Synthesis of syn- and enantioenriched anti-β-amino alcohols by highly diastereoselective borono-Mannich allylation reactions

A highly diastereoselective method for the synthesis of syn-β-amino alcohols and enantioenriched anti-β-amino alcohols has been developed involving α-hydroxyl aldehydes and chiral α-phenylaminoxyaldehydes or α-benzoyloxyaldehydes, respectively in Petasis borono-Mannich allylation reactions. This study broadens the scope and utility of the Petasis reaction to include pinacol allylboronate and highlights its unique reactivity and stereochemical outcomes.

(R)-3-(8'-Hydroxyfarnesyl)-indole and other chemical constituents from the flowers of Anomianthus dulcis and their antimalarial and cytotoxic activities

A new farnesylindole, (R)-3-(8'-hydroxyfarnesyl)-indole (1), as a scalemic mixture (33% ee) along with nine known compounds (2-10), including one farnesylindole, three flavanones, three flavone derivatives and two chalcone derivatives were isolated from the methanolic crude extract of the flowers from Anomianthus dulcis. All compounds were purified by appropriate chromatographic techniques and their structures elucidated by spectroscopic methods. Compounds 1, 2 and 8 showed moderate antiplasmodial activities against TM4/8.Two and K1CB1 strains of which compound 2 displayed the best activity with IC₅₀ values of 27.9 ± 2.57 and 21.4 ± 1.68 µM, respectively. In addition, compound 1 also presented modest cytotoxicity against a KB cell line with an IC₅₀ value of 22.3 ± 0.39 µM. None of these compounds showed cytotoxicity against Vero cells.

Antibacterial and cytotoxic activities of phenolic constituents from the stem extracts of Spatholobus parviflorus

A new 2-arylbenzofuran, spathobenzofuran (1), together with ten known compounds including a 2-arylbenzofuran, three pterocarpans and six isoflavones were isolated from the acetone crude extract of the stems of Spatholobus parviflorus. All compounds were characterised by spectroscopic methods. Compound 4 was active (MIC 8 µg/mL) against Gram-negative Pseudomonas aeruginosa TISTR 781 while compound 2 had modest activity against Gram-positive Staphylococcus aureus TISTR 1466 with a MIC value of 16 µg/mL. All isolated compounds showed no cytotoxicity against Vero and KB cells.

Antimalarial Oxoprotoberberine Alkaloids from the Leaves of Miliusa cuneata

Five new oxoprotoberberine alkaloids, miliusacunines A-E (1-5), along with nine known compounds, 6-14, were isolated from an acetone extract of the leaves and twigs of Miliusa cuneata. Their structures were elucidated by spectroscopic analysis. All isolated compounds were evaluated for their cytotoxicities against the KB and Vero cell lines and for antimalarial activities against the Plasmodium falciparum strains TM4 and K1 (a sensitive and a multi-drug-resistant strain, respectively). Compound 1 showed in vitro antimalarial activity against the TM4 strain, with an IC50 value of 19.3 ± 3.4 μM, and compound 2 demonstrated significant activity against the K1 strain, with an IC50 value of 10.8 ± 4.1 μM. Both compounds showed no discernible cytotoxicity to the Vero cell line at the concentration levels evaluated.

Cytotoxic and Antimalarial Alkaloids from the Twigs of Dasymaschalon obtusipetalum

One new p-quinonoid aporphine alkaloid, obtusipetadione (1), and eleven known compounds (2-12) were isolated from the acetone extract of the twigs of Dasymaschalon obtusipetalum. Their structures were elucidated by spectroscopic methods. The cytotoxic and antimalarial activities of the isolated compounds were evaluated. Compound 1 showed significant in vitro antiplasmodial activity against the P. falciparum strains TM4 and K1 (multidrug resistant strain) with IC50 values of 2.46 ± 0.12 and 1.38 ± 0.99 μg/mL, respectively with no cytotoxicity. Compound 9 had more modest antiplasmodial activity, but significant cytotoxicity.

Cytotoxic and Antimalarial Alkaloids from the Twigs of Dasymaschalon obtusipetalum

One new p-quinonoid aporphine alkaloid, obtusipetadione (1), and eleven known compounds (2–12) were isolated from the acetone extract of the twigs of Dasymaschalon obtusipetalum. Their structures were elucidated by spectroscopic methods. The cytotoxic and antimalarial activities of the isolated compounds were evaluated. Compound 1 showed significant in vitro antiplasmodial activity against the P. falciparum strains TM4 and K1 (multidrug resistant strain) with IC50 values of 2.46±0.12 and 1.38±0.99 μg/mL, respectively with no cytotoxicity. Compound 9 had more modest antiplasmodial activity, but significant cytotoxicity.