Maria Paola Germanò

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.

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.

Effects of Helichrysum italicum extract on growth and enzymatic activity of Staphylococcus aureus

Helichrysum italicum G. Don (Compositae) is a shrub commonly found in dry, sandy and stony areas of Mediterranean regions. This plant is known for its anti-inflammatory, anti-allergic and antimicrobial activity. The aim of this study was to evaluate the effect of the diethyl ether extract on growth of Staphylococcus aureus (ATCC 6538P, MRSA and MSSA isolates) and the influence of subminimum inhibitory concentrations (subMICs) on some enzymes which are considered virulence factors. The results indicate that the H. italicum extract had an inhibitory effect on S. aureus strains reducing both their growth and some of the enzymes such as coagulase, DNAse, thermonuclease and lipase. Helichrysum italicum extract could be a novel antimicrobial agent, less toxic to human skin and tissues, worthy of further studies.

Antiulcer activity of Pteleopsis suberosa.

The bark Pteleopsis suberosa is commonly used in Mali for the treatment of gastric ulcers. The present study evaluated the antiulcerogenic property of chloroform, ethanol and aqueous extracts and of decoction of P. suberosa bark against ulcer lesions induced by ethanol and indomethacin in rats. The results tend to confirm the popular use of the plant.

Characterization of the polyphenolic fraction of Morus alba leaves extracts by HPLC coupled to a hybrid IT-TOF MS system.

Infusions or dried leaves from Morus alba (L., Moraceae) have long been used in folk medicine for the prevention or treatment of several diseases. Despite the great interest in determining the role of phytonutrients as potential therapeutic agents, and the rising demand of natural sources with nutraceutic benefits, the antioxidant content of many foodstuffs is unknown, making accurate estimation for human dietary consumption and the correlation to human diseases difficult. The high content in polyphenols mainly accounts for in vitro and in vivo antioxidant activity of extracts obtained from this plant, and it is responsible for their preventive and therapeutic roles in a number of human diseases. In this study, we achieved full characterization and quantitation of flavonoids and other phenolic components extracted from lyophilized mulberry leaves, by maceration with ethanol. To tackle such a task, an RPLC-diode array detector-MS system was optimized, employing a partially porous octadecylsilica column as stationary phase. Identification of mulberry leaves constituents was carried out on the basis of the complementary information obtained from their migration times, diode array spectra, MS ions, and MS/MS fragments. The employment of the hybrid (IT-TOF) mass spectrometer further allowed the structural assignment of a series of structural isomers. To the best of our knowledge, 11 out of 22 identified compounds are being reported in mulberry leaves for the first time, and the relative amounts determined, in the two cultivars analyzed.

Effects of Pteleopsis suberosa extracts on experimental gastric ulcers and Helicobacter pylori growth

Pteleopsis suberosa Engl. et Diels was used in the traditional medicine of Mali for the treatment of gastric and duodenal ulcers. In an ethnopharmacological approach, Pteleopsis suberosa extracts of the stem bark were investigated for antiulcer and antibacterial activity against Helicobacter pylori standard strains and clinical isolates. The decoction, the traditional form of administration of the drug in Mali, and the methanolic extract were active against all the bacterial strains tested. The minimum inhibitory concentrations ranged from 62.5 to 500 microg/ml for the decoction and from 31.25 to 250 microg/ml for the methanolic extract. The results indicate that Pteleopsis suberosa may be a source of compounds with a therapeutic potential against gastric ulcers associated with Helicobacter pylori infections.

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.

Evaluation of Malian traditional medicines: screening for antimicrobial activity.

The antimicrobial properties of a decoction and methanol extract of 13 plant species used in the traditional medicine of Mali, for fever and respiratory tract diseases, have been tested for in vitro antibacterial activity against clinically isolated bacterial strains: Haemophilus influenzae (6 strains); Staphylococcus aureus (5 strains); Streptococcus pneumoniae (3 strains); Streptococcus pyogenes (8 strains) and Moraxella catarrhalis (5 strains) responsible for respiratory infections.

Vernoniosides and an androstane glycoside from Vernonia kotschyana

Five new stigmastane-type steroidal glycosides, vernoniosides D1, D2, D3, F1, and F2 and a new androst-8-en glycoside have been isolated from the root of Vernonia kotschyana. The aglycones of the first five compounds possess a common 3β-hydroxy-Δ8,14 steroidal nucleus and different side-chains; the glycosidic moieties are made up of one or two monosaccharides (glucose, xylose). Their structures have been elucidated using a combination of 1D and 2D NMR techniques as 3β,24β-trihydroxy-21,23:22,28:26,28-triepoxy-5α-stigmasta-8(9),14(15)-dien-3-O-β-d-glucopyranoside; 3β,24β-trihydroxy-21,23:22,28:26,28-triepoxy-5α-stigmasta-8(9),14(15)-dien-3-O-β-xylopyranosyl-(1 → 3)-β-d- glucopyranoside; 3β,24β-trihydroxy-21,23:22,28:26,28-triepoxy-5α-stigmasta-8(9),14(15)-dien-3-O-β-d-glucopyranosyl-(1 → 2)-β-d- glucopyranoside; 3β,24β,26,28α-tetrahydroxy-22,28-epoxy-5α-stigmasta-8(9),14(15)-dien-21,23-lactone-3-O-β-d-glucopyranoside; 3β,24β,26,28α-tetrahydroxy-22,28-epoxy-5α-stigmasta-8(9),14(15)-dien-21,23-lactone-3-O-β-d-xylopyranosyl-(1 → 3)-β-d- glucopyranoside.

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.