Rubescensins S and T: Seco‐ent‐Kaurane Diterpenoids from Isodon rubescens var. taihangensis

Han, Quan‐Bin; Li, Rong‐Tao; Zhang, Jixia; Sun, Han‐Dong

doi:10.1002/hlca.200490102

Cited by 31 publications

(27 citation statements)

References 13 publications

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“…This new compound, however, further expands the diversities of entkaurane diterpenoids in genus Isodon. (Table 1) were closely comparable to those of rubescensin T, 5 except for the signals due to a butoxyl group at C-20 in 2 rather than a methoxyl group at the same position in rubescensin T, which was proved by HMBC correlations from H-20 (d H 5.54) to one oxygenated methylene (d C 67.6). The (20S)-configuration was assigned on the basis of a ROESY cross-peak between H-20 and H 3 -19.…”

supporting

confidence: 65%

“…Thus far, more than 500 new ent-kaurane diterpenoids have been isolated from the genus Isodon by our group, 1 including many interesting novel ent-kaurane diterpenoids such as 1:1 complexes of natural ent-kauranoids, 2 a natural equimolecular mixture of two epimeric ent-kauranoids, 3 6,7:8,15-seco-ent-kauranoids, 4 8,15-seco-ent-kauranoids, 5 15,16-seco-ent-kauranoid, 5 20-nor-ent-kauranoid, 6 symmetric and asymmetric dimeric ent-kauranoids, 7 and novel C 19 skeleton ent-kauranoid. 8 Many of these diterpenoids display various biological activities, such as antibacterial, 9 anti-inflammatory, 10 and especially antitumor actions.…”

mentioning

confidence: 99%

“…A possible biogenetic pathway of compound 2a from 3 was also proposed in Scheme 1. 5 The cytotoxic activity of compounds 1 and 2 was evaluated in A549, HT-29, and K562 cell lines. Compound 2 exhibited modest activity against the above cell lines, with IC 50 value of 4.97, 12.44, and 5.81 lM, respectively.…”

mentioning

confidence: 99%

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A new rearranged and a new seco-ent-kaurane diterpenoids from Isodon parvifolius

Li¹,

Li²,

Xiao³

et al. 2006

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confidence: 65%

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confidence: 99%

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A new rearranged and a new seco-ent-kaurane diterpenoids from Isodon parvifolius

Li¹,

Li²,

Xiao³

et al. 2006

Tetrahedron Letters

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“…The results from previous studies showed that different second metabolic components have a greater change in structure type with the elevation of producing ecological environment such as water, soil and climatic conditions. In recent years 1, more than 30 diterpenoids have been isolated from I. rubescens , which have a variety of bioactivities 9–21.…”

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confidence: 99%

Simultaneous qualitative and quantitative analysis of 28 components in Isodon rubescens by HPLC‐ESI‐MS/MS

Liu

Yuan

et al. 2010

J of Separation Science

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A novel method, HPLC-MS/MS was developed to qualitatively identify and quantitatively determine the 28 components including 19 diterpenoids, 6 phenolic acids and 3 flavonoids in Isodon rubescens, an important traditional Chinese medicine. The separation was performed on a C(18) column with linear gradient elution with 0.1% aqueous formic acid/methanol containing 0.1% formic acid at a flow rate of 0.7 mL/min. The identification and quantification of those analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple-reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Full validation of the method was carried out (linearity, precision, accuracy, LOD and LOQ). The results indicated that the method was simple, rapid, specific and reliable. The proposed method was successfully applied for the qualitative and quantitative analysis of 28 chemical compositions in 21 batches of natural and cultured I. rubescens samples from different sources which had great variation on the contents. The results demonstrated that the method was useful for standardization and differentiation of large numbers of similar samples.

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“…8,15-seco-ent-Kauranoids, such as rubescensins T 17) and U, 18) and ent-abietanoids have almost the same skeleton but are distinguished by the orientation of the substituent (e.g. -H, -OH, or -OOH) at C-8 all the time.…”

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confidence: 99%

New ent-Abietane and ent-Kaurane Diterpenoids from Isodon rubescens

Liu

Zhan

Wang

et al. 2013

CHEMICAL & PHARMACEUTICAL BULLETIN

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Five new ent-abietane diterpenoids, ent-abierubesins A-E (1-5), and two new ent-kauranoids, hubeirubesins A and B (6, 7), together with three known diterpenoids (8-10), were isolated from the aerial parts of Isodon rubescens. Their structures were identified by means of extensive spectroscopic analysis, and the absolute stereochemistry of 1 was determined by single-crystal X-ray diffraction experiment. Isodon rubescens; ent-abietane; ent-abierubesin; ent-kaurane; hubeirubesin As an important class of diterpenoids, ent-abietanoids are not so widely spread and structurally diverse as their enantiomers, abietanoids. Among ent-abietanes, 12,17-olide-type ones are in a majority and isolated from plants of Euphorbiaceae and Acanthaceae families. Key words1) However, another type of ent-abietanes without 12,17-olide moieties have been obtained from the genus Isodon of Lamiaceae family.2,3) Our previous investigations on chemical constituents of Isodon rubescens (Hemsl.) Hara yielded mainly ent-kauranoids. [4][5][6] However, five new ent-abietanoids, ent-abierubesins A-E (1-5), and two new ent-kauranoids, hubeirubesins A and B (6, 7), together with another three known diterpenoids (8-10), were isolated from this species in our present research. Although belonging to ent-abietanes, compound 5 was quite different from other ent-abietanes (1-4, 8, 9) in functional groups of A-and B-rings. In contrast, 5 exhibited the same structural characteristics (even including the configuration of C-16) as the known ent-kauranoid (10) so that 5 might be assumed as an 8,15-seco product of 10. Current paper describes the isolation, structure elucidation, and cytotoxic evaluation of selected compounds. Results and DiscussionThe aerial parts of I. rubescens (10 kg) were extracted with 90% aqueous EtOH at room temperature and then the extract was partitioned between EtOAc and H 2 O. Repeated chromatography of the EtOAc soluble portion (550 g) yielded five new (1-5) and two known (8, 9) ent-abietane diterpenoids, together with two new (6, 7) and one known (10) ent-kaurane diterpenoids (Fig. 1). By comparing the spectroscopic data with literature values, three known compounds (8-10) were identified as hebeiabinin B (8), 7) ent-abienervonin C (9), 8) and rubescensin G (10), 9) respectively. ent-Abierubesin A (1) was obtained as colorless pieces in MeOH. The molecular formula was determined by positive high resolution-electrospray ionization mass spectrometry C-NMR and distortionless enhancement by polarization transfer (DEPT) spectra of 1, signals of a ketone carbonyl, a trisubstituted olefine, nine methylenes (including three oxygenated ones), three methines, one oxygenated and two nonoxygenated quaternary carbons, and two methyl groups were present (Tables 1, 3). Compound 1 retained three degrees of unsaturation except above-mentioned olefinic and carbonyl groups, and lacked one nonoxygenated quaternary carbon relative to the classical entkaurane skeleton, suggesting 1 to be a tricyclic diterpenoid.Comparison of NMR spectra of 1 and the ...

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Rubescensins S and T: Seco‐ent‐Kaurane Diterpenoids from Isodon rubescens var. taihangensis

Cited by 31 publications

References 13 publications

A new rearranged and a new seco-ent-kaurane diterpenoids from Isodon parvifolius

A new rearranged and a new seco-ent-kaurane diterpenoids from Isodon parvifolius

Simultaneous qualitative and quantitative analysis of 28 components in Isodon rubescens by HPLC‐ESI‐MS/MS

New <i>ent</i>-Abietane and <i>ent</i>-Kaurane Diterpenoids from <i>Isodon rubescens</i>

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