Halogenated Diterpenes with In Vitro Antitumor Activity from the Red Alga .

Eight new (-) structurally diverse diterpenes featuring five different carbocycles were isolated from the organic extracts of the red alga collected from the coastline of the Ionian Sea in Greece. The structures of the new natural products, seven of which were halogenated, and the relative configuration of their stereocenters were determined on the basis of comprehensive spectroscopic analyses, including NMR and HRMS data. Compounds and were found to possess in vitro antitumor activity against one murine and five human cancer cell lines with mean IC values 15 and 16 μM, respectively.

Secondary metabolites from Sida rhombifolia L. (Malvaceae) and the vasorelaxant activity of cryptolepinone.

The phytochemical study of Sida rhombifolia L. (Malvaceae) led to the isolation through chromatographic techniques of eleven secondary metabolites: sitosterol (1a) and stigmasterol (1b), sitosterol-3-O-b-D-glucopyranoside (2a) and stigmasterol-3-O-b-D-glucopyranoside (2b), phaeophytin A (3), 17³-ethoxypheophorbide A (4), 13²-hydroxy phaeophytin B (5), 17³-ethoxypheophorbide B (6), 5,7-dihydroxy-4'-methoxyflavone (7), cryptolepinone (8) and a salt of cryptolepine (9). Their structures were identified by ¹H- and ¹³C-NMR using one- and two-dimensional techniques.