Two new polyhalogenated monoterpenes from the red alga Plocamium cartilagineum

Biochemistry of the Elemental Halogens and Inorganic Halides

“…For example, the polyhalogenated monoterpenes 9 and 10 from the red alga Plocamium cartilagineum and poly halogenated sesquiterpenes from the red alga Laurencia obtussa, including isoobtusol (11) and isoobtusol acetate (12) (Fig. 7-3), showed potent activity against He La 229 human carcinoma cells (Gonzalez et al, 1978(Gonzalez et al, , 1982reviewed by Munro et al, 1987). (For additional examples, see Fusetani, 1987;Munro et al, 1987).…”

Phytochemical analysis of the Southern Australian marine alga, Plocamium mertensii using HPLC‐NMR

“…Recently the absolute configuration of this compound was determined on the basis of a single X-ray analysis study (König et al, 1999) and found to be as depicted in compound 41, which is opposite to that indicated by earlier workers (Higgs et al, 1977;Stierle and Sims, 1979). However, absolute configuration determination for polyhalogenated monoterpenes needs to be exercised with caution as there have been many instances where degradation has occurred during the acquisition thereby resulting in an incorrect assignment González et al, 1978;Sardina et al, 1985). The 1 H NMR spectrum extracted from the on-flow HPLC-NMR analysis is given in Fig.…”

“…An additional two cyclic monoterpenes (14 and 15) were isolated from P. cartilagineum in 1978 and their absolute configuration secured by a combination of spectroscopic and single X-ray diffraction studies. However, it was noted that during acquisition that 14 displayed considerable degradation (González et al, 1978). Compound 15 was tested for cytostatic and antibacterial activities and displayed inhibitory activity (ID 50 1-10 μg/mL; González et al, 1978González et al, , 1980.…”

“…However, it was noted that during acquisition that 14 displayed considerable degradation (González et al, 1978). Compound 15 was tested for cytostatic and antibacterial activities and displayed inhibitory activity (ID 50 1-10 μg/mL; González et al, 1978González et al, , 1980. Investigation of P. violaceum, collected from Monterey Bay California, resulted in the isolation of two additional cyclic monoterpenes plocamene D (16) and plocamene D ′ (17) for which the latter only differed from the former by the replacement of a chlorine with a bromine substituent .…”

On the absolute configuration determination by X-ray diffraction data

“…, (4) Gonzalez et al (1978b), (5) Gonzalez et al (1978c), (6) Fonseca et al (1979) Fayos et al (1979), (8) Alemany et al (1979a), (9) Alemany et al (1979b), (10) to be published To calculate the structure factors, F c ( -x e ), one can use more conveniently, the +x coordinates and just reverse the sign of f", the imaginary part of the scattering factors for the anomalous dispersors. In the same way, F c (+xj can be calculated from the -χ model.…”