Natural product protulactone A: Total synthesis from D-galactose, X-ray analysis and biological evaluation.

Synthesis of protulactone A (PLA, 1) and twelve of its analogues have been achieved starting from d-galactose. PLA was isolated in the crystalline state, and its crystal structure was determined utilizing X-ray crystallography, which confirmed the assumed stereochemistry at all stereocenters. All tested compounds displayed antiproliferative activity against a panel of tumour cell lines, and all of them were non-cytotoxic toward the normal cells (MRC-5). Natural product PLA (1) was the most active against the K562 and MCF-7 cell lines (IC50 6.52 and 2.20 µM, respectively). Some of the synthesized derivatives showed very potent cytotoxicity, especially analogues 11, 13 and 15 (IC50 1.08-1.14 µM against MCF-7), and 9 and 14 (IC50 1.29 and 1.64 µM against K562). SAR analysis indicated important structural motifs for antiproliferative activity. Unfortunately, PLA (1), its C-7 epimer (2) and demethylated analogue (3) did not display a significant antimicrobial activity (two Gram-positive and two Gram-negative bacteria and one fungal strain) and they also cannot affect the ability to modulate bacterial communication.

From D-xylose to terminal polyols: a simple synthetic route.

A simple and efficient synthetic approach toward different terminal alkyl tetraols and triols, starting from D-xylose, is described. The opening of the oxetane ring in a suitably protected 3,5-anhydro-D-xylose derivative with Grignard reagents leads to D-xylose-derived 5-deoxy-5-C-alkyl derivatives, which are suitable for reduction to terminal polyols after protecting group hydrolysis.