Simultaneous structure-activity studies and arming of natural products by C-H amination reveal cellular targets of eupalmerin acetate.

Natural products have a venerable history of, and enduring potential for the discovery of useful biological activity. To fully exploit this, the development of chemical methodology that can functionalize unique sites within these complex structures is highly desirable. Here, we describe the use of rhodium(II)-catalysed C-H amination reactions developed by Du Bois to carry out simultaneous structure-activity relationship studies and arming (alkynylation) of natural products at 'unfunctionalized' positions.

Aplysqualenol A binds to the light chain of dynein type 1 (DYNLL1).

A bidirectional affinity system has been developed for the identification of cancer-related natural products and their biological targets. Aplysqualenol A is thus selectively identified as a ligand of the dynein light chain. The use of forward and reverse affinity methods suggests that both small-molecule isolation and target identification can be conducted using conventional molecular biological methods.

Bioactive Cycloperoxides Isolated from the Puerto Rican Sponge Plakortis halichondrioides.

Two new five-membered-ring polyketide endoperoxides, epiplakinic acid F methyl ester (1) and epiplakinidioic acid (3), and a peroxide-lactone, plakortolide J (2), were isolated from the Puerto Rican sponge Plakortis halichondrioides, along with two previously reported cyclic peroxides, 4 and 5. The structures of the new metabolites were determined by spectroscopic and chemical analyses. The absolute stereostructures of 1, 2, and 5 were determined by degradation reactions followed by application of Kishi's method for the assignment of absolute configuration of alcohols.

Euryjanicin A: a new cycloheptapeptide from the Caribbean marine sponge Prosuberites laughlini.

A new proline-containing cycloheptapeptide, euryjanicin A (1), has been isolated from the marine sponge Prosuberites laughlini indigenous to Puerto Rico, and its structure established by an X-ray crystal structure determination. The absolute configuration of each amino acid residue was determined by Marfey's method.

Aplysqualenols A and B: Squalene-Derived Polyethers with Antitumoral and Antiviral Activity from the Caribbean Sea Slug .

The novel bromotriterpene polyethers aplysqualenol A () and aplysqualenol B () have been isolated from the Caribbean sea slug collected in Puerto Rico, and their structures and relative configurational assignments established from spectroscopic data aided by quantum mechanical calculations of NMR chemical shifts. Although both these compounds may be conceived as polyoxycyclic derivatives of the C30 squalene skeleton, remarkably and possess an unprecedented C15 to C24 flexible chain of 14* spatial disposition that contains a unique ether bridge between C16 and C19. Biological activity screening tests revealed that, although aplysqualenol A () does not have significant anti-infective properties, it possesses potent antitumoral and antiviral activities.

Isolation and structural elucidation of euryjanicins B-D, proline-containing cycloheptapeptides from the Caribbean marine sponge Prosuberites laughlini.

Three new cyclic peptides, euryjanicins B (2), C (3), and D (4), have been isolated from the Puerto Rican marine sponge Prosuberites laughlini, and the structures were elucidated by chemical degradation, ESIMS/MS, and extensive 2D NMR methods. When tested against the National Cancer Institute 60 tumor cell line panel, all of the purified isolates displayed weak cytotoxicity.