Inhibitory effects of ethanolic extracts from 10 Chinese herbs on
herpes simplex virus type 1 (HSV-1) replication were investigated. By a
bioassay-guided fractionation procedure, NN-B-5 was identified from
seeds of N. nucifera. NN-B-5 significantly blocked HSV-1 multiplication
in HeLa cells without apparent cytotoxicity. To elucidate the point in
HSV-1 replication where arrest occurred, a set of key regulatory events
leading to the viral multiplication was examined, including HSV-1 DNA
synthesis and viral immediate early gene expressions. Data from
polymerase chain reaction and Southern blotting showed that there were
impairments of HSV-1 DNA replication in HeLa cells treated with NN-B-5.
Results indicated that the production and mRNA transcription of
infected cell protein (ICP) 0 and ICP4 were decreased in NN-B-5 treated
HeLa cells. Results of an electrophoretic mobility shift assay
demonstrated that NN-B-5 interrupted the formation of
alpha-trans-induction factor/C1/Oct-1/GARAT multiprotein/DNA complexes.
The mechanisms of antiviral action of NN-B-5 seem to be mediated, at
least in part, through inhibition of immediate early transcripts, such
as ICP0 and ICP4 mRNA and then blocking of all downstream viral
products accumulation and progeny HSV-1 production.

PMID: 16132118 [PubMed - indexed for MEDLINE]