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Page 6 of 50 Siddiqui et al. Chem Synth 2023;3:25 https://dx.doi.org/10.20517/cs.2023.02

Figure 5. Biotransformation of (+)-menthol (21) with Macrophomina phaseolina.

methyloxepin-1-one (32) (2%) [Proposed Supplementary Figure 1], along with two known metabolites, 3-
hydroxy-5-isopropyl-2-methylcyclohexa-2,5-diene-1,4-dione (33) (8%), and 5-isopropyl-2-methylbenzene-
1,4-diol (34) (28%) [Figure 6] [Proposed Supplementary Figure 2].
[26]

BIOTRANSFORMATION OF SESQUITERPENES
Biotransformation of (+)-isolongifolen-4-one (35)
Five new oxidative derivatives, 12-hydroxyisolongifolen-4-one (36), 13-hydroxyisolongi-folen-4-one (37),
11-hydroxyisolongifolen-4-one (38), 10-hydroxyisolongifolen-4-one (39), and 9-hydroxyisolongifolen-4-
[27]
one (40) were synthesized through the microbial transformation of (+)-isolongifolen-4-one (35)
[Figure 7]. Compound 35 is used in the perfumery industry. Derivatives 37 (IC = 9.64 ± 0.0008 μM) and 40
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(IC = 6.68 ± 0.0096 μM) were identified as potent inhibitors of tyrosinase, an important enzyme for
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melanin biosynthesis, as compared to substrate 35 (IC = 51.91 ± 0.0245 μM). Metabolite 36 showed
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moderate inhibitory activity (IC = 101.01 ± 0.1978 μM).
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Biotransformation of (-)-isolongifolol (41)
Biotransformation of (-)-isolongifolol (41) with Fusarium lini resulted in three new polar oxygenated
derivatives, 10-oxoisolongifolol (42) (1.2%), 10α-hydroxyisolongifolol (43) (16%), and 9α-
hydroxyisolongifolol (44) (22%). The presence of an α-OH at C-10 in the metabolite 42 increased its
inhibitory potential against butyrylcholinesterase, an enzyme whose inhibition reduces memory deficiency
in Alzheimer’s patients, with the IC value of 13.6 μM, while the presence of an α-OH at C-11 in the
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