Antiherpetic activities of acidic protein bound polysacchride isolated from Ganoderma lucidum alone and in combinations with acyclovir and vidarabine

To investigate antiherpetic activity, an acidic protein bound polysaccharid e (APBP) was isolated from carpophores of Ganoderma lucidum. This brownish APBP was isolated from water soluble substances of the carpophores by activ ity-guided isolation method. APBP was tested for its antiviral activity aga inst herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) by plaque reduc tion assay in tissue culture. APBP showed potent antiviral activity against HSV-1 and HSV-2 in Vero cells at its 50% effective concentration (EC50) of 300 and 440 mu g/ml, respectively. APBP had no cytotoxicity on Vero cells at a concentration of 1x10(4) mu g/ml. APBP exhibited a potent antiviral ac tivity with selectivity index (SI) of more than 22.73. The combined antiher petic effects of APBP with nucleoside antiherpetic agents, acyclovir (ACV) and vidarabine (ara-A), were examined on the multiplication of these two st rains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. CI values were in the rang e 0.47-0.51 for a combination of APBP with ACV, and in the range of 1.02-1. 18 for a combination of APBP with ara-A. The combinations of APBP with ACV on HSV-1 and HSV-2 showed potent synergistic effects, and these results sug gest that the possibility of developing APBP as a new antiherpetic agent. ( C) 2000 Elsevier Science Ireland Ltd. All rights reserved.