Photoprotective Activity of some Mexican Plants - Natural Antioxidants and Biocides from Wild Medicinal Plants - page 256

polyphenolic compounds with antioxidant
properties may prevent inactivation of enzymes
such as CAT and SOD as well as prevent
photo-oxidative damage to DNA, proteins
and lipids. On the other hand, exposure to
UVR initiates a cascade of events that alters
gene expression and thus the signal trans-
duction involved in inflammation, apoptosis,
immunosuppression and cell proliferation
(Afaq et al ., 2005).
In recent years epidemiological and
experimental studies have focused on a wide
variety of natural products that provide pro-
tection to the development of skin cancer
because they can alter or correct a variety of
cellular functions induced by the UVR. The
use of natural products as photochemopre-
ventive agents can contribute in reducing
the risk of skin cancer in combination with
changes in lifestyle, diet and products for
skin care. Within this concept, a variety of
polyphenolic compounds with antioxidant,
photoprotective, anti-inflammatory, immu-
nomodulatory and antimutagenic properties
has been reported (Afaq et al ., 2005; Adhami
et al ., 2008).
Currently, in our laboratory we are inter-
ested in contributing to the phytochemical
study of various Mexican species, as well as
providing basic knowledge about the ability
of secondary metabolites to prevent short-
term UVB-radiation-mediated damage in skin.
These compounds possess sunscreen prop-
erties and antioxidant activity, which can
prevent the formation of erythema and avoid
a state of oxidative stress in the skin exposed
to UVR. In addition, phytochemicals may
have the advantage of being biodegradable
and will probably present fewer side effects
than the synthetic sunscreens. This know-
ledge provides a guideline for future studies
that will determine whether these metabo-
lites are involved in other processes such as
inflammation and immunosuppression, as
well as understanding the molecular mecha-
nisms of photochemopreventive agents.
In this chapter we present a review of
the antioxidant and photoprotective poten-
tial of the extracts and metabolites isolated
from various Mexican plants. Some flavo-
noids, stilbenes and phenylpropanoids
were isolated from two species of Buddleja

and Yucca periculosa . The natural com-
pounds and some derivatives have antioxi-
dant activity. In addition, the photoprotective
effect of substances against UVB-induced
cellular death was evaluated through chal-
lenge experiments using Escherichia coli .
Photoprotective activity was also evaluated
in an animal model. The SPF of the substances
was evaluated by a guinea pig bioassay and
a histopathological skin study.

17.3 Natural Products Isolated

from Buddleja

The Buddleja genus (Buddlejaceae) com-
prises about 100 species, 50 of which are
native to the Americas. Buddleja species
are small trees or shrubs that grow in
tropical lands of America, Asia and Africa.
In Mexico there are 20 species of Buddleja ,
which are distributed throughout the national
territory (Rzedowski and Rzedowski, 1985).
Some of these plants are used by Mexican
traditional medicine for the treatment of
erysipelas, such as healing, analgaesic, anti-
diarrhoea, anti-inflammatory and infec-
tions of the upper respiratory tract (INI,
1994). Buddleja perfoliata HBK is distrib-
uted in the states of San Luis Potosí,
Querétaro, Hidalgo and Puebla in Mexico,
is known popularly as 'salvia real' or 'salvia
de bolita' and is used as an antiperspirant,
a diuretic, to disinfect wounds and for gas-
trointestinal infections. This plant is a
shrub that can reach 1 m in height, is
branched with dense pubescence and has
leaves that are lanceolate oblong, with
finely crenate margins, with venation
prominent on the underside. Buddleja
scordioides HBK is a shrub that grows in
the Chihuahuan desert (Rzedowski and
Rzedowski, 1985). Decoctions of this plant
are used orally or topically for treatment of
several illnesses such as diarrhoea, head-
ache and pain (Aguilar et al ., 1994). In the
surroundings of Dr Arroyo, Nuevo León
México, where B. scordioides is known as
'escobilla', the outdoor workers use an
infusion of its aerial parts as a sunscreen
(personal communication).