Suberin Fatty Acids from Outer Birch Bark: Isolation and Physical Material Characterization.

The isolation and physical material properties of suberin fatty acids (SFAs) were investigated with special reference to their potential applications as novel pharmaceutical excipients. SFAs were isolated from outer birch bark (OBB) with a new extractive hydrolysis method. The present simplified isolation process resulted in a moderate batch yield and chemical purity of SFAs, but further development is needed for establishing batch-to-batch variation. Cryogenic milling was the method of choice for the particle size reduction of SFAs powder. The cryogenically milled SFAs powder exhibited a semicrystalline structure with apparent microcrystalline domains within an amorphous fatty acids matrix. The thermogravimetric analysis (TGA) of SFAs samples showed a good thermal stability up to 200 °C, followed by a progressive weight loss, reaching a plateau at about 95% volatilization at about 470 °C. The binary blends of SFAs and microcrystalline cellulose (MCC; Avicel PH 101) in a ratio of 25:75 (w/w) displayed good powder flow and tablet compression properties. The corresponding theophylline-containing tablets showed sustained or prolonged-release characteristics. The physicochemical and bulk powder properties of SFAs isolated from OBB are auspicious in terms of potential pharmaceutical excipient applications.

Abietane-Type Diterpenoid Amides with Highly Potent and Selective Activity against Leishmania donovani and Trypanosoma cruzi.

Dehydroabietylamine (1) was used as a starting material to synthesize a small library of dehydroabietyl amides by simple and facile methods, and their activities against two disease-causing trypanosomatids, namely, Leishmania donovani and Trypanosoma cruzi, were assayed. The most potent compound, 10, an amide of dehydroabietylamine and acrylic acid, was found to be highly potent against these parasites, displaying an IC50 value of 0.37 µM against L. donovani axenic amastigotes and an outstanding selectivity index of 63. Moreover, compound 10 fully inhibited the growth of intracellular amastigotes in Leishmania donovani-infected human macrophages with a low IC50 value of 0.06 µM. This compound was also highly effective against T. cruzi amastigotes residing in L6 cells with an IC50 value of 0.6 µM and high selectivity index of 58, being 3.5 times more potent than the reference compound benznidazole. The potent activity of this compound and its relatively low cytotoxicity make it attractive for further development in pursuit of better drugs for patients suffering from leishmaniasis and Chagas disease.

Suberin fatty acids isolated from outer birch bark improve moisture barrier properties of cellulose ether films intended for tablet coatings.

We showed that the addition of suberin fatty acids (SFAs) even at small concentrations significantly improves the water vapor barrier properties of hydroxypropyl methylcellulose (HPMC) films. SFAs were isolated from the outer birch bark using extractive hydrolysis. The effects of SFAs on the film formation of aqueous HPMC were investigated with free films plasticized with polyethylene glycol (PEG 400). Special attention was paid on the physical solid-state, moisture barrier and mechanical stress-strain properties of films intended for tablet film coatings. Topography and surface morphology, glass transition temperature (Tg), tensile strength, Young's modulus, and water vapor permeation (WVP) of films were studied. The addition of SFAs lowered the Tg of films suggesting partial enhancement in film plasticization. The WVP of films decreased with increasing SFAs concentration up to 15% (calculated as a % w/w from a polymer weight). The WVP value for a non-suberized reference film and suberized film plasticized with PEG 400 was 2.13×10(-6) and 0.69[×10(-6) g/(mm(2)×h)×mm/Pa], respectively. The addition of SFAs impaired the mechanical stress-strain properties of HPMC films by reducing the deformation capacity of film. In conclusion, the film properties and performance of aqueous HPMC can be modified by including SFAs in the films.