Sci. Pharm., Volume 73, Issue 3 (September 2005) – 7 articles , Pages 81-161

Thermodynamic studies of piroxicam in aqueous solution complexed with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD) and two β-cyclodextrin derivatives, hydroxypropyl-β-cyclodextrin (HP-P-CD) and methyl-β-cyclodextrin (Me-β-CD) were performed at different temperatures and pH values using the phase solubility method. The phase solubility diagrams of β-CD, γ-CD and HP-β-CD is of A_L-type behavior, indicating the formation of 1:l complexes. The related stability constants range from β-CD > γ-CD > Me-β-CD > HP-β-CD, respectively. An A_p-type solubility diagram is observed for Me-β-CD, indicating the formation of 1:2 complexes at higher CD concentrations. From the temperature dependence of the equilibrium constants the reaction enthalpies and entropies have been determined. The contributions of the reaction entropies are small and no enthalpy-entropy-compensation is observed, except for γ-CD, where a very small negative reaction entropy could be estimated. Moreover, the influence of the pH value is rather high because the differently charged forms of piroxicam show different solubility behavior in water. Full article

Lappula myosotis Moench. (Boraginaceae) is a plant growing wide-spread in the Mongolian Aimags Khubsgul, Khangai, Khentei, Mongol dahurica, Altai and Alasha Gobi [1]. From this plant four pyrrolizidine alkloids were isolated and their structures determined using spectroscopical methods: lycopsamine, intermedine and their acetylderivatives. This plant is used in the Mongolian traditional medicine externally but on account of its high level of alkaloids (~ 0.2%) the usage of L. myosotis may be hazardous for humans. Full article

Samples of the Himalayan medicinal plant Swertia chirata obtained from a local market in Nepal, from a micropropagated field cultivated clone, and from two in vitro-clones were compared by means of HPLC. The substance patterns of methanolic and dichloromethane extracts of the in vivo grown materials showed good conformity while in the samples from tissue culture major compounds were missing. Our findings confirm that the secondary metabolism of in vitro-cultivated plants normally differs from that of plants in their natural environment. Furthermore, the compound pattern of plants produced through micropropagation and subsequently cultivated in the field is comparable to that of plants collected from the wild. As an alternative to the uncontrolled depletion of the natural resources a sustainable use of Swertia chirata could hence be achieved by controlled field culture of micropropagated plants. Full article

From the aqueous acetone extract of the leaves of Psidium guajava L. the flavanols catechin and gallocatechin, the procyanidins B1, B2, B3 and two prodelphinidins (gallocatechin - (4α→8) - catechin; gallocatechin - (4α→8) - gallo-catechin) were isolated. A more abundant proanthocyanidin polymer was also isolated, purified and its chemical constitution studied by ¹³C-NMR and phloroglucinol degradation. The mean molecular weight of the polymer was estimated to be about 9 to 10 flavan-3-ol-units with a ratio of procyanidin: prodelphinidin units at 2 : 1 some of which are derivatized by gallic acid. Full article

Starting from 2-(6-methoxy-1-methyl-9H-carbazol-2-yl)ethylamine and 2-methylisonicotinic acid, 9-hydroxy-5,6-dimethyl-1-(2-methylpyridin-4-yl)-6H-pyrido[4,3-b]carbazole (5) was obtained. The new compound showed significant cytostatic activity for cultured L1210 cells and no inhibition of growth of the E. coli O56 strain was observed. The bactericidal activity of normal human serum against E. coli O56 was not affected by the examined compound 5 and its isomer 4. Full article

Cyclic hydroxamic acids like 2,4-dihydroxy-7-methoxy-2H-1 ,4-benzoxazin-3(4H)-one (DIM BOA) and 2,4-dihydroxy-2H-1 ,4-benzoxazin-3(4H)-one (DIBOA) are found in several plants playing an important role in the defense-system of plants against a variety of enemies. To investigate new mechanism and effects we synthesized the molecules using known synthetic pathways. Since the chemical data of DIMBOA are not complete or even false, we decided to publish the missing ones in this journal. Full article

It is well established through the last decade that niosomes have potential applications as drug carriers either to improve drug permeation across membranes or targeting to specific tissues. Having a considerable ability to improve the permeability of drugs through lipoid membranes, niosomes have been utilized as carriers to enhance atenolol absorption from the gastrointestinal tract. Two methods have been adopted to prepare niosomes, the proniosome-derived method (A) and the conventional film hydration method (B). The products from the two methods were compared in terms of their morphology, vesicle size, drug encapsulation efficiency, in vitro drug release and enhancement effect on drug permeation across the intestinal membrane using an everted sac technique. Proniosome-derived niosomes were smoother and exhibited a smaller (5 μm) vesicle size compared to those prepared by conventional methods (12 μm). High encapsulation efficiencies of 98.6% and 93.4% were achieved by methods A and B, respectively. In vitro drug release has been significantly retarded from both types of niosomes. Comparing to pure drug, which dissolved completely in 15 min, only 8.9% and 9.9% of the entrapped drug was released in the same time period. The drug release kinetics showed non-Fickian (anomalous) behavior. Permeation through an everted intestinal sac showed a significant enhancement effect (more than 4 fold) for both types of niosomes compared to untrapped drug; however, the difference between the two types of niosomes was not significant Full article