Ljiljana P. Stanojević

Antioxidant activity and total phenolic and flavonoid contents of Hieracium pilosella L. extracts.

The antioxidant activity of water, ethanol and methanol Hieracium pilosella L. extracts is reported. The antioxidative activity was tested by spectrophotometrically measuring their ability to scavenge a stable DPPH• free radical and a reactive hydroxyl radical trapped by DMPO during the Fenton reaction, using the ESR spectroscopy. Total phenolic content and total flavonoid content were evaluated according to the Folin-Ciocalteu procedure, and a colorimetric method, respectively. A HPLC method was used for identification of some phenolic compounds (chlorogenic acid, apigenin-7-O-glucoside and umbelliferone). The antioxidant activity of the investigated extracts slightly differs depending on the solvent used. The concentration of 0.30 mg/mL of water, ethanol and methanol extract is less effective in scavenging hydroxyl radicals (56.35, 58.73 and 54.35%, respectively) in comparison with the DPPH• radical scavenging activity (around 95% for all extracts). The high contents of total phenolic compounds (239.59–244.16 mg GAE/g of dry extract) and total flavonoids (79.13–82.18 mg RE/g of dry extract) indicated that these compounds contribute to the antioxidative activity.

ALLICIN AND RELATED COMPOUNDS: BIOSYNTHESIS, SYNTHESIS AND PHARMACOLOGICAL ACTIVITY †

In this review, the biosynthesis of allicin (allyl thiosulfinate) by enzymatic transformation of alliin and various methods of its synthesis with detailed investigation of mechanisms and kinetics are summarized. A convenient method is also described for determination of allicin stability and the utility of the inclusion complexes of this pharmacologically active agent with β-cyclodextrins in increasing its stability. Allicin is the initial precursor for the production of ajoene ((E)- and (Z)-4,5,9-trithiadodeca- 1,6,11-triene 9-oxides) and vinyldithiin (2-vinyl-4H-1,3-dithiin, and 3-vinyl-4H-1,2- dithiin), which are more stable and show various pharmacological effects. The mechanisms of allicin transformations to these compounds are given in detail. Finally, the data on the pharmacological effects of allicin and its transformation products, ajoene and vinyldithiin, are presented.

Thermal degradation, antioxidant and antimicrobial activity of the synthesized allicin and allicin incorporated in gel

The main carriers of the pharmacological activity of garlic (Allium sativum L.) are organic sulfur compounds, the most important among them being allicin, a sulfenic acid thioester, or allylthiosulfonate. In this paper, the identification of synthesized and purified allicin was determined by using various spectroscopic methods (UV/VIS, FTIR, NMR). A HPLC method was developed for the detection and determination of the allicin content. The thermal degradation of allicin by using FTIR method was monitored. The method for the production of allicin gel based on Carbopol 940 (poly(acrylic acid)) was elaborated. The antimicrobial activity of pure allicin and allicin incorporated into gel by using a disk diffusion method was determined. In order to determine the antioxidant activity of allicin DPPH test was done and it was proved that with low concentrations (1 mgcm-3) a high DPPH radicals scavenging capacity (90%) was achieved.

Transformation of Synthetic Allicin: The Influence of Ultrasound, Microwaves, Different Solvents and Temperatures, and the Products Isolation

The transformation of the synthesized allicin, using conventional method, the influence of ultrasound and microwaves, in different organic solvents (acetonitrile, acetone, methanol, and chloroform), at various temperatures (room temperature, 45°C, and 55°C) was investigated. Allicin degradation kinetic was monitored by HPLC. Allicin transformation under the effect of microwaves is faster than transformations performed under the influence of ultrasound or by conventional method. Increase of the temperature accelerates allicin transformation. Pharmacologically active compounds of (E)-ajoene, (Z)-ajoene, 3-vinyl-4H-1,2-dithiin, 2-vinyl-4H-1,3-dithiin, and diallyl disulfide were isolated from the mixture of transformation products of allicin under the influence of microwaves in methanol at 55°C, which is according to kinetic parameters (highest values of the order of reaction and the lowest activation energy) the optimal method.

Inclusion complexes of amlodipine besylate and cyclodextrins

AbstractIn this paper the procedure for the preparation of inclusion complexes of amlodipine besylate with β-cyclodextrin (β-CD) and 2-hydrohypropyl-β-cyclodextrin (HPβ-CD) and their structural characterization was described. Molecular inclusion complexes of amlodipine besylate are prepared by the coprecipitation method and characterised by the application of spectroscopic methods FTIR, 1H-NMR and XRD. The photosensitivity of amlodipine besylate in the inclusion complexes was also determined with respect to uncomplexed agent. DSC curves indicate the loss of the clear peak due to melting of amlodipine besylate at about 200°C, while on XR diffractograms certain reflections are lost belonging to amlodipine besylate in complexes. This indicates its inclusion in the vacancies of the host. The inclusion of amlodipine besylate with cyclodextrins increases the stability, i.e. decreases the photosensitivity of amlodipine besylate.

The effect of hydrodistillation techniques on yield, kinetics, composition and antimicrobial activity of essential oils from flowers of Lavandula officinalis L.

The essential oils from flowers of Lavandula officinalis L. (L. officinalis L.= L. angustifolia Mill.) were obtained by two hydrodistillation techniques: standard (technique I) and modified (technique II) Clevenger hydrodistillation. The yield, hydrodistillation kinetics, composition and antimicrobial activity of essential oils were investigated. The higher yield of oil was obtained by hydrodistillation technique II. The new analytical hydrodistillation kinetics model of essential oil from Lavandulae flowers was defined. The essential oil composition was analyzed by gas chromatography–mass spectroscopy (GC–MS). There were differences in chemical compositions of the oils obtained by different techniques. Antimicrobial activity of essential oil obtained by technique I and II against Salmonella enteritidis, Klebsiella pneumoniae, Staphylococcus aureus, Enterococcus faecalis, Candida albicans and Aspergillus niger was the same, while the activity against Escherichia coli and Pseudomonas aeruginosa was slightly different.

The protection of Nifedipin from photodegradation due to complex formation with β-cyclodextrin

AbstractThe inclusion complex β-cyclodextrin:nifedipin was prepared in solid state by coprecipitation with 1:1 mol ratio. The structure of the obtained complex and nifedipin was characterized by use of X-ray diffraction (XR), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC) methods. The photodegradation of nifedipin and the β-cyclodextrin:nifedipin inclusion complex in solid state was monitored under natural daylight by infrared spectroscopy, whereby the free nifedipin degraded four to five times faster than the complexed nifedipin. The photodegradation products of both free and complexed nifedipin, formed during irradiation at 350 nm (with corresponding energy flux of 18 W m−2) were monitored by liquid chromatography during various time intervals. The speed of formation of nitroso- and nitro-phenyl derivatives by nifedipin irradiation was significantly higher than those of complexed nifedipin irradiation, which indicates its increased photostability in the inclusion complex. The effect on this property is significant because it contributes both to the improvement of the therapeutic effect of nifedipin and to the safer application thereof.

The effect of hydrodistillation technique on the yield and composition of essential oil from the seed of Petroselinum crispum (Mill.) Nym. Ex. A.W. Hill

The essential oil was isolated from the seed of Petroselinum crispum (Mill.) Nym. ex. A.W. Hill by using different techniques of Clevenger-type hydrodistillation. The highest yield of oil, after five consecutive hydrodistillation runs (3.9 mL/100 g of plant material), was obtained by the technique in which water from the still flask was separated by filtration and used together with fresh water for immersing the plant material in a subsequent distillation. Regardless of the technique used, the oil contained different amounts of α-pinene, s-p/nene, limonene, 2,3,4,5-tetramethoxy-1-allylbenzene, apiole and 1,2-benzenedicarbonic acid.

Antioxidant activity of Galium mollugo L. extracts obtained by different recovery techniques

The yield of extractive substances, antioxidant activity, as well as total phenolic and total flavonoid contents of aqueous-ethanolic extracts obtained from aerial parts of Galium mollugo L. by different extraction techniques (maceration, reflux and ultrasonic extraction) were reported. The antioxidant activity of extracts was tested by measuring their ability to scavenge a stable DPPH free radical, while the total phenolic and total flavonoid contents were determined according to the Folin-Ciocalteu procedure and a colorimetric method, respectively. The Duncan’s multiple range tests were used to evaluate if there were significant differences among yields of extractive substances, total phenolics, total flavonoids and EC50 values for the extracts obtained by different extraction techniques. The extracts obtained by the reflux extraction contained higher amounts of extractive substances, as well as phenolic and flavonoid compounds, and showed a better antioxidant activity than those obtained by the two other recovering techniques.

Hydrodistillation kinetics and essential oil composition from fermented parsley seeds

The effect of fermentation conditions on the yield and composition of the essential oil from Petroselinum crispum (Mill.) Nym. ex. A.W. Hill seeds was studied. The yield of essential oil was determined by a Clevenger-type apparatur, and the composition of the oil by GC analysis. The highest yield of essential oil (5.90 mL per 100 g, i.e. 96.7% in regard to the oil content in parsley seeds) was obtained from disintegrated parsley seeds fermented for 4 h at 30°C with a hydromodulus of 1:20 w/v, after the sixth hydrodistillation each lasting 240 minutes. The obtained oil contained α-pinene, s-pinene, sabinene, myristicin, 2,3,4,5-tetramethoxy-1-allylbenzene, apiole and 1,2 benzene-dicarbonic acid. The density of the oil (d25) was 1.039 g/mL3, the refractive index, (nD20) was 1.5214 and the oil solubility was 8 volume parts of 80% vol. ethanol for 1 mL of oil.