title: Effect of storage on the chemical composition and biological activity of several popular South African medicinal plants.
abstract: The in vitro biological activity of nine frequently used medicinal plants in South Africa was assessed and re-assessed after various lengths of storage. The plants investigated were Alepidea amatymbica, Leonotis leonurus, Drimia robusta, Vernonia colorata, Merwilla natalensis, Eucomis autumnalis, Bowiea volubilis, Helichrysum cymosum and Siphonochilus aethiopicus. Water, ethanol and hexane extracts of fresh, 90-day-old and 1-year-old material were assayed for antibacterial activity against four strains of bacteria and for COX-1 inhibition activity. TLC-fingerprints of the fresh and stored extracts were produce to document chemical changes. Alepidea amatymbica, Eucomis autumnalis, Helichrysum cymosum, Leonotis leonurus, Siphonochilus aethiopicus and Vernonia colorata were investigated further as to the effect of 1 year's storage. Elevated temperature and humidity (55 degrees C and 100% relative humidity) were used to accelerate the ageing process of Alepidea amatymbica, Leonotis leonurus and Vernonia colorata plant material for further investigation. The TLC-fingerprints indicated that there was chemical breakdown during storage in certain species. The degree of changes in biological activity and chemistry due to storage were species-specific. In general, antibacterial activity was retained in most species while COX-1 inhibition activity was lost rapidly.
authors.affiliation: Faculty of Science and Agriculture, University of KwaZulu Natal, Pietermaritzburg, Private Bag X01, Scottsville, South Africa.
authors.forename: G I
authors.initials: GI
authors.lastname: Stafford
authors.forename: A K
authors.initials: AK
authors.lastname: Jäger
authors.forename: J
authors.initials: J
authors.lastname: van Staden
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D008519:Medicine, Traditional; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018514:Plant Structures; D010946:Plants, Medicinal / Q000737:chemistry*; D013019:South Africa; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D010936:Plant Extracts