A new ent-kaurane diterpenoid from Ixora amplexicaulis

A new ent-kaurane diterpenoid, 6α,16α-dihyroxy-ent-kaurane (1), was isolated from the stems of Ixora amplexicaulis, together with (24R)-6β-hydroxy-24-ethyl-cholest-4-en-3-one (2), 7β-hydroxysitosterol (3), maslinic acid (4), 3,3′-bis(3,4-dihydro-4-hydroxy-6-methoxy-2H-1-benzopyran) (5) and protocatechuric acid (6). Their structures were established by extensive spectroscopic analysis, including 2D NMR techniques. Compounds 2–5 were isolated from the genus Ixora for the first time and 6 obtained originally from I. amplexicaulis.     

Separation of abietane-type diterpenoids from Clerodendrum kaichianum Hsu by high-speed counter-current chromatography using stepwise elution

High-speed counter-current chromatography (HSCCC) was successfully used for the separation of abietane-type diterpenoids from the medicinal plant C. kaichianum, which were not separated in our previous study using preparative HPLC. The HSCCC separation employed the lower phases of n-hexane–ethyl acetate–methanol–water (HEMW) 4:5:4:5 and HEMW 4:5:5:4 as the mobile phase for stepwise elution while the upper phase of HEMW 4:5:4:5 was used as the stationary phase. HSCCC separation yielded 90.5 mg of compound 1(kaichianone A), 137.7 mg of compound 2 (kaichianone B), 125.0 mg of compound 3 (teuvincenone E), and 227.6 mg of compound 4 (taxusabietane A) with purities of 95.3%, 97.2%, 97.8%, and 98.6%, respectively, as determined by HPLC. Compounds 1–2 are two new abietane-type diterpenoids while Compounds 3–4 are known abietane-type diterpenoids, analyzed by ESIMS and NMR data. The results demonstrated that HSCCC can be an excellent alternative for other separation methods. The two new compounds showed significant cytotoxicity against ileocecal carcinoma HCT-8 and breast adenocarcinoma MCF-7 cells.     

加拿大一枝黄花二萜成分的抗肿瘤活性

通过对4株人癌细胞系，肝癌SMMC7721，红白血病K562、乳腺癌Bcap37和肺腺癌SPC-A1的体外抑制实验发现，加拿大一枝黄花花序的石油醚、乙酸乙酯浸膏具有较强的体外抑制肿瘤细胞生长的能力,二者对上述4株肿瘤细胞的半数抑制浓度（IC50）低于50μg／mL．依据初筛结果，采用MTT法进行活性成分的跟踪检测，从乙酸乙酯浸膏中分离到两个抗肿瘤活性二萜．由NMR确定它们的结构分别是6β-当归酰克拉文酸和6β-巴豆酰克拉文酸．这两个化合物对4株肿瘤细胞株的半数抑制浓度（IC50）在7～12μg／mL．由于两个化合物对人永生化上皮细胞系HaCaT的毒性较小（IC50〉50μg／mL），加拿大一枝黄花可能成为开发抗肿瘤药物的新来源，是一种具有研究价值的草药．     

Two new cassane diterpene lactams from the fruits of Caesalpinia mimosoides Lam

Two new cassane ditepenoid lactams, caesmimotam A (1) and B (2), along with eight known compounds (3–10) were isolated from the fruits of Caesalpinia mimosoides Lam. Their structures were identified by 1D and 2D NMR spectral data. Compounds 1 and 2 were evaluated for their cytotoxicity on HL-60, SMMC-7721, A-549, MCF-7 and SW-480 human cancer cell lines, but they were inactive.     

Tonalensin,a 5,10-seco-neoclerodane diterpenoid

We report the X-ray study on the structure of a newseco-neoclerodane diterpenoid, tonalensin, isolated from the aerial parts ofSalvia tonalensis. The compound crystallizes in the monoclinic space groupP2₁ witha=10.146(2),b=7.620(2),c=11.316(2) Å, =109.58(2)°. Thetrans,cis,cis-cyclodeca-1,3,5-triene ring adopts a boat-chair conformation in which the ^1,3,5-triene system is no longer coplanar. The -lactone and furan rings are essentially planar, while both five-membered rings of the dioxabicylooctane moiety arecis-fused and adopt a twist conformation.Contribution No. 1339 of Instituto de Química, UNAM.     

Napelline-type C_(20)-diterpenoid alkaloid iminiums from an aqueous extract of ‘‘fu zi': Solvent-/base-/acid-dependent transformation and equilibration between alcohol iminium and aza acetal forms

Three new napelline-type C₂₀-diterpenoid alkaloids, named aconicarmichinium A and B trifluoroacetates (1 and 2) and aconicarmichinium C chloride (3), were isolated from an aqueous extract of “fu zi”, the lateral roots of Aconitum carmichaelii. Their structures were elucidated by extensive spectroscopic data analysis. Compounds 1-3 represent the first examples of napelline-type C₂₀-diterpenoid alkaloid alcohol iminiums, of which the structures were fully characterized. In addition, transformation and equilibration between the alcohol iminiums (1-3) and the aza acetals 1a-3a were investigated by measurements of the NMR spectra in protic and aprotic deuteriumsolvents including alkali pyridine-d₅, along with evaporation under reduced pressure and gradual additions of TFA, AcOH, and HCl. The results demonstrated that the transformation and equilibration were solvent-, base-, and acid-dependent. Especially, in aqueous biological fluid, these C₂₀-diterpenoid alkaloids would more likely exist as the alcohol iminiums accompanied by anion counterparts in biosystems to increase their solubility, bioavailability, transportations, and functions. The absolute configurations of 1-3 were confirmed by X-ray crystallographic analysis of 2a.     

A New 6,7-Seco-Ent-Kaurane Diterpenoid from Isodon eriocalyx Var. laxiflora

Isodon eriocalyx var. laxiflora C. Y. Wu & H. W. Li, is a perennial herb naturally growing in the southern area of Yunnan province. In our continuing studies1 on its leaves collected from Xishuanbana prefecture, a new 6,7-seco-ent-kaurane diterpenoid, named laxiflorin E (1), together with two known 6,7-seco-ent-kaurane diterpenoids2, eriocalyxin A (2) and laxiflorin C (3), was isolated. Their structures were established by spectroscopic analysis. Compound 1, obtained as colorless rhombus…     

ARCUTININE, A NEW ALKALOID FROM Aconitum arcuatum

The structure of arcutinine isolated as a crystalline mixture with arcutine from the aerial part ofAconitum arcuatumwas established using ¹ H and ¹³ C NMR, IR, and mass spectra and comparison with arcutine. Arcutinine, like arcutine, contains a C-5-C-20 bond instead of the usual C-10-C-20 bond in the C ₂₀ - diterpenoid carbon skeleton.     

Alkaloids of Aconitum tuberosum. Structure of Tuberaconitine and Tubermesaconitine

Total alkaloids ofAconitum tuberosumroots afforded neoline and two new alkaloids, tuberaconitine and tubermesaconitine. The structures of the new alkaloids were proved based on spectral data and chemical transformations from aconitine and mesaconitine     

Terpenoid Glucosides from Aster Smithianus

A diterpenoid trisaccharide, smithoside A, and a saponin, smithoside B, as well as six known compounds, apigenin, apigenin-7-O-glucoside, daucosterol, shanzhiside methyl ester, 8-acetylshanzhiside methyl ester and acteoside, were isolated from Aster smithianus. On the basis of spectral evidence and chemical analytical results, smithosides A and B were identified as pimar-15(16)-β-ene-8β,11α-diol-3β-O-β-D-glucopyranosyl(1→3)-[β-glucopyranosyl(1→2)]-β-D-glucopyranoside and 2β,3β,16β,21β,23-pentahydroxy-12-ene-28 oleanoic acid lactone-3-O-β-D-glucopyranosyl(1→3)-β-D-glucopyranoside, respectively.