Effects of low molecular constituents from Aloe vera gel on oxidative metabolism and cytotoxic and bactericidal activities of human neutrophils.
In traditional South-East Asian medicine the therapeutic value of the parenchymous leaf-gel of Aloe vera for inflammatory-based diseases is well-reputed. The aim of this study is to investigate at which level gel-constituents exert their activity. We show here that low -Mr constituents of an aqueous gel-extract inhibit the release of reactive oxygen species (ROS) by PMA-stimulated human PMN. The compounds inhibit the ROS-dependent extracellular effects of PMN such as lysis of red blood cells. The capacity of the PMN to phagocytose and kill micro-organisms at the intracellular level is not affected. The inhibitory activity of the low-Mr compounds is most pronounced in the PMA-induced ROS production, but is significantly antagonized by the Ca-ionophore A23187. It is shown that the inhibitory effect of the low-Mr compounds is the indirect result of the diminished availability of intracellular free Ca-ions.
't Hart
L A
LA
Department of Pharmacognosy, Faculty of Pharmacy, University of Utrecht, The Netherlands.
Nibbering
P H
PH
van den Barselaar
M T
MT
van Dijk
H
H
van den Berg
A J
AJ
Labadie
R P
RP
D000504:Aloe; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002176:Candida albicans / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D005782:Gels; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D008970:Molecular Weight; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D010101:Oxygen Consumption; D010587:Phagocytosis / Q000187:drug effects; D010936:Plant Extracts / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010946:Plants, Medicinal; D013211:Staphylococcus aureus / Q000276:immunology; D013481:Superoxides / Q000378:metabolism
D005782:Gels; D010936:Plant Extracts; D013481:Superoxides; D000001:Calcimycin; D006861:Hydrogen Peroxide; D002118:Calcium