Hippospongic acid A: An unusual triterpenoic acid from a marine sponge, Hippospongia sp., which inhibits gastrulation of starfish embryos

Cytotoxic sesterterpenoids from a sponge Hippospongia sp

One new pentacyclic sesterterpene, hippospongide A (1), and one new scalarane sesterterpenoid, hippospongide B (2), along with six previously reported known scalarane–type sesterterpenes (3–8), were isolated from a sponge Hippospongia sp. The structures of these compounds were elucidated on the basis of their spectroscopic data and comparison of the NMR data with those of known analogues. These metabolites are the first pentacyclic sesterterpene and scalarane-type sesterterpenes to be reported from this genus. Compounds 3–5 exhibited significant cytotoxicity against DLD-1, HCT-116, T-47D and K562 cancer cell lines.

Hippolides A-H, acyclic manoalide derivatives from the marine sponge Hippospongia lachne

Eight new acyclic manoalide-related sesterterpenes, hippolides A-H (1-8), together with two known manoalide derivatives, (6E)-neomanoalide (9) and (6Z)-neomanoalide (10), were isolated from the South China Sea sponge Hippospongia lachne. The absolute configurations of 1-8 were established by the modified Mosher's method and CD data. Compound 1 exhibited cytotoxicity against A549, HeLa, and HCT-116 cell lines with IC50 values of 5.22×10(-2), 4.80×10(-2), and 9.78 μM, respectively. Compound 1 also showed moderate PTP1B inhibitory activitiy with an IC50 value of 23.81 μM, and compound 2 showed moderate cytotoxicity against the HCT-116 cell line and PTP1B inhibitory activity with IC50 values of 35.13 and 39.67 μM, respectively. In addition, compounds 1 and 5 showed weak anti-inflammatory activity, with IC50 values of 61.97 and 40.35 μM for PKCγ and PKCα, respectively.

Development of Aliphatic Alcohols as Nucleophiles for Palladium-Catalyzed DYKAT Reactions: Total Synthesis of (+)-Hippospongic Acid A

The ability to use aliphatic alcohols as competent nucleophiles in the palladium-catalyzed dynamic kinetic asymmetric transformation of Baylis-Hillman adducts is explored. High yield and enantioselectivity is obtained for both the kinetic transformation and dynamic kinetic transformation. The absolute stereochemistry of the products is used to explore the reactive conformation of 2-substituted pi-allyl complexes with DPPBA-based chiral ligands. The utility of this method is further demonstrated in the context of a concise total synthesis of the gastrulation inhibitor (+)-hippospongic acid A. The synthesis features three palladium-catalyzed allylic alkylation reactions to introduce three different bond types: C-S, C-H, and C-O.

Marine natural products

This review covers the literature published in 2003 for marine natural products, with 619 citations (413 for the period January to December 2003) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (656 for 2003), together with their relevant biological activities, source organisms and country or origin. Biosynthetic studies or syntheses that lead to the revision of structures or stereochemistries have been included (78), including any first total syntheses of a marine natural product.

Synthesis of (R)-(+)-hippospongic acid A, a triterpene isolated from the marine sponge, Hippospongia sp

Hippospongic acid A (1) is a triterpene metabolite of the marine sponge, Hippospongia sp., with inhibitory activity against the gastrulation of starfish embryos. (R)-(+)-1 was synthesized by employing enzymatic kinetic resolution as the key step.