Qian-Yun Sun

Trigonosins A-F, daphnane diterpenoids from Trigonostemon thyrsoideum.

Phytochemical study of the roots of Trigonostemon thyrsoideum led to the isolation of four new oxygenated daphnane-type diterpenoids, trigonosins A-D (1-4), and two new modified daphnanes, trigonosins E and F (5 and 6). The structures and relative configurations were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR experiments. All compounds isolated were evaluated for their cytotoxicity against HL-60, A549, and MCF-7 human cancer cell lines.

Pyrrolidinoindoline Alkaloids from Selaginella moellendorfii

Eight new pyrrolidinoindoline alkaloids (1-8) were isolated from the whole plant of Selaginella moellendorfii. Their structures were determined by mass spectrometry, 1D and 2D NMR spectroscopy, and chemical interconversions. These alkaloids have a 3-carboxybut-2-enyl group at C-3a and two methyl groups at N-8. The possible biogenetic route from selaginellic acid (1) to neoselaginellic acid (6) was postulated and chemically mimicked. Tautomerization between 6 and 6a was observed. Selected compounds were evaluated for antibacterial, cytotoxic, and acetylcholinesterase inhibitory activities.

Palhinine A, a Novel Alkaloid from Palhinhaea cernua

Palhinine A, a novel C(16)N-type Lycopodium alkaloid with a unique 5/6/6/9 tetracyclic ring system, was isolated from the whole plant of Palhinhaea cernua L. (Lycopodiaceae). Its structure was elucidated by spectroscopic methods, and the absolute configuration was determined by single-crystal X-ray diffraction analysis using the Flack parameter. Palhinine A is reported as the first example of Lycopodium alkaloids of which C-16 is fused to a new ring through a C-16-C-4 lingkage.

Acetylcholinesterase inhibitors from Corydalis yanhusuo

In a bioassay-guided search for acetylcholinesterase (AChE) inhibitors from Chinese natural resources, eight isoquinoline alkaloids, tetrahydropalmatine (1), corydaline (2), protopine (3), berberine (4), palmatine (5), jatrorrhizine (6), coptisine (7) and dehydrocorydaline (8), were isolated from the methanolic extract of the tubers of Corydalis yanhusuo. Structures of these compounds were identified by spectroscopic techniques. Compounds 4–8 inhibited AChE activity in a dose-dependent manner, and the IC50 values were 0.47 ± 0.01, 0.74 ± 0.06, 2.08 ± 0.09, 1.01 ± 0.03 and 0.62 ± 0.05 µM, respectively. Structure–activity relationship analysis suggested that aromatisation at ring C, as well as substitutions at C-2, C-3, C-9, C-10 and C-13 affect the AChE activity of protoberberine alkaloids.

Bioactive Isoquinoline Alkaloids from Corydalis saxicola

Twelve isoquinoline alkaloids including two new nitro-containing tetrahydroprotoberberines, (-)-2,9-dihydroxyl-3,11-dimethoxy-1,10-dinitrotetrahydroprotoberberine (1) and (+)-4-nitroisoapocavidine (2), were isolated from the whole plant of Corydalis saxicola Bunting. The structures of the new compounds were established by spectroscopic analysis and chemical evidence. The inhibitory activity of these isolates against cholinesterase and canine parvovirus were evaluated. Compounds 1 and 1A, (+)-1-nitroapocavidine (5), berberine (8), palmatine (9), dehydrocavidine (10), and sanguinarine (11) showed potent inhibitory activity against acetylcholinesterase with IC(50) values of less than 10 µM, while only compound 1 possessed weak activity against canine parvovirus. Structure-activity studies demonstrated that the nitro substituents at ring A in the tetrahydroprotoberberines led to an increase in the anti-acetylcholinesterase activity.

Sarmentosumols A to F, New Mono- and Dimeric Alkenylphenols from Piper sarmentosum

Two new mono- and four new dimeric alkenylphenols, namely sarmentosumols A to F (1-6), were isolated from the aerial parts of Piper sarmentosum. The structures of these compounds were determined through a detailed analysis of NMR and MS data. Their antimicrobial activity against Escherichia coli, Staphyloccocus aureus, and Candida albicans, and their cytotoxic activity against human myeloid leukemia (K562) and human lung adenocarcinoma (A549) cell lines were also evaluated. Except for sarmentosumol A (1), whose MIC on S. aureus was reported to be 7.0 µg/mL, none of the other newly discovered compounds exhibited antimicrobial property. The studied compounds did not possess any cytotoxic property.

Lycopodium alkaloids from Palhinhaea cernua

Two new Lycopodium alkaloids, acetyllycoposerramine M and palcernine A were isolated from whole plant extracts of Palhinhaea cernua L. together with ten previously identified compounds. The structures of the new compounds were elucidated by spectroscopic methods and single-crystal X-ray diffraction analyses using the Flack parameter.

Nudibaccatumone, a Trimer Comprising a Phenylpropanoid and Two Sesquiterpene Moieties from Piper nudibaccatum

A new complex natural product with a C39 skeleton, named nudibaccatumone, and the known sesquiterpenes (+)-spathulenol, (-)-4β,10α-aromadendranediol, and ent-T-muurolol, as well as the phenylpropanoid hydroxychavicol, were isolated from the aerial parts of Piper nudibaccatum. The structure and absolute configuration of nudibaccatumone were elucidated using spectroscopic methods and ECD calculations. A 1,8-Michael addition reaction and an intermolecular, inverse electron demand Diels-Alder reaction are proposed as the key steps in the biosynthesis of nudibaccatumone.

Chemical constituents from Saussurea deltoidea

Saussurea deltoidea (DC.) C. B. Clarke, a two-year herbage widely distributed in China, is commonly used in folk medicine in the treatment of tumours, rheumatism, diarrhea, dysentery, and inflammation [1]. In order to find the bioactive secondary metabolites from S. deltoidea, we investigated its aerial parts, which led to the isolation of 15 known compounds. All these compounds were isolated from S. deltoidea for the first time. The aerial parts of S. deltoidea were collected in Dafang (Guizhou province, China) in March 2006, and were authenticated by Prof. Qing-De Long, Guiyang Medical University, China. A voucher specimen was deposited in the School of Pharmacy, Guiyang Medical University. The aerial parts of S. deltoidea (4.2 kg) were extracted with 95% EtOH (3 × 10 L) for 2 h each at reflux. After solvent removal under vacuum, the viscous extract was partitioned with petroleum ether, EtOAc, and n-BuOH. The petroleum ether fraction and EtOAc fraction were purified by column chromatography with silica gel, RP-18, and Sephadex LH-20 to yield compounds 1–15. All compounds were identified by spectroscopic methods, including NMR and mass spectrometry. The spectroscopic data of all compounds were in good agreement with the literature data. Cytotoxic activities in vitro were tested for these compounds. Cynaropicrin (1), yellow oil, C19H22O6. EIMS m/z: 346 [M]+. 1H NMR (400 MHz, CDCl3, δ, ppm, J/Hz): 2.96 (1H, dd, J = 8.8, H-1α), 1.74 (1H, m, H-2α), 2.18 (1H, m, H-2β), 4.53 (1H, t, J = 7.2; 7.9, H-3α), 2.84 (1H, t, J = 10.0; 9.2, H-5), 4.29 (1H, t, J = 10.0; 9.6, H-6β), 3.21 (1H, m, H-7), 5.14 (1H, s, H-8), 2.40 (1H, dd, J = 3.6; 3.2, H-9), 2.69 (1H, dd, J = 5.2, H-9), 5.65 (1H, d, J = 2.8, H-13), 6.21 (1H, d, J = 3.2, H-13), 4.93 (1H, s, H-14), 5.15 (1H, s, H-14), 5.37 (1H, s, H-15), 5.47 (1H, s, H-15), 4.36 (2H, s, H-32 ), 5.99 (1H, s, H-4′), 6.34 (1H, s, H-4′) [2]. 13C NMR (100 MHz, CDCl3, δ, ppm): 44.9 (C-1), 38.6 (C-2), 73.2 (C-3), 151.9 (C-4), 50.9 (C-5), 78.5 (C-6), 47.1 (C-7), 74.0 (C-8), 36.5 (C-9), 141.6 (C-10), 137.1 (C-11), 169.3 (C-12), 122.7 (C-13), 118.0 (C-14), 113.1 (C-15), 165.2 (C-1′), 139.2 (C-2′′), 126.3 (C-3′′), 61.4 (C-4′′). Deacylcynaropicrin (2), yellow oil, C15H18O4. EIMS m/z: 262 [M]+. 1H NMR (400 MHz, CDCl3, δ, ppm, J/Hz): 2.94 (1H, m, H-1), 1.73 (2H, m, H-2), 2.18 (2H, s, H-2), 4.54 (1H, t, J = 7.6, H-3), 2.70 (1H, d, J = 5.2, H-5), 4.14 (1H, dd, J = 9.2, H-6), 2.81 (1H, m, H-7), 3.95 (1H, m, H-8), 2.30 (1H, d, J = 4.0, H-9), 2.66 (1H, d, J = 4.8, H-9), 6.23 (1H, d, J = 3.6, H-13), 6.16 (1H, d, J = 2.4, H-13), 5.11 (1H, s, H-14), 4.98 (1H, s, H-14), 5.44 (1H, s, H-15), 5.34 (1H, s, H-15) [3]. 13C NMR (100 MHz, CDCl3, δ, ppm): 45.0 (C-1), 39.0 (C-2), 71.8 (C-3), 152.3 (C-4), 51.1 (C-5), 78.9 (C-6), 50.8 (C-7), 73.5 (C-8), 41.2 (C-9), 142.6 (C-10), 138.1 (C-11), 170.1 (C-12), 123.2 (C-13), 117.0 (C-14),113.0 (C-15). 11,13β-Dihydrodesacylcynaropicrin (3), yellow oil, C15H20O4. EIMS m/z: 264 [M] +. 1H NMR (400 MHz, CDCl3, δ, ppm, J/Hz): 2.90 (1H, m, H-1), 1.73 (1H, m, H-2), 4.53 (1H, t, J = 7.2; 7.6, H-3), 2.80 (1H, t, J = 9.6, H-5), 4.05 (1H, t, J = 10.0, H-6), 2.01 (1H, dd, J = 9.6, H-7), 3.75 (1H, m, H-8), 2.24 (1H, m, H-9), 2.70 (1H, d, J = 4.8, H-9), 2.58 (1H, m, H-11), 1.39 (3H, d, J = 3.6, H-13), 4.99 (1H, s, H-14), 5.07 (1H, s, H-14), 5.35 (1H, s, H-15), 5.30 (1H, s, H-15) [2]. 13C NMR (100 MHz, CDCl3, δ, ppm): 44.9 (C-1), 38.6 (C-2), 73.2 (C-3), 152.8 (C-4), 50.3 (C-5), 79.3 (C-6), 55.9 (C-7), 74.7 (C-8), 41.8 (C-9), 143.2 (C-10), 43.8 (C-11), 179.2 (C-12), 15.8 (C-13), 116.0 (C-14), 111.6 (C-15).

A New Lathyrane Diterpenoid Ester from Euphorbia Dracunculoides

A new lathyrane diterpenoid ester, euphordracunculin C (1), together with a phenolic amide, 4-hydroxy-N-[3-(4-hydroxy-3-methoxyphenyl)-1-oxo-2-propen-1-yl]-3-methoxybenzamide (2), was isolated from the aerial parts of Euphorbia dracunculoides. The structure of the new compound was elucidated on the basis of spectroscopic analysis including 1D and 2D NMR techniques.