Geranylated carbazole alkaloids with potential neuroprotective activities from the stems and leaves of Clausena lansium

Clausena lansium (Lour.) Skeels is an evergreen small tree or shrub with great economic value, which belongs to the genus Clausena of the Rutaceae family. C. lansium is indigenous to Southern China, while currently widely cultivated in subtropical and tropical regions not only for the nutritional value and pharmacological uses of its fruits but also as a medicinal and ornamental plant. In this study, a systematic phytochemical study on the stems and leaves of C. lansium caused the separation and identification of two new geranylated carbazole alkaloids, clauselansiumines A (1) and B (2), as well as 10 known geranylated carbazole alkaloids (3–12). The chemical structures of these isolated geranylated carbazole alkaloids (1–12) were unambiguously determined based on comprehensive spectral data analyses. All these isolated geranylated carbazole alkaloids were tested for their neuroprotective effects against 6-hydroxydopamine induced cell death in human neuroblastoma SH-SY5Y cells in vitro. Compounds 1–12 displayed remarkable neuroprotective effects holding the EC₅₀ values ranging from 0.48 ± 0.04 to 12.36 ± 0.16 μM. These research results disclosed that the separation and purification of these geranylated carbazole alkaloids possessing remarkable neuroprotective effects separated from C. lansium could be extremely important to the discovery of new agents for the treatment and prevention for Parkinson's disease.     

Bioactive monoterpene indole alkaloids from Nauclea officinalis

Two new monoterpene indole alkaloids, naucleaoffines A (1) and B (2), together with six known alkaloids (3–8), were isolated from the stems and leaves of Nauclea officinalis. The structures of 1 and 2 were elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with the data reported in literature. All isolated compounds were evaluated for their anti-inflammatory activities and anti-HIV-1 activities. Compounds 1–8 exhibited significant inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in mouse macrophage RAW 264.7 cells in vitro with IC₅₀ values comparable to that of hydrocortisone. In addition, compounds 1–8 showed significant anti-HIV-1 activities with EC₅₀ ranged from 0.06 to 2.08 µM. These findings suggest that the discoveries of these indole alkaloids with significant anti-inflammatory activities and anti-HIV-1 activities isolated from N. officinalis could be of great importance to the development of new anti-inflammatory and anti-HIV agents.     

Taxonomic significance and antitumor activity of alkaloids from Clausena lansium Lour. Skeels (Rutaceae)

Phytochemical analysis of isolates from the aerial parts of Clausena lansium Lour. Skeels (Rutaceae) led to the identification of 14 alkaloids, including two indole alkaloids (1 and 2), one quinoline alkaloid (3), two pyridine alkaloids (4 and 5), four carbazole alkaloids (6–9) and five amides alkaloids (10–14). The phytochemical structures of the alkaloids were established by means of NMR and MS spectral analyses. Compounds (4, 5, 14) were three new natural products, while 1–3 and 10 were firstly reported from the genus Clausena and 8 and 9 were isolated from this species for the first time. The chemotaxonomic significance of these isolated alkaloids has also been discussed. All the isolated alkaloids were tested for their cytotoxic activity against Hela cancer cell line. Among them, four carbazole alkaloids 6–9 exhibited weak cytotoxicity with IC₅₀ values ranging from 69.31 to 138.32 μM.     

Alkaloids from the mangrove endophytic fungus Diaporthe phaseolorum SKS019

Six new alkaloids including four new chromeno[3,2-c]pyridines, diaporphasines A-D (1–4), and two new isoindolinones, meyeroguillines C and D (6–7), as well as three known compounds meyeroguilline A (5), 5-deoxybostrycoidin (8), and fusaristatin A (9), were isolated from an endophytic fungus Diaporthe phaseolorum SKS019. Their structures were determined by analysis of 1D and 2D NMR and mass spectroscopic data. Compounds 1–9 are alkaloid components reported for the first time from the Diaporthe sp., and diaporphasines A-D (1–4) are the third examples of alkaloids possessing the unique chromeno[3,2-c]pyridine nucleus. All isolated compounds 1–9 were evaluated for their cytotoxic activity in vitro using MDA-MB-435, HepG2, MCF10A, HCT116, and NCI-H460 human cell lines. Compound 8 exhibited cytotoxicity against MDA-MB-435 and NCI-H460 human cancer cell lines with IC₅₀ values of 5.32 and 6.57 μM, respectively, and compound 9 showed growth-inhibitory activity against MDA-MB-435 human cancer cell line with IC₅₀ value of 8.15 μM.     

Novel γ-lactone derivatives from Trigonostemon heterophyllus with their potential antiproliferative activities

Two novel γ-lactone derivatives, trigoheterophines A (1) and B (2), together with four known furan derivatives (3–6), were isolated from the stems and leaves of Trigonostemon heterophyllus. The structures of 1 and 2 were elucidated by extensive spectroscopic methods and the known compounds were identified by comparing with the data reported in literature. Among them, trigoheterophines A (1) and B (2) represent an unusual type of γ-lactone derivatives, possessing 21 carbon atoms on the carbon skeleton, and known compouds (3–6) are rare furan derivatives in the plant kingdom with diverse long-chain hydrocarbyl groups as substituents at C-4. All isolated compounds were evaluated for their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1–6 showed significant antiproliferative effects against various human cancer cell lines with IC₅₀ values ranging from 0.28 to 12.06 μM. These findings suggest that the discoveries of these novel γ-lactone derivatives and furan derivatives with significant antiproliferative activities isolated from T. heterophyllus could be of great importance to the development of new anticancer agents.     

Anti-inflammatory principles from Lindera aggregata

Four new sesquiterpenes (1–4), one new alkaloid (5), and one new benzenoid glycoside (6) were characterized from Lindera aggregata, and their structures were elucidated according to their spectrometric analytical data. Among these isolates, 3 and 4 were constructed as possessing unprecedented carbon skeletons from the natural source. Some of these purified constituents were examined for their anti-inflammatory bioactivity. Among the tested compounds, linderaggredin C (3), (+)-N-methyllaurotetanine, and (+)-isoboldine displayed the significant inhibition of superoxide anion generation in human neutrophils with IC₅₀ values of 7.45 ± 0.74, 8.36 ± 0.11, and 5.81 ± 0.59 μM, respectively.     

Bioactive secondary metabolites from the marine-associated fungus Aspergillus terreus

Three new compounds, including a prenylated tryptophan derivative, luteoride E (1), a butenolide derivative, versicolactone G (2), and a linear aliphatic alcohol, (3E,7E)-4,8-dimethyl-undecane-3,7-diene-1,11-diol (3), together with nine known compounds (4–12), were isolated and identified from a coral-associated fungus Aspergillus terreus. Their structures were elucidated by HRESIMS, one- and two-dimensional NMR analysis, and the absolute configuration of 2 was determined by comparison of its electronic circular dichroism (ECD) spectrum with the literature. Structurally, compound 1 featured an unusual (E)-oxime group, which occurred rarely in natural products. Compounds 1–3 were evaluated for the α-glucosidase inhibitory activity, and compound 2 showed potent inhibitory potency with IC₅₀ value of 104.8 ± 9.5 μM, which was lower than the positive control acarbose (IC₅₀ = 154.7 ± 8.1 µM). Additionally, all the isolated compounds were evaluated for the anti-inflammatory activity against NO production, and compounds 1–3, 5–7, and 10 showed significant inhibitory potency with IC₅₀ values ranging from 5.48 to 29.34 μM.     

Hexahydrobenzophenanthridine alkaloids from Corydalis bungeana Turcz. and their anti-inflammatory activity

As part of a bioprospecting program aimed at the discovery of anti-inflammatory agents from the Corydalis bungeana Turcz. (C. bungeana), five new hexahydrobenzophenanthridine alkaloids, corycaline A-E (1–5), along with four known alkaloids, were isolated from the whole plant of C. bungeana. Their structures including absolute configurations were elucidated on the basis of extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. The inhibitory activities of the nine compounds on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 mouse macrophage cells were determined; all tested compounds except 2 and 7 exhibited significant inhibitory effects with IC₅₀ values in the range of 1.00–2.79?μM.     

Prenylated chalcones from Desmodium renifolium

Three new prenylated chalcones, renifolins A–C (1–3), together with seven known ones (4–10), were isolated from whole Desmodium renifolium plants. All of their structures were determined by spectroscopic methods including 1D and 2D NMR. Compounds 1 and 2 are the first naturally occurring chalcones possessing a 4-methylfuran-2(5H)-one unit. All of the isolates were evaluated for cytotoxicity using five tumor cell lines. Compounds 3–8, and 10 exhibited moderate cytotoxicity against certain cell lines with IC₅₀ values from 4.2 to 8.8 μM.     

Prenylated C6–C3 compounds from the roots of Illicium henryi

Eleven prenylated C₆–C₃ compounds, illihenryifunones A, B (1, 2), illihenryifunol A (3), illihenryipyranol A (4), illihenryiones A−G (5–11), and three known prenylated C₆–C₃ compounds (12–14), were isolated from the roots of Illicium henryi. Structures of 1–11 were elucidated by spectroscopic methods including NMR, HRESIMS, and CD. The absolute configuration of the 11,12-diol moiety in 5 was determined by observing its induced circular dichroism after addition of Mo₂(OAc)₄ in DMSO. The absolute configuration of C-11 in 4 was determined as S based on the Rh₂(OCOCF₃)₄-induced CD data; the absolute configuration of 3 was determined as R by comparison of its experimental and calculated electronic circular dichroism (ECD). The antioxidant activities of compounds 1–14 were also evaluated. Compound 4 exhibited strong antioxidant activity with an IC₅₀ value of 2.97 ± 1.30 μM, whereas compounds 3 and 8 showed antioxidant activities with IC₅₀ values of 44.36 ± 0.30 and 48.00 ± 2.01 μM, respectively.     

Bioactive aporphine alkaloids from the stems of Dasymaschalon rostratum

Three undescribed aporphine alkaloids dasymaroine A (1), 3-methoxyoxoputerine N-oxide (2), and dasymaroine B (3), along with nine known analogues (4–12) were isolated from the stems of Dasymaschalon rostratum Merr. The structures were elucidated using spectroscopic methods and by comparison with published NMR spectroscopic data. Compound 1 is a rarely reported nitro aporphine alkaloid and its absolute configuration was defined based on negative specific rotation and single-crystal X-ray diffraction. Compound 2 represents the first example of oxoaporphine alkaloid N-oxide. All compounds were evaluated for their activities of six pathogenic bacteria, 1 exhibited significant inhibition against Escherichia coli and Saphylococcus aureus with MIC values of 1.2 and 2.5 μM, respectively. As well as compounds 1–5, 7, 10, 12 were evaluated for their anti-HIV activities with EC₅₀ ranged from 1.93 to 9.70 μM.     

Polyphenols from the bark of Rhus verniciflua and their biological evaluation on antitumor and anti-inflammatory activities

Bioassay-guided fractionation and chemical investigation of the extract of Rhus verniciflua bark resulted in the identification of six polyphenols, rhusopolyphenols A–F (1–6), together with four known compounds including (2R,3S,10S)-7,8,9,13-tetrahydroxy-2-(3,4-dihydroxyphenyl)-2,3-trans-3,4-cis-2,3,10-trihydrobenzopyrano[3,4-c]-2-benzopyran-1-one (7), peapolyphenol C (8), cilicione-b (9) and (αR)-α,3,4,2′,4′-pentahydroxydihydrochalcone (10). The structures of these polyphenols were elucidated by spectroscopic analysis, including 1D and 2D NMR, and HR-ESIMS, and their absolute configurations were further confirmed by a combination of chemical methods and CD data analysis. All isolates were evaluated for their antiproliferative activities against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15), and compounds 4–6, 9 and 10 showed antiproliferative activity against the tested cells, with IC₅₀ values of 3.31–18.51 μM. On the basis of the expanded understanding that inflammation is a crucial cause of tumor progression, the anti-inflammatory activities of these compounds were determined by measuring nitric oxide (NO) levels in the medium of murine microglia BV-2 cells. Compounds 5 and 10 significantly inhibited NO production in lipopolysaccharide (LPS)-stimulated murine microglia BV-2 cells with IC₅₀ values of 28.90 and 12.70 μM, respectively.     

Design,synthesis, anti-inflammatory,cytotoxic and cell based studies of some novel side chain analogues of myrrhanones A & B isolated from the gum resin of Commiphora mukul

Myrrhanones A (1) and B (2), isolated from the gum resin of Commiphora mukul, were reported to exhibit anticancer and anti-inflammatory activities. In view of their interesting skeletal features and biological activities they have been chemically modified by exploiting their side chain functionalities to synthesise 29 diverse analogues. All the synthesized analogues were screened for their cytotoxic potential against a panel of five human cancer cell lines which include DU145 (Prostate), HT-29 (Colon), MCF-7 (Breast), Hela (Cervical) and U87MG (Glioblastoma) along with a normal cell line (L132). The synthesized analogues were also screened for anti-inflammatory activity against TNF-α and IL-1β using LPS induced inflammation model employing U937 cells. The biological screening results revealed that compounds 4b (piperidine analogue), 9d (linear aliphatic four member amide analogue) and 9i (N-methyl piperazine analogue) displayed significant cytotoxic activity against MCF-7, HT-29 and DU145 [IC₅₀ (μM): 4.65 ± 1.28, 5.48 ± 0.13 and 6.63 ± 1.39] respectively. These analogues were further taken up for apoptotic assay, which confirmed that compounds 4b, 9d and 9i induced apoptosis in MCF-7, HT-29, DU145 cells and arrested in G0/G1 phase. Further, compounds 9c and 9g found to exhibit good anti-inflammatory activity against TNF-α with IC₅₀ (μM) values of 10.02 ± 2.13 and 10.53 ± 0.48 respectively, while compound 2 exhibited strong inhibitory activity against both TNF-α (IC₅₀: 9.39 ± 0.44 μM) and IL-1β (IC₅₀: 12.15 ± 1.36 μM).     

Leucoflavonine,a new bioactive racemic flavoalkaloid from the leaves of Leucosceptrum canum

A new flavoalkaloid racemate, leucoflavonine (1), together with its flavonoid precursor pectolinarigenin (2), was isolated from the leaves of Leucosceptrum canum collected from Tibet. Its structure was established by comprehensive spectroscopic analysis. Chrial separation of the enantiomers of 1 was achieved, and their absolute configurations were determined as S-(+)- and R-(?)-leucoflavonines ((+)-1a and (?)-1b) by comparison of their computational and experimental optical rotations. Biological assays indicated that both (+)-1a and (?)-1b exhibited inhibitory activity against acetylchlorinesterase (AChE) in vitro (IC₅₀?=?68.0?±?8.6 and 18.3?±?1.8?μM, respectively). Moreover, (?)-1b displayed cytotoxicity against human hepatoma cells HepG2 (IC₅₀?=?52.9?±?3.6?μM), and inhibited the production of interleukelin-2 (IL-2) in Jurkat cells (IC₅₀?=?16.5?±?0.9?μM), while (+)-1a showed no obvious activity in these assays.     

Monoterpenoid indole alkaloids from Kopsia hainanensis Tsiang

A phytochemical investigation on the twigs and leaves of Kopsia hainanensis Tsiang resulted in the isolation and identification of 18 alkaloids, including two sarpagine type alkaloids (1 and 2), five eburnane type alkaloids (3–7), three aspidofractinine type alkaloids (8–10), one vincadine type alkaloid (11), three akuammiline type alkaloids (12–13 and 15), one corynanthean type alkaloid (14), two ajmalicine-like type alkaloids (16 and 17), and one aspidospermine type alkaloid (18). The new structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS, and 1D and 2D NMR experiments. Compounds 1–2, 4–5, 7, and 10–17 are herein reported for the first time from this plant, while the compounds 1, 2, 7, and 12–17 have not been previously recorded in the Kopsia genus. The chemotaxonomic significance and distribution of these monoterpenoid indole alkaloids in Kopsia genus are discussed.     

Chemical constituents from the seeds of Cassia obtusefolia and their in vitro α-glucosidase inhibitory and antioxidant activities

Basing on chromatographic separation techniques, fifteen aglycones (1–15), including two new anthraquinone aglycones (1, 2) and thirteen known compounds (3–15), were isolated from the small polar fraction of Cassia obtusefolia (petroleum ether extract). Structural elucidations were performed by 1D/2D NMR spectroscopy and mass spectrometry. The in vitro antioxidant and α-glucosidase inhibitory activities of these fifteen compounds were determined. Except compounds 12 (IC₅₀ 3.03 ± 0.31 μg/mL, stronger than ascorbic acid, which IC₅₀ was 6.48 ± 2.30 μg/mL) and 13 (IC₅₀ 78.40 ± 2.39 μg/mL), the free radical scavenging capacities of other compounds were weak. Compounds 4, 5, 6 and 13 exhibited inhibitory activities on α-glucosidase with IC₅₀ values of 50.60 ± 1.10, 22.57 ± 0.07, 60.09 ± 1.40, and 80.01 ± 2.66 μg/mL separately, however, all the α-glucosidase inhibitory activities were weaker than positive control (acarbose).     

Design,synthesis, and biological evaluation of novel aminopyrimidinylisoindolines as AXL kinase inhibitors

A novel series of aminopyrimidinylisoindoline derivatives 1a-w having an aminopyrimidine scaffold as a hinge region binding motif were designed and synthesized. Among them, six compounds showed potent inhibitory activities against AXL kinase with IC₅₀ values of submicromolar range. Especially, compound 1u possessing (4-acetylpiperazin-1-yl)phenyl moiety exhibited extremely excellent efficacy (IC₅₀?=?<0.00050?μM). Their in vitro antiproliferative activities were tested over five cancer cell lines. Most compounds showed good antiproliferative activities against HeLa cell line. The kinase panel profiling of 50 different kinases and the selected inhibitory activities for the representative compound 1u were carried out. The compound 1u exhibited excellent inhibitory activities (IC₅₀?=?<0.00050, 0.025, and 0.050?μM for AXL, MER, and TYRO3, respectively) against TAM family, together with potent antiproliferative activity against MV4-11 cell line (GI₅₀?=?0.10?μM) related to acute myeloid leukemia (AML).     

Three new cucurbitane triterpenoids from Hemsleya penxianensis and their cytotoxic activities

Two new cucurbitane glycosides, hemslepenside A (1) and 16,25-O-diacetyl-cucurbitacin F-2-O-β-d-glucopyranoside (3), one new cucurbitacin, 16-O-acetyl-cucurbitacin F (2), along with three known cucurbitane compounds, were isolated from the roots of Hemsleya penxianensis. The structures of 1–6 were established on the basis of extensive spectroscopic and chemical methods. The isolated compounds were evaluated for their cytotoxic activities against different three human cancer cell lines, with IC₅₀ values in the low microgram range.     

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.     

Thiohydantoin derivatives incorporating a pyrazole core: Design,synthesis and biological evaluation as dual inhibitors of topoisomerase-I and cycloxygenase-2 with anti-cancer and anti-inflammatory activities

A new series of hybrid structures 14a–l containing thiohydantoin as anti-cancer moiety and pyrazole core possessing SO₂Me pharmacophore as selective COX-2 moiety was designed and synthesized to be evaluated for both anti-inflammatory and anti-cancer activities. The synthesized compounds were evaluated for their COX inhibition, in vivo anti-inflammatory activity, ulcerogenic liability, in vitro cytotoxic activity and human topoisomerase-1 inhibition. All compounds were more selective for COX-2 isozyme and showed good in vivo anti-inflammatory activity. Also, all derivatives were significantly less ulcerogenic (ulcer indexes = 2.64–3.87) than ibuprofen (ulcer index = 20.25) and were of acceptable ulcerogenicity when compared with the non-ulcerogenic reference drug celecoxib (ulcer index = 2.99). Regarding anti-cancer activity, most of the target derivatives showed activities against A-549, MCF-7 and HCT-116 cell lines (IC₅₀ = 5.32–17.90, 3.67–19.04 and 3.19–14.87 µM respectively) in comparison with doxorubicin (IC₅₀ = 0.20, 0.50 and 2.44 µM respectively). Compound 14a inhibited the human topoisomerase-1 with IC₅₀ = 29.7 µg/ml while 14b and 14c showed more potent inhibitory activity with IC₅₀ = 26.5 and 23.3 µg/ml. respectively in comparison with camptothecin (IC₅₀ = 20.2 µg/ml). Additionally, COX-2 and human topoisomerase-1 docking studies were carried out to explain the interaction of the synthesized hybrid structures 14a–l with the target enzymes.