Synthesis and biological evaluation of (-)-kunstleramide and its derivatives.

Stereoselective total synthesis of (-)-kunstleramide, a cytotoxic dienamide from the bark of Beilschmiedia kunstleri gamble, has been accomplished by using Keck's asymmetric allylation and Trost isomerization as key reactions. Application of the developed strategy for the synthesis of a series of amide analogues (8-22) was also reported. Furthermore, the synthesized compounds were evaluated for their in vitro anti-proliferative activities against human epithelial lung carcinoma (A549), human epithelial cervical cancer (HeLa), human breast adenocarcinoma (MCF7) and human neuroblastoma (IMR32) cell lines using the SRB assay. All the compounds show moderate anti-proliferative activity against all cell lines. Some of the piperazine derivatives (17-22) strongly inhibit the growth of breast cancer cells with IC50 values of 8-20 µM.

Isolation, semi-synthesis and bio-evaluation of spatane derivatives from the brown algae Stoechospermum marginatum.

A comprehensive investigation of chemical constituents from brown algae Stoechospermum marginatum yielded ten known spatane compounds (1-10). To develop the compound libraries on these scaffolds, a series of semi synthetic derivatives was prepared (1a-1d, 2a, 4a, 11 and 12) and investigated for their anti-microbial and anticancer activities. The results indicated that compounds 2a, 4, 1b and 4a exhibited potent cytotoxic activities against B16F10 cancer cell line with IC50 values of 3.28, 3.45, 3.62 and 4.11 µg/ml respectively, which are comparable to the standard drug (etoposide IC50=4.12 µg/ml). In addition, 4 and 1b were also manifested potent antimicrobial activities against tested bacterial and fungal strains. This is the first Letter on the synthesis and biological activities of these novel derivatives.

Stereoselective synthesis of alpinoid-C and its analogues and study of their cytotoxic activity against cancer cell lines.

A simple, highly efficient and stereoselective synthetic route has been developed for synthesis of alpinoid-C (1) and its analogues (2, 3 and 4) from commercially available starting materials by using Wittig olefination, Sharpless asymmetric epoxidation, Grubbs cross metathesis as key steps. All the compounds showed moderate anti-proliferative activity against human leukemia/carcinoma (U-937, THP-1, COLO-205 and HepG2) and mouse melanoma (B16-F10) cancer cell lines. Compounds 3 and 4 are found to be most potent with an IC(50) of 7.53 µM and 32.26 µM on THP-1, 11.12 µM and 7.21 µM on COLO-205 cell lines, respectively.

An efficient protocol for alcohol protection under solvent- and catalyst-free conditions.

A simple and highly efficient protocol for pivaloylation of alcohols without using a catalyst under solvent-free conditions has been developed. The key advantages of the reaction are short reaction time, high yields, simple workup, and no need for further purification. Selectivity was observed between primary alcohols vs. secondary alcohols and aliphatic alcohols vs. aromatic alcohols. The accentuated and relevant phenomenon of this method that we observed is in one-pot conversion of TBS protection into Piv protection of the hydroxyl group.