Scalarane Sesterterpenes from the Chinese Sponge Phyllospongia foliascens

Abstract

Three new scalarane sesterterpenes, phyllofolactone L (1), phyllofenone D (2) and phyllofenone E (3), were isolated from the acetone extract of the South China Sea sponge Phyllospongia foliascens. Their structures were elucidated on the basis of spectroscopic analysis. Phyllofenone D (2) was cytotoxic against the P388 leukemia cell line with an IC 50 value of 6.5 mg/ml. [7], and phyllofolactones [7] [8]. In our continuing studies on bioactive constituents of marine sponges collected from the South China Sea, the acetone extract of P. foliascens showed significant antineoplastic activity in vitro. Bioassay-guided separation led to the isolation of two new 24-homoscalarane sesterterpenes, phyllofolactone L (1) and phyllofenone D (2), and a new 20,24-bishomo-25-norscalarane sesterterpene, phyllofenone E (3), from this sponge. The details of isolation and structure elucidation are reported in this work.

Scalarane Sesterterpenoids

“…20,24-Dimethylscalarane 74 (phyllofenone A) was isolated from the South China Sea sponge, Phyllospongia foliascens, and showed weak antifungal activity against Candida pseudotropicalis [62]. Another specimen of the same Chinese sponge, Phyllospongia foliascens, contained a related 20,24dimethylscalarane, phyllofenone E (75) [63]. Indonesian sponge, Phyllospongia sp., and exhibited 30-95% inhibition of the growth of KB cells at 10 μg/mL [53].…”

“…The C-24 epimer of 156, 12 ,16 ,22trihydroxy-24 -methylscalar-25 ,24 -olide (158), was isolated from the Indo-Pacific sponge Lendenfeldia frondosa [104]. From a Chinese specimen of the sponge Phyllospongia foliascens was isolated phyllofolactone L (159) [63]. Within this subgroup of scalaranes there are three known bishomoscalaranes, compounds (160-162).…”

“…Other miscellaneous scalaranes are phyllofenone D (262) and the related bishomoscalarane homologue phyllofenone B (263), which were isolated from the sponge Phyllospongia foliascens collected at the South China Sea [63,106]. Phyllofenone D (262) was cytotoxic against the P388 leukemia cell line with an IC 50 value of 6.5 μg/mL [63], while phyllofenone B (263) was cytotoxic against the same target with an IC 50 value of 5.0 μg/mL [106]. Finally, two scalarane-related sesterterpenes, coscinalactone (264) and coscinafuran (265), were isolated from the sponge Coscinoderma mathewsi [140].…”

Sesterterpenoids with Anticancer Activity

“…13, Table 1), two other scalarane sesterterpenoids, were isolated from the sponge Phyllospongia foliascens collected in South China [83]. The first contains a cyclopent-2-enone ring joined to the D ring of the scalarane ring system, hydroxyl group at C12 and a trisubstituted double bond between C16 and C17, while the second incorporates the same functionalities in the scalarane skeleton as well as two hydroxyl and the ethanoyl groups at C12, C-18, and C17, respectively [83]. Phyllofenone D has a rare α,β-unsaturated ketone ring, while phyllofenone E possesses also a relatively rare 25-norscalarane framework.…”

“…Phyllofenone D showed cytotoxic activity against P388 leukemia cell line with the IC 50 growth inhibitory concentration of 17 µM. In contrast, phyllofenone E was inactive in this assay [83]. …”