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A new neo-clerodane diterpene, ajugacumbin G, was isolated from Ajuga decumbens THUNB. (Labiatae), and the structure was characterized as 6α-acetoxy-4α, 17-epoxy-18-(3'-hydroxy-2'-methylenebutyryloxy)-neo-cleroda-13-en-15, 16-olide by 1H-and 13C-NMR spectral study and by comparison with the known compounds of ajugacumbins A and B. Reactions to an epoxy moiety of ajugacumbin compounds with halogen acid, HX (X=Cl, Br and I) and with Jones reagent were prepared to supply some samples with different substituents at C-4 for insect antifeedant examination.

Tow novel abietane derivatives, cyrtophyllones A (1) and B (2), together with six known compounds, teuvincenone F (3), unicinatone (4), sugiol (5), friedelin (6), clerodolone (7), stigmasta-5, 22, 25-trien-3β-ol (8) and clerosterol (9), were isolated from the stem of Clerodendron cyrtophyllum. One of the abietane diterpenes, cyrtophyllone A, possesses a rearranged-abietane skeleton wich contains a 17(15-16)-abeo-abietane framework. The stereo-structure proposed for 1 was characterized as 16(S)-12, 16-epoxy-11, 14-dihydroxy-6-methoxy-17(15-16)-abeo-abieta-5, 8, 11, 13-tetraen-7-one on the basis of spectral analysis (UV, IR, MS, two dimensional (2D) NMR and CD) and X-ray diffraction. The structure of 2 was also characterized as (+)-11, 12, 16-trihydroxy-abieta-8, 11, 13-trien-7-one by a combination of spectroscopic comparison with sugiol.

A novel chlorine-containing neo-clerodane diterpene, teupernin D, and two known compounds, teucvidin and teuflin, were isolated from the whole parts of Teucrium pernyi. The structure of teupernin D was characterized as (12S)-15, 16-epoxy-8β-hydroxy-17-chloro-19-nor-10α-neo-cleroda-4, 13, 14-triene-18, 6β : 20, 12-diolide on the basis of spectral evidence. The absolute configuration was established by the circular dichroism (CD) spectrum and confirmed by X-ray crystallographic analysis.

Two novel royleanones, bungone A (1) and B (2) have been isolated from the stem of Clerodendrum bungei. The structures of these two compounds [9, 10-dihydro-3, 4, 9-trimethyl phenanthro[3, 2-b]pyran (7H)-7, 12(8H)-dione (bungone A) and 9, 10-dihydro-8-hydroxymethyl-3, 4, 9-trimethyl phenanthro[3, 2-b]pyran (2H)-7, 12-dione (bungone B)] were determined mainly on the spectral analysis.

Study on the chemical constituents of Ajuga decumbens resulted in the isolation of two new minor neo-clerodane diterpenes, ajugacumbins E and F, together with a known diterpene, ajugamarin and an iridoid, 8-acetyl-harpagide.By means of spectroscopic analysis, structures of the new diterpenes were determined to be 1α, 3α, 6α-triacetoxy-4, 7-expoxy 18α-(2'-hydroxy-3'-methylene-butyryloxy)-neo-cleroda-13-en-15, 16-olide for ajugacumbin E, and 4α, 6α-dihyeroxy-4β-hrdroxymethyl-18α-tigloyloxy-neo-cleroda-13-en-15, 16-olide for ajugacumbin F.

From the ethanol extract of whole herbs of Ajuga decumbens (Labiatae), four new neo-clerodane diterpenoids, named ajugacumbins A, B, C and D (1-4), were isolated. The configuration of 1 was determined to be 6α-acetoxy-4, 17-epoxy-18-tigloyloxy-neo-cleroda-13-en-15, 16-olide by X-ray analysis. THe other structures were also determined by spectroscopic analysis to be 4, 17-epoxy-6α-hydroxy-18-tigloyloxy-neo-cleroda-13-en-15, 16-olide (2), 1α, 3β, 6α-triacetoxy-4, 17-epoxy-18-tigloyloxy-neo-cleroda-13-en-15, 16-olide (3) and 6α-acetoxy-4, 17-epoxy-3β-hydroxy-18-tigloyloxy-neo-cleroda-13-en-15, 16-olide (4). These compounds displayed insect antifeedant activity.

The structures of two new flavones isolated from Scutellaria rehderiana, named rehderianin I and viscidulin III, were revised 2', 5, 5'-trihydroxy-7, 8-dimethoxyflavone and 3', 5, 6', 7-tetrahydroxy-2', 8-dimethoxyflavone, respectively, based on a comparison with the synthesized flavones.

Two new diterpenes, taxamairin A and B, were isolated from the bark of Taxus mairei. Their structures were determined by spectroscopic means, and finally confirmed by X-ray analysis.