In Vitro and In Silico Study of the α-Glucosidase and Lipase Inhibitory Activities of Chemical Constituents from Piper cumanense (Piperaceae) and Synthetic Analogs.

Digestive enzymes are currently considered important therapeutic targets for the treatment of obesity and some associated metabolic diseases, such as type 2 diabetes. Piper cumanense is a species characterized by the presence of bioactive constituents, particularly prenylated benzoic acid derivatives. In this study, the inhibitory potential of chemical constituents from P. cumanense and some synthesized compounds was determined on digestive enzymes (pancreatic lipase (PL) and α-glucosidase (AG)). The methodology included isolating and identifying secondary metabolites from P. cumanense, synthesizing some analogs, and a molecular docking study. The chemical study allowed the isolation of four prenylated benzoic acid derivatives (1-4). Four analogs (5-8) were synthesized. Seven compounds were found to significantly inhibit the catalytic activity of PL with IC50 values between 28.32 and 55.8 µM. On the other hand, only two compounds (6 and 7) were active as inhibitors of AG with IC50 values lower than 155 µM, standing out as the potential multitarget of these chromane compounds. Enzyme kinetics and molecular docking studies showed that the bioactive compounds mainly interact with amino acids other than those of the catalytic site in both PL and AG. This work constitutes the first report on the antidiabetic and antiobesity potential of substances derived from P. cumanense.

Multitarget Action of Xanthones from Garcinia mangostana against α-Amylase, α-Glucosidase and Pancreatic Lipase.

Digestive enzymes such α-amylase (AA), α-glucosidase (AG) and pancreatic lipase (PL), play an important role in the metabolism of carbohydrates and lipids, being attractive therapeutic targets for the treatment of type 2 diabetes and obesity. Garcinia mangostana is an interesting species because there have been identified xanthones with the potential to inhibit these enzymes. In this study, the multitarget inhibitory potential of xanthones from G. mangostana against AA, AG and PL was assessed. The methodology included the isolation and identification of bioactive xanthones, the synthesis of some derivatives and a molecular docking study. The chemical study allowed the isolation of five xanthones (1-5). Six derivatives (6-11) were synthesized from the major compound, highlighting the proposal of a new solvent-free methodology with microwave irradiation for obtaining aromatic compounds with tetrahydropyran cycle. Compounds with multitarget activity correspond to 2, 4, 5, 6 and 9, highlighting 6 with IC50 values of 33.3 µM on AA, 69.2 µM on AG and 164.4 µM on PL. Enzymatic kinetics and molecular docking studies showed that the bioactive xanthones are mainly competitive inhibitors on AA, mixed inhibitors on AG and non-competitive inhibitors on PL. The molecular coupling study established that the presence of methoxy, hydroxyl and carbonyl groups are important in the activity and interaction of polyfunctional xanthones, highlighting their importance depending on the mode of inhibition.

Fumigant toxicity and biochemical effects of selected essential oils toward the red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae).

Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is an insect popularly known as the red flour beetle, it is widely distributed worldwide and can cause serious damage to stored grains. Chemical control is the most used method for managing this pest, however, some substances are toxic to mammals and the environment. Therefore, the development of new effective and safe insecticides is necessary. Essential oils (EOs) can be considered as a potential alternative in the development of pesticides due to their physicochemical properties and varied effects against insects. In the current study, was determined the fumigant toxicity and biochemical effects of selected essential oils against T. castaneum. The 23 selected EOs were characterized by GC-MS and their fumigant lethal concentrations were determined. An exploratory Cluster analysis was performed to find a relationship between fumigant toxicity and chemical composition. Finally, the inhibition of the catalytic activity of acetylcholinesterase (AChE), glutathione S-transferase (GST) and catalase (CAT) was evaluated using protein homogenates obtained from T. castaneum. The results indicated that EOs with the highest fumigant potential were those with greater diversity in their composition, while the least active EOs presented mainly monoterpenes. The most active EOs were those obtained from Foeniculum vulgare and Zanthoxylum monophyllum with LC50 values of 16.23 and 18.54 µL/L air respectively. Regarding the inhibition of the enzymatic activity of the 23 EOs evaluated at 500 µL/L, only two caused an inhibition greater that 50% on AChE, which corresponded to EOs from Piper nigrum and Rosmarinus officinalis. Likewise, EOs from C. sinensis, Piper aduncum and Zanthoxylum monophyllum were the only ones able to inhibiting GST activity by more than 50%. Respecting CAT inhibition, 7 EOs caused and inhibition greater than 50%, highlighting those from Lavandula angustifolia, C. sempervirens and Eucalyptus sp. These results show that the EOs evaluated in this study seems to be a promising bio-controller of T. castaneum since have high fumigant toxicity and exert different mechanisms of action.

Antifungal Activity of Chemical Constituents from Piper pesaresanum C. DC. and Derivatives against Phytopathogen Fungi of Cocoa.

In this study, the antifungal potential of chemical constituents from Piper pesaresanum and some synthesized derivatives was determined against three phytopathogenic fungi associated with the cocoa crop. The methodology included the phytochemical study on the aerial part of P. pesaresanum, the synthesis of some derivatives and the evaluation of the antifungal activity against the fungi Moniliophthora roreri, Fusarium solani and Phytophthora sp. The chemical study allowed the isolation of three benzoic acid derivatives (1-3), one dihydrochalcone (4) and a mixture of sterols (5-7). Seven derivatives (8-14) were synthesized from the main constituents, of which compounds 9, 10, 12 and 14 are reported for the first time. Benzoic acid derivatives showed strong antifungal activity against M. roreri, of which 11 (3.0 ± 0.8 µM) was the most active compound with an IC50 lower compared with positive control Mancozeb® (4.9 ± 0.4 µM). Dihydrochalcones and acid derivatives were active against F. solani and Phytophthora sp., of which 3 (32.5 ± 3.3 µM) and 4 (26.7 ± 5.3 µM) were the most active compounds, respectively. The preliminary structure-activity relationship allowed us to establish that prenylated chains and the carboxyl group are important in the antifungal activity of benzoic acid derivatives. Likewise, a positive influence of the carbonyl group on the antifungal activity for dihydrochalcones was deduced.

Cinerin C: a macrophyllin-type bicyclo[3.2.1]octane neolignan from Pleurothyrium cinereum (Lauraceae).

The structure of naturally-occurring cinerin C [systematic name: (7S,8R,3'R,4'S,5'R)-Δ(8')-4'-hydroxy-5,5',3'-trimethoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan], isolated from the ethanol extract of leaves of Pleurothyrium cinereum (Lauraceae), has previously been established by NMR and HRMS spectroscopy, and its absolute configuration established by circular dichroism measurements. For the first time, its crystal structure has now been established by single-crystal X-ray analysis, as the monohydrate, C(22)H(26)O(7)·H(2)O. The bicyclooctane moiety comprises fused cyclopentane and cyclohexenone rings which are almost coplanar. An intermolecular O-H···O hydrogen bond links the 4'-OH and 5'-OCH(3) groups along the c axis.

In vitro anti-inflammatory effects of naturally-occurring compounds from two Lauraceae plants

The in vitro anti-inflammatory effects of seven known lignans and one dihydrochalcone isolated from the leaves of two Lauraceae species (Pleurothyrium cinereum and Ocotea macrophylla), were evaluated through the inhibition of COX-1, COX-2, 5-LOX and the aggregation of rabbit platelets induced by PAF, AA and ADP. (+)-de-4"-O--methylmagnolin 4 was found to be a potent COX-2/5-LOX dual inhibitor and PAF-antagonist (COX-2 IC50 2.27 µM; 5-LOX IC50 5.05 µM; PAF IC50 2.51 µM). However, all compounds exhibited an activity at different levels, indicating good anti-inflammatory properties to be considered in further structural optimization studies.

Os efeitos anti-inflamatórios in vitro de sete conhecidos lignanos e uma dihidrocalcona isolados das folhas de duas espécies da família Lauraceae (Pleurothyrium cinereum e Ocotea macrophylla) foram avaliados por meio da inibição da COX1, COX-2, 5-LOX e agregação de plaquetas de coelhos induzida por PAF, AA e ADP. A (+)-4"-O-metilmagnolina-4 foi encontrada como mais potente inibidora tanto da COX-2 quanto de 5-LOX e antagonista de PAF (COX-2 IC50 2,27 µM; 5- LOX IC50 5,05 µM; PAF IC50 2,51 µM). Entretanto, todos compostos mostram uma atividade em intensidades diferentes, indicando boas propriedades anti-inflamátorias a serem consideradas para futuros estudos de modificações e otimização estruturais.

In vitro anti-inflammatory effects of naturally-occurring compounds from two Lauraceae plants.

The in vitro anti-inflammatory effects of seven known lignans and one dihydrochalcone isolated from the leaves of two Lauraceae species (Pleurothyrium cinereum and Ocotea macrophylla), were evaluated through the inhibition of COX-1, COX-2, 5-LOX and the aggregation of rabbit platelets induced by PAF, AA and ADP. (+)-de-4"-O-methylmagnolin 4 was found to be a potent COX-2/5-LOX dual inhibitor and PAF-antagonist (COX-2 IC(50) 2.27 µM; 5-LOX IC(50) 5.05 µM; PAF IC(50) 2.51 µM). However, all compounds exhibited an activity at different levels, indicating good anti-inflammatory properties to be considered in further structural optimization studies.

PAF-antagonistic bicyclo[3.2.1]octanoid neolignans from leaves of Ocotea macrophylla Kunth. (Lauraceae).

Di-nor-benzofuran neolignan aldehydes, Delta(7)-3,4-methylenedioxy-3'-methoxy-8',9'-dinor-4',7-epoxy-8,3'-neolignan-7'-aldehyde (ocophyllal A) 1, Delta(7)-3,4,5,3'-tetramethoxy-8',9'-dinor-4',7-epoxy-8,3'-neolignan-7'-aldehyde (ocophyllal B) 2, and macrophyllin-type bicyclo[3.2.1]octanoid neolignans (7R, 8R, 3'S, 4'S, 5'R)-Delta(8)'-4'-hydroxy-5'-methoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan (ocophyllol A) 3, (7R, 8R, 3'S, 4'S, 5'R)-Delta(8)'-4'-hydroxy-3,4,5'-trimethoxy-2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan (ocophyllol B) 4, (7R, 8R, 3'S, 4'S, 5'R)-Delta(8)'-4'-hydroxy-3,4,5,5'-tetramethoxy-2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan (ocophyllol C) 5, as well as 2'-epi-guianin 6 and (+)-licarin B 7, were isolated and characterized from leaves of Ocotea macrophylla (Lauraceae). The structures and configuration of these compounds were determined by extensive spectroscopic analyses. Inhibition of platelet activating factor (PAF)-induced aggregation of rabbit platelets were tested with neolignans 1-7. Although compound 6 was the most potent PAF-antagonist, compounds 3-5 showed some activity.

3,6-Dihydroxy-2-(11-phenylundecanoyl)cyclohex-2-en-1-one from Virola venosa bark.

The structure of the title compound, C23H32O4, an arylalkanone isolated from the petroleum ether fraction of the ethanol extract of the bark of Virola venosa, has been established by NMR spectroscopy and, for the first time, by X-ray structure analysis. Two independent molecules of the same enantiomer are present in the unit cell. Both molecules exhibit an intramolecular hydrogen bond, which can be correlated with a rare signal observed at 18.28 p.p.m. in the 1H NMR spectrum. The packing, in space group P1, is determined by a pseudo-center of symmetry leading to a short intermolecular contact, which is present in one molecule but does not occur in the other. As a consequence, the O-C-C-O torsion angles [-16.9 (3) and -12.7 (3) degrees ] through the ketone and its adjacent hydroxy group are significantly different in the two molecules.