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 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.

Brazil has a great variety of native plants which could be explored and among them guabiju (Myrcianthes pungens) stands out. Thus, this study consisted of isolating pentacyclic triterpenes, α and β-amyrin from guajibu leaves, and determine the antioxidant activity. The leaves were dried, pulverized and submitted to a dynamic maceration process with ethanol 96º GL, concentrated to obtain crude leaf extract (CLE). CLE was eluted with dichloromethane until total depletion, resulting in a dichloromethane fraction (FRDicl) which was concentrated and analyzed by GC/MS and NMR.The result of the chemical analysis revealed the presence of pentacyclic triterpenes of oleanane (βamyrin), and ursane (α-amyrin) groups. The β-carotene bleaching method revealed a high antioxidant activity for the CLE as well as for FRDicl. The antioxidant protection equivalent to the trolox were of 137 and 129%, respectively at 500 µg/mL. The antioxidant potential of FRDicl can be explained by the presence of α and β-amyrins.

This study reports the results of ab initio and density functional theory (DFT) electronic structure calculations as well as (3)J(HH) experimental and calculated coupling constant data obtained in the investigation of the conformational equilibrium of 3-halo-derivatives of 1-methylpyrrolidin-2-one. The five-membered ring assumes an envelope conformation owing to the plane of formation of the O═C-N-R bond, with C4 forming the "envelope lid". When the conformation changes, the "lid" alternates between positions above and below the amide plane. The α-carbonyl halogen assumes two positions: a pseudo-axial and a pseudo-equatorial. In the gaseous phase, the calculations indicate that the pseudo-axial conformer is more stable and preferable going down the halogen family. Natural bond orbital analysis showed that electronic delocalization is significant only for the iodo derivative. In the other derivatives, the electrostatic repulsion between oxygen and the halogen determines the conformational equilibrium. When the solvated molecule was taken into account, the pseudo-equatorial conformer population increased with the relative permittivity of the solvent. This variation was strong in the fluoro derivative, and the preference was inverted. In the chlorine derivative, the two populations became closer in methanol and acetonitrile. In the bromine and iodine derivatives, the percentage of pseudo-equatorial conformer increased only slightly owing to the dipole moment of the conformation: the pseudo-equatorial conformation has a greater dipole moment and thus is stable in media with high relative permittivity.

A highly efficient regioselective synthesis of 1,4,5-trisubstituted pyrazoles and pyrazolo[3,4-d]pyridazinones from enamino diketone along with a theoretical and experimental study of the chemical reactivity enamino diketone.