Gas Chromatography-Mass Spectrometry (GC-MS) Combined with Retention Index Prediction for the Rapid Identification of Halogenated monoterpenes from a Namibian Plocamium species.

Plocamiun species collected from the Namibian coast display morphological features similar to those of both P. rigidum and P. suhrii which makes identification of these species a difficult task. It has been reported that the major secondary metabolites found in various Plocamium species are unique to each species [1]. In this study GC-MS combined with a retention index (RI) prediction strategy was used for the rapid identification of halogenated monoterpenes characteristic of a particular Namibian Plocatnium species. The RIs of the metabolites were matched with the predicted RIs of halogenated monoterpenes for which similar MS data have been reported for the same species of Plocamium. Based on the identification of the major secondary metabolite, IE,3R,4S,5E,7Z- 1-bromo-3;4,8- trichloro-7-(dichloromethyl)-3-methylocta-1,5,7-triene [2], it was proposed that these Namibian samples are closely related to that of P. suhrii. From. this, it was determined that the proposed P. suhrii specimens collected in Namibia contain four additional metabolites (with molecular formulae C10H16Br2C2, C10H11BrCI4, C10H9BrCl6 and an unknown compound) previously not reported in P. suhrii species. In addition, a compound previously identified in South African P. suhrii was not present in the Namibian Plocamium specimens.

Site-specific variability in the chemical diversity of the Antarctic red alga Plocamium cartilagineum.

Plocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like "P. cartilagineum" from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators. Secondary metabolites are highly variable in this alga, both qualitatively and quantitatively, leading us to probe individual plants to track the possible link of variability to genetic or other factors. Using cox1 and rbcL gene sequencing, we find that the Antarctic alga divides into two closely related phylogroups, but not species, each of which is further divided into one of five chemogroups. The chemogroups themselves, defined on the basis of Bray-Curtis similarity profiling of GC/QqQ chromatographic analyses, are largely site specific within a 10 km² area. Thus, on the limited geographical range of this analysis, P. cartilagineum displays only modest genetic radiation, but its secondary metabolome was found to have experienced more extensive radiation. Such metabogenomic divergence demonstrated on the larger geographical scale of the Antarctic Peninsula, or perhaps even continent-wide, may contribute to the discovery of cryptic speciation.

Elemental uptake by seaweed, Plocamium corallorhirza along the Kwazulu-natal coast of Indian Ocean, South Africa.

This study reports the elemental uptake by Plocamium corallorhiza, a Rhodophyta class of coralline alga grown richly along KwaZulu-Natal coastline. The uptake of seven important elements, namely Fe, Mn, As, B, Ti, Zn and Hg, selected based on their abundance in the samples, were investigated for a one-year cycle, from June 2002 to May 2003, at four chosen sites located along the KwaZulu-Natal coastline. The sites spread over 150 km from North to South Coast are Zinkwasi, Ballito, Treasure Beach and Park Rynie. P. corallorhiza possess good manganese and arsenic-accumulating ability and has potential to be an excellent indicator for most of the metals studied. A typical P. corallorhiza sample at Park Rynie (winter) recorded Mn (14 ppm), Fe (6.02 ppm), As (8.4 ppm), B (1580 ppb), Zn (234 ppb), Ti (751 ppb) and Hg (15.8 ppb). The general trend found at all sites was a large decrease in iron concentration in spring and summer and increase in winter. Mercury uptake was lowest in winter and autumn at all sites. The highest mercury levels in the seaweeds were recorded during spring or summer.