Ammar Bader

Sesterterpenes as Tubulin Tyrosine Ligase Inhibitors. First Insight of Structure-Activity Relationships and Discovery of New Lead

Twenty-four new sesterterpenes, compounds 1-24, were isolated from the aerial parts of Salvia dominica. Their structures were elucidated by 1D and 2D NMR experiments as well as ESIMS analysis and chemical methods. The evaluation of the biological activity of Salvia dominica sesterterpenes by means of a panel of chemical and biological approaches, including chemical proteomics, surface plasmon resonance (SPR) measurements, and biochemical assays were realized. Obtained results showed that 18 out of the 24 sesterterpene lactones isolated from Salvia dominica interact with tubulin-tyrosine ligase (TTL) an enzyme involved in the tyrosination cycle of the C-terminal of tubulin, and inhibit TTL activity in cancer cells. Besides, results of our studies provided an activity/structure relationship that can be used to design effective TTL inhibitors.

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.

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.

Preparation of mucoadhesive oral patches containing tetracycline hydrochloride and carvacrol for treatment of local mouth bacterial infections and candidiasis.

The specific aim of this work was to prepare mucoadhesive patches containing tetracycline hydrochloride and carvacrol in an attempt to develop a novel oral drug delivery system for the treatment of mouth infections. The bilayered patches were prepared using ethyl cellulose as a backing layer and carbopol 934 as a matrix mucoadhesive layer. Patches were prepared with different loading amounts of tetracycline hydrochloride and carvacrol. The antimicrobial activity was assessed for the prepared patches using the disc-diffusion method against the yeast Candida albicans and five bacterial strains, including Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Bacillus bronchispti. In this work, we highlighted the possibility of occurrence of a synergistic action between carvacrol and tetracycline. The best formulation was selected based on microbiological tests, drug release, ex-vivo mucoadhesive performance, and swelling index. Physical characteristics of the selected formulations were determined. These included pH, patch thickness, weight uniformity, content uniformity, folding endurance, and patch stability.

Achillea ligustica: composition and antimicrobial activity of essential oils from the leaves, flowers and some pure constituents ∗

The composition of the essential oils obtained from the leaves and the flowers of Achillea ligustica (Asteraceae) growing in Sicily has been studied. The main constituents of the leaves were 4-terpineol (19.3%), carvone (8.9%), γ-terpinene (7.2%) and β-phellandrene (6.8%). 4-terpineol (12.0%), carvone (10.0%), and β-phellandrene (5.4%), along with linalool (20.4%) and cedrol (4.3%) were detected in the flower’s oil. Furthermore, the antimicrobial activity of the essential oils and of some of the main constituents were assayed on bacteria and fungi.

The Composition of the Root Oil of Salvadora persica L.

Abstract The composition of the essential oil from the roots of Salvadora persica L. (Salvadoraceae), collected in Jordan, was analyzed by GC and GC/MS. Seventeen compounds were detected, the main constituents being benzyl isothiocyanate (70%), limonene (9.4%) and α-pinene (8.7%).

Secondary metabolites from the aerial parts of Salvia palaestina Bentham

Three sesterterpenes (1-3), one triterpene (4) and five diterpenes (5-9) were isolated from the aerial parts of Salvia palaestina Bentham (Lamiaceae), together with two sesquiterpenes, 10 known diterpenes, three triterpenes, and rosmarinic acid. Their structural elucidation was accomplished by extensive spectroscopic methods including 1D ((1)H, (13)C, (13)C DEPT, TOCSY, NOESY) and 2D NMR experiments (DQF-COSY, HSQC, HMBC, ROESY) as well as ESIMS analysis and chemical analysis.

Phenolic compounds from the roots of Jordanian viper's grass, Scorzonera judaica.

Nine new phenolic compounds, 3S-hydrangenol 40-O-R-L-rhamnopyranoysl-(1-->3)-β-D-glucopyranoside (1), thunberginol F 7-O-β-D-glucopyranoside (2), 2-hydroxy-6-[2-(4-hydroxyphenyl)-2-oxo-ethyl]benzoic acid (3), 2-hydroxy-6-[2-(3,4-dihydroxyphenyl)-2-oxo-ethyl]benzoic acid (4), 2-hydroxy-6-[2-(3,4-dihydroxyphenyl-5-methoxy)-2-oxoethyl]benzoic acid (5), hydrangeic acid 40-O-β-D-glucopyranoside (6), E-3-(3,4-dihydroxybenzylidene)-5-(3,4-dihydroxyphenyl)dihydrofuran-2-one (7), Z-3-(3,4-dihydroxybenzylidene)-5-(3,4-dihydroxyphenyl)-2(3H)-furanone (8), and 4-[β-D-glucopyranosyl)hydroxy]-pinoresinol (9), and nine known compounds were isolated from the roots of Scorzonera judaica. Structures of 1-9 were elucidated by mass spectrometry, extensive 1D and 2D NMR spectroscopy, and CD spectroscopy.All compounds were evaluated for cytotoxic activity.

A fast and efficient LC-MS/MS method for detection, identification and quantitative analysis of bioactive sesterterpenes in Salvia dominica crude extracts.

Sesterterpenes are a small group of terpenoids showing a number of interesting pharmacological properties, including cytotoxicity, anti-inflammatory, anti-microbial and anti-angiogenic activities and platelet aggregation inhibition. Recently, some sesterterpene lactones isolated from Salvia dominica have been shown to modulate enzymatic activity of tubulin tyrosine ligase (TTL), a promising target for new anticancer therapeutic strategies. However, to allow a direct use of S. dominica extracts as a source of TTL inhibitors, analytical method aimed to their fast qualitative and quantitative characterization is required. Despite the structural features and diverse biological activities of sesterterpenoids, actually no analytical method for their quantization into complex mixtures has been published. Here we describe an LC-MS/MS method aimed to qualitative and quantitative analysis of sesterterpenes lactones in the crude extracts obtained from different parts of S. dominica. This approach allowed us to characterize all the sesterterpenes by a single step analysis and also to identify two unknown compounds. Moreover, a quantitative comparison of the composition in sesterterpenes of extracts obtained from S. dominica leaves, roots and leaf galls was performed, leading to the definition of both leaves and leaf galls as suitable sources of TTL inhibitors.

Computational evaluation and experimental verification of antibacterial and antioxidant activity of 7-hydroxy-3-pyrazolyl-4H-chromen-4-ones and their o-glucosides: identification of pharmacophore sites

This paper reports the computational evaluation and experimental verification of 7-hydroxy-3-(1-phenyl-3-aryl-1H-pyrazol-5-yl)-4H-chromen-4-ones 3 and their o-β-d-glucopyranosides 5 for their antimicrobial and antioxidant activity. The prepared compounds were tested against various Gram-positive and Gram-negative bacteria species. Some of the synthesized compounds have shown potential antimicrobial and antioxidant activity. This POM bioinformatic study could greatly help to pharmacomodulate the potential antibiotics and antioxidants.Graphical AbstractThis paper describes the computational POM (Petra/Osiris/Molinspiration) evaluation and experimental verification of 7-o-β-d-glucopyranosyloxy-3-(1-phenyl-3-aryl-1H-pyrazol-5-yl)-4H-chromen-4-ones and metabolites for their antimicrobial and antioxidant activity.