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11.4 Potential Uses of Ecdysteroid-
like and Related Sterols from
Cactaceae
As far as we know, the biological activity of
phytoecdysteroids from Cactaceae has not
been investigated, even their possible ago-
nist or antagonist ecdysteroid effects.
The chemistry of the triterpenes, alka-
loids and sterols of some species of colum-
nar cacti has been well documented (Kircher,
1969, 1980). The cactophilic fruit flies
Drosophila pachea, Drosophila nigrospirac-
ula and Drosophila mojavensis develop
selectively in decaying tissues of Lophocereus
schottii (common name senita), Pachycereus
pringlei (cardón), Stenocereus gummosus
(agria) and S. thurberi (organ pipe). It is
known that sterols play a role in substrate
selection and nutrition of the flies (Kircher
et al ., 1984). D. pachea cannot develop
unless it has an intake of delta-7 sterols in
the diet, found only in L. schottii , its unique
host. On the other hand, D. nigrospiracula
larval success rate decreases when feeding
on S. thurberi (organ pipe), which contains
3b,6a-diols such as peniocerol, whereas
D. mojavensis can succeed in the organ pipe,
its natural host (Fogleman et al ., 1986). It is
therefore assumed that 3b,6a-diol sterols
exert a defensive role in plants (Fogleman
and Danielson, 2001). Recently we described
the development of Moneilema variolare lar-
vae, another cactophilic insect, in the roots
of Myrtillocactus geometrizans , which is a
new host to be reported for the insect (Salazar
et al. , 2004). A chemical study was per-
formed on the roots of M. geometrizans ,
resulting in the discovery of large quantities
of mixtures of 3b,6a-diols. Peniocerol and
macdougallin were the most abundant. In
order to investigate the effects of both ster-
ols against insects, Spodoptera frugiperda
and Tenebrio molitor were selected as model
systems. The results showed that peniocerol
and macdougallin at low doses (5-50 ppm)
inhibit insect moulting in S. frugiperda
when incorporated into the artificial diet.
When the larvae reached pupation, deformi-
ties were observed in the morphology of the
pupae (Fig. 11.11). By contrast, when
Fig. 11.11. Effects of peniocerol on Spodoptera
frugiperda : deformation of pupae.
solutions of both the sterols were applied topi-
cally to T. molitor larvae, pupation was antici-
pated with respect to the solvent control. Both
results indicate an effect on pupation, which
is mediated mainly by 20-hydroxyecdysone.
Thus, interference of the tested substances
with ecdysone metabolism is strongly sug-
gested (Céspedes et al ., 2005).
The above could be supported by the
fact that it has long been known that deriva-
tives of cholesterol with a double bond
between C-8 and C-9 can be metabolized by
rat liver homogenates to delta-7 cholesterol
(Gaylor et al ., 1966). Moreover, peniocerol
was converted by rat liver homogenates to
cholest-7-ene-3b,6a-diol, presumably by way
of 3b-hydroxy-cholest-7-en-6-one (Slaytor
and Bloch, 1965). Although the above results
involve mammal metabolism, no evidence
was found in insect metabolism, so the pro-
posal that peniocerol could be converted to
the 7-en-6-one chomophore in insects has to
be researched to try to explain the interfer-
ence of moulting activities. These studies
allow the proposal of ecdysteroids and
related sterols found in Cactaceae as poten-
tial candidates for developing natural insec-
ticidal agents.
Finally, another possible application
of these compounds is due to their phar-
macological activity. In a previous study,
lophenol showed anti-tumour activity, and
some derivatives were synthesized in
order to obtain more bioactive compounds
(He et al ., 2006). Furthermore, we evalu-
ated the anti-tumour activity against
some human cancer cell lines and anti-
inflammatory activities of peniocerol and
macdougallin. Both compounds showed
moderate cytotoxicity against central nerv-
ous system carcinoma (U-251), prostate
 
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