The NMR-directed investigation of the New Zealand marine sponge Hamigera tarangaensis has afforded ten new compounds of the hamigeran family, and a new 13-epi-verrucosane congener. Notably, hamigeran F (6) possesses an unusual carbon–carbon bond between C-12 and C-13, creating an unprecedented skeleton within this class. In particular, the structural features of 6, hamigeran H (10) and hamigeran J (12) imply a diterpenoid origin, which has allowed the putative biogenesis of three hamigeran carbon skeletons to be proposed based on geranyl geranyl pyrophosphate. All new hamigerans exhibited micromolar activity towards the HL-60 promyelocytic leukaemic cell line, and hamigeran G also selectively displayed antifungal activity in the budding yeast Saccharomyces cerevisiae. Homozygous deletion profiling (HOP) analysis suggests Golgi apparatus function as a potential target of this unusual class of sponge-derived terpenoids.

Introduced wasps (Vespula germanica and V. vulgaris) are costly invertebrate pests in New Zealand, with large impacts on the local ecology and economy. Wasps eat honeybees (Apis mellifera), which has potentially devastating effects on hive health, as well as agricultural and horticultural industries. Vespex bait, which contains fipronil in a proteinaceous carrier, has recently been introduced for wasp control. In over a decade of reported trials, honeybees have never been observed foraging on Vespex, likely because the bait contains no sugars to serve as a bee food source. However, the potential for the control agent fipronil to enter beehives has not been tested. Therefore, here, we investigated this using a liquid chromatography–mass spectrometry assay of fipronil and two of its environmental breakdown and metabolic derivatives, fipronil desulfinyl and fipronil sulfone. We did not detect fipronil in any of the worker bee, bee larva, honey or pollen samples (n = 120 per product) collected from 30 hives over a 2-year period. Furthermore, although we detected fipronil desulfinyl in one honeybee sample, this is thought to have originated from a single individual, representing a rare occurrence of intoxication, and there was no evidence that Vespex was the toxicant source. There was also no evidence of trophallactic transfer of fipronil or its derivatives in any of the hives sampled. Previous studies have reported the impairment of individual bee performance at fipronil doses similar to the detection limit of our study. However, our results provide confidence that if undetectable intoxication was occurring, it would involve an acute exposure for those few individuals affected, with minimal impairment to colonies. Therefore, we conclude that the use of Vespex in the vicinity of honeybees does not result in significant hive uptake while effectively reducing wasp pressure on honeybee colonies.

Seven new members of the hamigeran family of diterpenoids have been isolated from the New Zealand marine sponge Hamigera tarangaensis. Among the new additions are hamigeran R (1), considered to be the first benzonitrile-based marine natural product, and hamigeran S (2), the first dimeric structure in the series. The formation of 1 and 2 is thought to occur via the reaction of hamigeran G with a nitrogen source, where the nitrile carbon of 1 is derived from the terpenoid skeleton.

<p>This study describes the NMR-directed isolation and structural elucidation of several new and semi-synthesised compounds. Carrying on from the previous examinations on the sponge Hamigera tarangaensis undertaken at VUW resulted in the isolation of an additional seven congeners to the hamigeran family. These included three debrominated analogues (37, 60, 62), an alternative methyl ester analogue (63) and a 4-brominated analogue (64). Two structures with novel functionality were also isolated, which were found in fractions previously not investigated, the nitrile containing hamigeran R (61) and the dimer hamigeran S (65). The isolation of these novel compounds led to the proposal of a biosynthesis from a reaction with hamigeran G (40) and ammonia, similar to the previous nitrogenous hamigerans biosynthesis with amino acids.   Semi-synthesis was undertaken to probe the biosynthesis of these and the other nitrogenous compounds. The results of this produced four new compounds: two imine intermediates, hamigeran G imine (66) and hamigeran B imine (70), a glycine derived hamigeran (68) and the hamigeran D epimer (69).</p>

Gold nanoparticles make an appealing candidate as textile colorants due to the range of attractive colors they can produce and their exceptional stability compared to organic dyes. However, ensuring a strong interaction between the fabric and the nanoparticles remains a challenge. We have investigated the use of commercial reactive dyes to (1) reduce gold ions and form nanoparticles and (2) form a chemical link between the nanoparticles and wool fibers. For the first time, gold nanoparticles have been produced using organic reactive dyes as reducing agents. As part of this process, the chromophore of the dye has been chemically altered such that it does not contribute any color, and the red shades displayed result entirely from gold nanoparticles. These nanoparticles have then been tested for their ability to dye wool yarn samples. Careful analysis has indicated that a weak bond has formed between the particles and the fibers due to degradation of the dye structure during reduction. The mechanism of degradation has been studied, providing insight into the type of chemical structure that could be used in the future to achieve wash-fast gold nanoparticle textiles.