Boulbaba Selmi

In vitro antiviral activity of dermaseptin S(4) and derivatives from amphibian skin against herpes simplex virus type 2.

Herpes simplex virus (HSV) infections have become a public health problem worldwide. The emergence of acyclovir‐resistant viral strains and the failure of vaccination to prevent herpetic infections have prompted the search for new antiviral drugs. Accordingly, the present study was undertaken to synthesize chemically and evaluate Dermaseptin S4 (S4), an anti‐microbial peptide derived from amphibian skin, and its derivatives in terms of anti‐herpetic activity. The effects of biochemical modifications on their antimicrobial potential were also investigated. The peptides were incubated together with HSV‐2 on target cells under various conditions, and the antiviral effects were examined via a cell metabolic labeling method. The findings revealed that DS4 derivatives elicited concentration‐dependent antiviral activity at micromole concentrations. The biochemical modifications of S4 allowed for the reduction of peptide cytotoxicity without altering antiviral activity. Dermaseptins were added at different times during the viral cycle to investigate the mode of antiviral action. At the highest non‐cytotoxic concentrations, most of the tested derivatives were noted to exhibit high antiviral activity particularly when pre‐incubated with free herpes viruses prior to infection. Among these peptides, K4K20S4 exhibited the highest antiviral activity against HSV‐2 sensitive and resistant strains. Interestingly, the antiviral activity of K4K20S4 was effective on both acyclovir‐resistant and ‐sensitive viruses. The findings indicate that K4K20S4 can be considered a promising candidate for future application as a therapeutic virucidal agent for the treatment of herpes viruses. J. Med. Virol. 85:272–281, 2013.

Phenolic composition, antioxidant and anti-acetylcholinesterase activities of the Tunisian Scabiosa arenaria

Abstract Context: There is a need for the discovery of novel natural antioxidants and acetylcholinesterase inhibitors (AChEIs) that are safe and effective at a global level. This is the first study on antioxidant and anti-acethylcholinesterase activity of Scabiosa arenaria Forssk (Dipsacaceae). Objective: The antioxidant potential and anti-acetylcholinesterase (AChE) activity of S. arenaria were investigated. Material and methods: The crude, ethyl acetate (EtOAc), butanol (n-BuOH) and water extracts prepared from flowers, fruits and stems and leaves of S. arenaria were tested to determine their total polyphenol content (TPC), total flavonoid content (TFC), total condensed tannin content (CTC) and their antioxidant activity by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), reducing power and β-carotene bleaching inhibition activity. Anti-AChE activity was also determined. Results: EtOAc and n-BuOH fractions of fruits had both the highest (TPC) (269.09 mg gallic acid equivalents/g dry weight). The crude extract of stems and leaves had the highest TFC (10.9 mg quercetin equivalent/g dry weight). The n-BuOH fraction of stems and leaves had the highest CTC (489.75 mg catechin equivalents/g dry weight). The EtOAc fraction of flowers exhibit a higher activity in each antioxidant system with a special attention for DPPH assay (IC50 = 0.017 mg/mL) and reducing power (EC50 = 0.02 mg/mL). The EtOAc and n-BuOH fractions of stems and leaves showed strong inhibition of AChE (IC50 = 0.016 and 0.029 mg/mL, respectively). Discussion and conclusions: These results suggest the potential of S. arenaria as a possible source of novel compounds and as an alternative antioxidant and AChEIs.

Chemical Composition and Antimicrobial Activity of Essential Oils from Scabiosa arenariaForssk. Growing Wild in Tunisia

The essential oils isolated from three organs, i.e., fruits, stems and leaves, and flowers, of the endemic North African plant Scabiosa arenaria Forssk. were screened for their chemical composition, as well as their possible antibacterial, anticandidal, and antifungal properties. According to the GC‐FID and GC/MS analyses, 61 (99.26% of the total oil composition), 79 (98.43%), and 51 compounds (99.9%) were identified in the three oils, respectively. While α‐thujone (34.39%), camphor (17.48%), and β‐thujone (15.29%) constituted the major compounds of the fruit oil, chrysanthenone (23.43%), together with camphor (12.98%) and α‐thujone (10.7%), were the main constituents of the stem and leaf oil. In the case of the flower oil, also chrysanthenone (38.52%), camphor (11.75%), and α‐thujone (9.5%) were identified as the major compounds.

α-Glucosidase inhibition by Tunisian Scabiosa arenaria Forssk. extracts.

Recent decades have witnessed a sharp increase in the incidence and prevalence of type 2 diabetes mellitus. One antidiabetic therapeutic approach is to reduce gastrointestinal glucose production and absorption through the inhibition of carbohydrate-digesting enzymes such as α-amylase and α-glucosidase. In this study, crude extracts and their corresponding fractions of flowers, fruits, (stems and leaves) and roots of the endemic North African plant Scabiosa arenaria Forssk. were screened for their ability of α-glucosidase inhibition. It was found that the fruits ethyl acetate (EtOAc), the fruits butanolic (n-BuOH) and the flowers ethyl acetate (EtOAc) fractions inhibited α-glucosidase in a non competitive manner with IC50 values of 0.11±0.09, 0.28±0.04 and 0.221±0.01mg/ml, respectively. RP-HPLC analysis indicated that the major components of these active fractions are flavonoid aglycone, cinnamic acid and its derivatives. This result supports the conclusion that the three studied fractions could be a useful natural source for the development of a novel α-glucosidase inhibitory agent against diabetic complications.

Antimicrobial Activity of Scabiosa arenaria Forssk. Extracts and Pure Compounds Using Bioguided Fractionation

The emergence of multidrug resistant pathogens threatened the clinical efficacy of many existing antibiotics. This situation has been recognized globally as a serious concern and justifies further research to discover antimicrobial agents from natural origins including plant extracts. The aim of our work was to evaluate the antimicrobial activities of Scabiosa arenaria Forssk. extracts and pure compounds using a bioguided fractionation, and try to explain some traditional use of this genus. The best antimicrobial activity‐guided fractionation was obtained by BuOH fractions of flowers, fruits and (stems and leaves) against Escherichia coli, Pseudomonas aeruginosa and Candida albicans with minimum inhibitory concentration (MIC) values from 0.0195 to 5 mg/ml. Escherichia coli was the most affected bug, thus the MIC of fruits BuOH extract showed the best anti‐Escherichia coli activity (MIC = 0.0195 mg/ml), followed by the (stems and leaves) and flowers BuOH extracts; MIC = 0.078 and 0.15 mg/ml, respectively. Furthermore, the subfractions obtained from these three mixed fractions showed also an important antimicrobial activity against the three microorganisms, with MIC values between 0.0195 and 0.312 mg/ml. The fractionation of the aerial part BuOH fraction led to the isolation of oleanolic acid (1) and luteolin 7‐O‐glucopyranoside (2) which are reported here for the first time from S. arenaria. Both compounds showed good antimicrobial activities with MIC values ranging from 170 to 683 μm and 86 to 347 μm, respectively. These results support the use of the Scabiosa genus to inhibit the growth of tested pathogenic bacteria and yeasts which may reduce illnesses associated with their exposure.

Partial characterization of a novel amylase activity isolated from Tunisian Ficus carica latex

Context: A large number of plants still need to be investigated through screening of amylases suitable for industry. In the present study, and for the first time, we describe the amylolytic activity of Saint Pedro Ficus carica L. (Moraceae) crude latex of Kahli and Bidhi varieties. Objective: Effects of temperature, pH, metal ions, and inhibitors and compatibility with some commercial detergents were investigated for amylase activity. Materials and methods: Amylase activity was screened in crude latex using the DNS method and potato starch as a substrate. Analyses of amylolytic reaction products by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) were performed. Results: Bidhi and Kahli amylases were active in optimal pH of 6.5 and 7 at 45°C, respectively, displaying a half life of 85 and 60 min, respectively, at 80°C, and they were very stable in a wide range of pH (4–12). Bidhi amylase activity increased to 260% by addition of 10−3 mM Fe2+ or 10−2 mM Cu2+, and was strongly inhibited by Mg2+ and EDTA. In the presence of Ca2+ and Mg2+, Kahli amylase activity was dramatically enhanced by 220 and 260%, respectively. The compatibility of both amylases with certain commercial detergents was also shown to be good as enzymes retained up to 98% of their activities after 30 min of incubation at 80°C. Discussion and conclusion: Analysis of amylolytic reaction products by TLC and HPLC suggested that Kahli amylase was an amyloglucosidase and Bidhi amylase was β-fructose, α(1–4) glucose. Bidhi amylase is a good choice for application in starch, food, detergents and medical industries.

Chemical composition and biological activities of Eruca vesicaria subsp. longirostris essential oils

Abstract Context To date, there are no reports to validate the Tunisian traditional and folklore claims of Eruca vesicaria (L) Cav. subsp. longirostris (Brassicaceae) for the treatment of disease. Objective Investigation of the chemical composition antimicrobial and antioxidant activity of essential oils from Eruca longirostris leaves, stems, roots and fruits. Materials and methods The essential oils of E. longirostris from leaves, stems, roots and fruits were obtained after 4 h of hydrodistillation. Chemical compositions were determined using a combination of GC/FID and GC/MS. The in vitro antimicrobial activity of the volatile constituents of E. longirostris was performed in sterile 96-well microplates against three Gram-positive, four Gram-negative bacteria and one strain as yeast. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration values were reported. Furthermore, the antioxidant activity was evaluated by DPPH and ABTS assays. Results The main compound for fruits, stems and roots was the erucin (96.6%, 85.3% and 83.7%, respectively), while β-elemene (35.7%), hexahydrofarnesylacetone (23.9%), (E)-β-damascone (15.4%), erucin (10.6%) and α-longipinene (9.6%) constituted the major compounds in the essential oil of the leaves. The experimental results showed that in all tests, essential oil of fruits showed the better antioxidant activity than the others. On the other hand, the oils of stems, fruits and roots showed significant antimicrobial activity with MIC values ranging from 0.125 to 0.31 mg/mL against Candida species, Gram-positive and Gram-negative bacteria, mainly Salmonella enterica. Conclusions The present results indicate that essential oils of E. longirostris can be used as a source of erucin.

Characterisation of phenolic antioxidants in Scabiosa arenaria flowers by LC–ESI-MS/MS and NMR

This work describes the bioguided fractionation of the flowers ethyl acetate fraction of Scabiosa arenaria Forssk. (Dipsacaceae).

Phytoestrogens inhibit key-enzymes linked to obesity, type 2 diabetes and liver-kidney toxicity in high fructose-fat diet in mice

Abstract Objective: To evaluate the effect of the administration of phytoestrogens on obesity, type 2 diabetes, and liver-kidney toxicity. Methods: Phytoestrogens (phyto(E2)) were administrated to high fructose-fat diet (HFFD). Results: This study showed that administration of phyto(E2) to HFFD-mice inhibited lipase activity by 34%, decreased body weight by 20% and modulated lipid profile, showed a decrease in total-cholesterol (TC) and LDL-cholesterol (LDL-C) rates in the plasma by 59% and 42%, respectively, and increased the HDL-cholesterol (HDL-C) level by 31%. In addition, the administration of phytoestrogens to HFFD-mice exerts an inhibitory effect on α-amylase activity and decreased glucose level by 28% and increase in liver glycogen level by 33%; and ameliorate oral glucose tolerance test. Conclusions: This study demonstrate that phyto(E2) has both a promising potential with regards to the inhibition of intestinal lipase and α-amylase activities, and a valuable hypoglycemic and hypolipidemic function.