Sami Alakurtti

Anti-leishmanial activity of betulin derivatives.

Leishmanicidal activity of 24 derivatives of naturally occurring and abundant triterpenes belonging to the lupane series, betulin, betulinic acid and betulonic acid, is described in this study. The easily modified positions of the lupane skeleton, the hydroxy groups of C-3 and C-28, as well as the carbon–carbon double bond C-20–C-29 were used as a starting point to prepare a library of triterpenoid derivatives for bioactivity studies. The compounds were evaluated against Leishmania donovani axenic amastigotes on a microplate assay at 50u2009μM. GI50 values of the most effective compounds were evaluated, as well as their cytotoxicity on the human macrophage cell line THP-1, and anti-leishmanial activity against L. donovani-infected THP-1 macrophages was determined. Betulonic acid was the most potent derivative, yielding a GI50 value of 14.6u2009μM. Promising and distinct structure–activity relationships were observed, and these compounds can be regarded as significant lead molecules for further improvement and optimization.

Heterocycle-fused lupane triterpenoids inhibit Leishmania donovani amastigotes

The synthesis of heterocyclic betulin derivatives and their activity against Leishmania donovani is reported. Betulonic acid was used as a versatile intermediate. Several different fused heterocycles were introduced at the 2,3-position of the lupane skeleton including isoxazole, pyrazine, pyridine, indole and pyrazole rings. Also the 28-position was modified. Three compounds, 5, 8 and 25, showed low micromolar activity with IC50 values of 13.2, 4.3 and 7.2 μM, respectively. Compound 8 showed the best activity and selectivity, and its activity was tested on infected macrophages using a concentration, 5 μM, where no macrophage toxicity was exhibited. Interestingly, the activity of compound 8 on axenic amastigotes and Leishmania-infected macrophages was similar.

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.

Betulin Derivatives Effectively Suppress Inflammation in Vitro and in Vivo.

Betulin is a pharmacologically active triterpenoid found in the bark of the birch tree (Betula sp. L.). Betulin and betulinic acid are structurally related to anti-inflammatory steroids, but little is known about their potential anti-inflammatory properties. In the present study, the inflammatory gene expression and the anti-inflammatory properties of betulin, betulinic acid, and 16 semisynthetic betulin derivatives were investigated. Betulin derivatives 3, 4, and 5 selectively inhibited the expression of the inducible nitric oxide synthase (iNOS) in a post-transcriptional manner. They also inhibited nitric oxide (NO) production but had no effect on the other inflammatory factors studied. More interestingly, a new anti-inflammatory betulin derivative 9 with a wide-spectrum anti-inflammatory activity was discovered. Compound 9 was found to suppress the expression of cytokines interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1), as well as that of prostaglandin synthase-2 (COX-2) in addition to iNOS. The in vivo anti-inflammatory effect of compound 9 was indicated via significant suppression of the carrageenan-induced paw inflammation in mice. The results show, for the first time, that the pyrazole-fused betulin derivative (9) and related compounds have anti-inflammatory properties that could be utilized in drug development.

Direct assembly of 2-oxazolidinones by chemical fixation of carbon dioxide.

The reaction of β- and γ-haloamines with carbon dioxide to give pharmaceutically relevant 2-oxazolidinones and 1,3-dioxazin-2-ones, was found to proceed efficiently in the presence of a base and in the absence of catalyst. After optimization of reaction conditions, the system was successfully expanded to a variety of haloamines, even at multigram scale. The reaction was further studied in silico by DFT calculations.

Optimization of Invasion-Specific Effects of Betulin Derivatives on Prostate Cancer Cells through Lead Development

The anti-invasive and anti-proliferative effects of betulins and abietane derivatives was systematically tested using an organotypic model system of advanced, castration-resistant prostate cancers. A preliminary screen of the initial set of 93 compounds was performed in two-dimensional (2D) growth conditions using non-transformed prostate epithelial cells (EP156T), an androgen-sensitive prostate cancer cell line (LNCaP), and the castration-resistant, highly invasive cell line PC-3. The 25 most promising compounds were all betulin derivatives. These were selected for a focused secondary screen in three-dimensional (3D) growth conditions, with the goal to identify the most effective and specific anti-invasive compounds. Additional sensitivity and cytotoxicity tests were then performed using an extended cell line panel. The effects of these compounds on cell cycle progression, mitosis, proliferation and unspecific cytotoxicity, versus their ability to specifically interfere with cell motility and tumor cell invasion was addressed. To identify potential mechanisms of action and likely compound targets, multiplex profiling of compound effects on a panel of 43 human protein kinases was performed. These target de-convolution studies, combined with the phenotypic analyses of multicellular organoids in 3D models, revealed specific inhibition of AKT signaling linked to effects on the organization of the actin cytoskeleton as the most likely driver of altered cell morphology and motility.

Biotransformation of Cyclodextrine-Complexed Semisynthetic Betulin Derivatives by Plant Cells

In this study, three semisynthetic betulonic acid-based compounds, 20(29)-dihydrolup-2-en[2,3-d]isoxazol-28-oic acid, 1-betulonoylpyrrolidine, and lupa-2,20(29)-dieno[2,3-b]pyrazin-28-oic acid, were studied in biotransformation experiments using Nicotiana tabacum and Catharanthus roseus cell suspension cultures. Biotransformation was performed using cyclodextrin to aid dissolving poorly water-soluble substrates. Several new derivatives were found, consisting of oxidized and glycosylated (pentose- and hexose-conjugated) products.