Marine natural products possessing guanidine functionalities display a considerable array of biological activity and not surprisingly have attracted considerable synthetic interest. This review discusses the isolation of several guanidine containing metabolites, primarily from the sponge Ptilocaulis spiculifer, but also from other marine organisms. It also explores the synthetic methodologies adopted for their preparation and speculates on the structural similarity of the metabolite ptilomycalin A to abiotic guanidine based anionic receptor molecules. Isolation of ptilomycalin A and related metabolitesNaturally occurring and synthetic compounds containing guanidine are of considerable interest due both to the hydrogen-bond mediated interaction of guanidinium ions and because of the wide range of biological activities these substances display. 1 Recent interest in marine natural products has seen a steady increase in the number of metabolites isolated from these sources and a metabolite of particular interest isolated from the sponge Ptilocaulis spiculifer 2 in 1989 is ptilomycalin A 1. This alkaloid has a unique and fascinating structure consisting of a pentacyclic guanidinium core linked to a spermidine unit via a w-hydroxy acid spacer group. The same compound was also isolated from a Red Sea sponge of the genus Hemimycale sp. 3 and subsequently from the sponge Batzella sp. 4 and the starfishes Fromia monilis and Celerina heffernani 5 (Scheme 1).Ptilomycalin A displays a remarkable range of biological activities including cytotoxicity against the following cell lines; P388 (IC 50 0.1 mg mL 21 ), L1210 (IC 50 0.4 mg mL 21 ), and KB (IC 50 1.3 mg mL 21 ) in addition to antifungal activity against Candida albicans (MIC 0.8 mg mL 21 ) as well as very good antiviral activity (HSV) at a concentration of 0.2 mg mL 21 . 2 Previous to the isolation of ptilomycalin A the related guanidinium alkaloids ptilocaulin 2 and isoptilocaulin 3 had been isolated from the same sponge in 1981 6 (Scheme 2). Laura Heys graduated (MChem) from Bangor University in1999, she is currently pursuing a career in the chemical industry. Christopher G. Moore graduated (BSc Hons) from Bangor in 1995 and is currently finishing his postgraduate studies which have focused on the total synthesis of guanidine containing marine metabolites. Patrick J. Murphy graduated (Since gaining this post he has concentrated his research efforts on the development of new methodology and its applications in synthesis, with two key themes being the synthesis of naturally occurring guanidine containing marine alkaloids and new applications of Wittig chemistry.

Abstract. Wake steering is a form of wind farm control in which turbines use yaw offsets to affect wakes in order to yield an increase in total energy production. In this first phase of a study of wake steering at a commercial wind farm, two turbines implement a schedule of offsets. Results exploring the observed performance of wake steering are presented, as well as some first lessons learned. For two closely spaced turbines, an approximate 13 % increase in energy was measured on the downstream turbine over a 10° sector. Additionally, the increase of energy for the combined upstream/downstream pair was found to be in line with prior predictions. Finally, the influence of atmospheric stability over the results is explored.

HPLC-UV-ELSD-MS-guided fractionation of the anti-parasitic extract obtained from the marine sponge Monanchora arbuscula, collected off the southeastern coast of Brazil, led to the isolation of a series of guanidine and pyrimidine alkaloids. The pyrimidines monalidine A (1) and arbusculidine A (7), as well as the guanidine alkaloids batzellamide A (8) and hemibatzelladines 9-11, represent new minor constituents that were identified by analysis of spectroscopic data. The total synthesis of monalidine A confirmed its structure. Arbusculidine A (7), related to the ptilocaulin/mirabilin/netamine family of tricyclic guanidine alkaloids, is the first in this family to possess a benzene ring. Batzellamide A (8) and hemibatzelladines 9-11 represent new carbon skeletons that are related to the batzelladines. Evaluation of the anti-parasitic activity of the major known metabolites, batzelladines D (12), F (13), L (14), and nor-L (15), as well as of synthetic monalidine A (1), against Trypanosoma cruzi and Leishmania infantum is also reported, along with a detailed investigation of parasite cell-death pathways promoted by batzelladine L (14) and norbatzelladine L (15).

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