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the family Agavaceae. These are perennial,
succulent plants (Pellmyr
et al
., 2007).
Yucca periculosa
is an endemic plant in the
Mexican states of Puebla, Oaxaca, Tlaxcala
and Veracruz. It is known as 'ntaxha′o',
'izote' or 'palmillo'. It is a perennial tree, a
succulent measuring 5-15 m tall; its trunk
is generally smooth, although there may
be ramifications. These plants have rigid
leaves that are concave, glabrous, and linear-
lanceolate with a finely fibrous margin and
acute apex ending in a spine; the leaves are
clustered toward the ends of the branches
(Matuda and Piña, 1980).
Y. periculosa
has several phenolic
compounds with antioxidant properties
(Fig. 17.2). Resveratrol and
trans
-3,3′,5,5′-
tetrahydroxy-4′-methoxystilbene (MS) have
previous been isolated from the methanolic
extract of the bark of this plant (Torres
et al
.,
2003). MS showed strong radical scaveng-
ing and even stronger anti-platelet activity
than did resveratrol (Piacente
et al
., 2004).
This compound, like resveratrol, has pro-
tective effects against peroxynitrite-induced
oxidative/nitrative damage to human plate-
let proteins and lipids (Olas
et al
., 2008).
Resveratrol (3,4′,5-trihydroxystilbene) has
been found in various plants, including
grapes, berries and peanuts (Dong, 2003).
In recent years it has been the focus of
many studies aimed at understanding its
full range of beneficial health effects (De la
Lastra and Villegas 2007; Pezzuto, 2008),
which include mainly antioxidant and anti-
inflammatory activities, anti-platelet aggre-
gation effects, anti-atherogenic properties,
oestrogen-like growth-promoting effects,
growth-inhibiting activities, immunomod-
ulation and chemoprevention. We also
isolated from
Y. periculosa
a flavanone, narin-
genin (García-Bores
et al
., 2010). This com-
pound possesses some antioxidant activity,
but its activity is poor in comparison with
many other polyphenols and flavonoids
(Erlund, 2004).
17.5
Molar Extinction Coefficients
HO
One of the features of photochemopreven-
tive agents is the ability to absorb UVR.
Because of this, the first step in our research
is to determine whether extracts and isolated
metabolites absorb UVR. The UVB-absorbing
compounds linarin and verbascoside were
isolated from the methanolic extract of
B. perfoliata
and
B. scordioides
, and linarin
acetate was prepared in our laboratory.
Resveratrol, MS and naringenin were isolated
from the methanolic extract of
Y. periculosa.
We have reported the l
max
and molar extinc-
tion coefficient of natural compounds isolated
from
B. perfoliata
(Avila, 2002)
, B. scordioides
(Avila, 2002; Avila
et al
., 2005) and
Y. peric-
ulosa
(García-Bores
et al
., 2010).
As shown in Table 17.1, the meth-
anolic extracts and compounds isolated
have the maximum absorption in the UVB
region of the electromagnetic spectrum and
are therefore potentially photoprotective
substances. In addition, the metabolites
have similar extinction coefficients to those
reported for photoprotective substances
used commercially (Shaath, 1997, 2005;
Pattanaargson
et al
., 2004).
OH
HO
Resveratrol
HO
OH
MeO
HO
OH
Tr ans
-3,3
,5,5
-tetrahydroxy-4-methoxystilbene (MS)
OH
HO
O
Naringenin
O
OH
Fig. 17.2.
Structures of UVB-absorbing
compounds isolated from
Yucca periculosa.
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