Studies on the interactions between some flavonols and cyclodextrins.

The interactions of some natural flavonols with alpha, beta- and gamma-Cds have been investigated. Guest molecules were galangin, kaempferol and quercetin. Inclusion complexes were prepared by kneading and freeze-drying. The complexes were characterized using different physico-chemical methods based on differential scanning calorimetry (DSC), infrared spectroscopy (IR) and NMR spectroscopy. In the proton and carbon spectra the effects of complexation on the chemical shifts of the internal and external protons of Cds in the presence of each flavonoid were observed. Moreover, the water-solubility of the flavonols in the presence of Cds was also evaluated. The increased solubility of quercetin and kaempferol in the presence of beta-Cd was evidenced. For all three guests, multidimensional NMR experiments in DMSO and water are consistent with dynamic binding processes, dominated by insertion of the B ring into the wider rim of the Cd cavity.

Evaluation of the content and stability of the constituents of mother tinctures and tinctures: the case of Crataegus oxyacantha L. and Hieracium pilosella L.

As a part of our investigations on the content and stability of herbal drug preparations, we evaluated the content and stability of tinctures and mother tinctures of Hawthorn leaves and flowers and Hawkweed. Hawthorn preparations are mainly used by patients with cardiac diseases; Hawkweed is employed for the treatment of cellulitis and obesity due to its diuretic properties. Both tinctures (DER 1:5) and mother tinctures (DER 1:10) are herbal preparations reported in the European Pharmacopoeia. The first preparation is obtained using dried herbal drugs; the latter is a homoeopathic preparation obtained with fresh plant material, often used in substitution of tinctures. The aim of this work was to assess the qualitative and quantitative profile of the constituents of the investigated preparations and the chemical stability of their marker constituents from long-term testing using HPLC assays. Characteristic constituents of Hawthorn leaves and flowers are flavonoids such as vitexin-2''-O-rhamnoside and hyperoside and oligomeric procyanidins. Characteristic constituents of Hawkweed are caffeoyl-quinic acid derivatives, flavonoids and a coumarin:umbelliferone. Our investigation showed that Hawthorn mother tincture had a higher concentration of procyanidins with respect to the tincture but the stability of these constituents were very low in both preparations. Total flavonoidic content was 3.33 mg/ml, about 1.5 times more than the content of mother tincture and the shelf-life t(90) was about 7 months for both preparations. For Hawkweed preparations a content of caffeoyl-quinic acid derivatives (ca. 4 mg/ml) was found, but their stability was good only in the tincture. The concentrations of flavonoids and umbelliferone were two times as much in the tincture with respect to the mother tincture. Stability of these two classes of constituents was good for both preparations over a 9-month period.

Development and stability of semisolid preparations based on a supercritical CO2 Arnica extract.

Conventional herbal drug preparations (HDP) based on Arnica montana L. have a low content of the active principles, sesquiterpene lactones, which show poor stability and low physical compatibility in semisolid formulations. Recently, an innovative supercritical carbon dioxide (CO2) extract with high sesquiterpene content has been marketed. Development of six semisolid preparations (cetomacrogol, polysorbate 60, polawax, anphyphil, natrosol and sepigel) based on this innovative CO2 extract is discussed. Stability of these preparations was investigated according to ICH guidelines. The evaluation of in vitro release of active constituents was performed using the cell method reported in the European Pharmacopoeia. Preliminary data on in vivo permeation of three selected formulations is demonstrated using the "skin stripping" test, according to the FDA, in healthy subjects. Analysis of sesquiterpene lactones within the extract and in vitro and in vivo studies was performed by RP-HPLC-DAD-MS method. The cetomacrogol showed the best release profile in the in vitro test, while in the in vivo test the best preparation resulted polysorbate 60 and polawax.

Stability of the constituents of Calendula, milk-thistle and passionflower tinctures by LC-DAD and LC-MS.

As a part of our investigations on the stability of tinctures, we evaluated 40 and 60% v/v tinctures of Calendula flower, Milk-thistle fruit and Passionflower. These preparations are widely employed in phytotherapy, thus Calendula is used externally for anti-inflammatory properties, Milk-thistle and Passionflower are employed for hepatic injuries and in tenseness with difficulty in falling asleep, respectively. Aim of this work was to assess the chemical stability of their active or marker constituents from accelerated and long-term testing by using HPLC. For Calendula flower and Passionflower active constituents are not known, however, flavonoids seem to have a crucial importance for the activity, and thus are considered the markers of Calendula and of Passionflower. Active constituents of Milk-thistle are represented by silymarin that is a phytocomplex mainly constituted by three flavolignans: silybin, silychristin and silydianin. Our investigation showed a very low thermal stability of the constituents from accelerated and long-term testing and determined by HPLC-DAD and -MS analyses and was related both to the class of flavonoids and water content of the investigated tinctures. Thus, shelf-lives at 25 degrees C of the most stable tincture (Passionflower 60% v/v) was about 6 months and only about 3 months the stability of Milk-thistle tinctures.

NMR spectroscopy: a useful tool for characterisation of plant extracts, the case of supercritical CO2 arnica extract.

The efficiency of two-dimensional homonuclear (1)H-(1)H correlated spectroscopy (COSY) and two-dimensional reverse heteronuclear shift correlation spectroscopy (i.e. heteronuclear multiple quantum correlation, HMQC) in characterising the content of the constituents of innovative extracts is demonstrated. These experiments were performed directly on a supercritical carbon dioxide (CO(2)) commercial extract of arnica and were able to fully characterise the active constituents, sesquiterpenes, and other metabolites extracted with the supercritical CO(2), namely polyketides. Identification of constituents was performed by combining literature data and information obtained by 2D-NMR experiments.