Cytotoxic and antiherpetic activity of phloroglucinol derivatives from Mallotus japonicus (Euphorbiaceae).

The phloroglucinol derivatives isolated from Mallotus japonicus Muell. Arg. (Euphorbiaceae) and their derivatives were evaluated for their capacity to produce cytotoxicity in HeLa cells and to inhibit the replication of herpes simplex virus type 1 (HSV-1). The characterizations of an isolated new acetophenone, mallophenone (16), and cyclization products of mallotojaponin (1), isomallotochromene (17), mallotochroman (18) and isomallotochroman (19), were also described. All tested derivatives inhibited the replication of HSV-1 with ED50 in the range of 88 ng--48 micrograms/ml. The derivatives 12 and 19 were found in vitro therapeutic index with 10.9 and 9.1, respectively, and they were considered to be active antivirals.