Phytochemical and chemotaxonomic study on the leaves of Rhododendron dauricum L

The phytochemical study of the leaves of Rhododendron dauricum L. (Ericaceae) led to the isolation and identification of 44 compounds, including fourteen triterpenoids (1–14), thirteen flavonoids (15–27), eight phenols (28–35), four grifolin derivatives (36–39), two diterpenoids (40–41), two megastigmanes (42–43) and one sesquiterpenoid (44). The chemical structures of these compounds were identified by spectroscopic data and compared with those previously reported. This is the first report on compounds 25, 31, 34, 40, 43, and 44 from the family Ericaceae, compound 42 from the genus Rhododendron, and compounds 24, 28, 30, 32, 33 and 35 from R. dauricum. The chemotaxonomic significance of these compounds was discussed.     

Phytochemical and chemotaxonomic study on the leaves of Rhododendron amesiae

The phytochemical study of the leaves of Rhododendron amesiae (Ericaceae) led to the isolation and identification of 19 compounds, including six diterpenoids (1–6), six triterpenoids (7–12) and seven flavonoids (13–19). The chemical structures of these compounds were identified by spectroscopic data, as well as by comparison with previously reported data in literature. This is the first systematic study on the chemical constituents of Rhododendron amesiae. All the compounds were isolated from this plant for the first time. Compounds 12, 14 and 15 were first isolated and reported from the genus Rhododendron and the family Ericaceae. Furthermore, the chemotaxonomic significance of these compounds was discussed.     

Chemical constituents from the rhizome of Menispermum dauricum DC. and their chemotaxonomic significance

The phytochemical investigations on the rhizome of Menispermum dauricum DC. led to the isolation of 18 compounds, including eleven alkaloids (1–11), four amides (12–15) and three fatty acids (16–18). All chemical structures were established on the basis of NMR (¹H NMR and ¹³C NMR) spectroscopic data. Meanwhile, compounds 5–6, 9–10 and 13–18 are reported for the first time from Menispermum genus, as well as the rhizome of Menispermum dauricum DC. Notably, this is the first study to report compounds 10, 15–18 from the family Menispermaceae. These compounds laid the foundation for the chemical classification of this species.     

Secopieristoxins A and B,two unusual diterpenoids with a new 9,10-secograyanane skeleton from the fruits of Pieris formosa

Phytochemical studies on the fruits of Pieris formosa yielded two new grayanane diterpenoids, secopieristoxins A (1) and B (2), and their structures were elucidated on the basis of extensive analysis of NMR spectra, including two-dimensional NMR techniques. Compounds 1 and 2 were new highly acylated grayanane diterpenoids, of which ring B has suffered an oxidative cleavage between C-9 and C-10.     

Chemical constituents from the leaves of Lyonia ovalifolia var. hebecarpa

A phytochemical investigation of the leaves of Lyonia ovalifolia var. hebecarpa (Franch. ex F.B. Forbes & Hemsl.) Chun (Ericaceae) led to the isolation of 22 compounds, including eight diterpenoids (1–8), two sesquiterpenoids (9 and 10), two monoterpenoids (11 and 12), two iridoids (13 and 14), four phenylpropanoids (15–18), and four lignans (19–22). Their structures were determined by spectroscopic data analysis and comparison with literature data. The absolute configuration of bisdeacetylkalmitoxin VI (1) was determined by single-crystal X-ray diffraction analysis for the first time. Notably, all the isolates 1–22 were reported from the genus of Lyonia for the first time, and compounds 9–12 and 15–22 were obtained from the Ericaceae family for the first time. The chemotaxonomic significance of compounds 1–22 was discussed.     

Chemical constituents of soft coral Sarcophyton infundibuliforme from the South China Sea

Chemical investigation on soft coral Sarcophyton infundibuliforme collected from the South China Sea led to the isolation and identification of 14 secondary metabolites, including ten cembrene diterpenoids (1–10), one α-tocopheryl quinone derivative (11), one prostaglandin (12), one lipid (13) and one carotinoid (14). Their structures were determined by extensive analysis of their spectroscopic data. All of these metabolites were isolated from this species for the first time. Diterpenoids 1, 2, 7 and 10 showed potent antifouling activity against the larval settlement of barnacle Balanus amphitrite.     

Cytotoxic and apoptosis-inducing activities against human lung cancer cell lines of cassaine diterpenoids from the bark of Erythrophleum fordii

A phytochemical investigation into the bark of Erythrophleum fordii yielded four new compounds, two new cassaine diterpenoids (erythrofordin T and U, 1 and 2) and two new cassaine diterpenoid amines (erythroformine A and B, 6 and 7), as well as nine known compounds. We report for the first time the isolation of erythrofordin V (3) from a natural source and that of the remaining eight known diterpenoids (4–5, 8–13) from E. fordii. All structures were elucidated using spectroscopic analysis. Cytotoxic activity of the isolated compounds (1–13) was examined in vitro against three non-small cell lung cancer cell lines (A549, NCI-H1975, and NCI-H1229) using the MTT assay. Cassaine diterpene amines (6–10, 12, 13) exhibited potent cytotoxic activity against all three cell lines with IC₅₀ values between 0.4 μM and 5.9 μM. Erythroformine B (7) significantly induced apoptosis in all three cancer cells in a concentration-dependent manner.     

TNF-α inhibitory diterpenoids from the Chinese mangrove plant Excoecaria agallocha L.

Chemical examination of the stems and twigs of the mangrove plant Excoecaria agallocha L. resulted in the isolation of six ent-kaurane diterpenoids named agallochaols K–P (1–6), an atisane-type diterpenoid agallochaol Q (7), along with eight known diterpenoids (8–15). Their structures were elucidated on the basis of extensive spectroscopic analysis and by comparison of their NMR spectroscopic data with those reported in literature, in association with the biogenetic relationship with the X-ray structure of 9. Compounds 1, 5–7, 9–10, and 13 showed anti-inflammatory potency to suppress expression of NF-κB and AP-1 targeted genes including TNF-α and IL-6 induced by lipopolysaccharide (LPS) in mouse macrophages Raw 264.7 cells. In addition, compounds 1, 5–7, 9–10, and 13 block NF-κB activation, while compounds 1 and 7 block AP-1 activation dramatically, indicating these compounds possess an anti-inflammatory potential in vitro.     

Abietane diterpenoids and other constituents from Clerodendrum trichotomum

The genus Clerodendrum Linn., originally belonging to Verbenaceae, was assigned to Lamiaceae by APG (Angiosperm Phylogeny Group) Ⅱ. Seven abietane diterpenoids (1–7) along with three anthraquinones (8–10) and one neolignan (11) were isolated and identified from the stems of Clerodendrum trichotomum Thunb.. Among them, compounds 4, 6 and 8–11 were reported from the genus Clerodendrum Linn. for the first time. Compounds 1, 3 and 7 were obtained from this species for the first time. Isolation of abietane diterpenoids from C. trichotomum could further comfirm that the genus Clerodendrum belongs to Lamiaceae rather than Verbenaceae.     

Flavonoids and anthraquinones from Murraya tetramera C. C. Huang (Rutaceae)

Phytochemical investigation of Murraya tetramera C. C. Huang led to the isolation of ten flavonoids (1−10) and three anthraquinones (11−13). Their structures were determined on the basis of MS, NMR, specific optical rotation, and CD spectroscopic data analysis, and by comparison of the obtained data with those reported in the literature. This is the first report for the occurrence of compounds 2, 4–7, and 11–13 in the Murraya species, and all the compounds were isolated from M. tetramera for the first time with the exception of compound 3. The chemotaxonomic significance of these compounds was also discussed.     

Unusual ent-atisane type diterpenoids with 2-oxopropyl skeleton from the roots of Euphorbia ebracteolata and their antiviral activity against human rhinovirus 3 and enterovirus 71

Two novel ent-atisane type diterpenoids possessing the extra unusal 2-oxopropyl moiety (1 and 2) and four known analogues have been isolated from the roots of Euphorbia ebracteolata. The structures and absolute configurations of these compounds were determined by extensive spectroscopic data analysis, including 2D NMR, single-crystal X-ray crystallography, ¹³C NMR calculation, and electronic circular dichroism spectra calculation. Compounds 1 and 2 are the first examples of natural products with ent-atisane type diterpenoids possessing 2-oxopropyl skeleton. Compounds 2, 3, 5, and 6 show antiviral activities against human rhinovirus 3, with IC₅₀ values of 25.27–90.35 μM. Compounds 5 and 6 showed moderate antiviral activities against EV71 at a concentration of 100 μM.     

Diterpenoids from the South China Sea soft coral Sarcophyton solidum

Chemical investigation of the South China Sea soft coral Sarcophyton solidum has led to the isolation of one new (1) and seven known (2–8) diterpenoids, including three sarsolenanes (1–3), two capnosanes (4 and 5), and three cembranes (6–8). Sarsolilide B (4) was firstly confirmed by single-crystal X-ray diffraction. Compounds 1, 3, 4, and 6–8 were isolated from S. solidum for the first time, and 1, 2, and 4–7 were considered as the chemotaxonomic markers for the species S. solidum.     

Chemical study of the seeds of Erythrophleum ivorense A. Chev. (Fabaceae)

The Chemical study of methanolic extract of the seeds from Erythrophleum ivorense led to the isolation of one original cassane diterpenoid (1) along with six known cassane diterpenoids (2–7). In addition, the known compounds (2–7) are isolated for the first time in E. ivorense. Their structures were established according to their spectral data (NMR, HRESIMS, IR). This result confirms that cassane-type diterpenoids are one of the major constituents of Erythrophleum species. The identification of these compounds and their chemotaxonomic significance is discussed.     

Chemical constituents from the roots of Cichorium glandulosum Boiss. et Huet (Asteraceae)

A phytochemical investigation of the roots extract of Cichorium glandulosum led to the isolation and characterization of fourteen compounds, including five sesquiterpene lactones (1–5), five flavonoids (6–10), and four lignans (11–14). Their structures were determined by spectroscopic data analysis and comparison with the literatures. This is the first report of the crystal data of lactucopicrin (1). This is the first time to report the isolation of 6,8,11-epi-desacetylmatricarin (2), desacetylmatricarin (3), ixerisoslde C (4), magnodelavin (5), 2ʹ,4-dihydroxy-4ʹ-methoxy-6ʹ-O-β-glucopyranoside dihydrochalcone (6), (−)-evofolin B (7), isoquercitrin (8), myricetin 7-methyl-ether-3-O-glucoside (9), (+)-medioresinol (12), 4-O-methylcedrusin [2-(3ʹ,4ʹ-dimethoxyphenyl)-3-hydroxymethyl-2,3-dihydro-7-hydroxybenzofuran-5-propan-1-ol] (13), and (2R,3S)-samwirin A (14) from C. glandulosum. Among them, compounds 5, 9, 13, and 14 were obtained from Asteraceae family for the first time. The chemotaxonomic significance of all the isolates 1–14 was discussed.     

Characteristic lindenane sesquiterpenoid dimers and labdane diterpenoids from Chloranthus serratus

Chemical investigation on the roots of Chloranthus serratus (Chloranthaceae) afforded 11 terpenoids, including four lindenane-type sesquiterpenoid dimers (1–4), and seven labdane diterpenoids (5–11). The structures of these terpenoids were established by spectroscopic analysis (MS, ¹H, and ¹³C NMR). Compounds 4–11 were isolated from C. serratus for the first time. The chemotaxonomic significance of the isolated compounds was summarized herein.     

Cytotoxic terpenoids from the stem bark of Taxus wallichiana

Chemical study of the stem bark of Taxus wallichiana Zucc. afforded the isolation of two new cyclopenta[b]naphthalene terpenoids, wallichianones A (1) and B (2) and 13 taxane diterpenoids, baccatin III (3), 10-deacetylbaccatin III (4), baccatin IV (5), 1-dehydroxybaccatin IV (6), 1-deoxybaccatin VI (7), taxol (8), 10-deacetyltaxol (9), 7-epi-10-deacetyltaxol (10), taxol-7-xyloside (11), 7-xylosyl-10-deacetyltaxol C (12), cephalomannine (13), 10-deacetylcaphalomannine (14), and 7-epi-10-deacetylcephalomannine (15). Their structures were identified by comprehensive analyses of the spectroscopic methods, including NMR and mass spectra. The absolute configurations of 1 and 2 were clarified by time-dependent density functional theory (TD-DFT) electronic circular dichroism (ECD) spectroscopic analyses. Compounds 3 and 7–15 showed cytotoxicity against all five human cancer cell lines, including lung (SK-LU-1), liver (HepG2), breast (MCF7), skin (SK-Mel-2), and prostate (LNCaP), with IC₅₀ values ranging from 1.4 ± 0.2 to 88.1 ± 5.8 μM. Compounds 9–11, 14, and 15 were additionally cytotoxic against human embryonic kidney (HEK-293A) cell line (IC₅₀ = 14.5 ± 1.0–48.4 ± 1.0 μM), however, 13 was noncytotoxic toward this cell line. The positive control, ellipticine showed cytotoxicity against all the cell lines, with IC₅₀ values in a range of 1.5 ± 0.1–2.0 ± 0.3 μM. Preliminary analysis of the structural and cytotoxicity relationship of compounds 3–15 suggested that the phenylalanine substituent at C-13 may contribute an important role for the cytotoxicity of the taxane diterpenoids.     

Diterpenoids from the aerial parts of Orthosiphon aristatus var. aristatus

Seven new isopimarane diterpenoids, orthoarisins A?G (1–7), a new secoisopimarane diterpenoid, orthoarisin H (8), a new staminane diterpenoid, orthoarisin I (9), together with 15 previously reported diterpenoids were isolated from the aerial parts of Orthosiphon aristatus var. aristatus. Their structures were established on the basis of extensive spectroscopic analysis. Compounds 13, 17, and 23 showed weak inhibitory activity on the proliferation of the SKOV3, DU145, and PC-3 cell lines.     

Diterpenoids from the roots of Euphorbia ebracteolata and their anti-tuberculosis effects

Euphorbia ebracteolata was a natural medicine for the treatment of tuberculosis. The present work has performed the investigation of bioactive chemical substances from the roots of E. ebracteolata. Using various chromatographic techniques, 15 compounds were obtained from the roots of E. ebracteolata. On the basis of widely spectroscopic data analyses, the isolated compounds were determined to be diterpenoids, including rosane derivatives (1–12), isopimarane (13), abietane (14), and lathyrane (15), among which compounds 1–4, and 9 were undescribed previously. The inhibitory effects of isolated diterpenoids against Mycobacterium tuberculosis were evaluated using an Alamar blue cell viability assay. And two rosane-type diterpenoids 3 and 8 displayed moderate inhibitory effects on with the MIC values of 18 μg/mL and 25 μg/mL, respectively. For the potential inhibitor 3, the inhibitory effect against the target enzyme GlmU was evaluated, which displayed a moderate inhibitory effect with the IC₅₀ 12.5 μg/mL. Therefore, the diterpenoids from the roots of E. ebracteolata displayed anti-tuberculosis effects, which would be pay more attentions for the anti-tuberculosis agents.     

NO inhibitory phytochemicals as potential anti-inflammatory agents from the twigs of Trigonostemon heterophyllus

Studies on the relationship of nitric oxide (NO) and inflammation have revealed that compounds with NO inhibitory effects are potentially useful for inflammation and related inflammatory disorders. A phytochemical investigation to obtain new NO inhibitors resulted in the isolation of two new cleistanthane diterpenoids (1 and 2) and 11 known terpenoids (3–13) from Trigonostemon heterophyllus. The structures of these terpenoids were established by analysis of their NMR, MS, and electronic circular dichroism (ECD) data. Compounds 1 and 2 possess rare 3,4-seco-cleistanthane diterpenoid skeletons. All of the isolates were evaluated biologically for their NO inhibitory effects in lipopolysaccharide (LPS)-induced murine microglial BV-2 cells and compounds 1, 6, and 8–10 showed strong NO inhibitory effects with IC₅₀ values less than 40 μM. Using Western blotting experiments and molecular docking, the possible mechanism of NO inhibition was investigated.     

Two new labdane diterpenoids and one new β-lactam from the aerial parts of Roylea cinerea

Two new labdane diterpenoids cinereanoid C (1), cinereanoid D (2), a new β-lactam, cinerealactam E (3) as well as six known flavonoid glycosides (4–9) were isolated from the aerial parts of Roylea cinerea (Lamiaceae). The structures of (1–9) were all determined by MS, IR and NMR spectroscopy. The structure of cinereanoid D (2) was further proven by single crystal X-ray diffraction. Six known flavonoid glycosides (4–9) were also isolated for the first time from this plant. 2, 5, 6 and 7 were found to significantly inhibit the ATP binding of a tumour growth-promoting heat shock protein, Hsp90.