Water and methanol extracts of 30 traditional medicinal plants, collected in Indonesia, were tested for their anti HSV-1 activity. The extracts of eight plant species showed potent activity on the plaque assay at a concentration of 100 micrograms/mL. The therapeutic efficacy of seven selected plants was demonstrated by using a mouse HSV-1 infection assay, both the methanol extracts of the fruit of Melaleuca leucadendron (Myrtaceae) and the pericarp of Nephelium lappaceum (Sapindaceae) significantly prolonged the development of skin lesions and reduced the mortality.

By screening water and MeOH extracts of 30 Chinese medicinal plants for their anti-herpes simplex virus (HSV)-1 activity, a MeOH extract of the root tubers of Stephania cepharantha HAYATA showed the most potent activity on the plaque reduction assay with an IC50 value of 18.0 microg/ml. Of 49 alkaloids isolated from the MeOH extract, 17 alkaloids were found to be active against HSV-1, including 13 bisbenzylisoquinoline, 1 protoberberine, 2 morphinane and 1 proaporphine alkaloids, while benzylisoquinoline and hasubanane alkaloids were inactive. Although N-methylcrotsparine was active against HSV-1, as well as HSV-1 thymidine kinase deficient (acyclovir resistant type, HSV-1 TK-) and HSV-2 (IC50 values of 8.3, 7.7 and 6.7 microg/ml, respectively), it was cytotoxic. FK-3000 was found to be the most active against HSV-1, HSV-1 TK- and HSV-2 (IC50 values of 7.8, 9.9 and 8.7 microg/ml) with in vitro therapeutic indices of 90, 71 and 81, respectively. FK-3000 was found to be a promising candidate as an anti-HSV agent against HSV-1, acyclovir (ACV) resistant-type HSV-1 and HSV-2.

The antiviral activity of a MeOH extract of Stephania cepharantha (root tubers), its CHCl3-soluble fraction (alkaloid fraction) and the major alkaloid FK-3000 (1) were investigated in BALB/c mice cutaneously infected with HSV-1 strain 7401H. At doses of 125 and 250 mg/kg body weight, p.o., the MeOH extract significantly delayed skin lesion on score 2 (vesicles in the local region), limited the development of further lesions on score 6 (mild zosteriform lesion) and prolonged the mean survival time of HSV-1 infected mice. After p.o. administration of the CHCl3-soluble fraction at doses of 25 and 50 mg/kg or FK-3000 (1) at 10 and 25 mg/kg, similar results were obtained. Although the alkaloid improved the survival of infected mice, it had a narrow therapeutic index.

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Water and methanol extracts of 30 traditional medicinal plants, collected in Indonesia, were tested for their anti HSV‐1 activity. The extracts of eight plant species showed potent activity on the plaque assay at a concentration of 100 µg/mL. The therapeutic efficacy of seven selected plants was demonstrated by using a mouse HSV‐1 infection assay, both the methanol extracts of the fruit of Melaleuca leucadendron (Myrtaceae) and the pericarp of Nephelium lappaceum (Sapindaceae) significantly prolonged the development of skin lesions and reduced the mortality. Copyright © 1999 John Wiley & Sons, Ltd.