Abstract: A pharmacologically active substance obtained from the metabolites of β-caryophyllene was characterized as caryophyllone(8) on the basis of spectral analyses and chemical evidence. Consideration of the structures of the metabolites and the structure-activity theory led to the successful structural modification of β-caryophyllene to give an active hemisynthetic product(3).Pharmacological experiments showed that compounds(8) and (3) have a potent relaxation effect on isolated trachea of guinea pigs and compound(3) has a potent and long-acting inhibitory effect on guinea pig asthma induced by histamine and acetylcholine. Its LD₅₀ was found to be higher than 10.8 g/kg. Compound(3) holdes promise as a new anti-asthmatie drug.