A novel monoterpenoid indole alkaloid with anticancer activity from Melodinus khasianus

A novel monoterpenoid indole alkaloid with unprecedented 6/5/6/4/6 fused rings, khasuanine A (1), was isolated from the roots of Melodinus khasianus. The structure was determined by extensive analysis of its HR-MS, 1D-, and 2D-NMR spectra. Khasuanine A markedly inhibited the proliferation of PC3 cell with IC₅₀ value of 0.45 μM. Further study showed that khasuanine A was able to induce the apoptosis of PC3 cells by activation of caspase 3 and p53, and by inhibition of Bcl-2.     

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.     

Antileishmanial activity of indole alkaloids from Aspidosperma ramiflorum

The present study was designated to evaluate the antileishmanial activity of acid and basic fractions that were obtained after acid-basic extraction, from ethanolic 70% crude extract and pure compounds from the stem bark of Aspidosperma ramiflorum. The basic alkaloidal fraction presented a good activity against the extracellular form (promastigotes) of Leishmania (L.) amazonensis (LD(50) value<47 microg/ml). Based on these findings, the basic fraction was fractionated on silica gel column chromatography in a bioassay-guided fractionation affording individual purified ramiflorines A and B. Both ramiflorines A and B showed significant activity against Leishmania (L.) amazonensis (LD(50) values of 16.3+/-1.6 microg/ml and 4.9+/-0.9 microg/ml, respectively). Our results are promising, showing that these compounds are biologically active against Gram-positive bacteria.     

Cytotoxic monoterpenoid indole alkaloids from the leaves and twigs of Tabernaemontana bovina

Phytochemical investigation of the leaves and twigs of Tabernaemontana bovina led to the isolation of 10 monoterpenoid indole alkaloids, including two new taberbovinines A (1) and B (2) along with eight known analogs: mehranine (3), 14α,15β-dihydroxy-N-methylaspidospermidine (4), (16S*)− 15-epi-E-isositsirikine (5), (16R*)− 15-epi-E-isositsirikine (6), 16 R*-19,20-E-isositsirikine acetate (7), hecubine (8), voafinidine (9), and voacangarine (10). Taberbovinine B (2) represents the first case of an unusual ring C/D cleavage among the natural Corynanthe-type alkaloids. Compounds 2 and 8 exhibited weak cytotoxicity against five human cancer cell lines, including SK-LU-1, HepG2, MCF-7, SK-Mel-2, and LNCaP, with IC₅₀ values ranging from 42.9 to 66.3 μM, whereas compounds 4 − 6 and 9 were cytotoxic toward MCF-7, SK-LU-1 and LNCaP cells, with IC₅₀ values in a range of 51.6–93.3 μM.     

Polycyclic monoterpenoid indole alkaloids from Alstonia rostrata and their reticulate derivation

Five new alkaloids together with 20 known ones were isolated from Alstonia rostrata, and identified on the base of NMR, MS, UV and IR spectroscopic data. Additionally, alstrostine G (1) possessed an unprecedented 6/5/6/6/5/6-ring system. The analysis of those alkaloids’ biosynthetic pathway partly indicated their reticulate metabolic relationship. The research result disclosed diverse biogenesis of monoterpenoid indole alkaloids from Alstonia rostrata speciesin combination with previous reported alstrostine A.     

Effects of indole alkaloids from gramineae on aphids

The indole bases N_∞-methyltryptamine, 5-methoxy-N, N-dimethyltryptamine, 3-N,N-dimethylaminomethylindole (gramine) and 5-methoxytryptamine decreased survival of nymphs of Rhopalosiphum maidis with LD₅₀ of 3.8, 3.5, 2.9 and 2.3 mM, respectively, after 48 hr of feeding with a synthetic diet. Gramine also decreased survival of Schizaphis graminum with an LD₅₀ of 0.7 mM after 48 hr of feeding. The four compounds tested showed feeding deterrent activity on the aphids at concentrations as low as 0.5 mM. In addition, gramine showed toxic effects on S. graminum. Since the deleterious effects of gramine and related compounds in synthetic diets are observed at concentrations similar to those found in plants, it is possible that these molecules may have a role in protecting the plant against aphids     

Anticancer indole alkaloids of Ervatamia heyneana

The wood and stem bark of Ervatamia heyneana (Apocynaceae) yielded 14 indole alkaloids and 3 triterpenoids. Six of these isolates, camptothecin (2), 9-methoxycamptothecin (3), coronaridine (1), pericalline (25), heyneatine (18) and 10-methoxyeglandine- N-oxide (4) displayed cytotoxic activity. Three of the indole alkaloids 18, 4 and 10-hydroxycoronaridine (8) are new members in the iboga series and their structures were determined by a combination of spectral interpretation and chemical correlation.     

Illigerones A and B,two new long-chain secobutanolides from Illigera henryi W. W. Sm.

Two new long-chain secobutanolides, illigerones A (1) and B (2), together with five known compounds, actinodaphnine (3), cryptodorine (4), β-sitosterol (5), daucosterol (6), and stigmasterol (7) were isolated from Illigera henryi W. W. Sm. The structures of 1 and 2 were identified by HRESIMS, EIMS, 1D/2D NMR, and electronic circular dichroism (ECD) spectra. Compound 1 exhibited the moderate cytotoxic activities against five tumour cells. This is the first report of secobutanolides isolated from plants of Hernandiaceae.     

Monoterpene indole alkaloids in Uncaria rhynchophlly (Miq.) Jacks chinensis and their chemotaxonomic significance

From the Uncaria rhynchophlly (Miq.) Jacks, twelve monoterpene indole alkaloids, such as harman (1), strictosamide (2), vincosidelactam (3), cadambine (4), 3α-dihydrocadambine (5), 7-epi-javaniside (6), rhynchophylline (7), isorhynchophylline (8), hirsutine (9), vincosamide-6′-O-β-D-glucopyranoside (10), vincosamide-11-O-β-D-glucopyranoside (11) and 2′-O-[β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl]-11-hydroxyvincosamide (12) were isolated and identified. Structure elucidation of these compounds was performed on the basis of NMR spectroscopic data. Compounds 2, 5, 6, 10, 11 and 12 were obtained from this species for the first time. Chemotaxonomic significance of these compounds is described herein.     

New alkaloids from Strychnos icaja

The alkaloids of Strychnos icaja (Loganiaceae) have been studied. An extract from Zaire leaf material yielded nine alkaloids, comprising novacine, the new base 21,22-α-epoxy-4,14-dihydroxy-3-methoxy-N-methyl-sec.-pseudostrychnine, and seven others of known structure previously obtained from the plant. Cameroun leaf material gave five alkaloids, of which one, 21,22-α-epoxy-3,4-dimethoxy-N-methyl-sec.-pseudostrychnine, is new. Fruits from Gabon afforded eight alkaloids; two of them are new and are formulated as 21,22-α-epoxy-4-methoxy-N-methyl-sec.-pseudostrychnine and the corresponding 14-hydroxy derivative.     

Dehydroisostrychnobiline,matopensine and other alkaloids from Strychnos kasengaensis

Eighteen alkaloids have been identified in the root bark, stem bark and leaves of Strychnos kasengaensis from Zaire, They are isoretulinal, retuline, desacetyl isoretuline, desacetyl retuline, dehydroisostrychnobiline, matopensine and its mono-N-oxide, nordihydrotoxiferine, isoretuline, N(1)-desacetyl 18-acetoxyisoretuline, Wieland-Gumlich aldehyde and diol, desacetyl isoretulinal, O-acetyl retuline, 16R-isositsirikine, O-acetyl isoretuline, 11-methoxy retuline and 11-methoxy isoretuline.     

Majvinine: A new indole alkaloid of Vinca major

A new alkaloid, majvinine, was isolated from aerial parts of Vinca major. Its structure was determined by chemical and spectroscopic investigations     

Bioactive benzylisoquinoline alkaloids from Artabotrys hexapetalus

Two new benzylisoquinoline alkaloids, namely, hexapetalines A (1) and B (2), along with 11 known alkaloids were isolated from the stems of Artabotrys hexapetalus. The structures of 1 and 2 with their absolute configurations were elucidated by extensive spectroscopic methods and the known compounds were identified by comparisons with data in the literature. All new compounds were evaluated for their cytotoxicities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Alkaloids 1 and 2 exhibited inhibitory effects with IC₅₀ values comparable to those of cisplatin.     

Zoapatanolide A and B,two new heliangolides from Montanoa tomentosa

The re-investigation of Montanoa tomentosa afforded, in addition to known diterpenoids of the kaurene class, two new sesquiterpene lactones, zoapatanolide A and B, of the heliangolide type.     

Ervatinine,an indole alkaloid from Ervatamia coronaria

An indole alkaloid, ervatinine, has been isolated from the leaves of Ervatamia coronaria and its structure has been elucidated.     

Monoamine oxidase inhibition by monoterpene indole alkaloids and fractions obtained from Psychotria suterella and Psychotria laciniata

Alkaloid fractions of Psychotria suterella (SAE) and Psychotria laciniata (LAE) as well as two monoterpene indole alkaloids (MIAs) isolated from these fractions were evaluated against monoamine oxidases (MAO-A and -B) obtained from rat brain mitochondria. SAE and LAE were analysed by HPLC-PDA and UHPLC/HR-TOF-MS leading to the identification of the compounds 1, 2, 3 and 4, whose identity was confirmed by NMR analyses. Furthermore, SAE and LAE were submitted to the enzymatic assays, showing a strong activity against MAO-A, characterized by IC₅₀ values of 1.37?±?1.05 and 2.02?±?1.08 μg/mL, respectively. Both extracts were also able to inhibit MAO-B, but in higher concentrations. In a next step, SAE and LAE were fractionated by RP-MPLC affording three and four major fractions, respectively. The RP-MPLC fractions were subsequently tested against MAO-A and -B. The RP-MPLC fractions SAE-F3 and LAE-F4 displayed a strong inhibition against MAO-A with IC₅₀ values of 0.57?±?1.12 and 1.05?±?1.15 μg/mL, respectively. The MIAs 1 and 2 also inhibited MAO-A (IC₅₀ of 50.04?±?1.09 and 132.5?±?1.33 μg/mL, respectively) and -B (IC50 of 306.6?±?1.40 and 162.8?±?1.26 μg/mL, respectively), but in higher concentrations when compared with the fractions. This is the first work describing the effects of MIAs found in neotropical species of Psychotria on MAO activity. The results suggest that species belonging to this genus could consist of an interesting source in the search for new MAO inhibitors.     

Sativanine-a and sativanine-b,two new cyclopeptide alkaloids from the bark of Zizyphus sativa

From the bark of Zizyphus sativa, in addition to already described cyclopeptide alkaloids, two new compounds of this class, sativanine-A(1) and sativanine-B(2), were isolated. Both alkaloids contain 14-membered ring systems. 1 belongs to the integerrine type, while 2 is similar to nummularine-G, with an additional ring in the side chain.