Mollanol A, a Diterpenoid with a New C-Nor-D-homograyanane Skeleton from the Fruits of Rhododendron molle

Abstract

Two new grayanoids, mollanol A (1) and rhodomollein XXV (2), were isolated from the fruits of Rhododendron molle. Their structures were elucidated by spectroscopic methods and X-ray diffraction analyses. Mollanol A (1) possesses a new C-nor-D-homograyanane carbon skeleton, while rhodomollein XXV (2) is the first example of an 11,16-epoxygrayanane and features a caged oxa-tricyclo[3.3.1.0(3.7)]nonane ring system. Plausible biogenetic pathways for 1 were proposed. Compound 1 exhibited transcriptional activation effects on the xbp1 upstream promoter in IEC-6, 293T, and RAW264.7 cells.

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).…”

“…Grayanoids, a special type of diterpenoid, exist exclusively in the Ericaceae family with diverse structures and wide bioactivities. 1 To date, almost two hundred grayanoids with eleven carbon skeletons, including grayanane, 2,3 1,5-secograyanane, 4 3,4secograyanane, 5 9,10-secograyanane, 6 1,10:2,3-disecograyanane, 7 kalmane, 8 1,5-secokalmane, 9 leucothane, 10 micranthane, 11 mollane, 12 and rhodomollane, 13 have been reported. Notably, 3,4-secograyanane is a rare type of grayanoid, and only seventeen 3,4-secograyanoids have been isolated and characterized.…”

“…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).…”

Rhodomollins A and B, two Diterpenoids with an Unprecedented Backbone from the Fruits of Rhododendron molle

“…In particular, grayanoids with a wide spectrum of biological activities, such as sodium-channel-modulating2, analgesic3, sedative4, and insect antifeedant activities5, have been isolated from plants of the Rhododendron genus in recent years. Ten types of grayanane-related carbon skeletons have been reported, including grayanane (A- nor -B- homo ent -kaurane)6, 1,5-secograyanane7, 3,4-secograyanane8, 9,10-secograyanane9, 1,10:2,3-disecograyanane10, leucothane (A- homo -B- nor grayanane)11, kalmane (B- homo -C- nor grayanane)12, 1,5-seco kalmane13, micranthane (C- homo grayanane)14, and mollane (C- nor -D- homo grayanane)15. We previously reported mollolide A, a grayanoid with a new 1,10:2,3-disecograyanane skeleton10, and mollanol A, the first example with a C- nor -D- homo grayanane carbon skeleton15, from Rhododendron molle G. Don, a plant that is used in traditional Chinese medicine as an anodyne and anesthetic16.…”

“…Ten types of grayanane-related carbon skeletons have been reported, including grayanane (A- nor -B- homo ent -kaurane)6, 1,5-secograyanane7, 3,4-secograyanane8, 9,10-secograyanane9, 1,10:2,3-disecograyanane10, leucothane (A- homo -B- nor grayanane)11, kalmane (B- homo -C- nor grayanane)12, 1,5-seco kalmane13, micranthane (C- homo grayanane)14, and mollane (C- nor -D- homo grayanane)15. We previously reported mollolide A, a grayanoid with a new 1,10:2,3-disecograyanane skeleton10, and mollanol A, the first example with a C- nor -D- homo grayanane carbon skeleton15, from Rhododendron molle G. Don, a plant that is used in traditional Chinese medicine as an anodyne and anesthetic16. In our continuing efforts to identify structurally interesting and biologically important grayanoids, two new grayanoids, rhodomollin A ( 1 ) and rhodomollin B ( 2 ), possessing an unprecedented D- homo grayanane (featured a 5/7/6/6-fused ring system) carbon skeleton, were isolated from the fruits of R. molle .…”