New germacrane derivatives from gorgonian octocorals of the genus

Antikinetoplastid Activity of Sesquiterpenes Isolated from the Zoanthid Palythoa aff. clavata

Leishmaniasis and Chagas disease are neglected tropical diseases that cause problems in developing countries. The causative agents, Leishmania spp. and Trypanosoma cruzi, produce a clinical picture that can be fatal for the patient, such as Chagas heart disease, visceral leishmaniasis and megacolon, among others. Current treatments for these diseases are not very effective and highly toxic, since they require very prolonged treatments. The development of innovative, effective and safe drugs to fight infections caused by these parasites remains a challenge. For this reason, in recent years, there has been an increase in the search for new therapies. In this study, the antikinetoplastid activity of 13 sesquiterpene lactones obtained from Palythoa aff. clavata was screened against L. amazonensis, L. donovani and T. cruzi. The results revealed that the sesquiterpene lactones anhydroartemorin (2), cis,trans-costunolide-14-acetate (3) and 4-hydroxyarbusculin A (11) were the most selective against the kinetoplastid species studied. These molecules seem to induce the mechanisms involved in an apoptotic-like death or programmed cell death (PCD) in the kinetoplastids, and since they do not cause necrosis, the inflammatory events associated with this type of cell death will not be triggered.

Cyclized 9,11-secosterol enol-ethers from the gorgonian Pseudopterogorgia americana

Chemical investigation of the MeOH extract from the gorgonian Pseudopterogorgia americana afforded two rare sterols, ameristerenol A (1) and B (2), both 9,11-secosterols possesses a seven-membered cyclic enol-ether in ring C, and ameristerol A (3) is the first example of a naturally occurring 9,11-secosterol containing a gorgosterol side chain with a C-24(28) double bond. Ameristerenol A (1) was converted to the sterol derivatives 4-6 to provide additional chemical diversity and comparison for biological screening. The structures of compounds 1-6, along with three related known analogues 7-9, were determined on the basis of extensive spectroscopic analysis and by comparison with literature data. Compound 6 exhibited slight cytotoxicity activity against human breast cancer cell line MDA-MB-231.

Volatile secondary metabolites as aposematic olfactory signals and defensive weapons in aquatic environments

Olfaction is considered a distance sense; hence, aquatic olfaction is thought to be mediated only by molecules dissolved in water. Here, we challenge this view by showing that shrimp and fish can recognize the presence of hydrophobic olfactory cues by a "tactile" form of chemoreception. We found that odiferous furanosesquiterpenes protect both the Mediterranean octocoral Maasella edwardsi and its specialist predator, the nudibranch gastropod Tritonia striata, from potential predators. Food treated with the terpenes elicited avoidance responses in the cooccurring shrimp Palaemon elegans Rejection was also induced in the shrimp by the memory recall of postingestive aversive effects (vomiting), evoked by repeatedly touching the food with chemosensory mouthparts. Consistent with their emetic properties once ingested, the compounds were highly toxic to brine shrimp. Further experiments on the zebrafish showed that this vertebrate aquatic model also avoids food treated with one of the terpenes, after having experienced gastrointestinal malaise. The fish refused the food after repeatedly touching it with their mouths. The compounds studied thus act simultaneously as (i) toxins, (ii) avoidance-learning inducers, and (iii) aposematic odorant cues. Although they produce a characteristic smell when exposed to air, the compounds are detected by direct contact with the emitter in aquatic environments and are perceived at high doses that are not compatible with their transport in water. The mouthparts of both the shrimp and the fish have thus been shown to act as "aquatic noses," supporting a substantial revision of the current definition of the chemical senses based upon spatial criteria.

Secondary metabolites from the leaves of Neolitsea hiiranensis and the anti-inflammatory activity of some of them

Seven sesquiterpenoids, hiiranlactones A-D (1-4), (-)-ent-6α-methoxyeudesm-4(15)-en-1β-ol (5), (+)-villosine (6), hiiranepoxide (7), and one triterpenoid, hiiranterpenone (8), together with 22 known compounds, were isolated from the leaves of Neolitsea hiiranensis (Lauraceae). Their structures were elucidated by spectroscopic analysis and single crystal X-ray diffraction. Among the isolates, hiiranlactone B (2) and hiiranlactone D (4) exhibited inhibitory activity against fMLP-induced superoxide production by human neutrophils with IC(50) values of 21.86±3.97 and 25.78±4.77μM, respectively.

A surprising C-4 epimerization of 5-deoxy-5-sulfonylated pentofuranosides under Ramberg-Bäcklund reaction conditions

Treatment of methyl 5-deoxy-2,3-O-isopropylidene-5-(benzylsulfonyl)-β-D-ribofuranoside with CBr(2)F(2)-KOH/Al(2)O(3) afforded the corresponding olefinic sugar. The methyl- and the isopropyl-analogues in contrast underwent epimerization at C-4 to generate the α-L-lyxo derivatives.

Synthesis of octa- and dodecamers of d-ribitol-1-phosphate and their protein conjugates

The bacterial cell-wall-associated teichoic acids contain predominantly D-ribitol residues interconnected by phosphodiester linkages. Because of their location, these antigens may be vaccine candidates as part of conjugate vaccines. Here, we describe the synthesis of extended oligomers of D-ribitol-1-phosphate linked to a spacer having an amino group at its terminus. The synthesis utilized a fully protected D-ribitol-phosphoramidite that was oligomerized in a stepwise fashion followed by deprotection. The free oligomers were connected to bovine serum albumin using oxime chemistry. Thus, the ribitol phosphate oligomers were converted into keto derivatives, and the albumin counterpart was decorated with aminooxy groups. Reaction of the functionalized saccharide and protein moieties afforded conjugates having up to 20 ribitol phosphate chains.

Identification and quantitative determination of furanodiene, a heat-sensitive compound, in essential oil by 13C-NMR

A method based on 13C-NMR has been used as a tool for the identification and quantitative determination of two furanic sesquiterpenes: a heat-sensitive compound, furanodiene, and its rearrangement product, furanoelemene. Following a preliminary study using artificial mixtures which permitted the construction and verification of calibration curves for each compound, the method was used for the qualitative and quantitative analysis of furanodiene and furanoelemene in the essential oil of Smyrnium olusatrum.

Synthesis of methyl 2-O-allyl-(and 3-O-allyl)-5-O-benzyl-beta-D- ribofuranoside

D-Ribose was converted into methyl 5-O-benzyl-beta-D-ribofuranoside and this, on tin-mediated allylation, gave a mixture of the 2-O-allyl and 3-O-allyl derivatives which were separated by chromatography. The more polar isomer was characterised as the 3-O-allyl derivative after conversion via 3-O-allyl-5-O-benzyl-1,2-O-isopropylidene-alpha-D-ribofuranose (which was also synthesised from 3-O-allyl-1,2:5,6-di-O-isopropylidene-alpha-D-allofuranose) into the known 5-O-benzyl-1,2-O-isopropylidene-alpha-D-ribofuranose. Methyl 3-O-allyl-5-O-benzyl-beta-D-ribofuranoside was converted into methyl 2-O-allyl-5-O-benzyl-beta-D-ribofuranoside via methyl 2-O-allyl-5-O-benzyl-3-O-(prop-1-enyl)-beta-D-ribofuranoside.