In the current study, an NMR spectroscopic pattern-based procedure for probing scalarane derivatives was performed and four new 24-homoscalaranes, lendenfeldaranes A–D (1– 4), along with three known compounds, 12α-acetoxy-22-hydroxy-24-methyl-24-oxoscalar-16-en- 25-al (5), felixin F (6), and 24-methyl-12,24,25-trioxoscalar-16-en-22-oic acid (7) were isolated from the sponge Lendenfeldia sp. The structures of scalaranes 1–7 were elucidated on the basis of spectroscopic analysis. Scalaranes 1–7 were further evaluated for their cytotoxicity toward a series of human cancer cell lines and the results suggested that 5 and 7 dominated in the anti- proliferative activity of the extract. The 18-aldehyde functionality was found to play a key role in their activity.

Scalarane-type sesterterpenoids are known for their therapeutic potential in cancer treatments. However, the anti-inflammatory properties of this class of metabolites remain elusive. Our current work aimed to investigate the anti-inflammatory scalaranes from marine sponge Lendenfeldia sp., resulting in the isolation of six new 24-homoscalaranes, lendenfeldaranes E–J (1–6). The structures of the new metabolites were determined by extensive spectroscopic analyses, and the absolute configuration of 1 was established by electronic circular dichroism (ECD) calculations. Compounds 2 and 3 were discovered to individually reduce the generation of superoxide anions, and compound 1 displayed an inhibitor effect on the release of elastase. These three compounds were proven to be the first anti-neutrophilic scalaranes.

Five 8,17-epoxybriaranes, including three new compounds-briarenols I-K (1-3), along with two known analogues, briaexcavatolide P (4) and briaexcavatin P (5), were isolated from the octocoral Briareum excavatum. The structures of briaranes 1-3 were elucidated by spectroscopic methods, including 1D and 2D NMR studies and (+)-HRESIMS. Briarane 4 exerted inhibition effects on inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) release from RAW 264.7.Molecules 2020, 25, 1405 2 of 9 ( Figure 1). In the current study, the comprehensive workflow of isolation, structure determination, and anti-inflammatory activity evaluation, was implemented on briaranes 1-5.Molecules 2020, 25, x FOR PEER REVIEW 2 of 9 briaexcavatin P (5) [9], (Figure 1). In the current study, the comprehensive workflow of isolation, structure determination, and anti-inflammatory activity evaluation, was implemented on briaranes 1-5. 1: R1 = OAc, R2 = R6 = OH, R3 = n-OC(O)Pr, R4 = H, R5 = β-OH 2: R1 = R2 = OH, R3 = OAc, R4 = R6 = H, R5 = β-OH 3: R1 = OAc, R2 = R3 = R6 = H, R4 = OH, R5 = β-OH 4: R1 = OAc, R2 = OH, R3 = n-OC(O)Pr, R4 = R6 = H, R5 = β-OH 5: R1 = R3 = OAc, R2 = OH, R4 = R6 = H, R5 = β-OH 6: R1 = OAc, R2 = n-OC(O)Pr, R3 = R4 = R6 = H, R5 = β-OH 7: R1 = OAc, R2 = R3 = R6 = H, R4 = OH, R5 = α-OH Figure 1. Structures of briarenols I-K (1-3), briaexcavatolide P (4), briaexcavatin P (5), excavatolide B (6), and briareolide B (7).