Notes
The two novel acids reported in this work also present
J ournal of Natural Products, 1998, Vol. 61, No. 8 1051
determined by preparing the corresponding dimethyl
9
two important biological considerations. The 11-meth-
ylpentadecanoic acid is of interest because other methyl-
branched hexadecanoic acids, in particular the 13-
methylpentadecanoic acid, display antimicrobial activity
disulfide derivatives. Hydrogenations were carried out
in 10 mL of MeOH and catalytic amounts of PtO2.
Meth yl 10-Hydr oxydeca n oa te. 10-Hydroxydecano-
ic acid (3.77 g, 20.0 mmol) and catalytic amounts of HCl
were stirred in refluxing MeOH (25 mL) for 24 h. After
this time the solvent was removed in vacuo, affording
6
against the cariogenic Streptococcus mutans. Moreover,
it is also known that 3-methylpentadecanoic acid, which
was also identified in C. podatypa, has larvicidal activity
against the mosquito larvae of Culex pipiens quinque-
fasciatus.10 In addition, 10-methylpentadecanoic acid,
also identified in this C. podatypa, has been identified
in the phospholipids of the sulfate-reducing bacterium
Desulfobacter.11 Despite all of these findings, 11-meth-
ylpentadecanoic acid remained elusive until this report.
It is very likely that it has a bacterial origin and displays
some biological activity, but this will be the subject of
future work.
3
.75 g (99.3%) of the methyl ester, which was used in
7
the next step without further purification.
Meth yl 10-Br om od eca n oa te. Phosphorus tribro-
mide (0.35 mL, 3.7 mmol) was added dropwise to methyl
0-hydroxydecanoate (1.92 g, 9.5 mmol) at 0 °C. After
1
the addition, the reaction mixture was warmed to room
temperature and left to stand overnight. Unreacted
PBr3 was then quenched with ice and extracted with
ether. The organic layer was washed with brine, dried
over Na2SO4, and concentrated in vacuo to afford 2.40
g (96% yield) of the bromoester whose spectral data was
The long-chain fatty acid 10-tricosenoic acid seems
to be the result of a previously unrecognized fatty acid
biosynthetic sequence in sponges. The 6-nonadecenoic
acid was previously reported by us from the Caribbean
7
identical to that previously reported.
(
9-Me t h oxyca r b on yln on yl)t r ip h e n ylp h osp h o-
n iu m Br om id e. To a stirred solution of triphenyl-
phosphine (1.07 g, 4.1 mmol) in benzene was slowly
added methyl 10-bromodecanoate (1.09 g, 4.1 mmol).
The mixture was refluxed under nitrogen for 5 h. After
cooling, the C6H6 was removed in vacuo. The crude
product was dissolved in CH2Cl2 (20 mL) and precipi-
tated by slow dilution with ether (100 mL) to give the
1
2
sponge Geodia gibberosa and fits 10-tricosenoic acid
four-carbon extension) in a common biosynthetic se-
(
quence belonging to a rare n-13 fatty acid family. Work
is in progress elucidating the origin of unusual fatty
acids in marine sponges.
Exp er im en ta l Section
7
1
salt (1.9 g, 92% yield) as a clear syrup. H NMR (CDCl3,
Gen er a l Exp er im en ta l P r oced u r es. IR spectra
300 MHz) δ 7.83-7.69 (15H, m, -C H ), 3.62 (3H, s,
6
5
were recorded on a Nicolet 600 FT-IR spectrophotom-
-OCH ), 2.28 (2H, m, H-2), 1.58 (6H, m, H-3, H-9,
3
1
13
31
13
eter. H NMR, C NMR, and P NMR spectra were
H-10), 1.20 (10H, m, H-4, H-5, H-6, H-7, H-8); C NMR
recorded on a General Electric QE-300 or Bruker DPX-
(CDCl , 75 MHz) δ 174.3 (s, C-1), 135.1 (s), 133.7 (d),
3
1
3
00 spectrometers. H NMR chemical shifts were
133.5 (d), 130.4 (d), 51.34 (q, -OCH ), 34.29 (t), 33.99
3
1
3
recorded with respect to internal (CH3)4Si, C NMR
chemical shifts are reported in parts per million relative
to CDCl3 (77.0 ppm), and 31P NMR chemical shifts are
reported also in parts per million relative to triphenyl-
phosphine (-5.29 ppm) in CDCl3-MeOH (2:1) as sol-
vent. Fatty acid methyl esters were analyzed by GC-
MS at 70 eV using a Hewlett-Packard 5972A MS
ChemStation equipped with a 30 m × 0.25 mm special
performance capillary column (HP-5MS) of polymethyl
siloxane cross-linked with 5% phenyl methylpolysilox-
ane.
(t), 30.42 (t), 30.21 (t), 29.00 (t), 28.91 (t), 28.37 (t), 24.79
(t), 24.71 (t).
Meth yl 11-Meth yl-10-pen tadecen oate. To a stirred
solution of (9-methoxycarbonylnonyl) triphenylphospho-
nium bromide (1.05 g, 2.0 mmol) in THF (20 mL) at 0
°
C, and under a nitrogen atmosphere, was added
potassium t-butoxide (1.80 g, 2.0 mmol). The solution
was stirred for 10 min, and then a solution of 2-hex-
anone (0.21 g, 2.1 mmol) in THF (10 mL) was added.
The reaction mixture was allowed to stand overnight,
and then it was quenched with a saturated ammonium
chloride solution (25 mL), extracted with ether (2 × 50
mL), and dried over Na2SO4. After evaporation of the
solvent in vacuo, the crude product was chromato-
graphed on Si gel, eluting with hexane-ether (8:2, v/v)
and afforded the desired product [0.1 g, 18.6% yield of
a mixture of 2:1 (Z/ E) isomers]: IR (neat) υmax 3018
Sp on ge Collection . Calyx podatypa Van Soest
(
class Demospongiae, order Haplosclerida, family
Phloeodictyidae) was collected near Mona Island, Puerto
Rico, in 1992, at 20 m depth by scuba. A voucher
specimen (no. MI-030) is stored at the Chemistry
Department of the University of Puerto Rico, R ´ı o
Piedras campus.
(
dCH, olefinic), 2965, 2954, 2942, 2926, 2856, 1745 (Cd
-
1 1
Extr a ction a n d Isola tion of P h osp h olip id s. The
sponge (160.9 g) was carefully cleaned and cut into small
pieces. Extraction with 2 × 250 mL of CHCl3-MeOH
O), 1652, 1605, 1512, 1460, 1388, 1295, 1243 cm ; H
NMR (CDCl , 300 MHz) δ 5.10 [1H, br t, J
Hz, H-10, (E) and (Z)], 3.66 [3H, s, -OCH , (E) and (Z)],
2.30 [2H, t, J ) 7.5 Hz, H-2, (E) and (Z)], 2.02-1.97
3
9-10
) 6.6
3
(
(
1:1) yielded the total lipids (20.5 g). The neutral lipids
4.0 g), glycolipids (1.3 g), and phospholipids (4.2 g) were
[4H, m, H-9, H-12, (E) and (Z)], 1.67 [3H, br s, Me-16,
(Z)], 1.58 [2H, m, H-3, (E) and (Z)], 1.44 [3H, br s, Me-
16, (E)], 1.28 [14H, m, (E) and (Z)], 0.80 [3H, br t, J )
separated by column chromatography on Si gel (60-
1
3
2
00 mesh) using the procedure of Privett et al.
1
3
P r ep a r a tion a n d Isola tion of F a tty Acid Der iva -
7.0 Hz, Me-15, (E) and (Z)]; C NMR (CDCl3, 75 MHz)
δ 174.3 [s, C-1, (E) and (Z)], 135.4 [s, C-11, (Z)], 135.1
[s, C-11, (E)], 125.2 [d, C-10, (Z)], 124.5 [d, C-10, (E)],
51.4 [q, -OCH3, (E) and (Z)], 39.4 [t, (E) and (Z)], 34.1
[t, (E) and (Z)], 30.3 [t, (E) and (Z)], 30.2 [t, (E) and (Z)],
30.1 [t, (E) and (Z)], 29.9 [t, (E) and (Z)], 29.4 [t, C-5,
tives. The fatty acyl components of the phospholipids
were obtained as their methyl esters (0.088 g) by
reaction of the phospholipids (0.95 g) with methanolic
HCl followed by column chromatography.12 The double-
bond positions in the polyunsaturated fatty acids were
Carballeira, Nestor M.
