*3.1.1.1. Clerodane diterpenes by biotransformation from endophytic fungi*

Three strains of endophytic fungi *L. gonubiensis*, *N. ribis*, and *P. stromaticum* produced one known and five unknown compounds (B1–B4) through a process of biotransformation, while compounds Q1–Q2 are derived as chemical derivatization of compound 2 [30]. These compounds were actually isolated for the first time from *Croton argyrophylloides* (Euphorbiaceae) and further biotransformed by *Cunninghamella echinulata* and *Rhizopus stolonifer* fungi and produced a new diterpene, as previously described by Monte et al. [31] and Mafezoli et al. [32] (**Figure 3**).

*3.1.1.2. 13C-NMR date*

*3.1.1.3. Biological activity*

is in agreement with the molecular formula C20H30O5

15,16-epoxy-4-hydroxycleroda-13(16),14-diene (compound 1) [35].

C20H28O5

13C-NMR spectra of substrate 1 and B2 suggested the C-7 hydroxylation making the signal at δ 70.1 (CH) in B2. Compound B2 is identified as new metabolite (4S,5S,7R,8R,9S,10S)- 4,7-dihydroxy-15,16-epoxy-3,12-dioxocleroda-13(16),14-diene, and its molecular formula

**Figure 3.** Chemical structures of the metabolites by and chemical derivatives of the (3*R*,4*S*,5*S*,8*S*,9*R*,10*S*)-3,12-dioxo-

NMR spectrum of B3 showed the presence of one at δ 72.2 in the spectrum confirmed that compound 1 was regioselectively bioreduced at C-3. The new compound B3 was named (3*R*,4*S*,5*S*,7*R*,8*S*,9*R*,10*S*)-3,4,7-trihydroxy-15,16-epoxy-12-oxocleroda-13(16),14-diene, which

obtained only in the *P. stromaticum* culture. The 13C-NMR spectrum of B4 showed no reduction of carbonyl group at δ 213.5 (C-3) and the appearance of carbinol methane group at δ 71.8 (C-6). And it is named as (4S,5R,6R,8S,9R,10S)-4,6-dihydroxy-15,16-epoxy-3,12-dioxocleroda-

compound Q1 was named (4S,5S,7R,8R,9S,10S)-7-propionyloxy-4-hydroxy-15,16-epoxy-3,12 dioxocleroda-13(16),14-diene. The new derivative Q2 was named (4*S*,5*S*,7*R*,8*R*,9*S*,10*S*)-7-

Clerodane diterpenes possessed effective insect antifeeding and related insecticidal properties. There are approximately more than 400 natural and semisynthetic products that have

13(16),14-diene, which is in agreement with the molecular formula C20H28O5

benzyloxy-4-hydroxy-15,16-epoxy-3,12-dioxocleroda-13(16),14-diene [30].

been assayed in the laboratories showing potential antifeedant properties [33].

is sorted by HRMS. Compound B3 was unique for cultures of *N. ribis*. The 13C-

. The biotransformation product B4 was

Diterpenes from Different Fungal Sources and Their 13C-NMR Data

http://dx.doi.org/10.5772/intechopen.79186

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. The new

**Figure 2.** Clerodane skeleton, cis and trans structures of clerodane.

**Figure 3.** Chemical structures of the metabolites by and chemical derivatives of the (3*R*,4*S*,5*S*,8*S*,9*R*,10*S*)-3,12-dioxo-15,16-epoxy-4-hydroxycleroda-13(16),14-diene (compound 1) [35].
