Diterpenes and kawalactone from the rhizomes of Amomum uliginosum J.Koenig

Seven compounds, including three labdane diterpenes (1, 4, 6), one bisnorlabdane diterpene (2), one steroid (3), one sesquiterpene (5) and one kawalactone (7) were isolated from the rhizomes of Amomum uliginosum J.Koenig. Compounds 1–4, 6 and 7 were firstly isolated from the genus Amomum. This work represented the first phytochemical study on this plant. The chemotaxonomic significance of these compounds was summarized.     

New Labdane diterpenes as intestinal α-glucosidase inhibitor from antihyperglycemic extract of Hedychium spicatum (Ham. Ex Smith) rhizomes

Phytochemical investigation of antihyperglycemic extract of rhizomes of Hedychium spicatum led to the isolation of two new labdane type diterpenes 2, 3 along with seven known compounds (1, 4–9). Their structures were established on the basis of NMR (1D and 2D) and mass spectroscopic analysis. The new compound 2 displayed strong intestinal α-glucosidase inhibitory activity. Other compounds also displayed varying degree of intestinal α-glucosidase inhibitory potential.     

Three new labdane diterpenes from Loxocalyx urticifolius

Three new labdane diterpenes, namely loxocalyxin D (1), loxocalyxin E (2) and 13-epiloxocalyxin E (3), were isolated from the whole plants of Loxocalyx urticifolius Hemsl. Their structures were elucidated by extensive spectral analysis and chemical methods. The absolute configuration of loxocalyxin D (1) was confirmed by X-ray crystallographic analysis. The cytotoxic activities of the isolated labdane diterpenes were evaluated against the four human cancer cell lines A549, HepG2, HL-60 and MCF-7. 13-epiloxocalyxin E (3) exhibited selective cytotoxicity against A549 and MCF-7 with the IC₅₀ values of 22.4 and 47.3 μM, respectively.     

Chemical constituents from the flower buds of Daphne genkwa (Thymelaeaceae)

Phytochemical investigation on the flower buds of Daphne genkwa led to the isolation of 22 compounds, including 17 daphne diterpenes (1–17), three tigliane types (18–20), and two diphenylpentanes (21–22). Compounds 19–21 were isolated from D. genkwa for the first time. These compounds were elucidated using spectroscopic methods and by comparing their data to those reported in the literature. On the basis of chemical research, the chemotaxonomic significance of the isolated compounds were discussed.     

Chemical constituents from the roots of Euphorbia nematocypha Hand.-Mazz.

A new myrsinol-type diterpene (1), three myrsinol-type diterpenes (2–4), three ent-abietane-type diterpenes (5–7), one tigliane-type diterpene (8), two cycloartane-type triterpenes (9–10), and two tirucallane-type triterpenes (11–12) were isolated from the roots of Euphorbia nematocypha Hand.-Mazz. Their structures were identified by spectroscopic analyses and by comparison of their spectral data with those reported in the literature. Compound 12 was isolated and reported from plants for the first time. All compounds were isolated from E. nematocypha for the first time.     

New tetranorlabdane diterpenoids from the fruits of Elettaria cardamomum Maton

A pair of new tetranorlabdane diterpenoid epimers, named elettarins A (1) and B (2), together with five known labdane diterpenes (3–7), were isolated from Elettaria cardamomum Maton. The structures of elettarins A and B were established based on spectroscopic data (HRESIMS, 1D/2D NMR), and ECD experimentation. All isolates were evaluated for their inhibitory activities against nitric oxide (NO) production on BV-2 microglia cells.     

Chemical constituents from Euphorbia stracheyi Boiss

The chemical investigation of whole plants Euphorbia stracheyi Boiss. led to the isolation of 14 compounds, including eight diterpenes (1–8), one monoterpene (9), three coumarins (10–12), and two phenols (13–14). Their structures were elucidated by extensive spectroscopic analyses and by comparison with the literature. Compounds 1–6, and 8–12 were firstly isolated from E. stracheyi, while compounds 6, and 9 were isolated from Euphorbia genus for the first time. The chemotaxonomic significance of these isolated compounds is discussed.     

Chemical constituents from Euphorbia hirta

Thirty-one compounds, including fourteen triterpenoids (1–14), seven coumarins (15–21), four lignans (22–25), and six diterpenes (26–31) were isolated from the aerial part of Euphorbia hirta. The structures were elucidated by spectroscopic methods and by comparison of their reported spectroscopic data. These compounds have shown the chemical relationships between this plant and other species from the genus Euphorbia.     

Novel labdane diterpenoids from the aerial parts of Leonurus japonicus

Three new labdane diterpenoids, leojapones A–C (1–3), along with a new artifactual analogue (4) and four known terpenoids, were isolated from the EtOAc extract of the aerial parts of Leonurus japonicus Houtt. Their structures were elucidated by spectroscopic analyses and physicochemical evidences. The effects of new compounds against the abnormal increase in platelet aggregation induced by adenosine diphosphate were examined. But instead of inhibiting the abnormal platelet aggregation, compounds 1–3 boosted it significantly.     

Potential anti-inflammatory diterpenoids from the roots of Caesalpinia mimosoides Lamk.

Anti-inflammatory assay-guided separation of extracts from the roots of Caesalpinia mimosoides Lamk. led to isolation of seven compounds: four diterpenes (1–4), a dimer (9), and two dibenzo[b,d]furans (10, 11) together with eleven known compounds. Their structures were elucidated by 1D- and 2D-NMR techniques as well as UV, IR, mass spectral data and comparison with literature values. The anti-inflammatory activities of all compounds were evaluated for inhibitory activities against lipopolysaccharide (LPS) induced nitric oxide (NO) production in RAW264.7 cell lines. Compounds 4, 6, 8, and 12–14 were also tested for the inhibitory effect on LPS-induced tumor necrosis factor-alpha (TNF-α) release in RAW264.7 cells. The results indicated that 4 possessed potent inhibitory activity for both tests with IC₅₀ values of 3.0 and 6.5 μM, respectively.     

Chemical constituents from the stem bark of Clausena excavata Burm. f

Phytochemical study on the stem bark of Clausena excavata Burm. f. led to the isolation and identification of 11 compounds, including four prenylated coumarins (1–4), three carbazole alkaloids (5–7), a limonoid (8), a sterol (9), a depside (10) and a xanthone (11). The chemical structures of the compounds were elucidated based on NMR and mass spectroscopic data, and further supported by comparison with previously literature values. This is the first report on the isolation of compounds 10 and 11 from the genus Clausena. The chemotaxonomic significance of the isolated compounds is discussed.     

Chemical constituents of Euphorbia peplus

Phytochemical investigation of the whole plant of Euphorbia peplus Linn. led to the isolation of previously uncharacterized jatrophane type diterpenoid euphopepluanone L (1), along with seven known compounds, including three diterpenes (2–4), three bisnorsesquiterpenes (5–7), and a monoterpene (8). Their chemical structures were established based on extensive spectroscopic analysis. Compounds 3 (20-deoxyingenol) and 5–8 were firstly isolated from E. peplus, while PBI 345 (5) reported from the genus for the first time. Furthermore, the chemotaxonomic significance of the isolates 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.     

Chemical constituents from Schefflera leucantha R.Vig. (Araliaceae)

Processive phytochemistry and pharmacological investigation of Schefflera leucantha R.Vig. (Araliaceae) led to the isolation of fifteen known compounds: a nucleobase (1), six small aromatic molecules (2–7), three phenylpropanoids (8–10), four lignans (11–14) and a fatty acid derivative (15). Spectroscopic methods were used to establish the structure and configuration of isolates, followed by their unambiguous confirmation with literature data. We report for the first time (to the best of our knowledge), the isolation of β-amino-3-methoxy-4-hydroxybenzene-ethanol (4) from a natural source. Furthermore, compounds 1, 5, 9–15 are being reported from Araliaceae family for the first time, whereas compounds 2, 3, 6–8 from the genus Schefflera for the first time. The biological screening results show that compounds 9 and 10 induce a moderate inhibitory effect on aldose reductase, while compounds 3, 5, and 8 display significantly high neuroprotective activities.     

Isopimarane diterpenes and flavan derivatives from the twigs of Caesalpinia furfuracea

The first phytochemical investigation of Caesalpinia furfuracea twigs led to the isolation and identification of four new compounds including two isopimarane diterpenes, caesalfurfuric acids A (1) and B (2), and two flavans, (2R)-caesalflavans A (5) and B (6), together with four known compounds, 4-epi-isopimaric acid (3), methyl (E)-3-(3,4-dihydroxyphenyl)acrylate (4), (E)-resveratrol (7) and oxyresveratrol (8). Their structures were elucidated by intensive spectroscopic analysis. Compound 1 was found to exhibit antibacterial activity against MRSA SK1 with an MIC value of 16 μg/mL.     

Chemotaxonomic implications of the absence of sesquiterpene lactones in Grazielia multifida (DC.) R.M.King & H.Rob. (Asteraceae)

The phytochemical investigation of Grazielia multifida aerial parts yielded eight compounds, including four ent-kaurenic acid diterpenes derivatives, 15-tiglinoyloxy-ent-kaur-16-en-19-oic acid (1), 15-hydroxy-ent-kaur-16-en-19-oic acid (2), 17-hydroxy-ent-kaur-15-en-19-oic acid (3) and 15-isovaleroyloxy-ent-kaur-16-en-19-oic acid (4), one amino acid, tryptophan (5), and three flavonoids, eupafolin (6), guaijaverin (7) and quercitrin (8). The structures of the isolated compounds were established based on analysis of their spectroscopic data and comparison with literature. All the compounds were isolated from this species for the first time. The chemotaxonomic significance of the absence of sesquiterpene lactones in G. multifida has also been summarized.     

Chemical constituents from leaves of Lagerstroemia speciosa L.

This work describes the isolation and characterization of fourteen compounds from Lagerstroemia speciosa (L.) Pers, including four triterpenes (1–4), eight ellagic acids (5–12), one coumarin (13) and one neolignan (14). Their structures were elucidated on the basis of various spectroscopic methods (UV, IV and NMR, including 2D experiments). It was the first report of compounds 14 from the genus Lagerstroemia and the first report of compounds 9–12 from the family Lythraceae.     

Phytane and neoclerodane diterpenes from the aerial parts of Inula nervosa Wall.

Three new aliphatic diterpenes (1–3), together with three known neoclerodane-type diterpenes (4–6) were isolated from the aerial parts of Inula nervosa Wall. The structures of 1-3 were elucidated on the basis of 1D and 2D spectroscopic analysis. Additionally, phytane-type and neoclerodane-type diterpenes have not been reported in any species of the genus Inula yet. The phytane-type and neoclerodane-type diterpenes obtained from I. nervosa Wall. suggest this plant maybe have remote genetic relations with other Inula species.     

Chemical constituents from Psychotria arborea Hiern (Rubiaceae)

The chemical study of the stems extract of Psychotria arborea Hiern led to the isolation of thirteen compounds, including four anthraquinones: 2-methylanthracene-9,10-dione (1), 2-methoxyanthracene-9,10-dione (2), 2-hydroxy-3-methylanthracene-9,10-dione (3) and 3-hydroxy-1-methoxy-2-methylanthracene-9,10-dione (4); two diterpenes: ent-kaur-16-en-19-oic acid (5) and 15-acetoxy-ent-kaur-16-en-19-oic acid (6); two triterpenes, β-amyrin (8) and oleanolic acid (9), one flavonoid: Quercetin (7), three sterols: A mixture of stigmasterol (10) and β-sitosterol (11) and β-sitosterol-3-O-β-D-glucopyranoside (12) and one fatty acid (13). The structures of these compounds were elucidated based on NMR and HR-ESIMS analysis, further supported by comparison with previously reported spectral data. Compounds 1–4 and compounds 10–12 were tested for their antibacterial activity against three bacteria strains Escherichia coli, Staphylococcus aureus and Salmonella enterica. All these tested compounds were found to be inactive. Furthermore, the chemotaxonomic significance of the obtained compounds was discussed in detail.     

Chemical constituents from Pteris ensiformis Burm. (Pteridaceae)

Phytochemical study of Pteris ensiformis Burm. resulted in the isolation of eleven compounds, including three sesquiterpenoids (1–3), one alkaloid (5), one amino acid (6), one flavonoid (7), four phenolic acids (4, 8, 9 and 10), and one coumarin (11). Structures of these compounds were deduced from the ESI-MS and NMR data. This is the first report on the isolation of compounds 1, 2, 7 and 11 from P. ensiformis, compounds 6 and 9 from the genus Pteris, and compound 5 from the family Pteridaceae. In addition, a detailed discussion of the chemotaxonomic significance of these compounds was presented.