A new phenylpropanoid and an alkylglycoside from Piper retrofractum leaves with their antioxidant and α-glucosidase inhibitory activity

Two new compounds, piperoside (1) and isoheptanol 2(S)-O-β-d-xylopyranosyl (1→6)-O-β-d-glucopyranoside (11), along with 10 known compounds 3,4-dihydroxyallylbenzene (2), 1,2-di-O-β-d-glucopyranosyl-4-allylbenzene (3), tachioside (4), benzyl-O-β-d-glucopyranoside (5), icariside F₂ (6), dihydrovomifoliol-3′-O-β-d-glucopyranoside (7), isopropyl O-β-d-glucopyranoside (8), isopropyl primeveroside (9), n-butyl O-β-d-glucopyranoside (10), isoheptanol 2(S)-O-β-d-apiofuranosyl-(1→6)-O-β-d-glucopyranoside (12), were isolated from the leaves of Piper retrofractum. Their structures were determined from 1D-NMR, 2D-NMR, and HR-ESI-MS spectral, a modified Mosher’s method, and comparisons with previous reports. All of the isolated compounds showed modest α-glucosidase inhibitory (4.60 ± 1.74% to 11.97 ± 3.30%) and antioxidant activities under the tested conditions.     

Cordatols A–D,four new anti-inflammatory bis-monoterpenoids from Illigera cordata

Cordatols A–D (1–4), four new limonene-derived bis–monoterpenoids plausibly biosynthesized via hetero-Diels-Alder cyclization and sequential hydrolyses of their monoterpene precursors, were isolated from the aerial parts of Illigera cordata. The structures, including absolute configuration, were established by spectroscopic analysis and further confirmed by a two-steps bioinspired chemical transformation. Moreover, compounds 1–4 exhibited moderate in vitro anti-inflammatory activity with IC₅₀ values ranging from 17.5 to 24.6 μM. This study may provide a novel structural template for potential anti-inflammatory agent discovery.     

Ecliptamines A–D,four new guanidine alkaloids from Eclipta prostrata L.

Four structurally unique guanidine alkaloids ecliptamines A–D (1–4) and one known analog (5) were isolated from the aerial parts of Eclipta prostrata (Asteraceae). Their structures were elucidated on the basis of spectroscopic analyses and chemical methods. The inhibitory activities of 1, 2 and 5 were assayed with respect to cyclooxygenase-1 (COX-1) and -2 (COX-2). Compound 5 showed moderate inhibitory activities against COX-1 and -2 with IC₅₀ values of 3.0 × 10⁻³ M and 8.3 × 10⁻⁴ M, respectively, whereas aspirin as a positive control displayed the IC₅₀ values of 4.2 × 10⁻⁴ M (against COX-1) and 7.1 × 10⁻⁴ M (against COX-2).     

Repenins A–D,four new antioxidative coumarinolignoids from Duranta repens Linn.

Phytochemical investigations on the CHCl₃-soluble fraction of the whole plant of Duranta repens Linn. led to the isolation of four new coumarinolignoids, Repenins A–D (1–4), along with the known coumarinolignoids, cleomiscosin A (5) and durantin A (6). Their structures were determined by modern spectroscopic analysis including 1D and 2D NMR techniques and chemical studies. The compounds (1–6) showed potent antioxidative scavenging activity against DPPH radicals, with IC₅₀ values in the range 0.420–0.625 mM. Repenin B (2) displayed the strongest scavenging potential with IC₅₀ values of (0.420 mM).     

Ficuschlorins A - D, lactone Chlorins from the leaves of ficus microcarpa

Four new lactone chlorins, ficuschlorins A – D ( 1 – 4 , resp.), and six known pheophytins were isolated from the leaves of Ficus microcarpa. The structures of these compounds were determined by 1D‐ and 2D‐NMR spectroscopy, and other techniques. New natural pheophytins were rarely obtained. In the past ten years, only three new pheophytins were isolated from natural sources.     

Ximaosteroids A–D,new steroids from the Hainan soft coral Scleronephthya sp.

One novel uncommon steroid, ximaosteroid A (1), possessing an unusual tetrahydrofuran moiety and three new pregnane steroids, ximaosteroids B–D (2–4), were isolated from the Hainan soft coral Scleronephthya sp. Their structures were elucidated on the basis of detailed spectroscopic (IR, MS, and 2D NMR) analysis and by comparison with those reported in the literature.     

Ceramicines B–D,new antiplasmodial limonoids from Chisocheton ceramicus

Three new limonoids, ceramicines B–D (1–3), have been isolated from the bark of Chisocheton ceramicus. Structures and stereochemistry of 1–3 were fully elucidated and characterized by 2D NMR analysis. Ceramicines exhibited a moderate antiplasmodial activity.     

Phenylpropanoids and lignans from Prunus tomentosa seeds as efficient β-amyloid (Aβ) aggregation inhibitors

Alzheimer’s disease (AD) is characterized by the progressive accumulation of extracellular β-amyloid (Aβ) aggregates. Recently, lignans and phenylpropanoids are attracting increasing attention to discovery useful agents of inhibition on Aβ aggregation. In the present study, to develop potential agents for slowing the progression of AD, Prunus tomentosa seeds were selected as a raw material for bioactive compounds, which led to the separation of two pairs of new enantiomeric lignans and phenylpropanoids using chiral HPLC. The planar structures of these compounds were elucidated by spectroscopic data analyses. And their absolute configurations were determined by comparing of experimental and calculated electronic circular dichroism (ECD). The biosynthesis pathway was also discussed. Additionally, the inhibitory activity on Aβ aggregation of all optical pure compounds was tested by thioflavin T (ThT) assay. The isolates (1a, 1b, 2a and 2b) showed more potent inhibitory activity than positive control curcumin with inhibitory rate of 73.89 ± 3.41% 78.69 ± 1.50%, 63.25 ± 2.68%, and 67.13 ± 0.90% at 20 μM, respectively. More importantly, the inhibition profiles were explained by molecular dynamics and docking simulation studies.     

Virginols A–C,three new withanolides from Physalis virginiana

Virginols A–C are three new withanolides containing an epoxylactol at the side chain. They were isolated from the aerial parts of Physalis virginiana Miller. Structures of these compounds were determined by analyses of their spectroscopic data, including 1D and 2D NMR. The structure of virginol A was confirmed by X-ray diffraction analysis. The anti-inflammatory activity of virginols was evaluated in the TPA-induced ear mouse edema model.     

Oblongionosides A–F,megastigmane glycosides from the leaves of Croton oblongifolius Roxburgh

From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Croton oblongifolius Roxburgh, collected in Chiang Mai, Thailand, six megastigmane glycosides, named oblongionosides A–F were isolated together with eight known compounds, and their structures elucidated on the basis of spectroscopic data. Absolute structures were determined by HPLC analyses and application of the modified Mosher’s method.     

Alpneumines A–H,new anti-melanogenic indole alkaloids from Alstonia pneumatophora

Eight new indole alkaloids, alpneumines A–H (1–8) were isolated from the Malaysian Alstonia pneumatophora (Apocynaceae) and their structures were determined by MS and 2D NMR spectroscopic methods. Alpneumines E and G (5 and 7), vincamine, and apovincamine showed anti-melanogenesis in B16 mouse melanoma cells.     

Ganocapenoids A–D: Four new aromatic meroterpenoids from Ganoderma capense

Four new aromatic meroterpenoids, ganocapenoids A–D (1–4), together with twelve known analogues (5–16) were isolated from the fruiting bodies of Ganoderma capense. The structures of new compounds were determined through spectroscopic methods including 1D and 2D NMR and MS analyses. Their absolute configurations were assigned by ECD calculations and specific rotation comparison. The biological activities of these substances toward regulation of lipid metabolism, neurite outgrowth-promoting activity, and AchE inhibition were assessed. Compound 15 was found to be able to block lipid accumulation at a concentration of 20?μM, and compounds 4a, 4b, and 11 show moderate neurite outgrowth-promoting activity at 10?μM, while compounds 3, 6, 11, and 13 exhibit potent AchE inhibition with the IC₅₀ values of 28.6?±?1.9, 18.7?±?1.6, 8.2?±?0.2, 26.0?±?2.9?μM, respectively.     

Thaixylomolins D–F,new limonoids from the Thai true mangrove,Xylocarpus moluccensis

Three new limonoids, named thaixylomolins D–F (1–3), were obtained from the seeds of a Thai true mangrove, Xylocarpus moluccensis. The structures of these compounds were identified by extensive NMR and HR-ESIMS/MS investigations. They are further additions to the small group of phragmalins with a C-30 carbonyl moiety, among which thaixylomolins D–E (1–2) contain a Δ^8,14 double bond, whereas thaixylomolin F (3) possesses conjugated Δ^8,9 and Δ^14,15 double bonds.     

β-Amyrin acetate and β-amyrin palmitate as antidyslipidemic agents from Wrightia tomentosa leaves

The ethanolic extract and fractions of Wrightia tomentosa Roem. & Schult (Apocynaceae) leaves were tested in vivo for their antidyslipidemic activity in high fat diet (HFD) induced dyslipidemic hamsters. Activity guided isolation resulted in identification of antidyslipidemic compounds β-AA and β-AP. Compounds β-AA and β-AP decrease the levels of LDL by 36% and 44%, and increase the HDL-C/TC ratio by 49% and 28%, respectively, at a dose of 10mg/kg. In addition, the isolated compounds β-AA and β-AP showed significant HMG-CoA-reductase inhibition, which was further established by docking studies.     

Artostyracins A–C,three new isoprenylated 2-arylbenzofurans from Artocarpus styracifolius

Three new isoprenylated 2-arylbenzofurans, namely artostyracins A–C (1–3, resp.), together with a known one (4), were isolated from the root of Artocarpus styracifolius Pierre. Their structures were determined by spectroscopic methods (1D and 2D NMR, UV, IR, and HR-ESI-MS). All of the compounds were evaluated for the anti-respiratory burst properties using a cellular model reproduced by chemical stimulation of rat neutrophils. Compounds 1 and 3 offered the potently inhibitory effects on respiratory burst of rat neutrophils with IC₅₀ values of 1.42 and 1.91 μM, while compounds 2 and 4 revealed moderate suppression activity with IC₅₀ values of 11.56 and 46.91 μM.     

Scutelinquanines A–C,three new cytotoxic neo-clerodane diterpenoid from Scutellaria barbata

Three new neo-clerodane diterpenoids, named scutelinquanines A–C (1–3), were isolated from the whole plant of Scutellaria barbata. Their structures were established on the basis of detailed spectroscopic analyses. In vitro, the isolated three new compounds showed significant cytotoxic activities against three human cancer lines (HONE-1 nasopharyngeal, KB oral epidermoid carcinoma, and HT29 colorectal carcinoma cells), and gave IC₅₀ values in the range 2.7–6.7 μM.     

Four new asterosaponins, hippasteriosides A - D, from the Far Eastern starfish Hippasteria kurilensis

Four new sulfated steroidal glycosides (asterosaponins), hippasteriosides A-D (1-4, resp.), were isolated from the alcoholic extract of the Far Eastern starfish Hippasteria kurilensis, collected in the Sea of Okhotsk near Kuril Islands. Compounds 1-4 were determined to contain the same unprecedented hexasaccharide moiety, β-D-xylopyranosyl-(1→3)-β-D-fucopyranosyl-(1→2)-β-D-quinovopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-β-D-quinovopyranosyl, linked to C(6) of 3-O-sulfonylated steroidal aglycons, which differ from each other in their side-chain structures. Structures 1-4 were elucidated by extensive NMR and MS techniques, and chemical transformations. Not all the asterosaponins show a prominent cytotoxic activity against human colon tumor HT-29 cells, but some of them, especially compound 4 demonstrate a remarkable inhibition of the HT-29 colony formation in soft-agar clonogenic assay, suggesting its anticancerogenic properties.     

Japonicones A–D,bioactive dimeric sesquiterpenes from Inula japonica Thunb.

Four new dimeric sesquiterpene lactones japonicones A?D (1?4), comprised by eudesmane and guaiane sesquiterpenes, were isolated from the aerial part of Inula japonica Thunb. The structures and stereochemistry of 1?4 were elucidated by use of 2D NMR spectroscopic techniques, X-ray crystallography and modified Mosher method. Japonicone A (1) showed the most potent cytotoxicities against four tumor cell lines, A549, LOVO, CEM and MDA-MB-435.     

Tigliane diterpene esters with IFN γ-inducing activity from the leaves of Aleurites fordii

Bioactivity-guided fractionation on the leaves of Aleurites fordii led to the isolation of a new tigliane diterpene ester, 12-O-hexadecanoyl-7-oxo-5-ene-16-hydroxyphorbol-13-acetate (1) along with four known compounds, 12-O-hexadecanoyl-7-oxo-5-ene-phorbol-13-acetate (2), 12-O-hexadecanoyl-phorbol-13-acetate (3), 12-O-hexadecanoyl-16-hydroxyphorbol-13-acetate (4), and 12-O-hexadecanoyl-4-deoxy-4α-16-hydroxyphorbol-13-acetate (5). The structures of these compounds were determined by interpretation of NMR (1D and 2D) spectroscopic data and MS data. All the isolates were evaluated for their effects on the induction of IFN-γ in NK92 cells. Compounds 3 and 4 exhibited the most potent responses in IFN-γ induction, comparable to the positive control, phorbol 12-myristate 13-acetate (PMA).