Luca Rastrelli

Chemical composition of Lepidium meyenii

Abstract Lepidium meyenii Walpers, a tuber of Andine origin still cultivated in Peru for local preparation, was studied. The carbohydrate, lipid, protein, fibre and also the amino-acid, fatty acid, mineral and sterol fractions were determined. The results show that the tuber is nutritionally interesting. Alkaloid-like compounds were also found. It is concluded that this tuber can be a food source in countries, where economic and technological conditions are inadequate to combat malnutrition.

Determination of organophosphorus pesticide residues in Cilento (Campania, Italy) virgin olive oil by capillary gas chromatography

Abstract In this study, the occurrence of 18 organophosphorus pesticide residues in Cilento (Campania, Italy) virgin olive oil was investigated. Sixty-five samples were taken from the major production areas during 1999–2000. In 31 samples, nine organophosphorus pesticides, namely azinphos-ethyl, chlorpyrifos-methyl, diazinon, dimethoate, fenthion, formothion, methidathion, parathion and parathion-methyl were found in concentrations ranging from 0.030 to 0.120 mg/kg. Acefate, carbophenothion, chlorpyrifos, malaoxon, malathion, methamidophos, omethoate, paraoxon-methyl, and pirimiphos-methyl were not detected in any sample. Analysis was carried out using capillary gas chromatography with a Nitrogen/Phosphorus Detector (NPD) detector, after sample extraction with n -hexane and clean-up by a single-step multi-cartridge system. Recoveries of 18 pesticides at three fortification levels (0.5, 1.0 and 2.5 mg/kg) were in the range 82–110%. Only two samples contained dimethoate residue that exceeded the FAO/WHO Codex Alimentarius maximum residue limits (MRLs).

Plants used in Guatemala for the treatment of protozoal infections. II: Activity of extracts and fractions of five Guatemalan plants against Trypanosoma cruzi

The activities of crude plant extracts of five plants popularly used in Guatemala against bacterial and protozoal infections and some of their fractions have been evaluated against the trypomastigote and epimastigote forms of Trypanosoma cruzi in vitro. The most active fraction of Neurolaena lobata has also been screened in vivo. Main in vitro activities against trypomastigotes have been observed for the hexane and ethanol extracts of N. lobata (Asteraceae). Both extracts were also active against epimastigotes, whereas all other extracts tested had no effect on epimastigotes. For the hexane extracts of Petiveria alliacea (Phytolaccaceae) and Tridax procumbens (Asteraceae) a marked inhibition of trypomastigotes has been found. Also the ethanol extracts of Byrsonima crassifolia (Malpighiaceae) leafs and Gliricidia sepium (Papilionaceae) bark showed some trypanocidal activity. Fraction 2 of the ethanol extract of N. lobata was highly active against T. cruzi as well in vitro as in vivo. The chloroforme fraction of P. alliacea showed a high inhibition of trypomastigotes in vitro. Also three fractions of the active extract of B. crassifolia inhibited T. cruzi trypomastigotes. No fraction of G. sepium bark extract showed a marked trypanocidal activity.

Application of dispersive liquid–liquid microextraction for the determination of aflatoxins B1, B2, G1 and G2 in cereal products

The application of dispersive liquid-liquid microextraction (DLLME) technique for the rapid analysis of aflatoxins B(1), B(2), G(1) and G(2) in maize, rice and wheat products has been evaluated. After extraction of aflatoxins from cereal matrices with a mixture of methanol/water 8:2 (v/v), the analytes were rapidly transferred from the extract to another small volume of organic solvent, chloroform, by DLLME. Aflatoxins were determined using high performance liquid chromatography with florescence detection and photochemical post-column derivatization. Parameters affecting both extraction and DLLME procedures, such as extraction solvent, type and volume of DLLME extractant, volume of water and salt effect, were systematically investigated and optimized to achieve the best extraction efficiency. Under the optimal experimental conditions, the whole analytical method provides enrichment factors around 2.5 times and detection limits (0.01-0.17 μg kg(-1)) below the maximum levels imposed by current regulation for aflatoxins in cereals and cereal products intended for direct human consumption. Recoveries (67-92%) and repeatability (RSD<10, n=3), tested in three different cereal matrices, meet the performance criteria required by EC Regulation No. 401/2006 for the determination of the levels of mycotoxins in foodstuffs. The proposed method was successfully applied to the analysis of retail cereal products with quantitative results comparable to the immunoaffinity chromatography (IAC). The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost.

Cuban and Brazilian red propolis: botanical origin and comparative analysis by high-performance liquid chromatography-photodiode array detection/electrospray ionization tandem mass spectrometry.

Chemical composition of propolis depends on the specificity of the local flora at the site of collection and thus on the geographic and climatic characteristics of this place. This paper describes a comparative analysis of Cuban red propolis (CRP), Brazilian red propolis (BRP), and Dalbergia ecastophyllum exudates (DEE) by high-performance liquid chromatography with diode-array detection and tandem mass spectrometry. The aim of this study was to investigate the overall chemical profile and the botanical origin of red propolis and to suggest similarities and differences between samples collected in different tropical regions. Isoliquiritigenin (1), liquiritigenin and naringenin (2 and 17), isoflavones (3-4 and 16), isoflavans (5-7 and 18), and pterocarpans (8-13) were detected in CRP, BRP, and DEE, whereas polyisoprenylated benzophenones (PPBs) guttiferone E/xanthochymol (14a,b) and oblongifolin A (15) were detected only in BRP. Pigments responsible for the red color of DEE and red propolis were also identified as two C30 isoflavans, the new retusapurpurin B (19) and retusapurpurin A (20). PPBs and pigments were isolated and unambiguously characterized by 1D and 2D NMR analysis. These results show that red propolis samples from different tropical zones have a similar chemical composition. DEE is the main red propolis source, but the presence of PPBs in BRP suggests the contribution of different botanical sources for Brazilian samples. This chemical information is important for quality control of red propolis and its commercial products and for biological study.

HPLC-PDA-MS and NMR Characterization of C-Glycosyl Flavones in a Hydroalcoholic Extract of Citrus aurantifolia Leaves with Antiplatelet Activity

A hydroalcoholic extract of lime ( Citrus aurantifolia) leaves has been developed in Cuba to be used as a nutritional supplement and phytomedicine in the form of tincture (TLL). A HPLC-PDA-ESI/MS/MS method has been used for the comprehensive analysis of C-glycosyl flavones in TLL. Six C-glycosyl flavones were characterized and, to confirm the proposed structures and to elucidate the nature of the sugar units, a preparative procedure was applied, and isolated compounds were characterized by NMR. Apigenin-6,8-di-C-beta-D-glucopyranoside (vicenin II) (1), diosmetin-6,8-di- C-beta- d-glucopyranoside (2), apigenin-8-C-beta-D-glucopyranoside (vitexin) (3), apigenin-8-C-[alpha-L-arabinopyranosyl-(1-->6)]-O-beta-D-glucopyranoside (4), apigenin-6-C-[alpha-l-arabinopyranosyl-(1-->6)]-O-beta-D-glucopyranoside (5). and apigenin-6-C-beta-D-glucopyranoside (isovitexin) (6) were identified in TLL and quantified by HPLC-PDA. Compounds 4 and 5 were two new arabinosyl derivatives of vitexin and isovitexin. Inhibitor effect of TLL on platelet aggregation induced by physiological agonists of platelets was evaluated in human plasma. TLL inhibited significantly ADP and epinephrine-induced platelet aggregation in a concentration-dependent manner (IC 50=0.40 and 0.32 mg/mL, respectively).

Studies on the constituents of yellow Cuban propolis: GC-MS determination of triterpenoids and flavonoids.

In this study, on the basis of the information supplied by NMR and HPLC-PDA data, we reported a quali-quantitative GC-MS study of 19 yellow Cuban propolis (YCP) samples collected in different regions of Cuba. The profiles of YCP samples allowed us to define two main types of YCP directly related to their secondary metabolite classes: type A, rich in triterpenic alcohols and with the presence of polymethoxylated flavonoids as minor constituents, and type B, containing acetyl triterpenes as the main constituents. For the first time, triterpenoids belonging to oleanane, lupane, ursane, and lanostane skeletons were reported as major compounds in propolis. Also, the presence of polymethoxylated flavones or flavanones was found for the first time in propolis.

The identification of a novel natural activator of p300 histone acetyltranferase provides new insights into the modulation mechanism of this enzyme.

Many severe human pathologies are related to alterations of the fine balance between histone acetylation and deacetylation; because not all such diseases involve hypoacetylation, but also hyperacetylation, compounds able to enhance or repress the activities of histone acetyltransferases (HATs) could be promising therapeutic agents. We evaluated in vitro and in cell the ability of eleven natural polyisoprenylated benzophenone derivatives to modulate the HAT activity of p300/CBP, an enzyme that plays a pivotal role in a variety of cellular processes. Some of the tested compounds bound efficiently to the p300/CBP protein: in particular, guttiferone A, guttiferone E and clusianone inhibit its HAT activity, whereas nemorosone showed a surprising ability to activate the enzyme. The ability of nemorosone to penetrate cell membranes and modulate histone acetylation into the cell together with its high affinity for the p300/CBP enzyme made this compound a suitable lead for the design of optimized anticancer drugs. Besides, the studies performed at a cellular and molecular level on both the inhibitors and the activator provided new insights into the modulation mechanism of p300/CBP by small molecules.

Glycolipids from Byrsonima crassifolia

Abstract From the leaves of Byrsonima crassifolia four new glycolipids, 1,2-di- O -miristoyl-3- O -(6-sulpho-α- d -quinovopyranosyl)-glycerol, 1,2-di- O -(8-hexadecenoyl)-3- O -(6-sulpho-α- d -quinovopyranosyl)-glycerol, 1,2-di- O -palmitoyl-3- O -(β- d -glucopyranosyl)- glycerol and 1,2-di- O -(8-hexadecenoyl)-3- O -(β- d -glucopyranosyl)-glycerol, have been isolated. Nine known compounds were also found. The structures of new compounds were elucidated on the basis of chemical and spectral data.

Determination of phenolic compounds in honey using dispersive liquid-liquid microextraction.

Honey is a valuable functional food rich in phenolic compounds with a broad spectrum of biological activities. Analysis of the phenolic compounds in honey is a very promising tool for the quality control, the authentication and characterization of botanical origin, and the nutraceutical research. This work describes a novel approach for the rapid analysis of five phenolic acids and 10 flavonoids in honey. Phenolic compounds were rapidly extracted and concentrated from diluted honey by dispersive liquid-liquid microextraction (DLLME) and then analyzed using high performance liquid chromatography with UV absorbance detection (HPLC-UV). Some important parameters, such as the nature and volume of extraction and dispersive solvents, pH and salt effect were carefully investigated and optimized to achieve the best extraction efficiency. Under the optimal conditions, an exhaustive extraction for twelve of the investigated analytes (recoveries >70%), with a precision (RSD<10%) highly acceptable for complex matrices, and detection and quantification limits at ppb levels (1.4-12 and 4.7-40ngg(-1), respectively) were attained. The proposed method, compared with the most widely used method in the analysis of phenolic compounds in honey, provided similar or higher extraction efficiency, except in the case of the most hydrophilic phenolic acids. The capability of DLLME to the extraction of other honey phytochemicals, such as abscisic acid, was also demonstrated. The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost.