Abstract: Macrocalyxoformin D, an new diterpenoid having a spiro secokaurene- skeleton, was isolated from the leaves of Rabdosia macrocalyx (Dunn.) Hara from (Labiatae) collected in the south of Anhui. On the basis of chemical and spectroscopic data, the chemical structure of macrocalyxoformin D was established as (Ⅲ). Macroca- lyxoformin D was shown to have inhibitory action on Hela cells, staphylococcus aureus and bacillus hay in vitro.

Key words: Rabdosia macrocalyx (Dunn.) Hara form, New spirosecokaurene diterpenoid, Macrocalyxoformin D