In vitro 5-lipoxygenase and anti-oxidant activities of South African medicinal plants commonly used topically for skin diseases
Date
2006-11-14T10:27:22Z
Authors
Frum, Yakov
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Abstract
ABSTRACT
Thirty plant species traditionally used to treat skin pathologies were chosen from the
readily available ethnobotanical literature. Four plants (aqueous or methanol
extracts) displayed promising 5-lipoxygenase inhibitory activity with IC50 values
below 61 ppm. These included Aloe greatheadii, Melianthus comosus, Pentanisia
prunelloides and Warburgia solutaris. Essential oils generally displayed superior 5-
lipoxygenase inhibitory activity with IC50 values between 22 and 75 ppm. These
included the essential oils of Ballota africana, Helichrysum odoratissimum,
Heteropyxis natalensis and Lippia javanica. A large proportion of the plants
exhibited dose-dependent DPPH anti-oxidant activity with IC50 values between 5 and
94 ppm for the most active. These included Halleria lucida, Croton sylvaticus,
Melianthus comosus, Lippia javanica and Pentanisia prunelloides. Aqueous extracts
of Melianthus comosus exhibited the most potent anti-inflammatory and anti-oxidant
activity.
The methanol extract of the leaves of Halleria lucida was subjected to activity guided
fractionation and two anti-oxidant molecules were isolated, namely luteolin-5-Oglucoside
and verbascoside (acteoside). Isobologram construction resulted in a
concentration-dependent additive and antagonistic interaction being recognised
between the two isolated compounds.
Warburgia salutaris displayed promising 5-lipoxygenase inhibitory activity. Two
isolated compounds, mukadiaal and warburganal were found to partially contribute to
the anti-inflammatory activity of the plant. The essential oils of Helichrysum
odoratissimum, Heteropyxis natalensis and Lippia javanica were subjected to gas
chromatography and major compounds contributing to possible anti-inflammatory
effects identified. These included β-caryophyllene, 1,8-cineole, limonene and α-
humulene. Enantiomers and racemic mixtures of limonene displayed significantly
different 5-lipoxygenase inhibitory activity suggesting stereoselectivity of the
enzyme-catalysed reaction. The monoterpene 1,8-cineole appeared to cause partial
potentiation of the anti-inflammatory activity displayed by limonene.
These results provide some in vitro scientific rationale for their traditional use as
dermatological agents.
Description
Faculty of Health Sciences
School of Pharmacology
9410866v
kermifrum@yahoo.com
Keywords
Anti-inflammatory, 5-lipoxygenase, DPPH, Medical plants, skin