Livia Marques Casanova

Identification of chicoric acid as a hypoglycemic agent from Ocimum gratissimum leaf extract in a biomonitoring in vivo study.

Ocimum gratissimum L. is popularly used to treat diabetes mellitus. The hypoglycemic activity of this medicinal species has been confirmed by in vivo studies. The present study conducted a chemical investigation of a leaf decoction (10% p/v) of O. gratissimum monitored by in vivo hypoglycemic activity assays. Four phenolic substances were identified: L-caftaric acid (1), L-chicoric acid (2), eugenyl-β-D-glucopyranoside (3) and vicenin-2 (4). The acute hypoglycemic activity of the O. gratissimum decoction fractions Og1-S (300 mg/kg), Og1-A (240 mg/kg) and Og1-B (80 mg/kg) was evaluated intraperitoneally in normal and streptozotocin-induced diabetic mice. They reduced glycemia by 63%, 76% and 60% (in 120 min), respectively, in the diabetic mice. Subfractions of Og1-A were also evaluated under the same conditions: Og1-AS (200 mg/kg) and Og1-AP (40 mg/kg) produced a decrease of only 37% and 39%, respectively. Among the major phenolic substances, only chicoric acid (2; 3 mg/kg) reduced significantly the glycemic levels of diabetic mice by 53%, 120 min after treatment. This is the first study describing the hypoglycemic activity of chicoric acid in an animal model of diabetes mellitus. In addition, we suggest that there may be other substances contributing to this activity. Thus, for the first time, a correlation is established between the hypoglycemic activity of O. gratissimum and its chemical composition.

Antidiabetic activity of Sedum dendroideum: Metabolic enzymes as putative targets for the bioactive flavonoid kaempferitrin

The aim of this study was to evaluate the antidiabetic potential of a leaf extract and flavonoids from Sedum dendroideum (SD). Additionally, our goals were to establish a possible structure/activity relationship between these flavonoids and to assess the most active flavonoid on the glycolytic enzyme 6‐phosphofructo‐1‐kinase (PFK). SD juice (LJ), a flavonoid‐rich fraction (BF), and separately five flavonoids were evaluated intraperitoneally for their acute hypoglycemic activity in normal and streptozotocin‐induced diabetic mice. First, the major flavonoids kaempferol 3,7‐dirhamnoside or kaempferitrin (1), kaempferol 3‐glucoside‐7‐rhamnoside (2), and kaempferol 3‐neohesperidoside‐7‐rhamnoside (3) were tested. Then, the monoglycosides kaempferol 7‐rhamnoside (5) and kaempferol 3‐rhamnoside (6) were assayed to establish their structure/activity relationship. The effect of 1 on PFK was evaluated in skeletal muscle, liver, and adipose tissue from treated mice. LJ (400 mg/kg), BF (40 mg/kg), and flavonoid 1 (4 mg/kg) reduced glycemia in diabetic mice (120 min) by 52, 53, and 61%, respectively. Flavonoids 2, 3, 5, and 6 were inactive or showed little activity, suggesting that the two rhamnosyl moieties in kaempferitrin are important requirements. Kaempferitrin enhanced the PFK activity chiefly in hepatic tissue, suggesting that it is able to stimulate tissue glucose utilization. This result is confirmed testing kaempferitrin on C2C12 cell line, where it enhanced glucose consumption, lactate production, and the key regulatory glycolytic enzymes. The hypoglycemic activity of kaempferitrin depends on the presence of both rhamnosyl residues in the flavonoid structure when intraperitoneally administered. Our findings show for the first time that a flavonoid is capable of stimulating PFK in a model of diabetes and that kaempferitrin stimulates glucose‐metabolizing enzymes. This study contributes to the knowledge of the mechanisms by which this flavonoid exerts its hypoglycemic activity.

Anti-HSV-1 and HSV-2 flavonoids and a new kaempferol triglycoside from the medicinal plant Kalanchoe daigremontiana.

Kalanchoe daigremontiana (Crassulaceae) is a medicinal plant native to Madagascar. The aim of this study was to investigate the flavonoid content of an aqueous leaf extract from K. daigremontiana (Kd), and assess its antiherpetic potential. The major flavonoid, kaempferol 3‐O‐β‐d‐xylopyranosyl‐(1 → 2)‐α‐l‐rhamnopyranoside (1), was isolated from the AcOEt fraction (Kd‐AC). The BuOH‐soluble fraction afforded quercetin 3‐O‐β‐d‐xylopyranosyl‐(1 → 2)‐α‐l‐rhamnopyranoside (2) and the new kaempferol 3‐O‐β‐d‐xylopyranosyl‐(1 → 2)‐α‐l‐rhamnopyranoside‐7‐O‐β‐d‐glucopyranoside (3), named daigremontrioside. The crude extract, Kd‐AC fraction, flavonoids 1 and 2 were evaluated using acyclovir‐sensitive strains of HSV‐1 and HSV‐2. Kd‐AC was highly active against HSV‐1 (EC50 = 0.97 μg/ml, SI > 206.1) and HSV‐2 (EC50 = 0.72 μg/ml, SI > 277.7). Flavonoids 1 and 2 showed anti‐HSV‐1 (EC50 = 7.4 μg/ml; SI > 27 and EC50 = 5.8 μg/ml; SI > 8.6, respectively) and anti‐HSV‐2 (EC50 = 9.0 μg/ml; SI > 22.2 and EC50 = 36.2 μg/ml; SI > 5.5, respectively) activities, suggesting the contribution of additional substances to the antiviral activity.

The Use of NMR Metabolite Profiling and in vivo Hypoglycemic Assay for Comparison of Unfractionated Aqueous Leaf Extracts of Two Ocimum Species.

Ocimum basilicum and Ocimum gratissimum (Lamiaceae) are used to treat diabetes mellitus in Africa. In a previous work, we identified chicoric acid as a hypoglycemic substance in O. gratissimum. This study aims to compare the chemical metabolite profile and the hypoglycemic activity of unfractionated aqueous extracts from leaves of both Lamiaceae species. The metabolite composition of OB and OG decoctions (10% w/v) was analyzed using HPLC‐DAD and NMR tools. Chicoric acid showed to be the major phenolic in both extracts, besides caftaric, caffeic, and rosmarinic acids; nevertheless, there is approximately three times more of this substance in OG. From 1D‐ and 2D‐NMR analyses, 19 substances were identified in OB, while 12 in OG. The in vivo acute hypoglycemic activity of the extracts was assessed intraperitoneally in streptozotocin (STZ)‐induced diabetic mice. The doses of 100 and 200 mg/kg of both extracts significantly reduced their glycemia, compared to controls (P < 0.05). OB was a little more effective than OG, despite the lower content of chicoric acid in OB. This result strongly suggests that components other than chicoric acid contribute to the hypoglycemic activity of the two extracts. Despite the abundance of caffeic and rosmarinic acids in OB, their hypoglycemic activity observed at 8.3 μmol/kg was low. This is the first chemical profile of crude extracts from Ocimum species by NMR. Our findings confirmed the potential of both species in DM treatment in spite of marked differences in their chemical composition. However, long‐term studies are necessary in order to identify the most promising of the two species for the development of an herbal medicine.

Phenolic Substances from Ocimum Species Enhance Glucose-Stimulated Insulin Secretion and Modulate the Expression of Key Insulin Regulatory Genes in Mice Pancreatic Islets

Ocimum gratissimum and Ocimum basilicum are plants ethnopharmacologically used to treat diabetes mellitus, a life-threatening disease that affects millions of people worldwide. In order to further understand their antidiabetic potential, which has been previously demonstrated in animal models, we aimed to investigate the acute and chronic effects of major phenolic substances from both plants on insulin secretion and gene expression in pancreatic islets isolated from NMRI mice. Insulin secretion was measured after acute (1 h) and long-term (72 h) incubation of islets with one of four cinnamic acid derivatives (caftaric, caffeic, chicoric, and rosmarinic acids) or a C-glucosylated flavonoid (vicenin-2). All substances acutely enhanced glucose-stimulated insulin secretion (GSIS) from islets at concentrations from 10-10 to 10-6 M. They also increased GSIS after chronic incubation (10-8 M). None of them increased insulin secretion in the presence of low glucose concentration. Furthermore, these substances markedly changed the gene expression profile of key insulin regulatory genes INS1, INS2, PDX1, INSR, IRS1, and proliferative genes as well as glucose transporter 2 (GLUT2), in treated islets. Thus, they may play an important role in diabetes treatment. This is the first report on the insulin-secretory activity of caftaric acid, rosmarinic acid, and vicenin-2.

Metabolite Fingerprinting and Profiling of the Medicinal Grass Eleusine indica Based on HPLC-DAD, UPLC-DAD-MS/MS and NMR Analyses

Aqueous preparations of the grass Eleusine indica are used for treating malaria and lung infections. Despite its widespread occurrence and therapeutic potential, little is known about its chemical composition. This study reports a common chemical pattern for aqueous extracts of E. indica samples from four different localities, separated from each other by approximately 75 to 1340 km, in a wide variety of abiotic and biotic factors. High-performance liquid chromatography with diode array detection (HPLC-DAD), ultra-performance liquid chromatography with diode array detection and mass spectrometry (UPLC-DAD-MS/MS), and nuclear magnetic resonance (NMR) were the analytical techniques applied to characterize substances from E. indica, from each locality. Principal component analysis (PCA) confirmed that E. indica specimens came from four different localities. However, all of the four populations showed a common peaks pattern. This is the first chemical profile report of E. indica. Moreover, p-coumaric acid and isoschaftoside were characterized for the first time in this species.

Interações Sinérgicas em Produtos Naturais: Potencial Terapêutico e Desafios

Plantas medicinais constituem uma importante fonte de recursos terapeuticos, conforme atestam diversos medicamentos provenientes de substâncias de origem vegetal ou inspirados em seus farmacoforos. Entretanto, frequentemente, extratos de plantas medicinais exibem atividades biologicas mais pronunciadas que seus constituintes isolados. Isso se deve, frequentemente, as interacoes sinergicas entre tais componentes, envolvendo, em geral, a atuacao sobre multiplos alvos. A sinergia entre medicamentos tem sido explorada nos ultimos anos para o tratamento de diversas doencas, sobretudo o câncer e a AIDS. A combinacao de substâncias ativas mostra-se particularmente promissora no tratamento de doencas complexas, pois permite a atuacao simultânea sobre diversos alvos, garantindo maior eficacia e menor chance de resistencia aos farmacos empregados. Nesse contexto as plantas medicinais e seus metabolitos tem sido objeto de crescente interesse. Interacoes sinergicas, que podem ser observadas tanto entre componentes de extratos vegetais quanto entre produtos naturais e farmacos sinteticos, apresentam significante potencial terapeutico. Entretanto, sao necessarios metodos de estudo adequados para compreende-las. Adicionalmente, a aplicacao tecnologica de produtos de origem vegetal, cuja atividade biologica envolve sinergia, requer tecnicas que permitam analisar a composicao global destas. Na presente revisao serao discutidos exemplos relevantes de sinergia com enfoque em plantas medicinais e metabolitos secundarios bioativos de origem vegetal. Tambem serao discutidos metodos aplicaveis a estudos de sinergia, bem como tecnicas utilizaveis na padronizacao e no controle de qualidade de extratos vegetais cuja atividade farmacologica se deve a multiplos componentes.

Bioavailability of phenolic compounds: a major challenge for drug development?

Phenolic substances are an important class of secondary metabolites widely distributed in the plant kingdom. Several biological activities in vitro are assigned to this class of substances. However, some of these substances do not have the same profile of activity in in vivo assays. This fact could be partially explained by the low bioavailability of these substances. The main reasons for this low bioavailability may be low aqueous solubility, poor gastrointestinal stability and difficulty crossing membranes. The rapid and extensive metabolism by the intestinal flora and by some liver enzymes phenolic substances after oral administration, may explain the poor bioavailability. In contrast, biotransformation can also lead to potentially more active metabolites that the original substances. Given the importance of the topic, this article aims to address the impacts of metabolism of phenolic substances on their pharmacological effects. Additionally, we show strategies to improve the bioefficacy of these substances, contributing to their use in the development of drugs from vegetal origin.

Biodisponibilidade de compostos fenólicos: um importante desafio para o desenvolvimento de fármacos?

Phenolic substances are an important class of secondary metabolites widely distributed in the plant kingdom. Several biological activities in vitro are assigned to this class of substances. However, some of these substances do not have the same profile of activity in in vivo assays. This fact could be partially explained by the low bioavailability of these substances. The main reasons for this low bioavailability may be low aqueous solubility, poor gastrointestinal stability and difficulty crossing membranes. The rapid and extensive metabolism by the intestinal flora and by some liver enzymes of phenolic substances after oral administration, may explain the poor bioavailability. In contrast, biotransformation can also lead to metabolites potentially more active than the original substances. Given the importance of the topic, this article aims to address the impacts of metabolism of phenolic substances on their pharmacological effects. Additionally, we show strategies to improve the bioeffica cy of these substances, contributing to their use in the development of drugs of vegetal origin.