Hypoglycemic active principles from the leaves of Bauhinia holophylla: Comprehensive phytochemical characterization and in vivo activity profile.

Bauhinia holophylla leaves, also known as "pata-de-vaca", are traditionally used in Brazil to treat diabetes. Although the hypoglycemic activity of this medicinal plant has already been described, the active compounds responsible for the hypoglycemic activity have not yet been identified. To rapidly obtain two fractions in large amounts compatible with further in vivo assay, the hydroalcoholic extract of B. holophylla leaves was fractionated by Vacuum Liquid Chromatography and then purified by medium pressure liquid chromatography combined with an in vivo Glucose Tolerance Test in diabetic mice. This approach resulted in the identification of eleven compounds (1-11), including an original non-cyanogenic cyanoglucoside derivative. The structures of the isolated compounds were elucidated by nuclear magnetic resonance and high-resolution mass spectrometry. One of the major compounds of the leaves, lithospermoside (3), exhibited strong hypoglycemic activity in diabetic mice at the doses of 10 and 20 mg/kg b.w. and prevents body weight loss. The proton nuclear magnetic resonance (1H NMR) quantification revealed that the hydroalcoholic leaves extract contained 1.7% of lithospermoside (3) and 3.1% of flavonoids. The NMR analysis also revealed the presence of a high amount of pinitol (4) (9.5%), a known compound possessing in vivo hypoglycemic activity. The hypoglycemic properties of the hydroalcoholic leaves extract and the traditional water infusion extracts of the leaves of B. holophylla seem thus to be the result of the activity of three unrelated classes of compounds. Such results support to some extent the traditional use of Bauhinia holophylla to treat diabetes.

Development of a microwave-assisted extraction method for the recovery of bioactive inositols from lettuce (Lactuca sativa) byproducts.

A microwave-assisted extraction (MAE) method was developed for the extraction of bioactive inositols (D-chiro- and myo-inositols) from lettuce (Lactuca sativa) leaves as a strategy for the revalorization of these agrofood residues. Gas chromatography-mass spectrometry was selected for the simultaneous determination of inositols and sugars (glucose, fructose, and sucrose) in these samples. A Box-Behnken experimental design was used to maximize the extraction of inositols based on the results of single factor tests. Optimal conditions of the extraction process were as follows: liquid-to-solid ratio of 100:1 v/w, 40°C, 30 min extraction time, 20:80 ethanol:water (v/v), and one extraction cycle. When compared with conventional solid-liquid extraction (SLE), MAE was found to be more effective for the extraction of target bioactive carbohydrates (MAE 5.42 mg/g dry sample versus SLE 4.01 mg/g dry sample). Then, MAE methodology was applied to the extraction of inositols from L. sativa leaves of different varieties (var. longifolia, var. capitata and var. crispa). D-chiro- and myo-inositol contents varied between 0.57-7.15 and 0.83-3.48 mg/g dry sample, respectively. Interfering sugars were removed from the extracts using a biotechnological procedure based on the use of Saccharomyces cerevisiae for 24 h. The developed methodology was a good alternative to classical procedures to obtain extracts enriched in inositols from lettuce residues, which could be of interest for the agrofood industry.

Cucurbita ficifolia†Bouché (Cucurbitaceae) and D-chiro-inositol modulate the redox state and inflammation in 3T3-L1 adipocytes.

OBJECTIVES: Cucurbita ficifolia (characterised by its D chiro inositol (DCI) content) and of synthetic DCI on the redox state, mRNA expression and secretions of proinflammatory cytokines. Additionally, we evaluated the insulin-mimetic action of both treatments by assessing protein kinase B (PKB) activation in 3T3-L1 adipocytes. METHODS: Adipocytes were treated with C. ficifolia and synthetic DCI. The redox state was determined by spectrophotometry as changes in the reduced glutathione/oxidised glutathione (GSH/GSSG) ratio, glutathione peroxidase and glutathione reductase activities; H2 O2 levels were measured by flow cytometry. The mRNA expression and the protein level of cytokines were determinate by real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The activation of PKB activation was detected by Western blot. KEY FINDINGS: C. ficifolia extract and synthetic DCI reduced oxidative stress by decreased H2 O2 levels, increased glutathione peroxidase activity and changes in the GSH/GSSG ratio. Furthermore, DCI decreased the mRNA expression and secretion of tumour necrosis factor-α, interleukin 6 (IL-6) and resistin, while C. ficifolia reduced protein levels of resistin and increased IL-6 levels. Only DCI demonstrated insulin-mimetic action. CONCLUSIONS: The antioxidant and anti-inflammatory effects of C. ficifolia extract can be explained in part by its DCI content, which modulates the GSH/GSSG ratio and contributes to a reduced proinflammatory state. C. ficifolia and DCI treatments may reduce the disturbances caused by oxidative stress. Additionally, DCI may improve insulin sensitivity through its insulin-mimetic effects.

On-line activity screening for radical scavengers from Baccharis chilco.

Baccharis plants have been used since ancient times in American traditional medicine. Baccharis chilco is a perennial shrub of temperate regions of South America that grows well in rainfall forests of Colombia. Neither chemical composition nor biological studies of this plant have ever been reported. Two caffeoylquinic acid (CQA) derivatives, 5-O-[(E)-caffeoyl]quinic acid (1) and 3,5-di-O-[(E)-caffeoyl]quinic acid (3), and rosmarinic acid (2) have been isolated from B. chilco growing wild in Colombia, using the on-line HPLC-DAD-DPPH radical-scavenging detection technique as guidance. In the course of the purification work, L-chiro-inositol (4) was also isolated. Structures of the four isolated compounds were determined by spectroscopic methods. Antioxidants 2 and 3 exhibited high antiradical activities evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(.)) assay, although somewhat lower than that of the reference compound ascorbic acid. The on-line HPLC-DAD-DPPH technique allowed a rapid pinpointing of antioxidants in the studied EtOH extract, and the facile guided isolation of the target molecules.

Antimicrobial activities of sesquiterpene lactones and inositol derivatives from Hymenoxys robusta.

Six compounds from the aerial parts of the Argentinean plant Hymenoxys robusta (Rusby) Parker were isolated and their structures elucidated using extensive spectroscopic analyses. These compounds comprise two inositol derivatives and four 3,4-seco-pseudoguaianolides, including vermeerin. Bioactivity assays of these compounds against bacterial and fungal pathogens showed that only vermeerin possessed antimicrobial activity specific against Staphylococcus aureus, and showed no toxicity when exposed to human-derived macrophages.

First record of L-quebrachitol in Allophylus edulis (Sapindaceae).

Allophylus edulis, commonly called 'Chal chal', is a member of the Sapindaceae occurring in the Uruguayan and Brazilian native flora. During the phytochemical analysis of two Chal chal specimens from two well-differentiated geographical zones (Assis, São Paulo, Brazil, and Santa Lucía, Canelones, Uruguay), considerable amounts of L-quebrachitol were isolated from both samples. The isolation was carried out from the ethanolic twig extracts obtained by maceration of both vegetal samples. White easily distinguishable crystals were mechanically separated, washed, and characterized by 1D and 2D NMR experiments and by MS data. Such techniques confirmed that the crystals isolated from sources collected in both countries resulted in the same compound, l-quebrachitol, a natural product not previously reported for this species and one that has been investigated as a sugar substitute for diabetics. Worthy of note, the content of L-quebrachitol in A. edulis may be the chemical basis to explain its ethnobotanical uses, since infusions of this plant are used to treat diabetes in the practice of local traditional medicine.

D-(+)-pinitol, a component of the heartwood of Enterolobium cyclocarpum (Jacq.) Griseb.

D-(+)-Pinitol, a natural product of the group of cyclitols, was purified for the first time from an aqueous extract of the heartwood of Enterolobium cyclocarpum, and its chemical structure was determined.

Chalcone-flavone tetramer and biflavones from Aristolochia ridicula.

Biflavones and a chalcone-flavone tetramer were isolated from the leaves of Aristolochia ridicula, together with proto-quercitol. Their structures were determined by spectroscopic methods.