beta-Glucosidase activity in fetal bovine serum renders the plant glucoside, hypoxoside, cytotoxic toward B16-F10-BL-6 mouse melanoma cells.
By using p-nitrophenyl-beta-D-glucopyranoside as substrate, beta-glucosidase activity was observed in fetal bovine serum (FBS). This activity could be inhibited by heat inactivation of the serum. Gel chromatography of FBS indicated the presence of beta-glucosidase activity with an apparent molecular mass of 29 kDa. In McCoy's 5A medium supplemented with non-heat inactivated FBS, the diglucoside hypoxoside ([E]-1,5-bis[4'beta-D-glucopyranosyloxy-3'-hydroxyphenyl]pent-4-en - 1-yne) showed cytotoxicity toward B16-F10-BL-6 mouse melanoma cells. In incubations where the media were supplemented with FBS previously heat inactivated at 56 degrees C for 1 h or more, no cytotoxicity was observed in the presence of hypoxoside. The aglucone of hypoxoside, rooperol ([E]-1,5-bis[3',4'-dihydroxyphenyl]pent-4-en-1-yne), showed cytotoxicity regardless of whether the serum was heat inactivated or not. The kinetics of the heat inactivation of the beta-glucosidase activity in FBS coincided with the loss of apparent cytotoxicity of hypoxoside. High performance liquid chromatography analysis showed that rooperol could be generated by incubation of hypoxoside in non-heat inactivated FBS, but that this ability was lost in serum that was heat inactivated for 1 h or longer. Newborn bovine serum did not contain any beta-glucosidase activity whereas it was found in three different commercial sources of FBS. This observation is of practical importance because conventional heat inactivation of FBS at 56 degrees C for 30 min was not sufficient to inactivate the beta-glucosidase activity completely.
Department of Pharmacology, Faculty of Medicine, University of Stellenbosch, Tygerberg, South Africa.
E J
EJ
Theron
C F
CF
Albrecht
P B
PB
Kruger
K
K
Jenkins
M J
MJ
van der Merwe
D000480:Alkynes / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D016923:Cell Death / Q000187:drug effects*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D005312:Fetal Blood / Q000201:enzymology*; D005960:Glucosides / Q000378:metabolism / Q000494:pharmacology*; D006358:Hot Temperature; D007700:Kinetics; D008546:Melanoma, Experimental / Q000473:pathology*; D051379:Mice; D008970:Molecular Weight; D014407:Tumor Cells, Cultured; D001617:beta-Glucosidase / Q000097:blood*
D000480:Alkynes; D003470:Culture Media; D005960:Glucosides; C087941:hypoxoside; D001617:beta-Glucosidase