Pierisformotoxins A – D, Polyesterified Grayanane Diterpenoids from Pieris formosa and Their cAMP‐Decreasing Activities

Abstract

Four highly acylated diterpenoids, designated as pierisformotoxins A-D (1-4, resp.), along with 26 known compounds, were isolated from the flowers of Pieris formosa. Among them, pierisformotoxins A and B (1 and 2, resp.) were new highly acylated grayanane diterpenoids, of which the five-membered ring A has undergone an oxidative cleavage between C(3) and C(4), followed by lactonization, to give rise to a five-membered lactone ring between C(3) and C(5), differing from the previously reported grayanane diterpenoids with a 5/7/6/5 ring system. Results of the cAMP-regulation-activity assay showed that pierisformotoxin C (3) at 10 μM (inhibitory ratio (IR): 10.1%) or 2 μM (9.8%), and pierisformotoxin B (2) at 50 μM (13.9%) significantly decreased the cAMP level in N1E-115 neuroblastoma cells (p<0.05).

New Antifeedant Grayanane Diterpenoids from the Flowers of Pieris formosa

“…Ten known diterpenoids ( Figure 2 ), namely, pierisformotoxin C ( 4 ) [ 24 ], secorhodomollolides C ( 5 ), D ( 6 ), and F ( 7 ) [ 28 ], asebotoxins I ( 8 ), II ( 12 ), IV ( 10 ), and VIII ( 11 ) [ 26 , 29 ], pieristoxin I ( 9 ) [ 29 ], and pierisformosin ( 13 ) [ 30 ] were also isolated from P. formosa and were identified by comparison of their spectroscopic data with those reported in the literature.…”

“…The juice of both its fresh leaves and flowers are used as an insecticide and lotion for the treatment of ring worm and scabies, in folk medicine [ 19 , 20 , 21 ]. More than 60 grayanane diterpenoids with grayanane, 1,5-secograyanane, 3,4- seco -grayanane, 9,10- seco -grayanane, leucothane, 4,5- seco - ent -kauran, and pierisketane carbon skeletons have been isolated from the leaves, flowers, fruits, stems and roots of P. formosa [ 3 , 17 , 22 , 23 , 24 , 25 ]. In our previous work, two new highly esterified 3,4- seco -grayanane diterpenoids, pierisoids A and B, were reported from the flowers of P. formosa [ 20 ].…”

Biological and chemical guided isolation of 3,4-secograyanane diterpenoids from the roots of Pieris formosa

“…S4-S6 †), characteristic of the highly hydroxylated grayanane diterpenoids. Finally, seventeen new 3,4-secograyanoids (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), together with seven known 3,4secograyanoids (18)(19)(20)(21)(22)(23)(24), were isolated from the fractions D1a, D2a, D2b, E1a, E1b, and E2a by a combination of different chromatographic methods. Acetic acid-induced writhing test showed that compounds 1, 2, 4-8, 10-13, and 16-24 exhibited signicant analgesic activity at 5.0 mg kg À1 (ip).…”

“…The seven known diterpenoids, namely, secorhodomollolide C (18), 5 pierisoid B (19), 17 secorhodomollolide B (20), 5 secorhodomollolide A (21), 5 pierisformotoxin G (22), 18 pierisformotoxin B (23), 19 and pierisformotoxin A (24), 19 were identied by the comparison of the experimental and previously reported spectroscopic data.…”

“…14 In previous phytochemical investigations of P. formosa, een grayananes and three diterpenes with an unusual carbon skeleton were isolated and characterized, and most compounds were found to exhibited an analgesic effect. 15,16 In our on-going efforts, biological and chemical guided fractionation led to the isolation of seventeen new 3,4-secograyananes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), together with seven known 3,4-secograyanoids (18)(19)(20)(21)(22)(23)(24)) (see Fig. 1).…”