282
J. C. Pardo-Novoa and C. M. Cerda-García-Rojas
trivial name of illisimonin A (163) and the structure was deduced by extensive NMR
analysis. Its absolute configuration was established by comparison between experimental and theoretical ECD analytical data. The experimental spectrum of 163
showed a strong negative Cotton effect at 216 nm for the n → π* transition of
the lactone ring moiety. Calculation of the theoretical ECD spectrum for the two
possible enantiomers of this compound was carried out using time-dependent DFT
at the B3LYP/6-31G(d) level of theory. The similarity of both spectra allowed assignment of the (1R,4R,5R,6R,7S,9S,10S) configuration to 163. A biosynthesis pathway
for the formation of 163 from bisabolene through cedrane and seco-prezizaane intermediates was proposed. Interestingly, illisimonin A (163) demonstrated a neuroprotective effect against cellular injury induced by oxygen–glucose deprivation in
SHSY5Y cells with an EC 50 value of 27.7 μM [79].
O
O
O
HO
OH
HO
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
163 (illisimonin)
Four novel germacranolide sesquiterpene lactones named trichospirolides A–
D (164–167), were isolated from Trichospira verticillata, an unexplored species
collected in Alajuela Province, Costa Rica. Their structures were elucidated taking
into consideration extensive NMR spectroscopic analysis and molecular modeling,
including analysis of internuclear distances and coupling constants for all possible
diastereomers of each compound. A detailed ECD study was undertaken for the determination of absolute configuration of 164–167 [80] on the basis of the comparison
between experimental and calculated ECD and UV spectra. The excitation energies,
rotatory strengths, and oscillator strengths for each transition were calculated for
the first forty electronic states at the TDDFT/B3LYP/aug-cc-pVDZ level of theory
including the PCM with methanol as the solvent. The study was conducted to find
new antiplasmodial compounds and revealed that trichospirolide A (164) exhibited
the highest activity among the four compounds against the growth of Plasmodium
falciparum Dd2 strain (IC 50 value of 1.5 μM) [80].
J. C. Pardo-Novoa and C. M. Cerda-García-Rojas
trivial name of illisimonin A (163) and the structure was deduced by extensive NMR
analysis. Its absolute configuration was established by comparison between experimental and theoretical ECD analytical data. The experimental spectrum of 163
showed a strong negative Cotton effect at 216 nm for the n → π* transition of
the lactone ring moiety. Calculation of the theoretical ECD spectrum for the two
possible enantiomers of this compound was carried out using time-dependent DFT
at the B3LYP/6-31G(d) level of theory. The similarity of both spectra allowed assignment of the (1R,4R,5R,6R,7S,9S,10S) configuration to 163. A biosynthesis pathway
for the formation of 163 from bisabolene through cedrane and seco-prezizaane intermediates was proposed. Interestingly, illisimonin A (163) demonstrated a neuroprotective effect against cellular injury induced by oxygen–glucose deprivation in
SHSY5Y cells with an EC 50 value of 27.7 μM [79].
O
O
O
HO
OH
HO
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
163 (illisimonin)
Four novel germacranolide sesquiterpene lactones named trichospirolides A–
D (164–167), were isolated from Trichospira verticillata, an unexplored species
collected in Alajuela Province, Costa Rica. Their structures were elucidated taking
into consideration extensive NMR spectroscopic analysis and molecular modeling,
including analysis of internuclear distances and coupling constants for all possible
diastereomers of each compound. A detailed ECD study was undertaken for the determination of absolute configuration of 164–167 [80] on the basis of the comparison
between experimental and calculated ECD and UV spectra. The excitation energies,
rotatory strengths, and oscillator strengths for each transition were calculated for
the first forty electronic states at the TDDFT/B3LYP/aug-cc-pVDZ level of theory
including the PCM with methanol as the solvent. The study was conducted to find
new antiplasmodial compounds and revealed that trichospirolide A (164) exhibited
the highest activity among the four compounds against the growth of Plasmodium
falciparum Dd2 strain (IC 50 value of 1.5 μM) [80].