Oxytrofalcatins A–F,N-benzoylindole analogues from the roots of Oxytropis falcata (Leguminosae)

Indole alkaloids, oxytrofalcatins A–F (1–6), together with five other known alkaloids (7–11), were isolated from the roots of Oxytropis falcata. Their structures were elucidated by comprehensive spectroscopic analyses, including using 1D and 2D NMR spectroscopy and mass spectrometry. This is the first report of N-benzoylindoles from a natural source. Compounds 1–6 lacked significant cytotoxicity against SGC-7901 and HL-60 tumor cell lines.     

Indole alkaloids from Ervatamia chinensis

Four vobasinyl–ibogan type bisindole alkaloids, ervachinines A–D (1–4), along with 12 known terpenoid indole alkaloids, were isolated from the whole plant of Ervatamia chinensis. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR, and the absolute configurations of 1–4 were determined by CD exciton chirality method. All of the compounds were evaluated for in vitro cytotoxicity against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480. Bisindole alkaloids 1–6 exhibited inhibitory effects, with IC₅₀ values comparable to those of cisplatin.     

Phytochemical and chemotaxonomic study on Dictamnus angustifolius G. Don ex Sweet (Rutaceae)

A phytochemical investigation of Dictamnus angustifolius led to the isolation of 14 compounds, including six furoquinoline alkaloids (1–6), two sesquiterpenoids (7, 8) and six flavonoids (9–14). The structures of these compounds were identified by spectroscopic methods and a comparison of their data with those reported in the literature. This is the first report of three furoquinoline alkaloids 1–3 and six flavonoids 9–14 from the genus Dictamnus and the first isolation of compounds 4–8 from D. angustifolius. The chemotaxonomic significance of furoquinoline alkaloids and sesquiterpenoids has also been summarized.     

Chemical constituents of Gardneria ovata wall

A phytochemical investigation on the aerial parts of Gardneria ovata Wall resulted in the isolation and identification of 14 compounds, including three gardneria glycoalkaloids (1–2 and 6), seven gardneria alkaloids (3–5 and 7–10), and four oxindole alkaloids (11–14). The structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS together with 1D and 2D NMR experiments. Compounds 1–2 and 11–14 are the first time reported from of G. ovate, while the compounds 3–4, 6, and 8 are also the characteristic secondary metabolites of the title plant. The chemotaxonomic significance and distribution of these monoterpenoid indole alkaloids in Gardneria genus are discussed.     

Alkaloids of Toddalia asiatica (Rutaceae)

Phytochemical investigation of the alkaloidal extract of the roots of Toddalia asiatica led to the isolation of a new seco-benzophenanthridine alkaloid (1) and twelve known alkaloids (2–13). The new structure was elucidated by means of spectroscopic analysis, and the known alkaloids were identified by comparison with the literature. Among these alkaloids, 1 and 5–7 were reported from the genus Toddalia for the first time. The distribution of the isolated alkaloids at genus/family level was presented via network analysis and their chemotaxonomic significance was also discussed.     

Effects of Picrasma quassioides and its active constituents on Alzheimer's disease in vitro and in vivo

Alzheimer disease (AD), a prevalent neurodegenerative disorder, is one of the leading causes of dementia. However, there is no effective drug for this disease to date. Picrasma quassioides (D.Don) Benn, a Chinese traditional medicine, was used mainly for the treatment of inflammation, fever, microbial infection and dysentery. In this paper, we reported that the EtOAc extract of Picrasma quassioides stems showed potential neuroprotective activities in l-glutamate-stimulated PC12 and Aβ_25-35-stimulated SH-SY5Y cell models, as well as improved memory and cognitive abilities in AD mice induced by amyloid-β peptide. Moreover, it was revealed that the anti-AD mechanism was related to suppressing neuroinflammatory and reducing Aβ_1-42 deposition using ELISA assay kits. To clarify the active components of the EtOAc extract of Picrasma quassioides stems, a systematic phytochemistry study led to isolate and identify six β-carboline alkaloids (1–6), seven canthin-6-one alkaloids (7–13), and five quassinoids (14–18). Among them, four β-carbolines (1–3, and 6) and six canthin-6-ones (7–11, and 13) exhibited potential neuroprotective activities in vitro. Based on these date, the structure-activity relationships of alkaloids were discussed. Furthermore, molecular docking experiments showed that compounds 2 and 3 have high affinity for both of dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYPKIA) and butyrylcholinesterase (BuChE).     

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 Laggera pterodonta

A phytochemical investigation on the aerial parts of Laggera pterodonta resulted in the isolation and identification of fourteen compounds, including six sesquiterpenoids (1–6), five flavonoids (7–11), one lignan (12), and two pyrrole alkaloids (13, 14). Among them, compounds 1–3, 7–9, and 11 are the characteristic class of secondary metabolites of L. pterodonta. Compounds 4 and 5 were firstly isolated from L. pterodonta and this is the first report of the presence of compounds 6, 10, and 12 from the genus Laggera. Pyrrole alkaloids 13 and 14 may serve as potential chemotaxonomic markers for L. pterodonta and could be used to distinguish among species of Compositae.     

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.     

Five new C19-diterpenoid alkaloids from Aconitum carmichaeli

Five new aconitine-type C₁₉-diterpenoid alkaloids, namely, carmichaenine A–E (1–5), and six known diterpenoid alkaloids, namely, 14-benzoylneoline (6), neoline (7), 10-hydroxyneoline (8), neolinine (9), songoramine (10), and songorine (11), were isolated from the aerial parts of Aconitum carmichaeli. Their structures were determined by extensive spectroscopic methods, especially 2D NMR analyses. Compounds 8 and 9 were isolated for the first time from A. carmichaeli.     

Chemical constituents from the calyces of Physalis alkekengi var. franchetii

One new monoterpenoid glycoside (1), together with seven known compounds, including two alkaloids (2–3), three phenylpropanoids (4–6), and two nucleosides (7–8) were isolated from the calyces of Physalis alkekengi var. franchetii. Their structures were elucidated by a combination of detailed spectroscopic analyses, chemical methods, and comparison with reported data. These eight compounds were isolated for the first time from the genus Physalis. The chemotaxonomic significance of these compounds was summarized.     

Induction of apoptosis in HuH-7 cancer cells by monoterpene and β-carboline indole alkaloids isolated from the leaves of Tabernaemontana elegans

Three known (1–3) and a novel (4) monoterpene indole alkaloids have been isolated from the methanol extract of leaves of Tabernaemontana elegans and their structures were elucidated by a series of spectroscopic experiments, involving NMR, MS, UV, and IR techniques. The isolated monoterpene indole alkaloids along with previously described β-carbolines (5–7) from the same specimen were studied for their apoptosis induction activity in human hepatoma HuH-7 cells. Methodology for apoptosis induction studies included cell viability assays, nuclear morphology assessments, and general caspase-3-like activity assays. The monoterpene indole alkaloids, tabernaemontanine (1) and vobasine (3) showed the most promising apoptosis induction profile in HuH-7 cells.     

Alkaloid constituents from flower buds and leaves of sacred lotus (Nelumbo nucifera,Nymphaeaceae) with melanogenesis inhibitory activity in B16 melanoma cells

Methanolic extracts from the flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) were found to show inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extracts, a new alkaloid, N-methylasimilobine N-oxide, was isolated together with eleven benzylisoquinoline alkaloids. The absolute stereostructure of the new alkaloid was determined from chemical and physicochemical evidence. Among the constituents isolated, nuciferine, N-methylasimilobine, (?)-lirinidine, and 2-hydroxy-1-methoxy-6a,7-dehydroaporphine showed potent inhibition of melanogenesis. Comparison of the inhibitory activities of synthetic related alkaloids facilitated characterization of the structure-activity relationships of aporphine- and benzylisoquinoline-type alkaloids. In addition, 3–30 μM nuciferine and N-methylasimilobine inhibited the expression of tyrosinase mRNA, 3–30 μM N-methylasimilobine inhibited the expression of TRP-1 mRNA, and 10–30 μM nuciferine inhibited the expression of TRP-2 mRNA.     

Chemical constituents of Melodinus hemsleyanus diels

Phytochemical investigation on the aerial parts of Melodinus hemsleyanus diels (Jahrb, Syst, 1995) led to the isolation and identification of 27 compounds, including fifteen aspidosperma-type alkaloids (1–15), four quinoline-type alkaloids (16–19), three quebrachamine-type alkaloids (20–22), and five eburna-type alkaloids (23–27). The structure of compound 1 was elucidated by means of spectroscopic analysis, including HRESIMS, and 1D and 2D NMR experiments. Compounds 1–2, 6, 10, 12, 13, 15, 16 and 20–27 are herein reported for the first time from the studied plant, while the compounds 1–2 and 21 have not previously been recorded in the genus Melodinus. The aspidosperma-type monoterpenoid indole alkaloids in M. hemsleyanus could serve as chemotaxonomic markers.     

Chemical constituents of Physochlaina physaloides (L.) G. Don (Solanaceae)

The study of the whole plants of Physochlaina physaloides (L.) G. Don. has led to the isolation of eight alkaloids (1–6, 18, and 25), fourteen flavonoids (9, 11–17, and 19–24), two coumarins (7 and 10), one iridoid (8). The structures of these compounds were identified spectroscopically, and nuclear magnetic resonance (NMR) data were compared with previously reported data. This is the first study to describe the isolation and identification of compounds 1–3, 7, and 10–25 in P. physaloides. The chemotaxonomic significance of these compounds in the genus Physochlaina and its closely related genera was discussed.     

Pyrrole alkaloids from the fruits of Morus alba

Phytochemical investigation of the fruits of Morus alba afforded seventeen pyrrole alkaloids including five new compounds. The structures of five new pyrrole alkaloids, named morroles B–F (4, 5, 7, 16 and 17), were determined on the basis of spectroscopic interpretations. 4-[Formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl]butanoate (2) was synthesized by chemical reaction but first isolated from nature. Among isolated compounds, compounds 6 and 14 significantly inhibited pancreatic lipase activity.     

Prenylated indole alkaloids from the stem bark of Hexalobus monopetalus

Seven new prenylated indole alkaloids (1–7) together with two known compounds (8–9) were isolated from the stem bark of Hexalobus monopetalus. Their structures were established on the basis of comprehensive spectroscopic analysis, including HR-MS, 1D and 2D NMR and by comparison of their spectral data with those reported in literature. The new compounds were tested for antimicrobial activity against selected pathogenic bacteria and fungi but showed no activity. The marked presence of prenylated indole alkaloids in Hexalobus and closely related genera makes them useful chemotaxonomic markers.     

Phytochemical constituents from Neolamarckia cadamba (Roxb.) Bosser

Phytochemical study on Neolamarckia cadamba (Roxb.) Bosser has yielded ten indole alkaloids, neolarmarckine A-E (1–5), cadamine (6), 3β-isodihydrocadambine (7), angustine (8) and naulafine (9) and harmane (10). The structural elucidation of all the compounds were conducted based on the thorough analysis of spectroscopic data and comparison with reported data. The chemotaxonomic significance of all these compounds were summarized. Among all the indole alkaloids, compound 3–5 were new compounds and isolated from Neolamarckia cadamba (Roxb.) Bosser for the first time. Compounds 1 and 2 were only found in Neolamarckia species while compounds 6 and 7 were only isolated from the family of Rubiaceace. Besides, compound 8 has been found in six genera of Rubiaceae and two genera of Apocynaceae while compound 9 was isolated from Neolamarkia species for the first time. Compound 10 can be found in many genera of Rubiaceae and also more than ten families such as Zygophyllaceae, Cyperaceae, Passifloraceae, Bignoniaceae, Sapotaceae, Elaeagnaceae, Leguminosae, Loganiaceae, Apocynaceae, Combretaceae, Chenopodiaceae, Commelinaceae and Polygalaceae.     

Chemical constituents from Aristolochia tagala and their chemotaxonomic significance

Fifteen compounds were obtained from the extract of the whole herbs of Aristolochia tagala, which were divided into eight aristolactam-type alkaloids (1–6, 14 and 15) and seven aristolochic acid derivatives (7–13). Their structures were identified as aristolactam BII, aristolactam II, sauristolactam, aristolactam I, 7-methoxyaristolactam IV, aristolactam AII, 3-hydroxy-4-methoxy-10-nitrophenanthrene-1-carboxylic acid methyl ester, ariskanin A, ariskanin D, ariskanin E, aristolochic acid C, ariskanin C, ariskanin B, aristolactam-N-β-D-glucoside and cepharanone A N-β-D-glucoside by comparison of their spectral data with those reported previously in the literature. The chemotaxonomic relationships between A. tagala and other species of genus Aristolochia were also discussed. As a result, the isolated compounds closely matched the ones obtained in other species of the genus.     

Venezuelines A–G,new phenoxazine-based alkaloids and aminophenols from Streptomyces venezuelae and the regulation of gene target Nur77

Five new phenoxazine-based alkaloids venezuelines A–E (1–5) and two new aminophenols venezuelines F–G (6–7), as well as three known analogues exfoliazone, chandrananimycin D and carboxyexfoliazone were isolated from the fermentation broth of the marine-derived bacterium Streptomyces venezuelae. The structures of new compounds were determined on the basis of extensive spectroscopic analysis. The cytotoxic activity of these compounds against a panel of tumor cell lines were tested, while the regulation of gene target Nur77 of 2 and exfoliazone (8) were evaluated.