Indole Alkaloids from the Roots of Ervatamia hainanensis

Two new indole alkaloids, named ibogamine-18-carboxylic acid, 3, 4-didehydro-7, 8-dioxo-methyl ester 1, ibogamine-18-carboxylic acid, 16, 17-didehydro-9, 17-dihydro-9-hydroxy （2-oxopropyl）-methyl ester 2, were isolated from Ervatamia hainanensis. Their structures were elucidated on the basis of spectroscopic methods.

Four new indole alkaloids from Plantago asiatica

Four new indole alkaloids,plasiaticines A-D(1-4),together with two known ones,were isolated from the seeds of Plantago asiatica.The structures of the new compounds were elucidated on the basis of comprehensive analysis of spectroscopic data.All compounds were tested for their cytotoxic activity,and all compounds except 4 were tested for their acetylcholinesterase(AChE)inhibitory activities.

Indole Alkaloids Inhibiting Neural Stem Cell from Uncaria rhynchophylla

Uncaria rhynchophylla is commonly recognized as a traditional treatment for dizziness,cerebrovascular diseases,and nervous disorders in China.Previously,the neuro-protective activities of the alkaloids from U.rhynchophylla were intensively reported.In current work,three new indole alkaloids(1–3),identified as geissoschizic acid(1),geissoschizic acid N4-oxide(2),and 3b-sitsirikine N4-oxide(3),as well as 26 known analogues were isolated from U.rhynchophylla.However,in the neural stem cells(NSCs)proliferation assay for all isolated compounds,geissoschizic acid(1),geissoschizic acid N4-oxide(2),isocorynoxeine(6),isorhynchophylline(7),(4S)-akuammigine N-oxide(8),and(4S)-rhynchophylline N-oxide(10)showed unexpected inhibitory activities at 10 μM.Unlike previous neuro-protective reports,as a warning or caution,our finding showcased a clue for possible NSCs toxicity and the neural lesions risk of U.rhynchophylla,while the structure–activity relationships of the isolated compounds were discussed also.

Structural characterization of monoterpene indole alkaloids in ethanolic extracts of Rauwolfia species by liquid chromatography with quadrupole time-of-flight mass spectrometry

Rauwolfia species(Apocynaceae) are medicinal plants well known worldwide due to its potent bioactive monoterpene indole alkaloids(MIAs) such as reserpine,ajmalicine,ajmaline,serpentine and yohimbine.Reserpine,ajmalicine and ajmaline are powerful antihypertensive,tranquilizing agents used in hypertension.Yohimbine is an aphrodisiac used in dietary supplements.As there is no report on the comparative and comprehensive phytochemical investigation of the roots of Rauwolfia species,we have developed an efficient and reliable liquid chromatography-tandem mass spectrometry(LC–MS/MS) method for ethanolic root extract of Rauwolfia species to elucidate the fragmentation pathways for dereplication of bioactive MIAs using highperformance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry(HPLC–ESI–QTOF–MS/MS) in positive ion mode.We identified and established diagnostic fragment ions and fragmentation pathways using reserpine,ajmalicine,ajmaline,serpentine and yohimbine.The MS/MS spectra of reserpine,ajmalicine,and ajmaline showed C-ring-cleavage whereas E-ring cleavage was observed in serpentine via Retro Diels Alder(RDA).A total of 47 bioactive MIAs were identified and characterized on the basis of their molecular formula,exact mass measurements and MS/MS analysis.Reserpine,ajmalicine,ajmaline,serpentine and yohimbine were unambiguously identified by comparison with their authentic standards and other 42 MIAs were tentatively identified and characterized from the roots of Rauwolfia hookeri,Rauwolfia micrantha,Rauwolfia serpentina,Rauwolfia verticillata,Rauwolfia tetraphylla and Rauwolfia vomitoria.Application of LC–MS followed by principal component analysis(PCA) has been successfully used to discriminate among six Rauwolfia species.

Monoterpenoid Indole Alkaloids from Inadequately Dried Leaves of Alstonia scholaris

Six new indole alkaloids,named alstoniascholarines L–Q(1–6),together with nineteen known analogues were isolated from the inadequately dried leaves of Alstonia scholaris.Their structures were elucidated on the basis of extensive analysis of spectroscopic data and by comparison of their physical and spectroscopic data with the literature values.In addition,the new alkaloids were tested for their cytotoxic and neurite outgrowth-promoting activities.

Engineering Terpenoid Indole Alkaloids Biosynthetic Pathway in Catharanthus roseus Hairy Root Cultures by Overexpressing the Geraniol 10-hydroxylase Gene

Catharanthus roseus contains important anti-tumor terpenoid indole alkaloids (TIAs) such as vinblastine and vincristine. Cytochrome P450 enzyme geraniol 10-hydroxylase (G10H) is a putative rate-limiting enzyme involved in the TIAs biosynthetic pathway in C. roseus. In this study the g10h gene driven by the cauliflower mosaic virus 35S (CaMV 35S) promoter was introduced into C. roseus through Agrobacterium-mediated transformation. The integration and overexpression of the target gene (g10h) in hairy root lines were confirmed by polymerase chain reaction and RT-QPCR analysis respectively. Overexpression of g10h in transgenic hairy root lines significantly enhanced the accumulations of monomeric alkaloid ajmalicine and dimeric alkaloids, vincristine and vinblastine. Total TIAs production in hairy roots reached (9.51) mg/g DW, over 3-fold higher than that in the untransformed root lines. This is the first report that engineering of g10h into TIAs-producing plant species results in significant enhancement of TIAs accumulation in cultured hairy roots. This study demonstrates that the putative rate-limiting step catalyzed by G10H is indeed the real rate-limiting step involved in the TIAs biosynthetic pathway in C. roseus, which is one of the key targets for promoting TIAs production by genetic engineering.

Acute and Sub-chronic Toxicity of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br. in Beagle Dogs

Alstonia scholaris(L.)R.Br.,an evergreen tropical plant rich in indole alkaloids with significant physiological activity,is traditionally used to treat respiratory diseases in China.This study was conducted to establish the toxicity profile of the alkaloid extract(TA)of A.scholaris leaves in non-rodents.After oral administration of a single dose(4 g/kg.bw),a num-ber of transient symptoms,such as unsteady gait,drooling,emesis,and reddening of peri-oral mucosa,were observed,but no treatment-related mortality.A sub-chronic toxicity study with a range of doses of TA(20,60 and 120 mg/kg.bw)was conducted for a 13-week treatment period,followed by 4-week recovery observation.Except for emesis and drooling in majority of animals in 120 mg/kg.bw treatment group,no clinical changes were observed in TA-treated animals.Data from electrocardiography,bone marrow,urine,fecal,hematology and clinical chemistry analyses were comparable between TA-treated and control animals.No significant differences in the relative organ weights and histopathological characteristics were evident between the TA-treated and control groups.Accordingly,the non-observed-adverse-effect-level(NOAEL)of TA was established as 120 mg/kg.bw.Our results add further knowledge to the safety database for indole alkaloid extracts from A.scholaris with potential utility as novel drug candidates.

Monoterpenoid indole alkaloids from Alstonia rostrata

Four new monoterpenoid indole alkaloids,alstrostines C-F together with thirteen known alkaloids were isolated from the leaves and twigs of Alstonia rostrata.All structures of new compounds were elucidated based on NMR,FTIR,UV,and MS spectroscopic data.Alstrostines C-E might originate from keto-enol tautomerism of preakummicine during biogenetic pathway of akummicine.

Two New Indole Alkaloids from Evodia rutaecarpa

Two new indole alkaloids. wuchuyuamide I and II were isolated from the fruits of Evodia rutaecarpa (Juss.) Benth and their structures were elucidated on the basis of spectral data.

Three New Indole Alkaloids from Tabernaemontana divaricata

Three new monoterpene indole alkaloids,3a-hydroxymethyl-ibogamine(1),3a-acetatemethoxyl-ibogamine(2),16a-hy-droxyl-ibogamine(3)together with six known alkaloids were isolated from the branches and leaves of Tabernaemontana divaricata(Apocynaceae).The structures of these alkaloids were determined by spectroscopic analyses.All isolated compounds showed no significant cytotoxicity against SGC-7901 gastric cancer,HeLa,and A-549 lung cancer cell lines(IC50>20μM).

Acute and Chronic Toxicity of Indole Alkaloids from Leaves of Alstonia scholaris (L.) R. Br. in Mice and Rats

Alstonia scholaris(L.)R.Br.(Apocynaceae)is an evergreen tree that has been used to treat lung diseases.In this study,the toxicity profile of indole alkaloids from leaves of A.scholaris was investigated.In acute toxicity tests,mice were adminis-tered total alkaloids(TA)and five indole alkaloids.In a chronic toxicity test,rats were continuously administered TA(50,100,and 300 mg/kg bw)for 13 weeks,followed by a 4-week recovery.A single administration of TA affected the behavior of mice,and at 12.8 g/kg bw,prone position,shortness of breath,wheezing,and convulsion were observed.The half-lethal dose(LD50)in mice was 5.48 g/kg bw,almost 2740 times the clinical dose in humans.Among the five indole alkaloids,the maximum tolerance dose in mice ranged from 0.75 to 4 g/kg bw.The TA-treated rats did not die and showed no adverse effects or dose-dependent changes in weight or food and water consumption,despite fluctuations in hematological and bio-chemical parameters compared with historical data.Furthermore,both gross and histopathological observations revealed no abnormalities in any organ.With daily oral administration to rats,the non-observed-adverse-effect-level of TA was 100 mg/kg bw.The results indicate that TA is safe for clinical use.

Two new indole alkaloids from Nauclea officinalis

Two new indole alkaloids, 4-oxo-4,12-dihydroindolo[2,3-a]quinolizine-3-carbaldehyde (1) and 1,6,7-trihydro-indolo- [2,3-a]furan[3,4-g]quinolizine-3,4(13H)-dione (2), were isolated from Nauclea officinalis. Their structures were determined on the basis of 1D and 2D NMR spectral data.

New Iboga‑Type Indole Alkaloids from Tabernaemontana divaricata

Two hitherto unknown iboga-type indole alkaloids,namely(3R)-7,19-di-epi-3-methoxytabernoxidine(1)and(3R,19R)-19-hydroxy-3-(2-oxopropyl)voacangine(2),together with eight known alkaloids(3-10),were isolated from the twigs and leaves of Tabernaemontana divaricata.Their structures were established on the basis of spectroscopic data interpretation,single crystal X-ray diffraction analysis and circular dichroism spectrum.

STUDIES ON THE INDOLE ALKALOIDS OF GELSEMIUM ELEGANS

The modified Hofmann degradation of koumine(1) has proved abortive. The struture and stereochemistry of the main product(3) were deduced by spectral methods and confirmed by X-ray diffration analysis. From the roots of Gelsemium elegans, dihydrokounine was first isolated as a natural product.

Genotoxicity and Safety Pharmacology Studies of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br.

Indole alkaloids extract(IAAS)was prepared from leaves of Alstonia scholaris(L.)R.Br.,an evergreen tropical plant widely distributed throughout the world.This plant has been used historically by the Dai ethnic people of China to treat respiratory diseases.This study evaluated the genotoxicity and safety pharmacology of IAAS to support clinical use.The bacterial reverse mutation(Ames)test,in vitro mammalian chromosomal aberration test,and in vivo mammalian erythrocyte micronucleus(MN)test were performed to evaluate genotoxicity.Mice were administered IAAS(240,480,or 960 mg/kg bw)once orally to observe adverse central nervous system effects.Furthermore,beagle dogs were administered IAAS(10,30,60 mg/kg bw)once via the duodenum to evaluate its effects on the cardiovascular and respiratory systems.IAAS with or without S9-induced metabolic activation showed no genotoxicity in the Ames test up to 500μg/plate,in the mammalian chromosomal aberration test up to 710μg/mL,or in the MN test up to 800 mg/kg bw.No abnormal neurobehavioral effects were observed in mice following treatment with up to 960 mg/kg bw of IAAS.Moreover,blood pressure,heart rate,electrocardiogram parameters,and depth and rate of breathing in anesthetized beagle dogs did not differ among the IAAS doses or from the vehicle group.These data indicated that IAAS did not induce mutagenicity,clastogenicity,or genotoxicity,and no pharmaco-toxicological effects were observed in the respiratory,cardiovascular,or central nervous systems.Our results increased understanding of safety considerations associated with IAAS,and may indicate that IAAS is a possible drug candidate.

Diprenylated Indole Alkaloids from Fruits of Hexalobus monopetalus

New hexalobine type alkaloid,5-(200,300-epoxy-300-methylbutyl)-3-(30-hydroxy-30-methyl-10-acetyloxy-but-20-yl)indole(1)alongside the known hexalobines 3-(20,30-dihydroxy-30-methylbutyl)-5-(300-methylcrotonoyl)indole(2),3,5-hexalobine C(3)and 3,5-hexalobine D(4)were isolated from fruits of Hexalobus monopetalus.Compounds 3 and 4 exhibited antifungal activity against Candida albicans.

Fabrication of edge-curled petals-like covalent organic frameworks and their properties for extracting indole alkaloids from complex biological samples

In this study,a functionalized covalent-organic framework(COF)was first synthesized using porphyrin as the fabrication unit and showed an edge-curled,petal-like and well-ordered structure.The synthesized COF was then introduced to prepare porous organic polymer monolithic materials(POPMs).Two composite POPM/COF monolithic materials with rod shapes,referred to as sorbent A and sorbent B,were prepared in stainless steel tubes using different monomers.Sorbents A and B exhibited relatively uniform porous structures and enhanced specific surface areas of 153.14 m;/g and 80.01 m;/g,respectively.The prepared composite monoliths were used as in-tube solid-phase extraction(SPE)sorbents combined with HPLC for the on-line extraction and quantitative analytical systems.Indole alkaloids(from Catharanthus roseus G.Don and Uncaria rhynchophylla(Miq.)Miq.Ex Havil.)contained in mouse plasma were extracted and quantitatively analyzed using the online system.The two composite multifunctional monoliths showed excellent clean-up ability for complex biological matrices,as well as superior selectivity for target indole alkaloids.Method validation showed that the RSD values of the repeatability(n=6)were≤3.46%,and the accuracy expressed by the spiked recoveries was in the ranges of 99.38%-100.91%and 96.39%-103.50%for vinca alkaloids and Uncaria alkaloids,respectively.Furthermore,sorbents A and B exhibited strong reusability,with RSD values≤5.32%,which were based on the peak area of the corresponding alkaloids with more than 100 injections.These results indicate that the composite POPM/COF rod-shaped monoliths are promising media as SPE sorbents for extracting trace compounds in complex biological samples.

TWO NEW INDOLE ALKALOIDS FROM MELODINUS MORSEI

Two new indole alkaloids named 152-hydroxy-14,15-dihydro-vindo- linine and 152-hydroxy-14,15-dihydro-16-epi-vindolinine were isolated from Melodinus morsei.Their structures were established by spectroscopic means and comparison with related compounds.

Three new indole alkaloids from Rauvolfia yunnanensis

One rare tetracyclic macroline-type indole alkaloid,named rauvoyunine A(1),and two new picraline-type alkaloids rauvoyunines B and C(2 and 3)were isolated from the aerial parts of Rauvolfia yunnanensis.Their structures were elucidated on the basis of extensive spectroscopic analysis.Compounds 2 and 3 were evaluated for their in vitro cytotoxicity against five human tumor cell lines.

Rauvotetraphyllines A-E, new indole alkaloids from Rauvolfia tetraphylla

Five new indole alkaloids rauvotetraphyllines A-E(1-5),together with eight known analogues,were isolated from the aerial parts of Rauvolfia tetraphylla.The structures were established by means of spectroscopic methods.