ent-Kaurane-Based Diterpenoids, Dimers, and Meroditerpenoids from Isodon xerophilus

Abstract

Eight new diterpenoids (1–8) with varied structures were isolated from the aerial parts of Isodon xerophilus. Among them, xerophilsin A (1) was found to be an unusual meroditerpenoid representing a hybrid of an ent-kauranoid and a long-chain aliphatic ester, xerophilsins B–D (2–4) are dimeric ent-kauranoids, while xerophilsins E–H (5–8) are new ent-kauranoids. The structures of 1–8 were elucidated mainly through the analyses of their spectroscopic data. The absolute configurations of 2, 6, and 8 were confirmed by single-crystal X-ray diffraction, and the configuration of C-16 in 7 was established through quantum chemical calculation of NMR chemical shifts, as well as modeling of key interproton distances. Bioactivity evaluation of all isolated compounds revealed that 2, 3, and 5 inhibited NO production in LPS-stimulated RAW264.7 cells.

Highly Oxygenated Dimeric Grayanane Diterpenoids as Analgesics: TRPV1 and TRPA1 Dual Antagonists from Rhododendron molle

“…Diterpenoid dimers are composed of two homo‐ or hetero‐ monomeric diterpenoids linked through ether bonds, ester bonds, C—C carbon bonds, or ring moieties. [ 1 ] Dimeric diterpenoids are relatively rare in nature and were mainly reported from higher plants of Acanthaceae, [ 2 ] Annonaceae, [ 3 ] Asteraceae, [ 4 ] Calceolariaceae, [ 5 ] Chrysobalanaceae, [ 6 ] Cupressaceae, [ 7 ] Ebenaceae, [ 8 ] Ericaceae, [ 9 ] Euphorbiaceae, [ 10 ] Fabaceae, [ 11 ] Icacinaceae, [ 12 ] Lamiaceae, [ 13 ] Liliaceae, [ 14 ] Meliaceae, [ 15 ] Rhizophoraceae, [ 16 ] Sapindaceae, [ 17 ] Scapaniaceae, [ 18 ] Selaginellaceae, [ 19 ] Taxaceae, [ 20 ] Velloziaceae, [ 21 ] and Zingiberaceae. [ 22 ] Some of them exhibited significant anti‐inflammatory, [ 10 ] cytotoxic, [ 7 ] antiviral, [ 17 ] antimalarial, [ 15 ] and antibacterial activities.…”

New ent-kaurane diterpenoid acids from Nouelia insignis Franch and their anti-inflammatory activity

“…The remaining four ones exhibited the existence of a tetracyclic system in 1 . 7 Consequently, the four-ring was inferred to be a 6/6/6/5 fused rings A, B, C and D, a characteristic ent -kaurane diterpenoid skeleton, 8–10 based on the 2D NMR experiments (Fig. 2): the 1 H– 1 H COSY correlations of H 2 -1/H 2 -2/H 2 -3, H-5/H 2 -6/H 2 -7 and H-9/H-11/H-12/H-13/H 2 -14; the HMBC correlations from H 3 -19 to C-3, C-4, C-5 and C-18; from H 3 -20 to C-1, C-5, C-9 and C-10; from H 2 -7 to C-6 and C-8; from H-9 to C-5, C-8, C-10, C-11 and C-12; from H 2 -14 to C-8, C-9, C-13, C-15 and C-16; and from H 3 -17 to C-13, C-15 and C-16.…”

“…The remaining four ones exhibited the existence of a tetracyclic system in 1. 7 Consequently, the four-ring was inferred to be a 6/6/6/5 fused rings A, B, C and D, a characteristic ent-kaurane diterpenoid skeleton, [8][9][10] based on the 2D NMR experiments (Fig. 2): the 1 The relative conguration of 1 was determined through the NOESY spectrum (Fig.…”

“…Consequently, only a few biological activity studies were reported. In this manuscript, our phytochemical investigation of the MeOH extract of Nouelia insignis Franch led to the isolation and the identication of 27 ent-kaurane diterpenoid acids, including eleven new ones (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11), together with sixteen related known analogs (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Herein, the details of the The dried and crushed branch of Nouelia insignis Franch (20.0 kg) were ultrasonically extracted with 95% methanol overnight at room temperature (20 L Â 3).…”

Rubesanolides F and G: Two Novel Lactone-Type Norditerpenoids from Isodon rubescens

“…The genus has attracted considerable attention as a prolific source of diterpenoids with diverse structures and biological properties [2]. More than 50 Isodon species have been phytochemically investigated, leading to isolation of a large number of different types of diterpenoids, including kauranes, abietanes, labdanes, pimaranes, isopimaranes, gibberellanes, clerodanes and atisanes [3][4][5]. However, the lactone-type norditerpenoids, formed by losing the isopropyl group in C-ring of an abietane skeleton, has not been reported previously.…”