Cytotoxic Furan- and Pyrrole-Containing Scalarane Sesterterpenoids Isolated from the Sponge Scalarispongia sp.

Abstract

Three furan-containing scalarane sesterterpenoids (1–3) and a novel pyrrole-containing analog (4) were isolated from the sponge Scalarispongia species. Compound 3, reported in the literature as a synthetic derivative of furoscalarol 2, was for the first time isolated from a natural source. During the separation performed using a silica column in the presence of methanol, 16-methoxy derivatives (5, 6) were obtained from the unintended reaction of 2. The isolated natural products 3 and 4 and the artifact 5 showed moderate to high cytotoxicity against six human cancer cell lines, whereas compound 6, the C-16 epimer of 5, showed no cytotoxicity at a concentration of 60 μΜ.

Marine Pyrrole Alkaloids

“…The fused pyrrole 412 represents the first pyrrole derivative in the rare class of N-heterocyclic scalaranes ( Figure 35 ). MNP 412 was found to show moderate inhibition against six human cancer cell lines in bioactivity assays (GI 50 values ranging between 14.9 µM and 26.2 µM) [ 313 ].…”

Marine natural products from sponges (Porifera) of the order Dictyoceratida (2013 to 2019); a promising source for drug discovery

“…The formation of an a-product (89) was likely favored because of the approach of the nucleophile toward the pseudoaxial direction for maximum overlap with the p-orbital. 56 Another three sesquiterpenes (91-93) were isolated as solvent-generated artifacts from Spongia pertusa Esper because the extraction was processed with ethanol as a solvent. 43 On the other hand, four ester derivatives [acetyl (94), butyryl (95), hexanoyl (96), and benzoyl (97)] were prepared from 2-(30,50-dibromo-20-methoxyphenoxy)-3,5-dibromophenol and their activities were evaluated against PTP1B and two cancer cell lines in order to investigate the structure-activity relationship features.…”

“…Structures of compounds(53)(54)(55)(56)(57)(58)(59)(60)(61).34966 | RSC Adv., 2020, 10,34959-34976 This journal is © The Royal Society of Chemistry 2020 RSC Advances Review Open Access Article. Published on 21 September 2020.…”

4,5,6,7-Tetrahydroindol-4-Ones as a Valuable Starting Point for the Synthesis of Polyheterocyclic Structures

“…Matsumoto, Watanabe and Kobayashi reported the use of Pd(OAc) 2 as the catalyst for the synthesis of structure 114 [ 71 ]. However, while using Rh 2 (OAc) 4 , as well as Cu(acac) 2 , the C-H insertion occurred on the 5-position to obtain a [ 4 , 5 ]-annulated five-membered structure 117 . It is worth mentioning that N -substituted indoles did not form tetrahydrobenzo[ cd ]indole 114 .…”

“…Examples of natural occurrence of 1 derivatives are scarce. However, the pyrrolo fused scalarane sesterterpenoid 5 has been isolated from sponges [ 4 ]. Furthermore, dehydrogenation of the 4,5,6,7-tetrahydroindol-4-one structure gives rise to a 4-hydroxy-indole moiety which is found in many bioactive alkaloids such as psilocin and its precursor psilocybin 6 [ 5 ] and FDA approved drugs, for example the non-selective beta blocker pindolol 7 [ 6 ].…”