Biotechnology Towards Energy Crops

New crops are gradually establishing along with cultivation systems to reduce reliance on depleting fossil fuel reserves and sustain better adaptation to climate change. These biological assets could be efficiently exploited as bioenergy feedstocks. Bioenergy crops are versatile renewable sources with the potential to alternatively contribute on a daily basis towards the coverage of modern society’s energy demands. Biotechnology may facilitate the breeding of elite energy crop genotypes, better suited for bio-processing and subsequent use that will improve efficiency, further reduce costs, and enhance the environmental benefits of biofuels. Innovative molecular techniques may improve a broad range of important features including biomass yield, product quality and resistance to biotic factors like pests or microbial diseases or environmental cues such as drought, salinity, freezing injury or heat shock. The current review intends to assess the capacity of biotechnological applications to develop a beneficial bioenergy pipeline extending from feedstock development to sustainable biofuel production and provide examples of the current state of the art on future energy crops.     

Does conjugation of antioxidants improve their antioxidative/anti-inflammatory potential?

A series of symmetric and asymmetric spermine (SPM) conjugates with all-trans-retinoic acid (ATRA), acitretin (ACI), (E)-3-(trioxsalen-4′-yl)acrylic acid (TRAA) and l-DOPA, amides of ACI, l-DOPA and TRAA with 1-aminobutane, benzylamine, dopamine and 1,12-diaminobutane as well as hybrid conjugates of O,O′-dimethylcaffeic acid (DMCA) with TRAA or N-fumaroyl-indole-3-carboxanilide (FICA) and 2-(2-aminoethoxy)ethanol were synthesized and their antioxidant properties were studied. The reducing activity (RA)% of the compounds were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging assay and found to be in the range 0–92(20 min)%/96(60 min)% at 100 μM, the most powerful being the conjugates l-DOPA-SPM-l-DOPA (8, RA = 89%/96%) and l-DOPA-dopamine (13, RA = 92%/92%). Conjugate DMCA-NH(CH₂CH₂O)₂-FICA (14) was the most powerful LOX inhibitor with IC₅₀ 33.5 μM, followed by the conjugates ACI-NHCH₂Ph (10, IC₅₀ 40.5 μM), ACI-SPM-TRAA (7, IC₅₀ 41.5 μM), DMCA-NH(CH₂CH₂O)₂-TRAA (15, IC₅₀ 65 μM), 13 (IC₅₀ 81.5 μM) and ACI-dopamine (11, IC₅₀ 87 μM). The most potent inhibitors of lipid peroxidation at 100 μM were the conjugates 15 (98%) and ACI-SPM-ACI (4, 97%) whereas all other compounds showed activities comparable or lower than trolox. The most interesting compounds, namely ATRA-SPM-ATRA (3), 4, 10, 11 and 15, as well as unconjugated compounds such as ATRA and dopamine, were studied for their anti-inflammatory activity in vivo on rat paw oedema induced by Carrageenan and found to exhibit, for doses of 0.01 mmol/mL of conjugates per Kg of rat body weight, weaker anti-inflammatory activities (3.6–40%) than indomethacin (47%) with conjugate 3 being the most potent (40%) in this series of compounds. The cytocompatibility of selected compounds was evaluated by the viability of RAMEC cells in the presence of different concentrations (0.5–50 μM) of the compounds. Conjugates 3 (IC₅₀ 2.6 μM) and 4 (IC₅₀ 4.7 μM) were more cytotoxic than the corresponding unconjugated retinoids ATRA (IC₅₀ 18.3 μM) and ACI (IC₅₀ 14.6 μM), whereas conjugate 15 (IC₅₀ 12.9 μM) was less cytotoxic than either DCSP (IC₅₀ 11.3 μM) or the tert-butyl ester of TRAA (IC₅₀ 2.9 μM).     

Hierarchical ionic self-assembly of rod-comb block copolypeptide-surfactant complexes

Novel hierarchical nanostructures based on ionically self-assembled complexes of diblock copolypeptides and surfactants are presented. Rod-coil diblock copolypeptide poly(gamma-benzyl-L-glutamate)-block-poly(L-lysine), PBLG-b-PLL (Mn = 25,000 and 8000 for PBLG and PLL, respectively, polydispersity index 1.08), was complexed with anionic surfactants dodecanesulfonic acid (DSA) or dodecyl benzenesulfonic acid (DBSA), denoted as PBLG-b-PLL(DSA)1.0 and PBLG-b-PLL(DBSA)1.0, respectively. The complexation leading to supramolecular rod-comb architectures was studied by transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and polarized optical microscopy (POM). PBLG-b-PLL, PBLG-b-PLL(DBSA)1.0, and PBLG-b-PLL(DSA)1.0 self-assemble with alternating PBLG lamellae and PLL-containing lamellae with a periodicity of 27-33 nm. Within the PBLG lamellae, the rod-like PBLG helices pack with a periodicity of ca. 1.3 nm. The internal structure of the PLL-containing lamellae depends on the complexation. For pure PBLG-b-PLL, the PLL chains adopt a random coil conformation and the PLL domains are disordered. For PBLG-b-PLL(DSA)1.0, lamellar self-assembly of periodicity of 3.7 nm within the PLL(DSA)1.0 domains is observed due to crystalline packing of the linear n-dodecyl tails. For PBLG-b-PLL(DBSA)1.0 with branched dodecyl tails, a distinct SAXS reflection is observed, suggesting self-assembly within the PLL(DBSA)1.0 domains with a periodicity of 2.9 nm. However, due to the absence of higher order reflections, the internal structure cannot be conclusively assigned. The efficient plasticization which leads to fluid-like liquid crystallinity in PBLG-b-PLL(DBSA)1.0 and an alpha-helical conformation according to FTIR allows us to suggest that the PLL(DBSA)1.0 domains have a hexagonal internal structure. The interplay of self-assembly at different length scales combined with rod-like liquid crystallinity can open new routes to design functional materials.     

Improving derivatization efficiency of BMAA utilizing AccQ-Tag<Superscript>®</Superscript> in a complex cyanobacterial matrix

Two different assays have been developed and used in order to investigate the optimal conditions for derivatization and detection of acid beta-N-methyl-amino-L-alanine (BMAA) in a cyanobacterial sample. BMAA was extracted from cyanobacterial cultures both from the cytosolic ("free") fraction and in the precipitated ("protein") fraction using a newly developed extraction scheme and the sample matrix was standardized according to protein concentration to ensure the highest possible derivative yield. A rapid and sensitive HPLC method for fluorescence detection of the non-protein amino acid BMAA in cyanobacteria, utilizing the Waters AccQ-Tag chemistry and Chromolith Performance RP-18e columns was developed. Using this new method and utilizing a different buffer system and column than that recommended by Waters, we decreased the time between injections by 75%. The limit of quantification was determined to be 12 nmol and limit of detection as 120 fmol. The linear range was in the range of 8.5 nmol-84 pmol. Accuracy and precision were well within FDA guidelines for bioanalysis.     

Structure of bis(2-acetylpyridine 3-hexamethyleneiminylthiosemicarbazonato) palladium II,a potential antitumor complex

The crystal structure of the potential antitumor complex bis(2-acetyppyridine 3-hexamethyleneiminylthiosemicarbazonato)palladium(II) has been solved. The palladium(II) atom is in a square planar environment surrounded by two cis nitrogen atoms and two cis sulfur atoms. The ligands are not equivalent, one being tridentate with (N,N,S) donation, the other being monodentate using only the sulfur atom to coordinate to the metal. The tridentate ligand shows a Z, E, Z configuration while the monodentate ligand shows an E, E, Z. Intermolecular hydrogen bonds stabilize the structure, while the crystal packing is determined by Pd-C, Pd-pi, C-H-pi and pi-pi interactions.