Synthesis of both the enantiomers of dihydroactinidiolide. a pheromone component of the red imported fire ant

Faeces' odours attract gregarious locust hoppers

Collective motion is one of the most impressive common features of gregarious locusts: once formed, bands and swarms get moving for long distances. It was shown that visual perception of neighbours plays a key role in maintaining marching behaviour at a local scale. But at a larger scale, mechanisms underlying band cohesion are less understood. It was shown in several field studies that individuals separated from the band were able to get back to the group, even after being separated since a night. In this context, faeces' odours could be a possible indicator of the recent passage of a group. In this study, we tested if nymphs are attracted by faeces' odours and if this effect is modulated by the age of the faeces. To this end, we conducted individual olfactometric behavioural assays of 3^rd instar hoppers of desert locust, Schistocerca gregaria, exposed to odours of 1 h-old and 24 h-old faeces. We also used Gas Chromatography-Mass Spectrometry (GC-MS) to identify odours' volatile organic compounds from faeces. The results of behavioural assays indicated a strong attractive effect of faeces, with no preference for one of the two faecal age classes. Nymphs spent significantly more time in the side of the olfactometer where the faeces' odours came from, and 72.7% of tested individuals chose this side first. We filtered and annotated 11 volatile organic compounds present in both fresh and old faeces in GC-MS analyses, including guaiacol and phenol, which are known to cause an aggregative effect on desert locusts. As the attractive effect lasted over 24 h, band's faeces could still have an attractive effect when individuals are separated from the band since one day. In this situation, latecomers individuals would be able to get back to the group by following the traces of their predecessors.

Mitigation of oxidative stress with dihydroactinidiolide, a natural product against scopolamine-induced amnesia in Swiss albino mice

The present work describes the neuroprotective efficacy of DHAc under escalated oxidative stress condition in scopolamine-induced amnesic mice. During the toxicity test of DHAc in mice, the acute dose (LD₅₀) is found to be 3.468 mg/kg bw and the sub-acute dose is 0.68 mg/kg bw. Improved cognitive and learning abilities are observed in Morris water maze and Y-maze test in 10 days DHAc (0.68 mg/kg bw) treated scopolamine-induced male Swiss albino mice. In the molecular level these changes are monitored as reduced oxidative load followed by significantly lower lipid peroxidation and protein carbonylation, increased superoxide dismutase, catalase, acetylcholinesterase, caspase-3 activity and glutathione content followed by higher expression of anti apoptotic protein bcl-2 in mice brain as compared to scopolamine (1 mg/kg bw) treated mice. Meanwhile real time PCR shows higher expression of brain derived neurotrophic factor (BDNF) and synaptophysin in DHAc pretreated scopolamine treated mice brain. HPLC analysis suggested its possible blood brain barrier crossing ability. Overall DHAc reversed behavioral anomalies in the scopolamine treated mice via oxidative stress quenching, enhancing antioxidative enzyme activity, enhancing BDNF and synaptophysin mRNA levels and reducing expression of apoptotic protein Bax.

New γ-Halo-δ-lactones and δ-Hydroxy-γ-lactones with Strong Cytotoxic Activity

This paper presents the synthesis of γ -halo- δ -lactones, δ -iodo- γ -lactones and δ -hydroxy- γ -lactones from readily available organic substrates such as trans-crotonaldehyde and aryl bromides. Crystal structure analysis was carried out for lactones that were obtained in crystalline form. All halo- δ -lactones and δ -hydroxy- γ -lactones were highly cytotoxic against gastric cancer AGS cells with I C 50 values in the range of 0.0006-0.0044 mM. Some lactones showed high bactericidal activity against E. coli ATCC 8739 and S. aureus ATCC 65389, which reduced the number of CFU/mL by 70-83% and 87% respectively.

Synthesis, Characterization, Cytotoxicity, and Antibacterial Properties of trans-γ-Halo-δ-lactones

A new four-step pathway for the synthesis of γ-halo-δ-lactones is described from simple, commercially available substrates: aryl bromides and 3-methyl crotonaldehyde. The halogenolactonization reaction of β,δ-substituted, γ,δ-unsaturated carboxylic acid 4 a-c is regio- and stereoselective and gives only the trans-isomers of lactones 5 a-c, 6 a-c, and 7 a-c. The structures of all synthesized compounds were confirmed by using spectroscopic methods. For bromolactone, containing a naphthyl moiety in the structure, crystallographic analysis was also performed. The lactones were tested for their cytotoxic activity against L929 cell lines (mouse fibroblasts) and antibacterial activity against Escherichia coli strains ATCC 8739 and Staphylococcus aureus ATCC 65389. Compounds 5 a, 5 c, 7 a, and 7 b statistically significantly inhibited the metabolic activity of mouse fibroblasts L929. Compounds 5 b and 6 a were not cytotoxic towards L929 cells, but showed moderate bactericidal properties.

Bioactive natural products and chirality

Mori's synthetic works on bioactive natural products in general and pheromones in particular started about 40 years ago to establish their absolute configurations and also to clarify their stereochemistry-bioactivity relationships. Results indicate that bioactive natural products are not always enantiomerically pure, and the stereochemistry-bioactivity relationships are not simple but complicated. For example, neither (R)- nor (S)-sulcatol, the aggregation pheromone of an ambrosia beetle, is behaviorally bioactive, whereas their mixture is active. In the case of olean, the sex pheromone of the olive fruit fly, its (R)-isomer is active against the males and the (S)-isomer is active against the females. Recent synthesis of two new insect pheromones is discussed to illustrate the modern methods in enantioselective synthesis.

Acetylenic strongylodiols from a Petrosia (Strongylophora) Okinawan marine sponge

Seven new long-chain acetylenic alcohols, strongylodiols D-J, were isolated from an Okinawan marine sponge of the genus Petrosia (Strongylophora). The structures of these compounds were elucidated on the basis of the results of spectroscopic analysis and chemical reaction. Analysis of the MNA esters of the acetylenic alcohols disclosed that these compounds were each an enantiomeric mixture in a different ratio.