In order to produce bioactive derivatives of carvacrol and thymol, nine derivatives of each compound were prepared through modifications the phenolic hydroxyl group. The structures of compounds were confirmed by spectral data from MS, IR and NMR. Carvacrol, thymol and derivatives were submitted to the evaluation of the inhibition of the enzyme acetylcholinesterase, using a colorimetric method in which the inhibition of the enzyme is measured by coloration, and larvicidal activity against Aedes aegypti. Derivatives carvacryl acetate-1b and thymyl hexanoate-2b showed the best results for the inhibition of the acetylcholinesterase enzyme, and for the larvicidal activity the derivatives 1a, 1b, 1c, 3h, 2a, 2b, 2c and 4h showed positive results, emphasizing compound thymyl 4-methoxybenzoate-4h which showed LC50 values of 23.60 ppm, considered a very good result.

Five new withanolides, designated as 15-oxo-nicaphysalin B, 6β,7α-dihydroxynicandrenone 10, 24α,25β-dihydroxy-nicandrenone-2 and a mixture of the epimers 17-(1α/1β-methylpropanone)-nicandrenone, in addition to six known others, were isolated from the leaf acetone extract from Nicandra physalodes. The complete structures of the five new withanolides, particularly their relative stereochemistries, were established by extensive spectroscopic analyses, including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HRESIMS). The main isolated withanolides were evaluated for their antibacterial, antifungal and larvicidal properties, but, except nicandrenone, which showed marginal larvicidal activity, none of them was active.

Stemodinol, a new natural compound, together with known compounds including jaceidin, stemodin, stemodinoside B, isocrenatoside, verbascoside, crenatoside, and isoverbascoside, were isolated from Stemodia maritima Linn. The antioxidant (DPPH method) and antimicrobial activities of stemodin, stemodinoside B, and crenatoside were investigated. Among the components tested, only crenatoside isolated from the roots showed a high antioxidant power. Stemodin and stemodinoside B exhibited antibacterial activities.

The chemical investigation of the stems and branches of Macroptilium lathyroides led to the isolation of a mixture of β-sitosterol and stigmasterol. The extracts from the roots allowed the isolation of lasiodiplodin, a mixture of stigmast-4-en-6β-ol-3-one and stigmast-4,22-dien-6β-ol-3-one, de-O-methyllasiodiplodin, genistein and lupinalbin A. The structures of the isolated compounds were assigned on the basis of their NMR data, including comparison of their spectral data with values described in the literature. The antibacterial activity of crude extracts from stems, branches and roots was evaluated. This is the first report involving the chemical investigation of this species.

The essential oil from the leaves of Myrcia ovata Cambess., commonly used in Brazil for the treatment of gastric illnesses, was screened for antimicrobial activity and action in the formation of microbial biofilms by Enterococcus faecalis. The oil was obtained by hydrodistillation using a clevenger-type system. Its chemical composition was analyzed using GC and GC-MS. Both MIC and MBC of the essential oil were determined by broth microdilution techniques and agar dilution method. The essential oil showed antimicrobial activity against E. faecalis, Escherichia coli, Pseudomonas aeruginosa, Salmonella choleraesuis, Staphylococcus aureus, Streptococcus pneumoniae and Candida parapsilosis. The results showed that the essential oil of M. ovata Cambess. was effective against the formation of biofilm by E. faecalis when compared with the control. Four volatile compounds, representing 92.1 % of the oil, were identified and geranial was the major component (50.4 %). At the best of our knowledge, this is the first report of the chemical composition and antimicrobial activity of the essential oil from leaves of M. ovata.

Um novo diterpeno, (5S*,8S*,9R*,10S*)-11β,12β-epoxi-9α-hidróxi-19(4→3) abeo-abieta-3,13-dieno-19,18-olideo, e as substâncias conhecidas estemodina, D-manitol, ácido betulínico, uma mistura de 3β-O-β-D-glicopiranosil-β-sitosterol e 3β-O-β-D-glicopiranosilestigmasterol, e 5,7,4'-triidróxi-3,8,3'-trimetoxiflavona, foram isolados das folhas e talos de Stemodia maritima. A elucidação estrutural de todas as substâncias baseou-se na interpretação de dados espectrais, principalmente RMN (1D e 2D) e espectrometria de massa (EM), envolvendo comparação com valores descritos na literatura.

A new diterpene, (5S*,8S*,9R*,10S*)-11β,12β-epoxy-9α-hydroxy-19(4→3) abeo-abieta-3,13-diene-19,18-olide, together with the known compounds stemodin, D-mannitol, betulinic acid, a mixture of 3β-O-β-D-glucopyranosyl-β-sitosterol and 3β-O-β-D-glucopyranosylstigmasterol and 5,7,4'-trihydroxy-3,8,3'-trimethoxyflavone were isolated from the leaves and stems of Stemodia maritima. Structural elucidation of all compounds was based on interpretation of spectral data, mainly NMR (1D and 2D) and MS, including comparison with values described in the literature.

No presente trabalho descreve-se a composição química dos óleos essenciais de Rollinia leptopetala R.E. Fries (Annonaceae) e as atividades larvicidas dos óleos essenciais, do extrato metanólico das raízes desta espécie e do alcalóide oxoaporfinico, liriodenina (1), frente às larvas no terceiro estágio do mosquito Aedes aegypti. O extrato metanólico mostrou-se ativo com CL50 64,6 ± 1,5 ppm e uma forte atividade foi exibida para o composto (1), CL50 3,6 ± 0,4 ppm. Os óleos essenciais das folhas e galhos também mostraram atividade com CL50 104,7 ± 0,2 and 34,7 ± 0,3 ppm, respectivamente. Estes dados sugerem que R. leptopetala é fonte potencial de larvicidas naturais. A composição química do óleo essencial e as atividades descritas são comunicadas pela primeira vez.

The aim of present study was to describe the chemical composition of the essential oils from the leaf and stem of Rollinia leptopetala R. E. Fries (Annonaceae) and to evaluate the larvicidal activities of these essential oils, of the methanol extract from roots of this plant and of the oxoaporphine alkaloid, liriodenine (1) against the third-instar of Aedes aegypti larvae. The methanol extract from the roots showed larvicidal activity with LC50 64.6 ± 1.5 ppm. Higher activity was observed for the isolated alkaloid liriodenine (1), LC50 3.6 ± 0.4 ppm. The essential oils from the leaves and stems, also exhibited larvicidal activity with LC50 104.7 ± 0.2 and 34.7 ± 0.3 ppm, respectively. These results suggest R. leptopetala as a source of natural larvicidal compounds. This is the first report about the chemical composition and larvicidal activity of the leaf and stem essential oils of R. leptopetala.

The chemical investigation of the methanolic extract of the aerial part of Sebastiania macrocarpa allowed the isolation of the mixture of steroids β-sitosterol and stigmasterol, gallic acid, and scopoletin. The hexane extract of the roots allowed the isolation of the triterpene lupeol and of the macrociclic diterpene (+)-tonantzitlolone. The structures of all compounds isolated were identified on the basis of their spectral data and by comparison of their spectral data with values described in the literature. This is the first report involving the chemical investigation of this species.

Duas novas e duas conhecidas saponinas triterpênicas foram isoladas da casca do caule de Pentaclethra macroloba. As estruturas foram determinadas usando uma combinação de técnicas de RMN homo- (1D: RMN¹H, RMN13C-{¹H}, RMN13C-DEPT135; 2D: ¹H-¹H-COSY, ¹H-¹H-TOCSY, ¹H-¹H-NOESY) and heteronuclear 2D (HMQC and HMBC), espectros de massas obtidos com ionização por pulverização eletrônica (ESIMS) e métodos químicos. As estruturas das duas novas saponinas triterpênicas foram estabelecidas como 3beta-O-{[beta-D-glicopiranosil-(1->3)-alfa-L-ramnopiranosil-(1->2)],beta-D-glicopiranosil- (1->4)}-alfa-L-arabinopiranosilhederagenina (3) e ácido 3beta-O-{[beta-D-glicopiranosil-(1->4)-beta-D-glicopiranosil-(1->3)-alfa-L-ramnopiranosil- (1->2)],beta-D-glicopiranosil(1->4)}-alfa-L-arabinopiranosiloleanólico (4).

Two new and two known triterpenoid saponins were isolated from the stem bark of Pentaclethra macroloba. Their structures were determined using a combination of homo- (1D ¹H NMR, 13C NMR-HBBD and 13C NMR-DEPT) and heteronuclear 2D NMR techniques (¹H-¹H-COSY, ¹H-¹H-TOCSY, ¹H-¹H-NOESY, HMQC and HMBC), ESIMS and chemical methods. The structures of the two new pentacyclic triterpenoid saponins were established as 3beta-O-{[beta-D-glucopyranosyl-(1->3)-alpha-L-rhamnopyranosyl-(1->2)],beta-D- glucopyranosyl-(1->4)}-alpha-L-arabinopyranosylhederagenin (3) and 3beta-O-{[beta-D-glucopyranosyl-(1->4)-beta-D-glucopyranosyl-(1->3)-alpha-L-rhamnopyranosyl- (1->2)],beta-D- glucopyranosyl(1->4)}-alpha-L-arabinopyranosyloleanolic acid (4).