New oxygenated africanenes from the soft coral sinularia dissecta

Scalable Syntheses and Biological Evaluation of Africane-type Sesquiterpenoids

Practical total syntheses of africane-type sesquiterpenoids were realized by reexamination of a divergent strategy employing optimized three-component coupling followed by ring-closing metathesis and substrate-controlled cyclopropanation. This sequential eight-step conversion provided Δ9(15)-africanene, a common bicyclo[5.3.0]decane intermediate for the syntheses of africane derivatives, in more than twice the yield as in the previous approach. The scalability and robustness of this improved synthetic route were confirmed by gram-scale preparation of Δ9(15)-africanene. In vitro cell-based assays of the synthesized africane-type sesquiterpenoids disclosed that ester-incorporating derivatives showed cytotoxic activity against HeLa cells. The effect of relative and absolute stereochemistry of africane-9,15-diol monoacetates on the cytotoxicity against HeLa cells was also investigated.

Acid catalysed rearrangement of Δ9,15-africanene: A cytotoxic sesquiterpene

Acid catalysed rearrangements of Δ9,15-africanene, a cytotoxic sesquiterpene isolated from the soft corals of the genus Sinularia, have been studied for the first time and a marked difference was observed between the compositions of the conversion products with and without refluxing conditions.

Unusual Terpenoid Constituents of the Soft Coral Sinularia dissecta

Chemical examination of the soft coral Sinularia dissecta furnished six known terpenoids, along with a new sequiter-penoid seco-africanane (1) and a new norcembrane diterpene (2)

Trends in the discovery of new marine natural products from invertebrates over the last two decades--where and what are we bioprospecting?

It is acknowledged that marine invertebrates produce bioactive natural products that may be useful for developing new drugs. By exploring untapped geographical sources and/or novel groups of organisms one can maximize the search for new marine drugs to treat human diseases. The goal of this paper is to analyse the trends associated with the discovery of new marine natural products from invertebrates (NMNPI) over the last two decades. The analysis considers different taxonomical levels and geographical approaches of bioprospected species. Additionally, this research is also directed to provide new insights into less bioprospected taxa and world regions. In order to gather the information available on NMNPI, the yearly-published reviews of Marine Natural Products covering 1990-2009 were surveyed. Information on source organisms, specifically taxonomical information and collection sites, was assembled together with additional geographical information collected from the articles originally describing the new natural product. Almost 10000 NMNPI were discovered since 1990, with a pronounced increase between decades. Porifera and Cnidaria were the two dominant sources of NMNPI worldwide. The exception was polar regions where Echinodermata dominated. The majority of species that yielded the new natural products belong to only one class of each Porifera and Cnidaria phyla (Demospongiae and Anthozoa, respectively). Increased bioprospecting efforts were observed in the Pacific Ocean, particularly in Asian countries that are associated with the Japan Biodiversity Hotspot and the Kuroshio Current. Although results show comparably less NMNPI from polar regions, the number of new natural products per species is similar to that recorded for other regions. The present study provides information to future bioprospecting efforts addressing previously unexplored taxonomic groups and/or regions. We also highlight how marine invertebrates, which in some cases have no commercial value, may become highly valuable in the ongoing search for new drugs from the sea.

Vibrational circular dichroism of Africanane and lippifoliane sesquiterpenes from Lippia integrifolia

The agreement between theoretical and experimental vibrational circular dichroism curves of (4R,9R,10R)-(+)-african-1(5)-ene-2,6-dione (1) and (4R,9S,10R)-lippifoli-1(6)-en-5-one (2), isolated from the widely used plant Lippia integrifolia, allowed the determination of the conformation and absolute configuration of 1 and confirmed both structural features for 2. Molecular modeling of 1 and 2 was carried out by means of a systematic and a Monte Carlo search protocol followed by geometry optimization employing density functional theory calculations with the B3LYP/6-31G(d), B3LYP/DGDZVP, and/or B3PW91/DGDZVP2 functionals/basis sets. Validation of the minimum energy conformations for both tricyclic substances was achieved by comparison of the experimental and theoretical vicinal (1)H-(1)H NMR coupling constants obtained by DFT-GIAO calculations.

Microbial transformation of delta 9(15)-africanene

Incubation of delta 9(15)-africanene with fungi Aspergillus niger and Rhizopus oryzae for 8 days yielded two oxidized derivatives, 10 alpha-hydroxy-delta 9(15)-africanene and 9 alpha,15-epoxyafricanane. The structure of the two products were assigned by interpretation of their spectral data.