PROGRESS OF STUDIES ON THE NATURAL CEMBRANOIDS FROM THE SOFT CORAL SPECIES OF SARCOPHYTON GENUS - Medicinal Chemistry of Bioactive Natural Products - page 258

18

16

4

19

8 1 15

12

17

20

1

Cembrene (2)

Figure 6-1

Sarcophyton,andSinularia are the most prolific. This review mainly pertains to the
cembrane-type constituents of the soft corals of the Sarcophyton genus.

6.2 CEMBRANE-TYPE CONSTITUENTS FROM THE
SARCOPHYTON GENUS

Sarcophyton species contain diterpenes up to 10% of their dry weight, and this large
quantity of secondary metabolites plays an important role in the survival of Octo-
corals with defensive, competitive, reproductive, and possibly pheromonal func-
tions. 5 Soft corals lacking physical defense thus seem to be protected from
predation by the presence of diterpene toxins in their tissue. Nearly 25 species of
this genus occurring in different seawaters have been examined chemically so far,
and more than 80 cembranoid diterpenes have been isolated from the Sarcophyton
genus since the 1970s.

6.2.1 Sarcophytols from the Sarcophyton Genus

Up to 20 sarcophytols were isolated from the Sarcophyton genus with the name
of sarcophytol from A to T (except sarcophytol L, including two sarcophytol T)
(Figure 6-2).
Chemical examination of Sarcophyton glaucum collected at Ishigaki island,
Okinawa Prefecture, resulted in the isolation of seven cembranoid diterpenes,
namely sarcophytol A (3), sarcophytol A acetate (4), sarcophytol B (5), sarcophy-
tonin A (6), and minor constituents sarcophytol C (7), D (8), and E (9). 9 These
compounds were found to be susceptible to autooxidation while being purified.
The structural determination of these compounds was made mainly based on proton
and carbon nuclear magnetic resonance (NMR) spectral evidence and degradative
studies by ozonolysis. X-ray crystallographic analysis for the two crystalline
compounds, sarcophytol B (5) and D (8), has been reported. The total lipid extracts
of S. glaucum comprise about 40% sarcophytol A (3), 5% each of sarcophytol A
acetate (4) and sarcophytonin A (6), about 1% sarcophytol B (5), and minor
amounts of sarcophytol C (7), D (8), and E (9).
Eight new cembranoids, sarcophytol G (11), sarcophytol H (12) and its acetate
(13), sarcophytol I (14), sarcophytol J (15), sarcophytol M (17), sarcophytol N (19),