Valeria D'Angelo

Extraction methods and bioautography for evaluation of medicinal plant antimicrobial activity

A comparative study on the antimicrobial properties of extracts from medicinal plants obtained by two different methods was carried out. The screening of the antimicrobial activity of extracts from six plants was conducted by a disc diffusion test against Gram‐positive, ‐negative and fungal organisms. The most active extracts (inhibition diameter ≥12 mm) were assayed for the minimum inhibitory concentration and submitted to phytochemical screening by thin‐layer chromatography and bioautography. The results obtained indicate that the diethyl ether extracts were the most efficient antimicrobial compounds. The activity was more pronounced against Gram‐positive and fungal organisms than against Gram‐negative bacteria. Bioautography showed that the antimicrobial activity was probably due to flavonoids and terpenes.

Betula pendula leaves: Polyphenolic characterization and potential innovative use in skin whitening products

The research of new tyrosinase inhibitors is currently important for the development of skin whitening agents; particularly, birch leaves extracts are included in many skin cosmetic products. In this study, the potential ability of Betula pendula leaves ethanolic extract (BE) was evaluated on mushroom tyrosinase activity. Results showed that BE was capable to inhibit dose-dependently l-DOPA oxidation catalyzed by tyrosinase. The inhibition kinetics, analyzed by Lineweaver-Burk plots, showed a noncompetitive inhibition of BE towards the enzyme, using l-DOPA as substrate. The inhibitory mechanism of BE as studied by spectrophotometric analysis, demonstrated its ability to chelate copper ion in the active site of tyrosinase. In addition, BE exhibited Fe(2+)-chelating ability (IC(50)=614.12±2.14 μg/mL), reducing power and radical-scavenging properties (IC(50)=137.22±1.98 μg/mL). These results suggest the usefulness of birch leaves extracts in cosmetic and pharmaceutical industries for their skin-whitening and antioxidant effects. Determination of the polyphenolic compounds in BE extracts was afterward achieved by means of high-performance liquid chromatography (HPLC) with photodiode array (PDA) and mass spectrometry (MS) detection. A total of 25 compounds were positively identified, through the complementary analytical information, and are reported in such a matrix for the first time. Knowledge on the qualitative composition and contents of these natural sources in fact represents mandatory information, for rational consumption and correlation of the beneficial effects to the specific amounts.

Hepatoprotective properties in the rat of Mitracarpus scaber (Rubiaceae).

The effect of Mitracarpus scaber on carbon tetrachloride‐induced acute liver damage in the rat has been evaluated.

Hepatoprotective activity of Trichilia roka on carbon tetrachloride-induced liver damage in rats

Trichilia roka Chiov. (Meliaceae) is a tree widely distributed in tropical Africa. It has been used in Mali folk medicine for the treatment of various illnesses. A decoction of the roots is taken as a remedy for colds and pneumonia, and it is used as a diuretic and in hepatic disorders. We have evaluated the hepatoprotective effects of a decoction of Trichilia roka root on CCl4‐induced acute liver damage in rats. Treatment with the decoction showed a significant protective action made evident by its effect on the levels of glutamate oxalacetate transaminase and glutamate pyruvate transaminase in the serum, on the protein content and lipid peroxidation levels in the liver homogenate. Histopathological changes produced by CCl4, such as necrosis, fatty change, ballooning degeneration and inflammatory infiltration of lymphocytes around the central veins, were clearly recovered by the treatment with Trichilia root decoction. On fractionating this extract into diethyl ether‐soluble and water‐soluble fractions, the activity was retained in the diethyl ether‐soluble fraction. Moreover, the administration of decoction prevented a preferential deposition of collagen around the sinusoidal cell layer, which is responsible for the perisinusoidal fibrosis in the early stage of CCl4 damage. This study showed that treatment with Trichilia roka extracts or silymarin (as reference) appeared to enhance the recovery from CCl4‐induced hepatotoxicity. The hepatoprotective properties of Trichilia roka may be correlated to polyphenol content of the decoction and its diethyl ether‐soluble fraction.

Effects of Some Malian Medicinal Plants on the Respiratory Tract of Guinea-pigs

Crossopteryx febrifuga, Pteleopsis suberosa and Entada africana are used in Mali traditional medicine for fever and various respiratory diseases. We have investigated the effects of these three drugs in the form of a decoction on the respiratory tract using different experimental models.

Antihepatotoxic properties of Entada africana (Mimosaceae)

The effect of Entada africana extracts on carbon tetrachloride (CCl4)‐induced acute liver damage was evaluated. Plasma enzyme levels, glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase, hepatic 5′‐nucleotidase activity and triglyceride levels increased with CCl4 administration, were lowered by pretreatment with Entada extracts. The results of this study showed that Entada, according to its therapeutic indication in various liver diseases in traditional medicine, could afford a protective action against CCl4‐induced hepatocellular injury.

Polyphenolic Compounds and Antioxidant Activity of Cold-Pressed Seed Oil from Finola Cultivar of Cannabis sativa L.

The aim of this study was to characterize the polyphenolic compounds and antioxidant activity of cold‐pressed seed oil from Finola cultivar of industrial hemp (Cannabis sativa L.). Several methodologies have been employed to evaluate the in vitro antioxidant activity of Finola hempseed oil (FHSO) and both lipophilic (LF) and hydrophilic fractions (HF). The qualitative and quantitative composition of the phenolic fraction of FHSO was performed by HPLC analyses. From the results is evident that FHSO has high antioxidative activity, as measured by DPPH radical (146.76 mmol of TE/100 g oil), inhibited β‐carotene bleaching, quenched a chemically generated peroxyl radical in vitro and showed high ferrous ion chelating activity. Reactivity towards 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) radical cation and ferric‐reducing antioxidant power values were 695.2 µmol of TE/100g oil and 3690.6 µmol of TE/100 g oil respectively. FHSO contains a significant amount of phenolic compounds of which 2780.4 mg of quercetin equivalent/100 g of total flavonoids. The whole oil showed higher antioxidant activity compared with LF and HF. Our findings indicate that the significant antioxidant properties shown from Finola seed oil might generally depend on the phenolic compounds, especially flavonoids, such as flavanones, flavonols, flavanols and isoflavones. Copyright

Trichilia roka Chiov. (Meliaceae): pharmacognostic researches.

The dried aqueous extract of Trichilia roka Chiov. (Meliaceae) root was evaluated for its potential antipyretic activity on yeast-induced hyperthermia in rats. The drug showed a significant reduction of body temperature when administered orally at the doses of 0.25, 0.5 and 1.0 g/kg. The antipyretic activity of T. roka was compared to indomethacin treatment (50 mg/kg), used as a reference drug. The results of this study confirm the validity of traditional usage of T. roka as an antipyretic agent. Moreover, micromorphological investigations were carried out by scanning electron microscopy obtaining useful phytognostic elements for the correct identification of the drugs both in scraped and powdered forms because this is of great interest for quality control in basic research and drug production, especially for imported items and for raw material sold by traditional herborists.

Anti-angiogenic activity of Entada africana root

Entada africana roots are used in African traditional medicine for various diseases including inflammation. This application may be mediated through anti-angiogenic effects. Thus, in this study the anti-angiogenic activity of E. africana root extracts (n-hexane, chloroform, chloroform/methanol and methanol) was preliminarily evaluated by the quantitative determination of endogenous alkaline phosphatase in zebrafish embryos. A bioactivity-guided fractionation of chloroform/methanol extract yielded apigenin and robinetin as the main constituents from the most active fractions. In addition, a marked reduction on capillary formation was evidenced in chick chorioallantoic membrane after treatment with the active fractions or isolated compounds. Results obtained in this study suggest that the anti-angiogenic effects of E. africana root may account for its use in inflammatory diseases and other related pathological conditions.

Polyphenolic profile and biological activities of black carrot crude extract ( Daucus carota L. ssp. sativus var. atrorubens Alef.)

Black carrot (Daucus carota L. ssp. sativus var. atrorubens Alef.) is a valuable source of carbohydrates, minerals and vitamins and contains also high amounts of anthocyanins giving the characteristic deep-purple color. These latter compounds are known as natural dyes used in the food and pharmaceutical industry that have recently attracted much attention for their healthful properties. The aim of this work was to investigate for the first time the polyphenolic profile and biological properties of a black carrot crude extract (BCCE) through an in-depth analysis of the main polyphenolic classes evaluating its antioxidant, cytoprotective and anti-angiogenic properties. Twenty five polyphenols were quantified by LC-DAD-FLD-MS/MS analysis (anthocyanins 78.06%, phenolic acids 17.89% and other flavonoids 4.06%) with polyglycosylated cyanidins as major components. In addition, BCCE showed a strong antioxidant and free radical scavenging activity particularly in the hydrogen transfer-based assays (ORAC and β-carotene bleaching) and a significant increase in the cell viability. Furthermore, BCCE exhibited a strong anti-angiogenic activity at the highest concentration assayed on the chick chorioallantoic membrane (50μg/egg). In conclusion, the obtained results demonstrated the antioxidant, cytoprotective and anti-angiogenic properties of BCCE, which highlight that the higher biological activity of BCCE is probably due to the synergic effects exerted by various polyphenolic classes.