Three new diterpenoid alkaloids from the roots of Aconitum duclouxii

Three new C₁₉-diterpenoid alkaloids, ducloudines C (1), D (2), and E (3), were isolated from the roots of Aconitum duclouxii. Their structures were established on the basis of extensive spectroscopic analyses. Ducloudine C (1) is the first aconitine-type C₁₉-diterpenoid alkaloid with a C = O group at C-3 and a C = C bond between C-1 and C-2. All compounds were tested for their biological activities against one pathogenic fungi and two pathogenic bacteria.     

Four new C19-diterpenoid alkaloids from Aconitum hemsleyanum var. circinatum

Four new C19-diterpenoid alkaloids, hemaconitines A–D (1–4), were isolated from the roots of Aconitum hemsleyanum var. circinatum. Their structures were elucidated as 19R-hydroxyl-secoyunnaconitine (1), (3R)-hydroxyl-liwaconitine (2), 14-anisoyl-leucanthumsine E (3), and 19R -acetonyl-8-O-methyltalatisamine (4) by extensive spectroscopic analysis (IR, UV, HR-ESI-MS, 1D, and 2D NMR).     

Four new taraxastane-type triterpenoic acids from Cirsium setosum

Four new taraxastane-type triterpenoids acids 3β,22α-dihydroxy-20-taraxasten-30-oic acid (1), 3β-hydroxy-22-oxo-20-taraxasten-30-oic acid (2), 3-oxo-22α-hydroxy-20- taraxasten-30-oic acid (3), and 3β,19β-dihydroxy-20-taraxasten-30-oic acid (4) were isolated and characterized from Cirsium setosum (Willd.) MB. Their structures were determined by the combination of 1D and 2D NMR experiments (¹H-¹HCOSY, HSQC, HMBC and ROESY) and mass spectrometry. Compound 2 exhibited potent selective cytotoxicity against human ovarian cancer cell line A2780 with an IC₅₀ value of 3.9 μM.     

A new <Emphasis Type="Italic">ent</Emphasis>-kaurane type diterpenoid glycoside from <Emphasis Type="Italic">Inula japonica</Emphasis> Thunb.

A new ent-kaurane type diterpenoid glycoside, 17-O-β-D-glucopyranosyl-16α-ent-kauran-19-oic acid (1), together with 17-hydroxy-16α-ent-kauran-19-oic acid (2), 16α,17-dihydroxyl-ent-kauran-19-oic acid (3), and 16α-hydroxy-17-acetoxy-ent-kauran-19-oic acid (4) were isolated from the aerial parts of Inula japonica Thunb. The structure of 1 was determined mainly by use of 1D and 2D NMR spectroscopic techniques including HSQC, ¹H-¹H COSY, HMBC, and NOESY. In addition, 4 exhibited significant inhibitory activity on NO production in LPS-stimulated RAW264.7 cells with IC₅₀ value of 14.3 μg/mL.     

Two new C19-diterpenoid alkaloids from Aconitum straminiflorum

Two new C₁₉-diterpenoid alkaloids, straconitines A (1) and B (2), were isolated from the roots of Aconitum straminiflorum. Their structures were elucidated as 14-benzoylducloudine D (1) and 6-hydroxy-14-benzoylducloudine D (2) based on spectroscopic analysis, including IR, ESI-MS, HR-ESI-MS, 1D, and 2D NMR.     

Two new C19-diterpenoid alkaloids from Aconitum tsaii

Two new C₁₉-diterpenoid alkaloids, 14-benzoylliljestrandisine (1) and 14-anisoylliljestrandisine (2), were isolated from the roots of Aconitum tsaii. Their structures were elucidated by different spectroscopic (IR, UV, 1D and 2D NMR) and mass-spectrometric techniques.     

Prenylated C6–C3 compounds from the fruits of Illicium simonsii

Two new prenylated C₆–C₃ compounds, 4-epi-illicinone E-12-shikimate (1) and 3-hydroxyillifunone B (2), together with five known prenylated C₆–C₃ compounds (3–7), were isolated from the fruits of Illicium simonsii. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D and 2D NMR, CD spectra, and ESI-MS analysis.     

Diterpenoids from the freshwater green algae Rhizoclonium hieroglyphicum with antibacterial activity

Three new isopimarane diterpenes 7β-hydroxy-19α-methylmalonyloxy-isopimara-8(14),15-diene (1), 7β-hydroxy-14-oxo-isopimara-8(9),15-dien-19oic acid (2), and 7β-hydroxy-14-oxo-19α-methylmalonyloxy-isopimara-9(11),15-diene (3) in addition to the known compounds isopimaric acid (4), 7oxo-13-epi-pimara-14,15-dien-18oic acid (5), 7oxo-13-epi-pimara-8,15-dien-18oic acid (6), and 6β-hydroxyisopimaric acid (7) were isolated from the hexane extract of Rhizoclonium hieroglyphicum. The structures of compounds 1–7 were established by 1D and 2D NMR techniques. The isolated diterpenoids were screened for antimicrobial activity against gram-positive and gram-negative bacteria and yeast strains.     

Chemical constituents of the red alga Laurencia tristicha

Six new sesquiterpenes, 10-hydroxy-epiaplysin (1), 10-hydroxy-aplysin (2), 10-hydroxy-debromoepiaplysin (3), aplysin-9-ene (4), epiaplysinol (5) and debromoepiaplysinol (6), together with 13 known compounds (7–19), have been isolated from the red alga Laurencia tristicha. The structures of 1–6 were determined by spectroscopic methods including IR, EI-MS, HREI-MS, and 1D and 2D NMR techniques. All compounds were obtained from this species for the first time and were tested for cytotoxic activities against several human cancer cell lines including lung adenocarcinoma (A549), stomach cancer (BGC-823), hepatoma (Bel 7402), colon cancer (HCT-8) and HeLa cell lines. Compound 6 showed selective cytotoxicity against HeLa cell line with IC₅₀ 15.5 μM, cholest-5-en-3β,7α-diol (14) was toxic to all tested cell lines with IC₅₀ values of 16.8, 5.1, 0.5, 0.5, and 0.3 μM, respectively, and other compounds were inactive (IC₅₀>10 μg/ml).     

Cytotoxic gelsedine-type indole alkaloids from Gelsemium elegans

The ethanol extract of the leaves and branches of Gelsemium elegans afforded three new gelsedine-type indole alkaloids, 11-methoxy-14,15-dihydroxyhumantenmine (1), 11-methoxy-14,15-dihydroxy-19-oxogelsenicine (2), and 11-methoxy-14-hydroxygelsedilam (3), along with one known alkaloid 11-methoxy-14-hydroxyhumantenmine (4). The structures of isolated compounds were established based on 1D and 2D (¹H-¹H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high-resolution mass spectrometry. The isolated alkaloids were tested in vitro for cytotoxic potential against four laryngeal tumor cell lines including Hep-2, LSC-1, TR-LCC-1, and FD-LSC-1. As a result, compounds 1 and 4 exhibited some cytotoxic activities against all tested tumor cell lines with IC₅₀ values of 10.9–12.1 μM and 9.2–10.8 μM, respectively.     

A new triterpenoid from <Emphasis Type="Italic">Panax ginseng</Emphasis> exhibits cytotoxicity through p53 and the caspase signaling pathway in the HepG2 cell line

A new triterpenoid, 20(R),22(ξ),24(S)-dammar-25(26)-ene-3β,6α,12β,20,22,24-hexanol (1), and three known triterpenoids, β-D-glucopyranoside,(3β,12β)-12,20-dihydroxydammar-24-en-3-yl,6-acetate (2), 20(R)-ginsenoside Rg₃ (3), and 20(R)-ginsenoside Rh₂ (4), were isolated from the leaves of Panax ginseng. Their structures were determined by chemical analysis and spectral methods (IR, 1D and 2D NMR, HR-ESI-MS). Compounds 1–4 were exhibited various degrees of cytotoxicity in the human hepatoma cell line, HepG2. Compound 1 had the highest cytotoxic potency, with an IC₅₀ value of 20.1 μM, by stimulating p53-mediated cell cycle arrest at the G1 to S phase transition, leading to apoptosis via activation of the caspase signaling pathway.     

Three new guaiane sesquiterpene lactones from rhizomes of Curcuma wenyujin

Three new guaiane sesquiterpene lactones (4S)-4-hydroxy-gweicurculactone (1), zedoalactone G (2), and (1R, 4R, 5S, 10S)-zedoalactone B (3), and three known guaiane sesquiterpene lactones, including zedoarolide B (4), zedoalactone B (5), and a new natural product (+)-zedoalactone A (6), were isolated from the rhizomes of Curcuma wenyujin Y.H. Chen et C. Ling. The structures were elucidated by spectroscopic methods including 1D and 2D NMR and HR-ESI-MS. The absolute configuration of 2 was determined via the calculated electronic circular dichroism (ECD), whereas the absolute configurations of 1 and 3 were determined via the ECD data of the [Rh₂(OCOCF₃)₄] complex and [Mo₂(OAc)₄] complex, respectively. The inhibitory effects of compounds 1–6 on nitric oxide production in lipopolysaccharide-activated macrophages were evaluated. All of them exhibited weak anti-inflammatory activity.     

Terpenoids from the tuber of Cremastra appendiculata

Two new terpenoids including a cadinane sesquiterpene (1), and an ent-kaurane diterpene diglycoside (2), together with a known triterpene containing 32 carbons (3), have been isolated from the ethanolic extract of Cremastra appendiculata. Their structures were established by the spectroscopic methods including the IR, MS, 1D-, and 2D-NMR experiments as ( ? )-cadin-4,10(15)-dien-11-oic acid (1), ( ? )-ent-12β-hydroxykaur-16-en-19-oic acid, 19-O-β-d-xylopyranosyl-(1 → 6)-O-β-d-glucopyranoside (2), and (+)-24,24-dimethyl-25,32-cyclo-5α-lanosta-9(11)-en-3β-ol (3). Compounds 1–3 were evaluated against several human cancer cell lines. Compound 3 showed in vitro-selective cytotoxicity against human breast cancer cell lines (MCF-7) with an IC₅₀ of 3.18 μM, but 1 and 2 were inactive (IC₅₀>10 μg/ml).     

New dianthramide and cinnamic ester glucosides from the roots of Aconitum carmichaelii

Four new compounds N-salicyl-3-hydroxyanthranilic acid methyl ester (1), N-(2′-dehydroxysalicyl)-3-hydroxyanthranilic acid methyl ester (2), methyl-4-β-D-allopyranosyl-ferulate (3), and methyl-4-β-D-gulopyranosyl-cinnamate (4), along with six known compounds (5–10), were isolated from the roots of Aconitum carmichelii Debx. Their structures were elucidated on the basis of spectral data analysis, including 1D, 2D-NMR, and HR-ESI-MS. Compounds 1 and 2 showed the inhibition of nitric oxide (NO) production with IC₅₀ values of 9.13 and 19.94 μM, respectively.     

Antimicrobial and antioxidant effects of phenolic constituents from Klainedoxa gabonensis

Bioassay-guided fractionation of the methanol extract of the stem bark of Klainedoxa gabonensis Pierre ex Engl. (Irvingiaceae) afforded 12 compounds, namely, ellagic acid (1), ellagic acid 3,3′-dimethylether (2), gallic acid (3), methyl gallate (4), lupeol (5), β-amyrin (7), erythrodiol (8), oleanolic acid (9), betulinic acid (6), hederagenin (10), bayogenin acid (11), and stigmasterol-3-O-β-d-glucopyranoside (12). Compounds 1-3 and 7-12 were isolated for the first time from this genus. The structures were established on the basis of 1D/2D NMR experiments and mass spectrometric data. Crude extract, fractions (A, B, C and D) and pure compounds were tested for their antimicrobial activity using paper disk agar diffusion assay. The test delivered a range of low to high activities for phenolic compounds 1-4, low or missing activities for terpenoid compounds 5-11, and impressive very high antibacterial/antifungal values for two fractions C and D probably due to synergistic effects of compounds. The broth microdilution assay revealed MICs of 15.4-115.1?μg/mL for phenolic compounds, MICs higher than 1?mg/mL for terpenoids and MICs of 4.5-30.3?μg/mL for fractions C and D. The determination of the radical scavenging activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay gave high antioxidant values for the methanol extract and fraction D (IC₅₀ 10.45 and 5.50?μg/mL) as well as for the phenolic compounds 1-4 (IC₅₀ 45.50-48.25?mM) compared to the standard 3-t-butyl-4-hydroxyanisole (BHA) (IC₅₀ 44.20?mM).     

A dimeric triterpenoid glycoside and flavonoid glycosides with free radical-scavenging activity isolated from <Emphasis Type="Italic">Rubus rigidus</Emphasis> var. <Emphasis Type="Italic">camerunensis</Emphasis>

The aerial part of Rubus rigidus var. camerunensis (Rosaceae) is used to treat respiratory and cardiovascular disorders in the Cameroonian traditional medicine. The ethanol extract exhibited more potent antioxidant activity (E_maxs of 119% and 229% activity on DPPH and β-carotene test) than aqueous extract. Bioactivity-guided fractionation of the ethanol extract based on free radical-scavenging assay (DPPH assay) afforded five flavonoid glycosides (four flavonol glycosides and an anthocyanin) and three glucosides of 19α-hydroxyursane-type triterpenoid (two monomeric and one dimeric triterpenoids). The flavonoids were identified as kaempferol 3-O-(2″-O-E-p-coumaroyl)-β-D-glucopyranoside (1), kaempferol-3-O-β-D-glucopyranoside (astragalin, 2), kaempferol-3-O-α-L-arabinofuranoside (juglanin, 3), quercetin-3-O-β-D-glucopyranoside (isoquercitrin, 4), pelargonidin-3-O-β-D-glucopyranoside (callistephin, 5). The three triterpenoids were 2α, 3β, 19α, 23-tetrahydroxyurs-12-ene-28-O-β-D-glucopyranosyl ester (nigaichigoside F₁, 6), 2α, 3β, 19α-trihydroxyurs-12-ene-23-carboxyl-28-O-β-D-glucopyranosyl ester (suavissimoside R₁, 7) as monomeric triterpenoids and coreanoside F₁ (8) as a dimeric triterpenoid. The flavonoids exhibited potent antioxidant activities (66 to 93.56% against DPPH radical) and they were also active on β-carotene test. Coreanoside F₁ exhibited a 63% antioxidant activity, meanwhile the other two triterpenoids showed a weak activity. Three important facts on structure-activity relationship were observed: Compound 8, a dimeric triterpenoid glycoside, strongly enhanced antioxidant activity of its monomers, compound 3 with 3-O-α-L-arabinofuranyl has much more potent activity than compound 2 with 3-O-β-D-glucopyranosyl, and antocyanin (5) is more potent than its corresponding flavonol glycosides.     

Three new elemanolides from the seeds of Vernonia anthelmintica

Three new elemanolides, named vernonilides D (1), E (2), and F (3), along with four known sesquiterpenoids, including two elemanolides (4, 5), a guaianolide (6), and a germacranolide (7) were isolated from the seeds of Vernonia anthelmintica. The structures of them were elucidated based on 1D and 2D NMR experiments and comparison with published data. Cytotoxicity of the compounds against four human tumor cell lines was assayed. 6 showed strongly inhibitory effect against HCT-15 and PC-3 cell lines with IC₅₀ values of 0.56 and 0.69 μM, respectively. The new compounds showed moderate cytotoxicity against four cell lines with IC₅₀ values ranging from 9.1 to 28.1 μM.     

Urease inhibitory constituents from Daphne retusa

The bioassay-guided fractionation of Daphne retusa Hemsl. has led to the isolation of a new aryl tetrahydronaphthalene lignan derivative named as daphnretusic acid (1), along with six new source compounds such as 5,7-dihydroxyflavone (2), 7-hydroxyflavone (3), 6-methoxyflavone (4), (+) pinoresinol (5), (+) sesamin (6), and β-sitosterol-3-O-β-D-glucopyranoside (7). Their structures were elucidated by ¹H NMR, ¹³C NMR, 1D, 2D NMR, UV, IR, and EIMS analyses. All the fractions (n-hexane, CHCl₃, AcOEt, CH₃OH, and water) and pure compounds (1–7) were subjected to the assay of urease and α-chymotrypsin inhibitory activities. Chloroform and methanol soluble fractions showed moderate urease inhibition. Compound 2 exhibited significant urease inhibition with IC₅₀ value 60.4 ± 0.72 μM, whereas compounds 1 and 3–7 remained inactive during urease inhibition and α-chymotrypsin bioassays.     

Two new compounds from the broth of the marine fungus Penicillium griseofulvum Y19-07

Two new compounds, 4-hydroxyphenethyl methyl succinate (1) and 4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate (2), were isolated from the EtOAc extract of the broth of the marine fungus Penicillium griseofulvum Y19-07. Five known compounds were also obtained in this study. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. All of the isolates were evaluated for their scavenging properties toward the 2,2-diphenyl-1-picrylhydrazyl free radical by spectroscopic assays. Also, in the cytotoxicity assay of the two new compounds against HL-60 and PC-3 prostate cancer cell lines, compound 2 showed potential activity with an IC₅₀ value of 64.5 μM against human HL-60 cancer cells.     

New prenylated flavones from <Emphasis Type="Italic">Artocarpus champeden</Emphasis>, and their antimalarial activity in vitro

Two new prenylated flavones, artocarpones A and B (1 and 2), and seven known isoprenylated flavonoids, artonin A (3), cycloheterophyllin (4), artoindonesianin E (5), artoindonesianin R (6), heterophyllin (7), heteroflavanone C (8), and artoindonesianin A-2 (9), have been isolated from the stem bark of Artocarpus champeden. Their structures were determined by spectroscopic analysis. Among the compounds isolated, 8 had the most potent inhibitory activity against the growth of Plasmodium falciparum 3D7 clone, with an IC₅₀ value of 1 nmol L⁻¹.