Biotransformation of Triterpenes by Glomerella fusarioides
Journal of Natural Products, 2006, Vol. 69, No. 4 607
Biotransformation of 24-Methylenecycloartanol (2) and Isolation
of Metabolites. Biotransforamtion of 2 by G. fusarioides yielded a
crude extract (248 mg), which was chromatographed on silica gel (15
g). Elution of the column with n-hexanes-EtOAc (19:1, 300 mL; 9:1,
100 mL; 4:1, 500 mL) yielded fractions A′ (14.2 mg), B′ (179.0 mg),
C′ (13.0 mg), D′ (2.5 mg), and E′ (17.6 mg). Fraction B′ was subjected
to HPLC I to yield 6 (3.8 mg, tR 27.2 min), 7 (1.4 mg, tR 8.4 min), and
8 (5.2 mg, tR 18.4 min) in addition to unmetabolized 2 (125.6 mg).
(24R,S)-24-Methylcycloartane-3â,24,241-triol (7): fine needles, mp
175-177 °C; [R]25D +25.5 (c 0.10, CHCl3); IR νmax 3407 (OH), 3040
Acknowledgment. The authors thank Dr. W. C. M. C. Kokke
(Ardmore, PA) for reviewing the manuscript. The authors are also
indebted to Mr. M. Ukiya (College of Science and Technology, Nihon
University) for his technical assistance. This work was supported, in
part, by a grant “Academic Frontier” Project for Private Universities:
matching fund subsidy from MEXT (Ministry of Education, Culture,
Sports, Science and Technology) 2002-2006.
References and Notes
1
(cyclopropyl) cm-1; H and 13C NMR, see Table 1; EIMS m/z 474
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[M]+ (8), 456 [M - H2O]+ (30), 441 [M - Me - H2O]+ (23), 438 [M
- 2H2O]+ (19), 423 (m/z 438 - Me) (30), 413 (13), 395 (8), 369 [M
- C5H11O2 (species formed by the cleavage of C-23-C-24 bond) -
2H]+ (10), 334 [M - C9H16O (ring A)]+ (23), 316 (20), 315 [M -
C9H19O2 (side-chain)]+ (19), 297 (m/z 315 - H2O) (19), 273 [m/z 315
- C3H6 (ring D)] (4), 255 (m/z 273 - H2O) (7), 95 (100); HREIMS
m/z 474.4064 (calcd for C31H54O3, 474.4073).
(24R,S)-241-Methoxy-24-methylcycloartane-3â,24-diol (8): fine
needles, mp 168-171 °C; [R]25 +4.3 (c 0.10, CHCl3); IR νmax 3409
D
(OH), 3040 (cyclopropyl) cm-1; 1H and 13C NMR, see Table 1; EIMS
m/z 488 [M]+ (13), 470 [M - H2O]+ (45), 457 [M - OMe]+ (100),
438 (m/z 470 - MeOH) (37), 428 [M - CH2OMe - Me]+ (26), 423
(m/z 438 - Me) (52), 395 (17), 369 [M - C6H13O2 (species formed
by the cleavage of C-23-C-24 bond) - 2H]+ (17), 348 [M - C9H16O
(ring A)]+ (14), 317 [M - C10H21O2 (side-chain) + 2H]+ (19), 297 [M
- side-chain - H2O]+ (21); HREIMS m/z 488.4229 (calcd for
C32H56O3, 488.4228).
Biotransformation of Cycloartenone (3) and Isolation of Me-
tabolites. Column chromatography on silica gel (15 g) of the crude
extract (192 mg) eluted with n-hexanes-EtOAc [19:1, 500 mL; 4:1,
200 mL; 1:1, 350 mL] gave fractions A′′ (109 mg), B′′ (11 mg), and
C′′ (46 mg) in ascending order of polarity. Fraction A′′ was subjected
to further chromatography on silica gel, which yielded fractions A′′-1
(86 mg) and A′′-2 (14 mg), of which the former was identified as
unmetabolized 3. HPLC II of fraction A′′-2 afforded 10 (1.2 mg, tR
16.2 min), 11 (3.6 mg, tR 13.8 min), and 14 (1.6 mg, tR 12.9 min).
Fraction B′′ (11 mg), upon HPLC II, gave 9 (1.4 mg, tR 6.9 min). HPLC
II of fraction C′′ (46 mg) afforded 12 (1.6 mg, tR 16.5 min) and 13
(4.0 mg, tR 8.7 min).
4r,4â,14r-Trimethyl-9â,19-cyclopregnane-3,20-dione (9): fine
needles, mp 198-199 °C; [R]25 +8.3 (c 0.16, CHCl3); IR νmax 3055
D
1
(cyclopropyl), 1710 (>CdO) cm-1; H and 13C NMR, see Table 1;
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EIMS m/z 356 [M]+ (100), 341 [M - Me]+ (52), 313 [M - C2H3O]+
(52), 271 (m/z 313 - C3H6 (ring D), 218 [M - C9H14O (ring A)]+
(100), 175 [m/z 218 - C2H3O (side-chain)] (70); HREIMS m/z 356.2714
(calcd for C24H36O2, 356.2715).
(24R,S)-25-Hydroxy-24-methoxycycloartan-3-one (14): fine needles,
mp 165-168 °C; [R]25 +16.4 (c 0.18, CHCl3); IR νmax 3445 (OH),
D
3060 (cyclopropyl), 1710 (>CdO) cm-1; 1H and 13C NMR, see Table
1; EIMS m/z 472 [M]+ (15), 440 [M - MeOH]+ (29), 425 (m/z 440 -
Me) (15), 422 (m/z 440 - H2O) (17), 407 (m/z 422 - Me) (5), 399
(11), 354 [M - C6H13O2 (species formed by the cleavage of C-22-
C-23 bond) - H]+ (15), 334 [M - C9H14O (ring A)]+ (8), 313 [M -
C9H19O2 (side-chain)]+ (50), 271 [m/z 313 - C3H6 (ring D)] (4), 73
(100); HREIMS m/z 472.3908 (calcd for C31H52O3, 472.3916).
(21) Itoh, T.; Tamura, T.; Ogawa, S.; Matsumoto, T. Steroids 1975, 25,
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NP058120D