Antiplasmodial phloroglucinol derivatives from Syncarpia glomulifera

Bioassay guided fractionation of a MeOH extract of the stem bark of Syncarpia glomulifera (Myrtaceae) led to the isolation of the two new phloroglucinol derivatives (±)-rhodomyrtosone F (1) and (±)-calliviminone C (2), the three known triterpenes, betulinic acid (3), ursolic acid-3-acetate (4), and ursolic acid (5), and 1-(2,4,6-trihydroxyphenyl)-1-hexanone (6). Compound 1 exhibited strong antiplasmodial activity, while compounds 2–4 were moderately active and 5 and 6 were inactive in this assay. The structures of 1 and 2 were elucidated based on analyses of their mass spectrometric data, 1D and 2D NMR spectra, and comparison with related compounds.     

Agarofuran sesquiterpenes from Schaefferia argentinensis

Sixteen dihydro-β-agarofuran sesquiterpenes were isolated from the aerial parts of Schaefferia argentinensis Speg. Their structures were determined by a combination of 1D and 2D NMR and MS techniques. The in vitro antiproliferative activity of the major sesquiterpenes was examined in T47D, MCF7, and MDA-MB231 human cancer cell lines, but was found to be marginal.     

Antiplasmodial constituents from the stem bark of Polyalthia longifolia var pendula

Along with two known compounds (1 and 2), four new clerodane diterpenes were isolated and identified from the stem bark of Polyalthia longifolia: cleroda-3-ene pyrrole-15,16-dione (3), cleroda-3-ene, pyrrolidine-15,16-dione (4), cleroda-3,13(14)E-diene-15,16-diamide (5), and cleroda-3-ene-15,16-diamide (6). Their structures were elucidated by combinations of NMR, MS and IR. Using the WHO Mark III Microtest assay, the isolated compounds were evaluated for their antiplasmodial effects. They showed antiplasmodial effects, with IC₅₀s ranging from 4.5 to 213.8 μM.     

Antiplasmodial anthraquinones and hemisynthetic derivatives from the leaves of Tectona grandis (Verbenaceae)

Chemical investigation of the methanol extract of the leaves of Tectona grandis led to the isolation of one new anthraquinone derivative, grandiquinone A (3-acetoxy-8-hydroxy-2-methylanthraquinone) (1), along with nine known compounds: 5,8-dihydroxy-2-methylanthraquinone (2), hydroxysesamone (3), 3-hydroxy-2-methylanthraquinone (4), quinizarine (5), betulinic acid (6), ursolic acid (7), tectograndone (8), corosolic acid (9) and sitosterol 3-O-β-d-glucopyranoside (10). Compounds 2 and 3 were isolated for the first time from the leaves of this plant, while 5 has never been reported from the genus Tectona. Hydroxysesamone (3) and tectograndone (8) were subjected to cyclisation and acetylation reactions to afford two hemisynthetic derivatives, 6,9-dihydroxy-2,2-(dimethyldihydropyrano)-3,4-dihydro-2H-benzo[g]chromene-5,10-dione (11) and acetyltectograndone (12) respectively, which are reported here for the first time. The ethyl acetate-soluble portion, some of the isolated compounds and hemisynthetic derivatives were evaluated for their antiplasmodial activity against the multidrug-resistant Dd2 strain of Plasmodium falciparum. Compound 3 showed a prominent activity, while 2, 8, 9, 11 and 12 showed significant in vitro anti-malarial activity. Compound 1 was weakly active in this test. The structures of the compounds were elucidated by spectroscopic methods and comparison of the data with the literature.     

Bioactive Neolignans and Other Compounds from Magnolia grandiflora L.: Isolation and Antiplasmodial Activity

Bioassay‐guided fractionation of a methanol extract of Magnolia grandiflora against Plasmodium falciparum yielded two new ( 1 and 2 ) and six known ( 3 – 8 ) bioactive compounds. The structures of the new compounds were assigned by mass spectrometric and 1D‐ and 2D‐NMR data. Known compounds were identified by comparison of ¹H‐NMR and MS data with literature data. The two known neolignans 3 and 4 showed moderate antiplasmodial activity with the IC₅₀ values of 2.8 ± 0.1 and 3.4 ± 0.1 μm , respectively. Weak antiplasmodial activity was recorded for compounds 1 , 2 , 5 , 6 , 7 , and 8 , with the IC₅₀ values of 38 ± 2, 23 ± 2, 16.5 ± 0.2, 86 ± 1, 44 ± 4, and 114 ± 9 μm , respectively.     

Antiplasmodial and cytotoxic activity of lanostane type triterpenoids isolated from Leplaea mayombensis

Leplaeric acid E 5, leplazarin 6a and 21-epileplazarin 6b, three new 3,4-seco-lanostane type triterpenes have been isolated from the stem bark of Leplaea mayombensis (Pellegr.) Staner along with fourteen known compounds from the fruits and roots. Leplaeric acid E, leplazarin and 21-epileplazarin, 15-α-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid, mayomlactones A and B, lanosta-7,24-dien-3-one, leplaeric acid A, B and C were screened in vitro for antiplasmodial activity against chloroquine-sensitive (Pf3D7) and chloroquine-resistant (PfINDO) strains of Plasmodium falciparum and for cytotoxicity against CAL-27, CaCo2, Skov-3, and HepG2 cells line. Three compounds including 15-α-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid (IC₅₀ 5.65–7.09 μM), lanosta-7,24-dien-3-one (IC₅₀ 7.18–9.07 μM), and leplaeric acid C (IC₅₀ 7.59–8.47 μM) were the most active against both strains of P. falciparum. All the compounds exhibited cytotoxicity against the three-cell lines with IC₅₀ ranging from 12.30 to 181.88 μM. These results confirm the usage of the medicinal plant L. mayombensis for the management of malaria and suggest that further lead optimization studies on potent compounds identified from this study could lead to the identification of potential of lead molecules as scaffold for new antimalarial drug discovery.     

New bisabolane sesquiterpenes and coumarin from Leontopodium longifolium

From the roots of Leontopotium longifolium, three new bisabolane sesquiterpenes, rel-(1S,4R,5S,6R)-4,5-diacetoxy-6-[(R)-1,5-dimethylhexa-3,5-dienyl]-3-methylcyclohex-2-enyl (Z)-2-methylbut-2-enoate (1), rel-(1S,4R,5S,6R)-4,5-diacetoxy-6-[(R)-5-hydroxy-1,5-dimethylhex-3-enyl]-3-methylcyclohex-2-enyl (Z)-2-methylbut-2-enoate (2), rel-(1R,2S,4R,5S)-4-acetoxy-2-[(R)-5-hydroxy-1,5-dimethylhex-3-enyl]-5-methylcyclohexyl (Z)-2-methylbut-2-enoate (3), and a new coumarin, 2,3-dihydro-5-hydroxy-2-(1-methylethenyl)-7H-pyrano[2,3-g][1,4]benzodioxin-7-one (4) together with nine known compounds have been isolated. The structures of these compounds were established by spectroscopic methods. Compounds 1 and 2 exhibited moderate cytotoxic activities against human promyelocytic leukemia (HL-60) cells.     

New eudesmane sesquiterpenes from the marine-derived fungus Penicillium thomii

Four new eudesmane-type sesquiterpenes thomimarines A–D (1–4) were isolated from the marine-derived fungus Penicillium thomii. Their structures were established based on spectroscopic methods. The absolute configurations of 1–4 were determined by time-dependent density functional theory (TD-DFT) calculations of ECD spectra. Inhibitory effects of compounds 1, 2 and 4 on NO production in LPS-induced RAW 264.7 murine macrophages were evaluated.     

Isolation of the New Antiplasmodial Butanolide,Malleastrumolide A,from Malleastrum sp. (Meliaceae) from Madagascar

An extract of Malleastrum sp. (Meliaceae) collected in Madagascar by the Madagascar International Cooperative Biodiversity Group was found to have antimalarial activity, with an IC ₅₀ value between 2.5 and 5 μg ml^?1. After purification by liquid‐liquid partition, chromatography on a Diaion open column, C ₁₈ SPE and C ₁₈ reversed phase HPLC , the new butanolide, malleastrumolide A, was isolated. The structure of malleastrumolide A was determined by mass spectrometry, NMR , and ECD . The double bond position was determined by cross‐metathesis and mass spectrometry. The compound has antiproliferative activity against the A2780 ovarian cancer cell line with an IC ₅₀ value of 17.4 μm and antiplasmodial activity against the drug‐resistant Dd2 strain of Plasmodium falciparum with an IC ₅₀ value of 2.74 μm .     

Four new cassane diterpenes from the seeds of Caesalpinia minax

In our survey on the chemical composition of traditional Chinese medicines to further elucidate their chemical substances for the treatment of diseases, we investigated the chemical constituents of the seeds of plants Caesalpinia minax. The investigation led to the isolation and identification of four new cassane diterpenes, caesalpines A–D (1–4). Their structures were elucidated on the basis of extensive 1D and 2D NMR (COSY, HMQC, HMBC, and NOESY) and mass (ESIMS and HR-ESIMS) spectroscopic data analyses. The phytochemical results imply that cassane diterpenes are maybe regarded as the characteristic constituents of C. minax.     

Chemotaxonomic significance of sesquiterpenes and amide derivatives from Chloranthus angustifolius Oliv.

Phytochemical investigation of the aerial parts of Chloranthus angustifolius Oliv. (Chloranthaceae) resulted in the isolation and characterization of seven sesquiterpenes (1–7) and six amide derivatives (8–13). All structures were established based on analysis of their spectroscopic data. This is the first report of compounds 2 and 8–13 from the family Chloranthaceae, and the first report of compounds 3–5 from C. angustifolius. Moreover, the chemotaxonomic significance of these compounds was summarized.     

Four new sesquiterpenes from the rhizomes of Curcuma wenyujin

Four new sesquiterpenes, namely wenyujinols I – L (1 – 4), along with eleven known ones were isolated from the rhizomes of Curcuma wenyujin. The structures of new compounds were elucidated using spectroscopic and spectrometric data analyses. All isolated compounds were evaluated for their inhibitory effects on melanin production and tyrosinase activity in B16F10 cells. Compound 1 exhibited significant inhibition against melanin production.     

Sesquiterpenes and nor sesquiterpenes from Schefflera leucantha R.Vig. (Araliaceae)

One new nor sesquiterpenes, Schesesquiterpene (1), together with nine reported sesquiterpenes and nor sesquiterpenes (2–10) were obtained from Schefflera leucantha R.Vig. (Araliaceae). The structures were determined according to spectroscopic data analysis and chemical evidence. Noteworthily, Compound 7 was isolated as a new natural product, and other compounds (2–6 and 8–10) were obtained from the family Araliaceae for the first time.     

Antiplasmodial and antimycobacterial cyclopeptide alkaloids from the root of Ziziphus mauritiana

Investigation of the MeOH extract obtained from the root of the Ziziphus mauritiana grown in Thailand resulted in the isolation of two 14- and 13-membered cyclic alkaloids, mauritine L (1) and mauritine M (2), and three known cyclopeptide alkaloids, nummularines H (3), B (4) and hemsine A (5). Their structures were elucidated on the basis of extensive NMR spectroscopic analysis. The first single crystal X-ray diffraction study of the 13-membered ring cyclopeptide, nummularine B methiodide (4′), revealed all S configurations on the amino acid residues. The isolated alkaloids exhibited potent antiplasmodial activity against the parasite Plasmodium falciparum with the inhibitory concentration (IC₅₀) ranging from 3.7 to 10.3 μM. Compounds 2 and 3 also demonstrated antimycobacterial activity against Mycobacterium tuberculosis with the MIC of 72.8 and 4.5 μM, respectively.     

Antiplasmodial flavanones and a stilbene from Carpha glomerata

Bioassay-guided fractionation of an extract of Carpha glomerata (Cyperaceae) led to the isolation of seven compounds. Compounds 1 (carphorin A), 3 (carphorin C), 4 (carphorin D), and 5 (carphabene) are new compounds, and compound 2 (8-(3″-hydroxyisoamyl)-naringenin) was isolated for the first time as a natural product. All structures were elucidated based on analyses of their HR-ESIMS and 1D and 2D NMR data. Compounds 1, 2, and 6, which have prenyl or hydroxyprenyl side chains, exhibited antiplasmodial activities with IC₅₀ values of 5.2?±?0.6, 3.4?±?0.4, and 6.7?±?0.8?µM against the drug-resistant Dd2 strain of Plasmodium falciparum. In addition the prenylated stilbene 5 also showed good activity, with IC₅₀ 5.8?±?0.7?µM.     

Chemical constituents from Salacia impressifolia (Miers) A. C. Smith collected at the Amazon rainforest

The phytochemical investigation of Salacia impressifolia (Miers) A. C. Smith led to the isolations of 15 compounds, including triterpene quinonemethides, which are employed as the common characteristic constituents of the Celastraceae family. Pristimerin (9) and tingenone (12) were isolated as the main compounds in the studied tissues. Additionally, friedelane, lupane, oleanane, and ursane triterpenoids were also isolated. All of them were isolated from this plant for the first time.     

Evaluation of Cytotoxicity and Antifungal Activity of Friedelanes from Salacia elliptica Roots

Plants from Salacia genus are used in traditional medicine for a wide range of diseases. Previous studies reported bioactive pentacyclic triterpenoids from S. elliptica leaves and branches. In this study, the novel pentacyclic triterpenoid 7α,15α-dihydroxyfriedelan-3-one ( 1 ) was obtained from the roots of Salacia elliptica, along with seven known compounds: friedelan-3-one ( 2 ), friedelan-3β-ol ( 3 ), friedelan-1,3-dione ( 4 ), friedelan-3,15-dione ( 5 ), 15α-hydroxyfriedelan-3-one ( 6 ), 15α,26-dihydroxyfriedelan-3-one ( 7 ), and 26-hydroxyfriedelan-3,15-dione ( 8 ). Additionally, one steroid, spinasterol ( 9 ), was also identified. The chemical structures of all compounds were established through ¹H and ¹³C-NMR. Compound 1 was analysed by additional 2D experiments (HMBC, HSQC, COSY, and NOESY) for complete elucidation. Furthermore, the cytotoxicity of compounds 2 , 3 , 6 , 7 and 8 against the A549 lung cancer cells model was evaluated. The flow cytometry analysis revealed a significant cytotoxic activity similar to that exhibited by the triterpenoid lupeol. Additionally, compounds 2 , 3 , 6 , and 7 were tested for in vitro antifungal activity against Candida, Cryptococcus and Sporothrix strains. However, all compounds showed no activity at the tested concentrations.     

Five new germacrane sesquiterpenes with anti-inflammatory activity from Salvia petrophila

Five new germacrane sesquiterpene lactones, petrophins A–E (1–5), were isolated from the whole herbs of Salvia petrophila. The structures were established using spectroscopic analysis (1D and 2D NMR, HR-ESI-MS) and compatible with values in the literature. These sesquiterpenes are unusual with an endocyclic double bond in the γ-lactone ring. All the isolated compounds were evaluated for their inhibitory effects on the LPS-induced nitric oxide production using murine macro-phage RAW264.7 cells.     

Antiplasmodial alkaloids from bulbs of Amaryllis belladonna Steud.

A bioassay-guided fractionation and chemical investigation of Amaryllis belladonna Steud. bulbs resulted in the isolation and identification of the new crinane alkaloid 1,4-dihydroxy-3-methoxy powellan (1), along with the 3 known crinane alkaloids 2–4 and the two lycorane alkaloids 5–6. The structures were elucidated by interpretation of combined HR-ESIMS, CD and 2D NMR spectroscopic data. Among these isolated compounds the lycorane-type alkaloid acetylcaranine (5) exhibited strong antiplasmodial activity, while compounds 3 and 4 were moderately active, and compounds 1 and 6 were inactive.