Fluevirines E and F,two new alkaloids from Flueggea virosa

Abstract

Two new alkaloids, fluevirines E (1) and F (2), along with six known Securinega alkaloids, were isolated from the methanol extract of the twigs and leaves of Flueggea virosa. The structures and absolute configurations of the new compounds were elucidated by means of MS, NMR, and ECD analyses. Compound 1 is a new dimeric indole alkaloid while 2 is a new securinega-type alkaloid. The in vitro cytotoxic activities of the isolated alkaloids against several human cancer cell lines and their acetylcholinesterase inhibitory activity were also evaluated.     

Fluevirines A–D,four new securinega-type alkaloids from Flueggea virosa

Four new securinega-type alkaloids, fluevirines A–D (1–4), along with ten known ones, were isolated from the twigs and leaves of Flueggea virosa. The structures of the new ones were elucidated by means of spectroscopic methods, and their absolute configurations were assigned by CD spectra. Among them, fluevirine A (1) was a novel C,C-linked dimeric indolizidine alkaloid and showed weak antimicrobial activity against Staphylococcus aureus.     

Alkaloids from the Twigs and Leaves of Daphniphyllum macropodum

Three new alkaloids, macrodumines A–C ( 1 – 3 , resp.), along with ten known analogs, were isolated from the twigs and leaves of Daphniphyllum macropodum. Their structures were elucidated on the basis of spectroscopic methods. The 11‐OH configuration of the known alkaloid hydroxydaphgraciline ( 4 ) was assigned as α for the first time by comparing the NMR data with those of macrodumine C ( 3 ).     

Isolation and structure of rosicine from Catharanthus roseus

An investigation of the alkaloidal constituents of the leaves of Catharanthus roseus has led to the isolation of a new alkaloid, “rosicine”, to which structure (1) has been assigned on the basis of spectroscopic studies. Two other alkaloids isolated have been identified as 14, 15-dehydroepivincadine and 19-hydroxytabersonine.     

Monoterpenoid Indole Alkaloids from Alstonia mairei

Three new monoterpenoid indole alkaloids, (14α,15α)‐14,15‐epoxyaspidofractinine ( 1 ) and maireines A and B ( 2 and 3 , resp.), together with 19 known alkaloids, were isolated from the leaves and twigs of Alstonia mairei. The structures of the new compounds were elucidated by 1D‐ and 2D‐NMR spectroscopic methods in combination with MS experiments.     

Two New Alkaloids from Flueggea virosa

Two new securinega‐type alkaloids and four known ones were isolated from the twigs and leaves of Flueggea virosa. The structures of the new compounds were elucidated by means of spectroscopic methods (UV, IR, HR‐ESI‐MS, and 1D‐ and 2D‐NMR), and the absolute configurations were assigned by CD spectra. The structures of the known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature.     

Seven New Monoterpenoid Indole Alkaloids from Gelsemium elegans

Seven new indole alkaloids were isolated from the roots of Gelsemium elegans Benth. and their structures were determined by spectroscopic analysis and chemical transformation from known alkaloids. Kounaminal ( 1 ) is a new koumine‐type alkaloid that contains an unusual aminal moiety. Humantenoxenine ( 2 ) and 15‐hydroxyhumantenoxenine ( 3 ) are humantenine‐type alkaloids that contain a novel β‐amino‐α,β‐unsaturated ketone residue. The other four novel alkaloids are two gelsedilam‐related and two gelsenicine‐related alkaloids.     

Berberis alkaloids. XXV. Structures of bernumidine and bernumicine

The alkaloid compositions of young shoots and leaves ofBerberis nummularia Bge. have been studied. The new alkaloids bernumidine (II) and bernumicine (III) have been isolated from the leaves, and their structures have been established.     

Two new monoterpenoid indole alkaloids from Tabernaemontana divaricata

Two new monoterpenoid indole alkaloids, tabervarines A (1) and B (2), along with seven known monoterpenoid indole alkaloids, were isolated from the methanol extract of the twigs and leaves of Tabernaemontana divaricata. The structures including the absolute configurations of the new alkaloids were elucidated based on MS, NMR, and ECD calculation. The in vitro cytotoxic activities of the isolated alkaloids against several human cancer cell lines were also evaluated.     

Diterpenoid Alkaloids from Delphinium tatsienense

Three new C₂₀‐diterpenoid alkaloids, along with twenty‐two known alkaloids, were isolated from the whole herbs of Delphinium tatsienense. The new alkaloids include a vakognavine‐type C₂₀‐diterpenoid alkaloid, designated as tatsienenseine A ( 1 ), and two hetisine‐type C₂₀‐diterpenoid alkaloids, designated as tatsienenseines B ( 2 ) and C ( 3 ). Their structures were elucidated by IR, HR‐ESI‐MS, 1D‐ and 2D‐NMR analyses.     

Meloslines A and B,two novel indole alkaloids from Alstonia scholaris

An unprecedented indole alkaloid melosline A (1), with 6/5/6/6 tetracyclic ring skeleton, together with a new alkaloid melosline B (2) and one known compound (3) were isolated from the leaves and twigs of Alstonia scholaris. The new structures were elucidated by comprehensive spectroscopic analysis. The absolute configuration of compound 1 was confirmed by comparison of experimental data with calculated electronic circular dichroism (ECD). Compound 1 exhibited moderate cytotoxicity against MCF-7 cancer cell lines.     

Trimeric and Dimeric Carbazole Alkaloids from Murraya microphylla

Seventeen new carbazole alkaloid derivatives, including a trimeric carbazole racemate, (±)-microphyltrine A (1), 15 dimeric carbazole racemates, (±)-microphyldines A–O (2–16), and a C-6–C-3″-methyl-linked dimeric carbazole, microphyldine P (17), were isolated from the leaves and stems of Murraya microphylla (Merr. et Chun) Swingle. The structures of the new compounds were elucidated on the basis of HRESIMS and NMR data analysis. The optically pure isomers of these isolated carbazole alkaloids were obtained by chiral HPLC separation and their absolute configurations were determined by electronic circular dichroism (ECD) data analysis.     

Diterpenoid Alkaloids from Delphinium yunnanense

Three new diterpenoid alkaloids, along with eleven known alkaloids, were isolated from the whole herbs of Delphinium yunnanense. The new alkaloids include a rearranged‐type C₁₉‐diterpenoid alkaloid, named yunnanenseine A ( 1 ), and two hetisine‐type C₂₀‐diterpenoid alkaloids, named yunnanenseine B and C ( 2 and 3 , resp.). Their structures were elucidated by detailed NMR‐spectroscopic studies.     

Leucomidines A–C,novel alkaloids from Leuconotis griffithii

Two novel indole alkaloids and new quinazoline alkaloids, namely leucomidines A–C (1–3), were isolated from the barks of Leuconotis griffithii. The structures including the absolute configuration were elucidated on the basis of spectroscopic data, chemical means, and CD calculations. The quinazoline alkaloid, 3, is proposed to be derived from the same biogenetic precursor as the indole alkaloids 1 and 2.     

Anti-inflammatory chromone alkaloids and glycoside from Dysoxylum binectariferum

Herein we report isolation of a new chromone alkaloid chrotacumine K (12) from fruits and a chromone glycoside schumaniofioside A (13) from leaves of Dysoxylum binectariferum Hook f. Schumaniofioside A is reported for the first time from Meliaceae family. Other known alkaloids isolated include rohitukine (1) and chrotacumine E (6). The structure of new alkaloid 12 was elucidated on the basis of extensive 1D and 2D NMR analysis, synthesis and chemical hydrolysis. Chemically, chrotacumine K (12) is a 3′-O-acetyl rohitukine which on chemical or enzymatic hydrolysis produces rohitukine. The new alkaloid 12 is also present in seeds and stem-barks of this plant. The glycoside schumaniofioside A (13) is present only in leaves, and in abundance (～1% w/w of dried leaves). The isolated compounds and extracts were evaluated for in vitro effect on the proinflammatory cytokines (TNF-α and IL-6) in human monocytic THP-1 cells. The alkaloid 12 displayed potent inhibition (57%) of TNF-α at 0.3 µM, and was non-toxic to THP-1 cells up to 40 µM, indicating its excellent therapeutic window. Furthermore, a nitrobenzoyl ester analog 15e showed better inhibition of IL-6 than parent natural product chrotacumine K.     

Rhazimine - a new alkaloid from the leaves of rhazya stricta

Studies on the alkaloids in the leaves of Rhazya stricta have resulted in the isolation of a new alkaloid “rhazimine” (2) bearing a novel skeletal system closely related to the ajmaline group of alkaloids.     

New oxindole and indole alkaloids from Gelsemium rankinii

Six new humantenine-type (1-6) and two new gelsemine-type (7, 8) oxindole alkaloids and one new indole alkaloid (9) were isolated from the leaves and branches of Gelsemium rankinii. The structures of the new alkaloids were determined by spectroscopic analyses. Among them, 6-hydroxyhumantenine (5) is the first example of a Gelsemium alkaloid with an oxygen function at C-6 position, and is a plausible biogenetic precursor of gelsemine-type alkaloids.     

Two new cytotoxic furoquinoline alkaloids isolated from Aegle marmelos (Linn.) Correa

Two new cytotoxic furoquinoline alkaloids were isolated from the leaves of Aegle marmelos (Linn.) Correa; one from the total alkaloidal fraction (acid/base shake-out method) of the CHCl₃ extract and identified as 7,8-dihydroxy-4-hydrofuroquinoline and named trivially as Aegelbine-A. The other new alkaloid isolated from the pet. ether extract and identified as 4-hydro-7-hydroxy-8-prenyloxyfuroquinoline and named trivially as Aegelbine-B, together with a known alkaloid; aegeline and a known phenolic acid; ρ-hydroxybenzoic acid. The structures of all the isolated compounds were established based on 1D and 2D NMR spectroscopy and HR-ESI/MS. The cytotoxic activity of the isolated compounds was evaluated in vitro against HepG-2, PC3, A549 and MCF-7 cell lines. The obtained results revealed promising activity with structure-based relationship which is discussed briefly.     

Two New Indole Alkaloids from Emmenopterys henryi

Two new indole alkaloids, 5‐oxodolichantoside ( 1 ) and deglycocadambine ( 2 ), were isolated from the twigs and leaves of Emmenopterys henryi, together with four known indole alkaloids and five known iridoids. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analyses, including 1D‐ and 2D‐NMR experiments, and confirmed by single‐crystal X‐ray diffraction studies. This is the first report on the isolation of indole alkaloids from this species. The indole alkaloids were evaluated for their cytotoxic activities against five human cancer lines.     

Virosaines A and B, two new birdcage-shaped Securinega alkaloids with an unprecedented skeleton from Flueggea virosa

Two new Securinega alkaloids, virosaines A (1) and B (2), were isolated from the twigs and leaves of Flueggea virosa. The structures and absolute configurations were elucidated by means of NMR, X-ray diffraction, and CD analyses. Compounds 1 and 2 represent the first examples of Securinega alkaloids bearing a 7-oxa-1-azabicyclo[3.2.1]octane ring system, whose plausible biogenetic pathways were also proposed.