In vitro 5-lipoxygenase and anti-oxidant activities of South African medicinal plants commonly used topically for skin diseases

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dc.contributor.authorFrum, Yakov
dc.date.accessioned2006-11-14T10:27:22Z
dc.date.available2006-11-14T10:27:22Z
dc.date.issued2006-11-14T10:27:22Z
dc.descriptionFaculty of Health Sciences School of Pharmacology 9410866v kermifrum@yahoo.comen
dc.description.abstractABSTRACT 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.en
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dc.identifier.urihttp://hdl.handle.net/10539/1674
dc.language.isoenen
dc.subjectAnti-inflammatoryen
dc.subject5-lipoxygenaseen
dc.subjectDPPHen
dc.subjectMedical plantsen
dc.subjectskinen
dc.titleIn vitro 5-lipoxygenase and anti-oxidant activities of South African medicinal plants commonly used topically for skin diseasesen
dc.typeThesisen
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