Diterpenoids with diverse carbon skeletons from the roots of Pieris formosa and their analgesic and antifeedant activities.

Seven new diterpenoids, including four ent-kaurane-type pierisentkaurans B-E (1-4), one 4,5-seco- ent-kaurane-type pierisentkauran F (5), two leucothane-type 3ß,7α,14ß-trihydroxy-leucoth-10(20),15-dien-5-one (6) and 10α,16α-dihydroxy-leucoth-5-one (7), along with three known diterpenoids ent-kaurane-type 16α-dihydroxy-6-oxo-ent-kauran-18-oic-acid (8), kalmane-type rhodomollein XXIII (9), and grayanane-type pierisformosoid J (10), were isolated from the roots of Pieris formosa. Their structures with absolute configurations were determined by a series of spectroscopic methods and electronic circular dichroism (ECD) calculations. Compounds 2 and 7 displayed weak analgesic activity at a dose of 5.0 mg/kg (i.p.) compared to the vehicle tests (p < 0.05) in an acetic acid-induced writhing test. At a dose of 0.5 mg/mL, compounds 3 and 7 showed antifeedant activity against Plutella xylostella larvae with inhibition ratios of 27.1% and 52.5%, respectively.