identified by HPLC-DAD, was also performed by comparison with an authentic sample. In future studies, it will be possible the exhaustive isolation of the diterpene of this extract allowing new biological studies with potential for the development of new tuberculostatic drugs.