Bio-active sesquiterpenoids and norsesquiternoids from the Red Sea octocoral Rhytisma fulvum fulvum

Three previously undescribed nardosinane-type sesquiterpenes

(1–3), together with six known compounds (4–9) were isolated

from the alcyonacean soft coral Rhytisma fulvum fulvum. 2 and 3

are 13-nornardosinane, and 6,7-seco-13-nornardosinane derivatives,

respectively. 2 could be an artifact due to C-6 epimerization

of the known one 4. Chemical structures were elucidated based

on 1D, 2D NMR and MS spectral data. Compounds 1-8 showed

cytotoxic activity against NCI-H1299, HepG2 and MCF-7 with

IC50 values between 0.0352–0.0974, 0.0717–0.3745 and

0.0341–0.1325mM, respectively. The antibacterial activity of all

isolated compounds have examined against a number of Grampositive

(Bacillus cereus, Staphylococcus aureas) and Gram-negative

(Escherichia coli, Klebsiella pneumoniae and Pseudomonas sp.) bacteria.

Compounds 6 and 7 showed a high degree of inhibition

against B. cereus, S. aureus and Pseudomonas sp. Interestingly,

neolemnane (6) showed strong inhibition against two fungi,

Aspergillus niger and Fusarium oxysporum; while 8 showed positive

inhibition against Fusarium oxysporum at 150 mg/mL.