Antimicrobial and Antioxidant Activities of the Extract and Fractions of Tetradenia riparia (Hochst.) Codd (Lamiaceae) Leaves from Brazil

Tetradenia riparia (Lamiaceae) is native to Central Africa popularly known as myrrh, used in folk medicine to treat various diseases like malaria, gastroenteritis, and tropical skin disease. This research was to evaluate the antioxidant and antibacterial activities of the crude extract (CE) and fractions (FR) of the T. riparia by classical chromatography. The CE of T. riparia leaves was submitted to column chromatographic fractionation to obtain four fractions of the interest, which were identified by nuclear magnetic resonance and gas chromatograph coupled to mass spectrum: FR-I (abieta-7,9(11)-dien-13-β-ol), FR-II (Ibozol), FR-III (8 (14), 15-sandaracopimaradiene-2α, 18-diol and 8 (14), 15-sandaracopimaradiene-7α, 18-diol), and FR-IV (Astragalin, Boronolide and Luteolin). Total phenol content of CE and FR were measured, and antioxidant action by methods of DPPH (2,2-diphenyl-1-picrylhydrazyl), β-carotene/linoleic acid system, and ferric reducing/antioxidant power (FRAP) and the antibacterial activity was evaluated by the broth microdilution method with the determination of the minimum inhibitory concentration (MIC). The FR-IV presented antioxidant potential with 181.67 μg gallic acid/mg, IC 50 of 0.61 μg/mL by DPPH method, 55.61% oxidation protection by β-carotene/linoleic acid system and 4.59 µM ferrous sulfate/mg of sample by FRAP, and the FR-I showed higher antibacterial potential on the strain Staphylococcus aureus with MIC 0.98 μg/mL , Enterococcus faecalis and Bacillus cereus with MIC 31.2 μg/mL. Thus, the fractionation of CE was extremely important to detect fractions with potential activities, and investigations are necessary regarding the mechanism of action and action in vivo. Graphical Abstract