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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.

Arthrinins E–G (1–3), three new sesquiterpenoids possessing non-isoprenoid botryane skeleton, were isolated from the fermentation of an endophytic fungus named Arthrinium sp. HS66 which colonized in the stems of Isodon xerophilus. Their structures were determined by extensive spectroscopic methods. Furthermore, the structure of 1 was unambiguously confirmed by X-ray diffraction, while those of 2 and 3 were verified through quantum chemical calculation of NMR data and ECD spectra.

Pestaloamides A and B ( 1 and 2 ), two novel alkaloids featuring an unprecedented spiro[imidazothiazoledione-alkylidenecyclopentenone] scaffold, were obtained from the cultures of an endophytic fungus Pestalotiopsis sp. HS30 which inhabited the stems of Isodon xerophilus . Their planar structures and absolute configurations were fully determined by extensive spectroscopic analysis and X-ray crystallography. In addition, both compounds 1 and 2 showed the latent tumor immunotherapy activity through markedly promoting the cell surface engagement of NKG2D ligands involving MICA/B and ULBP1 in HCT116 cells.

Further investigation on the leaves of Isodon xerophilus afforded three novel ent-kaurane diterpenoids, xerophilusins D-F (1-3), together with seven known compounds, phyllostachysin Lambda (4), oleanolic acid, caffeic acid, rosmarinic acid, rutin, quercetin-3-O-beta -D-glucopyranoside, and quercetin. Structures of 1-3 were elucidated on the basis of their spectral properties and X-ray crystallographic analysis. Compound 1 showed broad spectra inhibiting human tumor cells and significant cytotoxicity.

The tow novel ent-abietane diterpenoids 1 and 2, named xerophilusins R and S, respectively (= (11beta)-6,11-dihydroxy-7,20-dioxo-ent-abieta-5,8(14),15(17)-trien-16-oic acid delta-lactone and (11beta,15S)-6,11,17-trihydroxy-7,20-dioxo-ent-abieta-5,8(14)-dien-16-oic acid delta-lactone, resp.), were isolated from Isodon xerophilus (C. J. Wu et H. W. U) H. H-ARA. Their structures were established by spectroscopic means.

Three new 7,20:14,20-diepoxy-ent-kaurane diterpenoids, xerophilusins A-C (1-3), together with a known one, macrocalin B (4), were isolated from the leaves of Isodon. xerophilus. Their structures were elucidated on the basis of their spectral properties and X-ray crystallographic analysis. Compounds 1, 2, and 4 showed significant cytotoxic activity against K562, HL-60, and MKN-28 cells.

From the ethanolic extract of the leaves of Isodon xerophilus, three new ent-kaurane diterpenoids named xerophilusins L-N (1 - 3), together with three known ones designated as rabdoternin A (4), longikaurin F (5) and ponicidin (6), were isolated and structurally elucidated. Compound 6 demonstrated most potent cytotoxic activity against K562 and T24 human tumor cell lines with IC(50) = 0.09 and 0.32 microg/ml, respectively.

Four 7.20-epoxy ent-kaurane diterpenoids. xerophilusins G (1) and I-K (2-4). were isolated from the leaves of Isodon xerophilus. along with four known ones, enanderianin C (5), rosthorin A (6), longikaurin B (7), and rabdoternin D (8). Their structures were determined primarily using NMR spectroscopic techniques. The structure and stereochemistry of 3 were confirmed by X-ray crystallography. Compounds 4 and 7 exhibited broad cytotoxicity against four kinds of human tumor cells (K562, HL-60, HCT, and MKN-28 cells) in the range of 2.23-15.35 and 0.30 8.61 mug/ml, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.

Two new ent-kaurane diterpenoids, xerophilusin E (1) and xerophilusin F (2), were isolated from the leaves of Isodon xerophilus. Their structures were determined as 3, 20: 7, 20-diepoxy-ent-kaur-16-en-15-one and 7 beta, 14 beta, 20 (R)-trihydroxy-11 beta-acetoxy-7,20-cyclo-ent-kaur-16-en-6, 15-dione, respectively, by spectral methods and X-ray crystallographic analysis.