Hydroxylation of (+)-menthol by Macrophomina phaseolina

Article abstract of DOI:10.3109/10242422.2011.577209

Biotransformation of (+)-menthol with Macrophomina phaseolina led to hydroxylations at C-1, C-2, C-6, C-7, C-8 and C-9, with the C-8 position being preferentially oxidized. The resulting metabolites were identified as 8-hydroxymenthol (2), 6R-hydroxymenthol (3), 1R-hydroxymenthol (4), 9-hydroxymenthol (5), 2R,8-dihydroxymenthol (6), 8S,9-dihydroxymenthol (7), 6R,8-dihydroxymenthol (8), 1R,8-dihydroxymenthol (9) and 7,8-dihydroxymenthol (10). Metabolites 6-10 are described here for the first time. Their structures were characterized by spectroscopic analysis.

Full text of DOI:10.3109/10242422.2011.577209

Biocatalysis and Biotransformation, March–June 2011; 29(2–3): 77–82
ORIGINAL ARTICLE
Hydroxylation of (ϩ)-menthol by Macrophomina phaseolina
SYED GHULAM MUSHARRAF, MUHAMMAD ARIF AHMED, RAHAT AZHER ALI &
MUHAMMAD IQBAL CHOUDHARY
H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences,
University of Karachi, Karachi, Pakistan
Abstract
Biotransformation of (ϩ)-menthol with Macrophomina phaseolina led to hydroxylations at C-1, C-2, C-6, C-7, C-8 and
C-9, with the C-8 position being preferentially oxidized. The resulting metabolites were identified as 8-hydroxymenthol
(2), 6R-hydroxymenthol (3), 1R-hydroxymenthol (4), 9-hydroxymenthol (5), 2R,8-dihydroxymenthol (6), 8S,9-dihydroxy-
menthol (7), 6R,8-dihydroxymenthol (8), 1R,8-dihydroxymenthol (9) and 7,8-dihydroxymenthol (10). Metabolites 6–10
are described here for the first time. Their structures were characterized by spectroscopic analysis.
Keywords: Macrophomina phaseolina, biotransformation, (ϩ)-menthol, hydroxylation
Introduction
1991; Figueiredo et al. 1996; Atta-ur-Rahman et al.
1998; Mitsuo et al. 1999, 2003a,b; Mohammadreza
et al. 2005), but there are few reports of biotransfor-
mation of (ϩ)-menthol (1) (Mitsuo et al. 1999;
Yoshinori et al. 1991;Yutaka et al. 1991).
In continuation of our work on biotransforma-
tion of bioactive compounds (Choudhary et al.
2006a,b,c), we describe here the biotransformation
of (ϩ)-menthol (1) by Macrophomina phaseolina,
which had previously been screened with various
terpenoidal compounds and showed interesting
structural modification of the parent compounds
(Choudhary et al. 2006a; Musharraf et al. 2010).
Some potential p-menthane-diol products, such
compounds 2 and 5, are relevant industrial pro-
ducts with applications as flavors and fragrances
(Kenmochi et al. 1999).
Microbial transformation of terpenes is of increasing
interest and new metabolites with unique structural
features and enhanced biological activity have been
produced (Aranda et al. 1991; Maurs et al. 1999;
Abraham et al. 2000). The potential for insertion of
a hydroxyl group in a single step with high regio- and
stereoselectivity at unactivated carbons is a major
advantage of microbial transformation (Holland
1982) and represents an inexpensive route to asym-
metric building blocks that can be used as hemisyn-
thesis intermediates, chiral auxiliaries and chiral
synthons for asymmetric synthesis (Azerad 2000; de
Carvalho & da Fonseca 2006).
Menthol is an abundantly available bioactive
monoterpene from the natural chiral pool. Menthol
and its derivatives have wide applications in synthetic
organic chemistry, particularly in asymmetric syn-
thesis (Oertling et al. 2007), because of their non-
toxic, environmental friendly and crystalline nature.
They are also available in bulk quantities in both
enantiomeric (Ϯ) forms at low cost. Biotransforma-
tion of (Ϫ)-menthol has already been studied (Shukla
et al. 1987; Tsutomu et al. 1989; Yoshinori et al.
Methods
General experimental method
(ϩ)-Menthol (1) was purchased from Sigma Aldrich
(USA). TLC used plates pre-coated with silica gel
Correspondence: S. G. Musharraf, H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi,
Karachi – 75270, Pakistan. Tel: ϩ92-321-4824924. Fax: ϩ92 321-4819018/9. E-mail: musharraf1977@yahoo.com
(Received 27 October 2010; revised 26 January 2011; accepted 29 March 2011
ISSN 1024-2422 print/ISSN 1029-2446 online © 2011 Informa UK, Ltd.
DOI: 10.3109/10242422.2011.577209

78 S. G. Musharraf et al.
After filtration, extraction and evaporation, a
brown gum (1.32 g) was obtained which after
repeated column chromatography with a gradient
mixture of petroleum ether–EtOAc yielded 1
(21.3 mg; with petroleum ether–EtOAc 9:1), 2
(44.6 mg; with petroleum ether–EtOAc 8.6:1.4), 3
(15.1 mg; with petroleum ether–EtOAc 8.4:1.6), 4
(33.5 mg; with petroleum ether–EtOAc 8.1:1.9), 5
(13.2 mg; with petroleum ether–EtOAc 8:2), 6 and
7 (15.3 mg; with petroleum ether–EtOAc 7.6:2.4), 8
(8.1 mg; with petroleum ether–AcOEt 7.1:2.9), 9
(6.8 mg; with petroleum ether–EtOAc 7:3) and 10
(9.4 mg; with petroleum ether–EtOAc 6.7:3.3). An
impure fraction containing compounds 6 and 7 was
purified byTLC on pre-coated plates using petroleum
ether (EtOAc) (7.9:2.1) as mobile phase where
compounds 6 (6.4 mg) and 7 (5.2 mg) were obtained.
Compound 6 was obtained as a colorless viscous
liquid. [α]2D5: ϩ31.4° (c ϭ 0.11, CHCl ). IR (CHCl ),
(PF254, 20 ϫ 20 cm, 0.25 mm; Merck) and column
chromatography used silica gel (70–230 mesh;
Merck, USA). Melting points were determined using
a Buchi-535 melting point apparatus (Swizerland);
optical rotations in MeOH solutions used a Jasco
DIP-360 digital polarimeter (Tokyo, Japan); IR
spectra in cm–1 in CHCl3 solutions used an FTIR-
8900 spectrophotometer (Shimadzu, Japan). 1H and
13C NMR spectra in CDCl3 solutions used a Bruker
Avance 400 NMR spectrometer (Swizerland) at 400
2
and 100 MHz; D experiments with CDCl3 solu-
tions used the same instrument. Chemical shifts (δ)
are given in ppm relative to SiMe4 as an internal
standard; coupling constants J are in Hz. EI-MS
and HRFAB-MS used a Jeol JMS-600H mass
spectrometer (Japan) in m/z (rel. %). Compounds
were detected byTLC with the help of vanillin spray
reagent.
3
3
νmax (cmϪ1): 3381, 1472, 1388. For H and 13C
NMR spectroscopic data, see Table I. EI-MS, m/z
(rel. %): 173 ([M – Me]ϩ) (4); 170 ([M – H2O]ϩ)
(2); 155 ([M – Me – H2O]ϩ) (9); 137 (15); 112
(100); 97 (53). HRFAB-MS (ϩve), m/z: 189.1422.
Calcd for C10H21O3: 189.1491.
1
Organisms and culture media
Stock cultures of M. phaseolina (KUCC 730) were
maintained at 4°C on agar plates (Sabouraud dex-
trose agar). The medium for M. phaseolina was pre-
pared by mixing the following ingredients in distilled
H2O (3.0 L): glucose (30.0 g), peptone (15.0 g), yeast
extract (15.0 g), KH2PO4 (15.0 g) and NaCl (15.0 g).
Compound 7 was obtained as a colorless viscous
liquid. [α]2D5: ϩ50.1° (c ϭ 0.21, CHCl ). IR (CHCl ),
3
3
1
νmax (cmϪ1): 3412, 1462, 1032. For H and 13C
NMR spectroscopic data, see Table I. EI-MS, m/z
(rel. %): 157 ([M – CH2OH]ϩ) (24); 139 (38); 109
(11); 95 (44); 81 (100); 55 (70). HRFAB-MS (ϩve),
m/z: 189.1479. Calcd for C10H21O3: 189.1491.
Compound 8 was obtained as a white crystalline
Fermentation of (ϩ)-menthol (1) with M. phaseolina
The fermentation medium was distributed into 30 flasks
of 250 mL capacity (100 mL in each) and autoclaved
at 121°C for 20 min. The substrate (600 mg) was
dissolved in acetone (15 mL) and the resulting solu-
tion evenly distributed among the 30 flasks contain-
ing 24-h-old stage II cultures of M. phaseolina (20 mm
culture/flask) and fermentation continued for 12 days
on a shaker (200 rpm) at 29 ° C. During the fermen-
tation period, aliquots were taken out from the cul-
ture daily and analyzed byTLC in order to determine
the degree of transformation of the substrate. In all
experiments, one control flask without fungus (for
checking substrate stability) and another flask with-
out exogenous substrate (for checking endogenous
metabolites) were used. The culture media and
mycelium were separated by filtration.The mycelium
was washed with CH2Cl2 (1 L) and the filtrate was
extracted with CH2Cl2 (3 ϫ 1.5 L). The combined
organic extract was dried over anhydrous Na2SO4,
evaporated under reduced pressure and analyzed by
TLC. Control flasks were also harvested and com-
pared with the test by TLC to confirm the presence
of biotransformed products.
solid, mp 91–92°C. [α]2D5: ϩ27.4° (c ϭ 0.51, CHCl ).
3
IR (CHCl3), νmax (cmϪ1): 3441, 1464, 1382, 1022.
For 1H and 13C NMR spectroscopic data, seeTable I.
EI-MS, m/z (rel. %): 173 ([M – Me]ϩ) (4); 175
([M – H2O]ϩ) (2); 155 ([M – Me – H2O]ϩ) (9); 137
(15); 112 (100); 97 (53). HRFAB-MS (ϩve), m/z:
189.1399. Calcd for C10H21O3: 189.1491.
Compound 9 was obtained as a white crystalline
solid, mp 85–86°C. [α]2D5: ϩ61.4° (c ϭ 0.81, CHCl ).
3
IR (CHCl3), νmax (cmϪ1): 3318, 1469, 1374. For 1H
and 13C NMR spectroscopic data,seeTable I.EI-MS,
m/z (rel.%):173 ([M – Me]ϩ) (5);170 ([M – H2O]ϩ)
(3); 165 ([M – Me – H2O]ϩ) (13); 137 (16); 112
(31); 94 (91); 87 (59). HRFAB-MS (ϩve), m/z:
189.1411. Calcd for C10H21O3: 189.1491.
Compound 10 was obtained as a colorless vis-
cous liquid. [α]2D5: ϩ83.7° (c ϭ 0.75, CHCl ). IR
(CHCl3), νmax (cmϪ1): 3374. For 1H and 13C3NMR
spectroscopic data, see Table I. EI-MS, m/z (rel. %):
173 ([M – Me]ϩ) (3); 155 (15); 94 (87); 79 (100);
59 (32). HRFAB-MS (ϩve), m/z: 189.1438. Calcd
for C10H21O3: 189.1491.

Biotransformation of (ϩ)-menthol 79
Results and discussion
Incubation of compound 1 (C10H20O) with M.
phaseolina for 12 days resulted in the production of
two sets of metabolites (Scheme 1): monohydroxy-
lated derivatives 2–5 and dihydroxylated derivatives
6–10. Compounds 2–5 are all known compounds,
reported as biotransformed products of compound
1 by Aspergillus niger (Yoshinori et al. 1991), while
all dihydroxylated derivatives 6–10 were found to be
new compounds. Structures of metabolites were elu-
cidated through comparative spectroscopic studies
with substrate 1 and comparison with reported data
(Yoshinori et al. 1991); however, for compound 5 the
stereochemistry at C-8 remains to be clarified.
The EI-MS of compound 6 showed the [M –
Me]ϩ and [M – H2O]ϩ ions at m/z ϭ 173 and 170,
respectively. The HRFAB-MS (ϩve) exhibited the
[M ϩ H]ϩ ion at m/z ϭ 189.1422 corresponding to
the formula C10H21O3, consistent with a dihydroxy
derivative of 1.The 1H NMR spectrum of 6 (CDCl3,
400 MHz) exhibited a new downfield methine signal
at δ ϭ 3.04 ppm (t, J2ax,1ax/3ax ϭ 9.6 Hz), while H-3
also appeared as a clear triplet at δ ϭ 3.47 ppm
(J3ax,2ax/4ax ϭ 9.7 Hz).This suggested the presence of
an additional OH group at the C-2 position. In addi-
tion to this, C-8 geminal secondary methyls appeared
as singlets, instead of doublets, at δ ϭ 1.20 and 1.22
ppm. This indicated hydroxylation at a C-8 tertiary
carbon. The 13C NMR spectrum of 6 showed two
new signals at δ ϭ 81.1 and 74.4 ppm, correspond-
ing to C-2 and C-8, respectively. The COSY 45°
spectrum had interactions of H-1 (δ ϭ 1.51 ppm)
and H-3 (δ ϭ 3.47 ppm) with the newly oxygenated
methine H-2 (δ ϭ 3.04 ppm), while the HMBC
spectrum showed interaction of H3-7 (δ ϭ 1.02
ppm) and H-3 (δ ϭ 3.47 ppm) with C-2 (δ ϭ 81.1
ppm).The H3-9 (δ ϭ 1.20 ppm) and H3-10 (δ ϭ 1.22
ppm) showed HMBC with C-8 (δ ϭ 74.4 ppm),
which further suggested the presence of a hydroxyl
group at C-8. The multiplicity of the H-2 signal at
δ ϭ 3.04 ppm (t, J2ax,1ax/3ax ϭ 9.6 Hz) suggested
α-orientation of H-2, and hence the structure of
compound 6 was deduced as 2R,8-dihydroxymenthol
(6), formed by the C-2β hydroxylation of compound
2 (Scheme 1).
The EI-MS of compound 7 exhibited the [M –
CH2OH]ϩ peak at m/z ϭ 157. The HRFAB-MS
(ϩve) showed the [M ϩ H]ϩ ion at m/z ϭ 189.1479,
corresponding to the formula C10H21O3, as a dihy-
droxy derivative of 1. The 1H NMR spectrum
(CDCl3, 400 MHz) was similar to that of 1, with
additional AB doublets at δ ϭ 3.73/3.42 ppm
(JAB ϭ 11.2 Hz) due to an oxygen-bearing CH2.
Moreover, a 3H singlet at δ ϭ 1.20 ppm and
the disappearance of H3-9 suggested the vicinal

80 S. G. Musharraf et al.
7
1
4
6
5
2
3
OH
8
10
9
1
OH
HO
OH
OH
OH
OH
OH
OH
2
5
7
3
8
4
9
OH
OH
OH
OH
HO
OH
OH
OH
OH
OH
OH
6
OH
7
OH
8
OH
9
OH
10
Scheme 1. Biotransformation of (ϩ)-menthol by M. phaseolina.
hydroxylation at C-8 and C-9. The 13C NMR spec-
trum of 7 lacked C-8 and C-9 signals, in comparison
to 1, and showed an additional quaternary carbon at
δ ϭ 76.9 ppm (C-8) and a methylene carbon at
δ ϭ 68.7 ppm (C-9).The position of the OH groups
at C-8 and C-9 was further inferred on the basis of
HMBC cross-peaks between C-10 methyl protons
(δ ϭ 1.20 ppm) and C-8 (δ ϭ 76.9 ppm) and C-9
(δ ϭ 68.7 ppm).The stereochemistry of C-8 OH was
further inferred from the chemical shift (in CDCl3)
and by comparison with the reported 13C NMR
configuration at C-8 of an epimeric mixture of 8,
9-dihydroxymenthol (Yuasa &Yuasa 2004). C-10 in
7 appeared at δ ϭ 23.3 ppm, which was in agreement
with reported data for 8S,9-dihydroxymenthol.Thus
the structure of compound 7 was deduced as 8S,9-
dihydroxymenthol, which may be formed by the C-9
or C-7 hydroxylation of compound 2 or 5, respec-
tively (Scheme 1).
Compound 8 showed the [M ϩ H]ϩ ion at
m/z ϭ 189.1399 in HRFAB-MS (ϩve), corresponding
1
to the formula C10H21O3. The H NMR spectrum
showed an additional downfield signal at δ ϭ 3.10
ppm (dt, J6ax,5eq ϭ 4.3 Hz, J6ax,5ax/1ax ϭ 10.4 Hz),
indicating the presence of a hydroxyl group at C-5
or C-6. Moreover, C-8 secondary methyls appeared
as singlets at δ ϭ 1.17 and 1.20 ppm, supporting a
hydroxyl at C-8.The 13C NMR spectrum of 8 showed
two additional signals, one methine (δ ϭ 76.3 ppm)
and one quaternary carbon signal (δ ϭ 75.1 ppm),
along with the upfield shift of the C-7 signal (δ ϭ 18.6
ppm). These observations further supported the
position of the OH at C-6 and C-8. H-6 showed
vicinal coupling with H-1 (δ ϭ 1.48 ppm) and H2-5

Biotransformation of (ϩ)-menthol 81
appeared after 3 days’ incubation, while all transfor-
mation products 2–10 could be visualized by TLC
together with residual compound 1 after 7 days. Fur-
ther continuation of the experiment increased the
yields of transformed products until day 12.
(δ ϭ 1.81, 1.37 ppm) in the COSY 45° spectrum.
The β-stereochemistry of the hydroxyl group was
deduced by the multiplicity of the 6-αH signal
(δ ϭ3.10 ppm,dt,J6ax,5eq ϭ 4.3 Hz, J6ax,5ax/1ax ϭ10.4 Hz)
and the NOESY correlations of H-6α with H3-7
(δ ϭ 0.91 ppm) and H-4α (δ ϭ 1.42 ppm). Thus
compound 8 was characterized as 6R,8-dihydroxy-
menthol, which may be formed by the monohydrox-
ylation at C-8 or C-6β of compound 2 or 3,
respectively (Scheme 1).
Conclusions
M. phaseolina performed regio- and stereocon-
trolled hydroxylations of 1 at C-1β, C-2β, C-5β,
C-7, C-8 and C-9, which resulted in the produc-
tion of nine hydroxylated products 2–10.A hydroxyl
group at C-8 was common in all dihydroxylated
derivatives, indicating preferential oxidation at
this position in 1 by M. phaseolina. The dihydroxy-
lated derivatives, 6–10, were found to be new
compounds.
The HRFAB-MS of metabolite 9 displayed an
[M ϩ H]ϩ peak at m/z ϭ 189.1411 corresponding to
the formula C10H21O3 and indicating the incorpora-
tion of two oxygen moieties in 1.The 1H NMR spec-
trum of compound 9 showed three methyl singlets
at δ ϭ 1.25 (H3-7), 1.24 (H3-9) and 1.23 (H3-10)
ppm.The 13C NMR spectrum of 9 showed two qua-
ternary carbon signals at δ ϭ 71.5 and 75.6 ppm,
while the disappearance of C-1 and C-8 methine
carbons suggested that hydroxylation had taken
place at C-1 and C-8. The HMBC spectrum of 9
showed the interactions of H3-7 (δ ϭ 1.25 ppm),
H2-2 (δ ϭ 1.92, 1.40 ppm) and H2-6 (δ ϭ 1.61, 1.38
ppm) with C-1 (δ ϭ 71.5 ppm),while H3-9 (δ ϭ 1.24
ppm) and H3-10 (δ ϭ 1.23 ppm) and H-4 (δ ϭ 1.38
ppm) were correlated with C-8 (δ ϭ 75.6 ppm).The
NOESY spectrum showed the interaction of H3-7α
with H-4α, supporting a β-orientation of OH at C-1.
Thus the structure of 9 was deduced as 1R,8-dihy-
droxymenthol, formed by C-1β or C-8 hydroxylation
of compound 2 or 4, respectively (Scheme 1).
The [M ϩ H]ϩ ion of compound 10 was found
to be at m/z ϭ 189.1438, corresponding to the for-
Declaration of interest: The authors gratefully
acknowledge the financial support of the Higher
Education Commission (HEC) to various scholars
involved in this study. The authors report no con-
flicts of interest. The authors alone are responsible
for the content and writing of the paper.
References
Abraham WR, Arfmann HA, Kieslich K, Haufe G. 2000.
Regioselectivity of the microbial hydroxylation of nortri-
cyclanol and its derivatives. Biocatal Biotransformation 18:
283–290.
Aranda G, El-Kortbi MS, Lallemand JY, Neuman A, Hammoumi
A, Facon I, Azerad R. 1991. Microbial transformation of diter-
penes: hydroxylation of sclareol, manool and derivatives by
Mucor plumbeus. Tetrahedron 47:8339–8350.
Atta-ur-Rahman, Yaqoob M, Farooq A, Anjum S, Asif F,
Choudhary MI. 1998. Fungal transformation of (1R,2S,5R)-
(Ϫ)-menthol by Cephalosporium aphidicola. J Nat Prod 61:
1340–1342.
Azerad R. 2000. Regio- and stereoselective microbial
hydroxylation of terpenoid compounds. In: Patel RN, editor.
Stereoselective biocatalysis. New York: Marcel Dekker. pp.
153–180.
Choudhary MI, Ranjit R, Atta-ur-Rahman, Devkota KP, Mushar-
raf SG, Shrestha TM. 2006a. Hydroxylation of the sesterter-
pene leucosceptrine by the fungus Rhizopus stolonifer.
Phytochemistry 67:439–443.
Choudhary MI, Siddiqui ZA, Nawaz SA,Atta-ur-Rahman. 2006b.
Microbial transformation and butyrylcholinesterase inhibitory
activity of (Ϫ)-caryophyllene oxide and its derivatives. J Nat
Prod 69:1429–1434.
Choudhary MI, Siddiqui ZA, Khan S, Musharraf SG.
2006c. Biotransformation of (Ϫ)-caryophyllene oxide by cell
suspension culture of Catharanthus roseus. Z Naturforsch
61:197–200.
de Carvalho CCCR, da Fonseca MMR. 2006. Biotransformation
of terpenes. Biotechnol Adv 24:134–142.
1
mula C10H21O3, in HRFAB MS (ϩve). The H
NMR spectrum of 10 showed an additional dou-
blet at δ ϭ 3.47 ppm (2H, J ϭ 6.2 Hz) and disap-
pearance of the H3-7 signal, which indicated
oxidation of the C-7 methyl to C-7 CH2OH. Sec-
ond, a 6H singlet at δ ϭ 1.21 ppm, due to the two
methyls of an isopropyl moiety, indicated that
another hydroxyl group was introduced at C-8.
The 13C NMR spectrum of 10 showed the disap-
pearance of the C-8 methine and C-7 methyl
carbon signals, in comparison to 1, while oxygen-
bearing quaternary and methylene carbons
appeared at δ ϭ 75.5 and 67.9 ppm, respectively.
The position of the OH at C-7 and C-8 was further
inferred by HMBC between H-4 (δ ϭ 1.41 ppm)
and H6-9/10 (δ ϭ 1.22 ppm) and with C-8
(δ ϭ 75.5 ppm), while H-1 (δ ϭ 1.51 ppm) showed
cross-peaks with C-7 (δ ϭ 67.9 ppm). The struc-
ture of compound 10 was deduced as 7,8-dihy-
droxymenthol, which may be formed by the C-7
hydroxylation of compound 2 (Scheme 1).
Time-course studies on compound 1 showed
that the monohydroxylated derivatives, 2 and 4,
Figueiredo AC, Almendra MJ, Barroso JG, Scheffer JC. 1996.
Biotransformation of monoterpenes and sesquiterpenes by

82 S. G. Musharraf et al.
cell-suspension cultures of Achillea millefolium L. ssp. millefo-
lium. Biotechnol Lett 18:863–868.
Holland HL. 1982. The mechanism of the microbial hydroxy-
lation of steroids. Chem Soc Rev 11:371–3950.
Musharraf SG, Najeeb A, Khan S, Pervez M, Ali RA,
Choudhary MI. 2010. Microbial transformation of
5α-hydroxycaryophylla-4(12),8(13)-diene with Macrophomina
phaseolina. J Mol Catal B: Enzym 66:156–160.
Kenmochi H, Akiyama T,YuasaY, Kobayashi T, Tachikawa A. 1999.
Method for producing p-menthane-3,8-diol. US Patent, 956,161.
Maurs M, Azerad R, Cortés M, Aranda G, Delahaye MB, Ricard
L. 1999. Microbial hydroxylation of natural drimenic lactones.
Phytochemistry 52:291–296.
Mitsuo M, Shingo K, Hiromu K, 1999. Biotransformation of (ϩ)
and (Ϫ)-menthol by the larvae of common cutworm (Spodop-
tera litura). J Agric Food Chem 47:3938–3940.
Mitsuo M, Hideki K, Mitsuro H, 2003a. Biotransformation of
L-menthol by Rhizoctonia solani. J Chem Technol Biotechnol
78:620–625.
Mitsuo M, Hideki K, Mitsuro H. 2003b. Biopreparation of
(–)-(1S,3R,4S,6S)-6-hydroxymenthol and (–)-(1S,3R,4S)-1-
hydroxymenthol from 1-menthol by Rhizoctonia solani AG-1-IA
and IB. Nat Prod Res 17:307–311.
Oertling H, Reckziegel A, Surburg H, Heinz-Juergen B. 2007.
Applications of menthol in synthetic chemistry. Chem Rev 107:
2136–2164.
Shukla OP, Bartholomus RC, Gunsalus IC. 1987. Microbial
transformation of menthol and menthane-3,4-diol. Can J
Microbiol 33:489–497.
Tsutomu F,Yutaka O, Hiromitsu M. 1989. Biotransformation of
(–)-menthol by Eucalyptus perriniana cultured cells. J Chem Soc
Perkin Trans 1 10:1711–1719.
Yoshinori A, Hironobu T, Masao T, Yoshiaki N. 1991.
Biotransformationofmonoterpenenoids,(Ϫ)-and(ϩ)-menthols,
terpinolene and carvotanacetone by Aspergillus species. Phyto-
chemistry 30:3981–3987.
Yuasa Y, Yuasa Y, 2004. Synthesis and absolute configuration at
C(8) of p-menthane-3,8,9-triol derived from (–)-isopulegol.
Helv Chim Acta 87:2602–2607.
Yutaka O, Hiromitsu M, Tsutomu F. 1991. Triglucosylation
on the biotransformation of (ϩ)-menthol by cultured cells of
Eucalyptus perriniana. Phytochemistry 30:1843–1845.
Mohammadreza S, Alireza G, Parmis B, Abdolali M. 2005.
Biotransformation of terpenes and related compounds by sus-
pension culture of Glycyrrhiza glabra L. (Papilionaceae). Fla-
vour Fragr J 20:141–144.