Chemical and Biological Aspects of Montanine-Type Alkaloids Isolated from Plants of the Amaryllidaceae Family.

Plants of the Amaryllidaceae family are promising therapeutic tools for human diseases and have been used as alternative medicines. The specific secondary metabolites of this plant family, called Amaryllidaceae alkaloids (AA), have attracted considerable attention due to their interesting pharmacological activities. One of them, galantamine, is already used in the therapy of Alzheimer's disease as a long acting, selective, reversible inhibitor of acetylcholinesterase. One group of AA is the montanine-type, such as montanine, pancracine and others, which share a 5,11-methanomorphanthridine core. So far, only 14 montanine-type alkaloids have been isolated. Compared with other structural-types of AA, montanine-type alkaloids are predominantly present in plants in low concentrations, but some of them display promising biological properties, especially in vitro cytotoxic activity against different cancerous cell lines. The present review aims to summarize comprehensively the research that has been published on the Amaryllidaceae alkaloids of montanine-type.

Astrernestin, a novel aurone-phenylpropanoid adduct from the roots of Astragalus ernestii.

Astragalus ernestii has been used as a substitute for Radix Astragali (Huang-Qi) in southwest China. To better understand the chemical rationale for the medicinal usage, the phytochemistry of A. ernestii was recently studied. As a result, a novel aurone-phenylpropanoid adduct astrernestin (1), together with five known phenoloids calycosin-7-O-ß-D-glucopyranoside (2), 4,4'-dimethoxy-3'-hydroxy-7,9':7',9-diepoxylignan-3-O-ß-D-glucopyranoside (3), syringaresinol-4-O-ß-D-monoglucoside (4), hedyotol D 4″-O-ß-D-glucopyranoside (5) and trifolirhizin (6), were isolated from the roots of A. ernestii. The structure of compound 1 was elucidated by extensive spectroscopic analysis and optical rotation calculation.

Lycodine-type alkaloids from Lycopodiastrum casuarinoides and their acetylcholinesterase inhibitory activity.

Five previously undescribed lycodine-type alkaloids, named huperzine Y (1), 8,15-epoxy-N-demethylhuperzinine (2), 7-hydroxyl-huperzinine (3), huperzine Z (4), and huperzine D N-oxide (5), were isolated from the aerial parts and roots of Lycopodiastrum casuarinoides (Lycopodiaceae), along with ten known analogues. The structures of the new compounds were elucidated by means of spectroscopic technique (IR, UV, MS and NMR). The absolute configurations of the new compounds were established on the basis of comparison of their experimental and TD-DFT (time-dependent density functional theory) calculated ECD spectra. Moreover, all the isolates were evaluated for acetylcholinesterase (AChE) inhibitory activity. Only huperzine C showed moderate activity, with an IC50 value of 0.525 ±â€¯0.140 µM, which was comparable with the positive control, huperzine A (IC50 = 0.143 ±â€¯0.029 µM).

Antibiotic-Potentiating Activity of Phanostenine Isolated from Cissampelos sympodialis Eichler.

Cissampelos sympodialis Eichler is well studied and investigated for its antiasthmatic properties, but there are no data in the literature describing antibacterial properties of alkaloids isolated from this botanical species. This work reports the isolation and characterization of phanostenine obtained from roots of C. sympodialis and describes for the first time its antimicrobial and antibiotic modulatory properties. Phanostenine was first isolated from Cissampelos sympodialis and its antibacterial activities were determined. Chemical structures of the alkaloid isolate were determined using spectroscopic and chemical analyses. Phanostenine was also tested for its antibacterial activity against standard strains and clinical isolates of Escherichia coli and Staphylococcus aureus. Minimal inhibitory concentration (MIC) was determined in a microdilution assay and for the evaluation of antibiotic resistance-modifying activity. MIC of the antibiotics was determined in the presence or absence of phanostenine at sub-inhibitory concentrations. The evaluation of antibacterial activity by microdilution assay showed activity for all strains with better values against S. aureus ATCC 12692 and E. coli 27 (787.69 mm). The evaluation of aminoglycoside antibiotic resistance-modifying activity showed reduction in the MIC of the aminoglycosides (amikacin, gentamicin and neomycin) when associated with phanostenine, MIC reduction of antibiotics ranging from 21 % to 80 %. The data demonstrated that phanostenine possesses a relevant ability to modify the antibiotic activity in vitro. We can suggest that phanostenine presents itself as a promising tool as an adjuvant for novel antibiotics formulations against bacterial resistance.

Lycodine type alkaloids from Lycopodiastrum casuarinoides with cytotoxic and cholinesterase inhibitory activities.

A chemical investigation on the 70% EtOH extract of the aerial parts of Lycopodiastrum casuarinoides led to the isolation of six novel lycodine type alkaloids, lycocasuarines A-F (1-6). The structures of the isolated compounds were established based on 1D and 2D (1H1H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated alkaloids were tested in vitro for cytotoxic potentials against seven malignant melanoma cell lines as well as acetylcholinesterase (AChE) and butyrocholinesterase (BuChE) inhibitory activities. As a result, alkaloids 1 and 3 exhibited significant cytotoxic activities against all the tested tumor cell lines with IC50 values <10 µM and the inhibitory activities for AchE (0.94 ±â€¯0.15 and 0.24 ±â€¯0.03 µM, respectively) and BuchE (1.82 ±â€¯0.12 and 7.31 ±â€¯0.42 µM, respectively).

Sesquiterpene Lactones from Vernonia cinerascens Sch. Bip. and Their in Vitro Antitrypanosomal Activity.

In the endeavor to obtain new antitrypanosomal agents, particularly sesquiterpene lactones, from Kenyan plants of the family Asteraceae, Vernonia cinerascens Sch. Bip. was investigated. Bioactivity-guided fractionation and isolation in conjunction with LC/MS-based dereplication has led to the identification of vernodalol (1) and isolation of vernodalin (2), 11ß,13-dihydrovernodalin (3), 11ß,13-dihydrovernolide (4), vernolide (5), 11ß,13-dihydrohydroxyvernolide (6), hydroxyvernolide (7), and a new germacrolide type sesquiterpene lactone vernocinerascolide (8) from the dichloromethane extract of V. cinerascens leaves. Compounds 3-8 were characterized by extensive analysis of their 1D and 2D NMR spectroscopic and HR/MS spectrometric data. All the compounds were evaluated for their in vitro biological activity against bloodstream forms of Trypanosoma brucei rhodesiense and for cytotoxicity against the mammalian cell line L6. Vernodalin (2) was the most active compound with an IC50 value of 0.16 µM and a selectivity index of 35. Its closely related congener 11ß,13-dihydrovernodalin (3) registered an IC50 value of 1.1 µM and a selectivity index of 4.2.

The role of Ntcp, Oatp2, Bsep and Mrp2 in liver injury induced by Dioscorea bulbifera L. and Diosbulbin B in mice.

Dioscorea bulbifera L. (DB) is a traditional Chinese herb used in thyroid disease and cancer. However, the clinical use of DB remains a challenge due to its hepatotoxicity, which is caused, in part, by the presence of Diosbulbin B (DIOB), a toxin commonly found in DB extracts. As abnormal expression of hepatobiliary transporters plays an important role in drug-induced liver injury, we assessed the hepatotoxicity induced by DB and DIOB, and explored their impacts on hepatobiliary transporter expression levels. Following liquid chromatography-tandem mass analysis of the DIOB content of DB extract, male ICR mice were randomly orally administered DB or DIOB for 14days. Liver injury was assessed by histopathological and biochemical analysis of liver fuction. The levels of transporter protein and mRNA were determined by western blotting and real-time PCR. Liver function and histopathological analysis indicated that both DB and DIOB could induce liver injury in mice, and that DIOB might be the primary toxic compound in DB. Moreover, down-regulation of Mrp2 blocked the excretion of bilirubin, glutathione disulfide, and bile acids, leading to the accumulation of toxic substrates in the liver and a redox imbalance. We identified down-regulated expression of Mrp2 as potential factors linked to increased serum bilirubin levels and decreased levels of glutathione in the liver and increased liver injury severity. In summary, our study indicates that down-regulation of Mrp2 represents the primary mechanism of DB- and DIOB-induced hepatotoxicity, and provides insight into novel therapies that could be used to prevent DB- and DIOB-mediated liver injury.

Isolation of insecticidal components in Inula salsoloides Ostenf. and characterisation of their activities.

The ethanol extract from Inula salsoloides (Turcz.) Ostenf was found to cause high mortality against Plutella xylostella L. (Lepidoptera: Plutellidae). The active components were isolated and identified. Two compounds were obtained and identified to be inulasalsolin and taraxasterol. Both compounds showed anti-feedant effects against third instar larvae of P. xylostella with AFC50 of 0.030 and 0.053 mg/mL and insecticidal activities with LC50 of 0.19 and 0.49 mg/mL, respectively. The two compounds also exhibited high toxicity to cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae) with LC50 values of 0.021 and 0.098 mg/mL. This is the first report on the study of insecticidal components of I. salsoloides and their activity against insects.

NMR reassignment of stictic acid isolated from a Sumatran lichen Stereocaulon montagneanum (Stereocaulaceae) with superoxide anion scavenging activities.

The phytochemical study of Stereocaulon montagneanum harvested in Sumatra (Indonesia) led to the isolation of 11 known compounds including two metabolites not previously described in the genus Stereocaulon, peristictic acid (8) and menegazziaic acid (10). The complete 1H and 13C NMR spectral assignments of stictic acid derivatives are reported with some revisions. Five depsidones belonging to the stictic acid chemosyndrome were superoxide anion scavengers as potent as ascorbic acid and with no toxicity on two human cell lines.

Isolation, characterization and quantification of an anxiolytic constituent - mahanimbine, from Murraya koenigii Linn. Spreng Leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Leaves of M. koenigii Linn. Spreng (Rutaceae) have been used as traditional medicine for anxiety disorders. Aim of the study was to isolate antianxiety principle(s) from the leaves of M. koenigii using bioactivity guided approach. MATERIAL AND METHODS: Hydroalcoholic extract of M. koenigii leaves was prepared using soxhlet apparatus, and the same was evaluated for antianxiety activity at 250, 500 and 750mg/kg, po, using Elevated plus-maze (EPM). The extract was further partitioned successively with pet ether, chloroform, ethyl acetate and 1-butanol. All the fractions were evaluated for antianxiety activity. The bioactive ethyl acetate fraction was column chromatographed to get 5 fractions (F1-F5). All the fractions were evaluated for antianxiety activity using EPM. A pure compound, separated out from F2, was characterized using standard spectroscopic techniques, and its anxiolytic activity was evaluated using EPM. Antianxiety activity of isolated compound was further evaluated using Actophotometer and m-CPP induced anxiety model. TLC-densitometric method was developed to quantify mahanimbine in the plant. RESULTS: The present study resulted in the isolation of mahanimbine, which exhibits potent antianxiety activity at 3mg/kg, and the activity was statistically comparable to that of diazepam (2mg/kg). The developed TLC-densitometric method is specific, linear, precise, accurate, repeatable and robust. CONCLUSIONS: This study validates the ethnopharmacological use of M. koenigii leaves in the management of anxiety disorders. Mahanimbine is responsible for the antianxiety effect of M. koenigii leaves.