Alessandra Braca

Antioxidant activity of flavonoids from Licania licaniaeflora

In our screening program for antioxidants with DPPH radical scavenging activity we tested several flavonoids isolated from the leaves of Licania licaniaeflora (Chrysobalanaceae family) and identified by spectroscopic evidence, particularly with 1H and 13C NMR. All the isolated compounds exhibited DPPH radical scavenging activity: quercetin derivatives showed the strongest action, while the flavanone 8-hydroxy-naringenin and kaempferol 3-O-alpha-rhamnoside had the lowest.

Quali-quantitative analyses of Flavonoids of Morus nigra L. and Morus alba L. (Moraceae) fruits.

Morus nigra L., belonging to the Moraceae family, is a decidious tree widely cultivated in Europe and West Asia. It has a long history of medicinal use in Chinese medicine, as a remedy for many kinds of diseases. The aim of the present study was to evaluate the profile of the phenolic constituents of M. nigra fruits and to compare their content with the fruits of another species of Morus, Morus alba, which is also very well known in folklore medicine. The fruits of black and white mulberries have been studied, and five compounds from the methanol extract have been identified by means of HPLC/PDA/ESI-MS. Four compounds (quercetin 3- O-glucoside, quercetin 3- O-rutinoside, kaempferol 3- O-rutinoside, and 5- O-caffeoylquinic acid) have been isolated by use of Sephadex LH-20 column chromatography and HPLC and characterized by means of NMR and ESI-MS. Furthermore, HPLC/PDA/ESI-MS analysis of the red pigment of M. nigra fruits revealed the presence of four anthocyanins recognized as cyanidin 3- O-glucoside, cyanidin 3- O-rutinoside, pelargonidin 3- O-glucoside, and pelargonidin 3- O-rutinoside. All of the compounds were quantified.

Chemical composition and antimicrobial activity of Momordica charantia seed essential oil

The essential oil obtained from the seeds of Momordica charantia was analyzed by GC/MS. Twenty-five components, representing 90.9% of the oil, were identified. The main constituents were trans-nerolidol, apiole, cis-dihydrocarveol and germacrene D. Furthermore, the oil was tested for its antibacterial and antifungal activities. Staphylococcus aureus was found to be the most sensitive microorganism with MIC values <500 microg/ml.

Flavonoid characterization and in vitro antioxidant activity of Aconitum anthora L. (Ranunculaceae)

In this paper, we report studies on morphological, phytochemical, and biological aspects of a population belonging to Aconitum anthora L. Two compounds, quercetin 3-O-((beta-D-glucopyranosyl-(1-->3)-(4-O-(E-p-coumaroyl))-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-galactopyranoside))-7-O-alpha-L-rhamnopyranoside (1) and kaempferol 3-O-((beta-D-glucopyranosyl-(1-->3)-(4-O-(E-p-coumaroyl))-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-galactopyranoside))-7-O-alpha-L-rhamnopyranoside (2), together with two known flavonol glycosides (3-4) were isolated and identified from A. anthora. The antioxidant activity of the four identified flavonoids was screened by three in vitro tests.

A chemical-biological study reveals C9-type iridoids as novel heat shock protein 90 (Hsp90) inhibitors.

The potential of heat shock protein 90 (Hsp90) as a therapeutic target for numerous diseases has made the identification and optimization of novel Hsp90 inhibitors an emerging therapeutic strategy. A surface plasmon resonance (SPR) approach was adopted to screen some iridoids for their Hsp90 α binding capability. Twenty-four iridoid derivatives, including 13 new natural compounds, were isolated from the leaves of Tabebuia argentea and petioles of Catalpa bignonioides. Their structures were elucidated by NMR, electrospray ionization mass spectrometry, and chemical methods. By means of a panel of chemical and biological approaches, four iridoids were demonstrated to bind Hsp90 α. In particular, the dimeric iridoid argenteoside A was shown to efficiently inhibit the chaperone in biochemical and cellular assays. Our results disclose C9-type iridoids as a novel class of Hsp90 inhibitors.

New pregnane glycosides from Caralluma dalzielii

Twenty-seven new pregnane glycosides were isolated from the whole plant of Caralluma dalzielii, and their structures elucidated from extensive 2D NMR analysis as well as ESI-MS experiments. All isolated compounds were tested for their antiproliferative activity on J774.A1, HEK-293, and WEHI-164 cell lines. Moderate to high potency of cytotoxicities were found in almost all tested compounds, confirming the significant cytotoxic activity of pregnane glycosides.

New pregnane glycosides from Caralluma negevensis

Twenty new pregnane glycosides were isolated from the whole plant of Caralluma negevensis. Their structures were elucidated by extensive spectroscopic methods including 1D-(1H, 13C, 13C DEPT, TOCSY, ROESY) and 2D-NMR experiments (DQF-COSY, HSQC, HMBC, HOHAHA) as well as ESI-MS analysis. Pregnane glycosides were tested for their cytotoxic and genotoxic activity.

Triterpene Derivatives as Inhibitors of Protein Involved in the Inflammatory Process: Molecules Interfering with Phospholipase A2, Cycloxygenase, and Lipoxygenase

Over the past years, there was an explosion in the knowledge of the protein target and molecular mechanism associated with various disease types and in the new research of drugs of natural origin. The key idea is to evaluate bioactive natural products interacting with protein domains of different genetic origin but structurally preserved to develop libraries of compounds biologically validated and selected from an evolutionistic point of view. Compared with synthetic compounds, natural products have a major number of unused scaffolds and not comparable to the libraries of synthetic compounds, and could represent a promising starting points for the discovery of new bioactive compounds. Many natural products are reported to interact with proteins involved in serious diseases, such as inflammation and cancer. Recently various chemical classes of plant secondary metabolites have emerged as potential therapeutic compounds in several inflammatory diseases. Owing to the findings that triterpenoids, a common class of plant secondary metabolites, have anti-inflammatory and anti-cancer effects on humans, the interest in their potential application in human health and disease is increasing. The present review describes anti-inflammatory triterpenes derivatives from plant and fungi reported during the last two decades in order to provide an account of this field of investigation, sorting compounds according to their targets, phospholipase A(2) (PLA(2)), cycloxygenase (COX), and lipoxygenase (LOX). The attempt is also being made to enumerate the possible leads for further synthetic and drug discovery program development.

Antioxidant and free radical-scavenging activity of constituents from two Scorzonera species

The aim of this study was to investigate the secondary metabolites content of Scorzonera papposa DC., an edible plant eaten in the desert region of Jordan and to assess its antioxidant and free radical-scavenging activity. By using this bioassay-oriented approach nine compounds, including the new natural compounds (6-trans-p-coumaroyl)-3-O-β-D-glucopyranosyl-2-deoxy-D-riburonic acid (1), (6-cis-p-coumaroyl)-3-O-β-D-glucopyranosyl-2-deoxy-D-riburonic acid (2a), (6-trans-p-coumaroyl)-3-O-β-D-glucopyranosyl-2-deoxy-D-riburonic acid methyl ester (3), and (6-trans-p-coumaroyl)-3-O-β-D-glucopyranosyl-(5-acetyl)-2-deoxy-D-riburonic acid (4), having the rare deoxy-D-riburonic acid moiety, were isolated. Their structures were elucidated by UV, MS, (1)H and (13)C NMR and 2D NMR. The antioxidant activity of the S. papposa pure compounds and of related derivatives isolated from another Scorzonera species (S. judaica Eig.) was also tested. The Relative Antioxidant Capacity Index (RACI) was applied as an integrated method to compare the antioxidant activities obtained using different chemical methods.

New monoterpene glycosides from Paeonia lactiflora

Three new monoterpene glycosides named 4-O-methyl-paeoniflorin (1), isopaeoniflorin (2), and isobenzoylpaeoniflorin (3), together with two known monoterpene glycosides, paeoniflorin (4) and benzoylpaeoniflorin (5), were isolated from the roots of Paeonia lactiflora. Their structures were established on the basis of spectral and chemical evidence.