Chemical composition, antimycobacterial and anti-inflammatory activities of iridoids and triterpene from Psychotria suterella (Rubiaceae)

Abstract

Background: Psychotria species are known for their medicinal properties and psychoactive activities. Extracts of Psychotria suterella showed anti-tuberculosis (TB) activity; however, the substances related to this activity are unknown. Objectives: The objective was to study on the chemical constituents of the leaves of plant and evaluate the anti-TB and anti-inflammatory activity. Materials and Methods: Solvent extraction, partition, and column chromatography were used to separate the compounds. The structures of these compounds were determined by extensive one dimensional-and two dimensional-Nuclear Magnetic Resonance, infrared and mass spectrometry spectroscopic analyses. Some compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis and their ability to inhibit nitric oxide (NO) production by lipopolysaccharide-stimulated macrophages. Results: This study led to the isolation and characterization of a new iridoid, named epi-geniposidic acid (1), together with nine known compounds: geniposidic acid (2), 3-O-acethyloleanolic acid (3), pomolic acid (4), spinolic acid (5), maslinic acid (6), tormentic acid (7), methyl oleanolate (8), lyalosidic acid (9), and strictosidinic acid (10). Triterpene 3-O-acethyloleanolic acid (3) was found to display antimycobacterial activity against M. tuberculosis H37Rv strain and hypervirulent strain (minimum inhibitory concentration 6.7 ± 0.1 and 89.1 ± 1.3 μg/mL, respectively). Epi-geniposidic acid (1), geniposidic acid (2), and 3-O-acethyloleanolic acid (3) showed promising inhibitory activities against NO production (IC50 range 4.12–5.12 μg/mL). The iridoid mixture showed no cytotoxicity against RAW 264.7 macrophages up to a concentration of 100 μg/mL. Conclusion: P. suterella presents relevant biological properties and should be considered for further in vivo studies using a pulmonary TB model.