Synthesis and Cytotoxicity Assessment of Novel 7-O- and 14-O-Derivatives of Glaucocalyxin A.

BACKGROUND: Rabdosia japonica has been historically used in China as a popular folk medicine for the treatment of cancer, hepatitis, and gastricism. Glaucocalyxin A (GLA), an ent-kaurene diterpene isolated from Rabdosia japonica, is one of the main active ingredients showing potent inhibitory effects against several types of tumor cells. To the best of our knowledge, studies regarding the structural modification and Structure- Activity Relations (SAR) of this compound have not yet been reported. OBJECTIVE: The aim of this study was to discover more potent derivatives of GLA and investigate their SAR and cytotoxicity mechanisms. METHODS: Novel 7-O- and 14-O-derivatives of GLA were synthesized by condensation of acids or acyl chloride. The anti-tumor activities of these derivatives against various human cancer cell lines were evaluated in vitro by MTT assays. Apoptosis assays of compound 17 (7,14-diacylation product) were performed on A549 and HL-60 cells by flow cytometry and TUNNEL. The acute toxicity of this compound was tested on mice, at the dose of 300mg per kg body weight. RESULTS: Seventeen novel 7-O- and 14-O-derivatives of GLA (1-17) were synthesized. These compounds showed potent cytotoxicity against the tested cancer cell lines, and almost all of them were found to be more cytotoxic than GLA and oridonin. Of the synthesized derivatives, compound 17 presented the greatest cytotoxicity, with IC50 values of 0.26µM and 1.10µM in HL-60 and CCRF-CEM cells, respectively. Furthermore, this compound induced weak apoptosis of A549 cells but showed great potential in stimulating the apoptosis of HL- 60 cells. Acute toxicity assays indicated that compound 17 is relatively safer. CONCLUSION: The results reported herein indicate that the synthesized GLA derivatives exhibited greater cytotoxicity against leukemia cells than against other types of tumors. In particular, 7,14-diacylation product of GLA was found to be an effective anti-tumor agent. However, the cytotoxicity mechanism of this product in A549 cells is expected to be different than that in other tumor cell lines. Further research is needed to confirm this hypothesis.

Monomeric and dimeric ent-kauranoid-type diterpenoids from rabdosia japonica and their cytotoxicity and anti-HBV activities.

Two new ent-kauranoid-type diterpenoids (1 and 2) and one new rare dimer of ent-kauranoids (3) with a cyclobutane ring by a [2+2] cycloaddition, together with nine known diterpenoids (4-12) were obtained from the aerial parts of Rabdosia japonica. Their chemical structures were established by 1D and 2D NMR techniques and mass spectrometry and by comparison with spectroscopic data reported. All ent-kauranoids were test for their cytotoxic effects against A549, HCT116, CCRF-CEM and HL-60 tumor cell lines. Compounds 1, 2, 4, 5, 7, 10 and 12 showed potent and selective cytotoxicity. In addition, some selected ent-kauranoids were test for their anti-HBV activities, and the results showed compound 8 had inhibitory effect on HBsAg with a 59% inhibition ratio at the concentration of 20µg/mL.

Chemical constituents from the rhizome of Polygonum paleaceum and their antifungal activity.

A new compounds neopaleaceolactoside (1), along with nine known compounds phyllocoumarin (2), quercetin (3), quercitrin (4), quercetin-3-methyl ether (5), vincetoxicoside B (6), isoquercitrin (7), kaempferol (8), (-)-epicatechin (9), and chlorogenic acid (10), was isolated from Polygonum paleaceum Wall. Their chemical structures were established based on one-dimensional and two-dimensional nuclear magnetic resonance techniques, mass spectrometry and by comparison with spectroscopic data reported. Some selected compounds were screened for their antifungal activity. Quercetin (3), vincetoxicoside B (6), kaempferol (8), and (-)-epicatechin (9) showed synergistic antifungal activities with the FICI values <0.5. A preliminary structure-activity relationship could be observed that free 3-OH in the structure of flavonoids was important for synergistic antifungal activity.

A Schisandra-Derived Compound Schizandronic Acid Inhibits Entry of Pan-HCV Genotypes into Human Hepatocytes.

Despite recent progress in the development of hepatitis C virus (HCV) inhibitors, cost-effective antiviral drugs, especially among the patients receiving liver transplantations, are still awaited. Schisandra is a traditional medicinal herb used to treat a range of liver disorders including hepatitis for thousands of years in China. To isolate the bioactive compounds of schisandra for the treatment of HCV infection, we screened a schisandra-extracts library and identified a tetracyclic triterpenoid, schizandronic acid (SZA), as a novel HCV entry inhibitor. Our findings suggested that SZA potently inhibited pan-HCV genotype entry into hepatoma cells and primary human hepatocytes without interfering virus binding on cell surface or internalization. However, virion-cell fusion process was impaired in the presence of SZA, along with the increased host membrane fluidity. We also found that SZA inhibited the spread of HCV to the neighboring cells, and combinations of SZA with interferon or telaprevir resulted in additive synergistic effect against HCV. Additionally, SZA diminished the establishment of HCV infection in vivo. The SZA target is different from conventional direct-acting antiviral agents, therefore, SZA is a potential therapeutic compound for the development of effective HCV entry inhibitors, especially for patients who need to prevent HCV reinfection during the course of liver transplantations.

[Chemical Constituents from Polygonum paleaceum].

Objective: To isolate and identify the chemical constituents from Polygonum paleaceum. Methods: Chemical constituents were isolated and purified by column chromatography on silica gel,Sephadex HL-20 and macroporous resin etc. The chemical structures were identified by MS,NMR and spectral analysis. Results: Ten compounds were isolated and their structures were elucidated as ethyl chlorogenate( 1),methyl chlorogenate( 2), kaempferol-3-O-α-L-rhamnopyranoside( 3), (-)-epicatechin( 4), paleaceolactoside( 5), protocatechuic acid( 6), kaempferol( 7), gallic acid( 8), chlorogenic acid( 9) and isoquercitrin( 10). Conclusion: Compounds 1,3,6,7 and 10 are isolated from this plant for the first time.

Phenolics from Bidens bipinnata and their amylase inhibitory properties.

A new chlorinated flavonoid, 3, 6, 8-trichloro-5, 7, 3', 4'-tetrahydroxyflavone (1), a new biscoumaric acid derivative, 4-O-(2″, 3″-O-diacetyl-6″-O-p-coumaroyl-ß-D-glucopyranosyl)-p-coumaric acid (2), and 8, 3', 4'-trihydroxyflavone-7-O-ß-D-glucopyranoside (3) together with twenty-four known compounds (4-27) were isolated from the whole plant of Bidens bipinnata. All chemical structures were established on the basis of UV-, MS- and NMR (¹H, ¹³C, ¹H-¹H COSY, HMQC and HMBC) spectroscopic data. Some of the isolated compounds were tested for the inhibition of α-amylase. The result showed that isookanin (6) was a potent inhibitor of α-amylase (IC50=0.447 mg/ml).

A new furostanol saponin from Asparagus cochinchinensis.

A new furostanol saponin, (25S)-26-O-ß-D-glucopyranosyl-5ß-furost-20(22)-en-3ß, 15ß,26-triol-3-O-[α-L-rhamnopyranosyl-(1-4)]-ß-D: -glucopyranoside, namely, aspacochioside D (1) were isolated from Asparagus cochinchinensis (Lour.) Merr, along with three known saponins, aspacochioside C (2), (25S)-5ß-spirostan-3ß-yl-O-[O-α-L-rhamnopyranosyl-(1-4)]-ß-D-glucopyranoside (3), and pseudoprotoneodioscin (4). The structure of 1 was elucidated on the basis of chemical reactions and spectral analysis (IR, GC, ESI-MS, (1)H-NMR, (13)C-NMR, DEPT, HMBC, HMQC and NOESY). The antiproliferative effects of 1-4 were evaluated in a cytotoxicity assay against the human tumor cell line, A549. Compound 2 (Aspacochioside C) exhibited moderate cytotoxicity against A-549, with an IC(50) value of 3.87 µg/mL.

Two new triterpenoid acids from Kadsura coccinea.

An investigation of EtOAc extracts of Kadsura coccinea (Lem.) A. C. Smith, has led to the isolation of two new compounds characterized as 3-hydroxy-12-hydroxyl coccinic acid (1) and 3-hydroxy-neokadsuranic acid A (2). Their structures were established by 1D and 2D NMR techniques and mass spectroscopy. Antiproliferative effects of the isolated compounds were evaluated against four human tumor cell lines (A549, HCT116, HL-60 and HepG2), and it was found that compound 1 exhibited antiproliferative effects with IC(50) values ranging from 3.01 to 18.08 µg/mL.

Chemical constituents of Trachelospermum jasminoides.

Ten compounds, comprising a new C(8) normonoterpenoid glycoside, trachelinoside (1), structurally as 4-(2-O-beta-D-glucopyranosyl)-hydroxyethyl-5,5-dimethyldihydrofuran-2(3H)-one, together with nine known compounds, were isolated from the 85% ethanol extract of the vines and leaves of Trachelospermum jasminoides (Lindl.) Lem.

[Study on the flavonoids constituents of Trachelospermum jasminoides].

OBJECTIVE: To study the flavonoids constituents of Trachelospemum jasminoides. METHODS: The compounds were separated and purified by column chromatography with silica gel, and identified by IR, MS, NMR and 2D-NMR. RESULTS: Six flavonoids were identified as apigenin (I), apigenin 7-O-beta-glucoside (II), apigenin 7-O-beta-neospheroside (III), luteoloside (IV), narngin (V) 6,8-di-C-glucopyanosylapigenin (VI), respectively. CONCLUSION: Compounds V and VI are isolated from this plant for the first time.

Two new triterpenoids from the roots of Actinidia chinensis.

Two new triterpenoids (1, 2), together with one flavonoid glycoside and thirteen known triterpenoids were isolated from the roots of Actinidia chinensis Planch (Actinidiaceae). The structures of the new constituents were elucidated as 12α-chloro-2α, 3ß, 13ß, 23-tetrahydroxyolean-28-oic acid-13-lactone (1), 2α, 3α, 19α, 23, 24-pentahydroxyurs-12-en-28-oic acid (2). Structure elucidation was accomplished by 1D, 2D NMR spectra (HMQC, HMBC, (1)H-(1)H COSY, TOCSY, and NOESY) and mass spectrometry (ESIMS). Moreover, two known triterpenoids showed positive cytotoxic activity against LOVO and HepG2 cell lines.

Three new compounds from Arnebia euchroma.

A new naphthoquinone dimer, arnebiabinone (1), a new phenolic compound, ethyl 9-(2',5'-dihydroxyphenyl) nonanoate (2), and a new natural product, octyl ferulate (3), were isolated from the EtOH extract of dried roots of Arnebia euchroma (Royle) Johnst. Their structures were elucidated on the basis of chemical reaction and spectral analysis.

A new indole alkaloid from Ervatamia yunnanensis.

The stems of Ervatamia yunnanensis have afforded a new indole alkaloid, ervataine (1), whose structure was determined by spectroscopic analysis. Five known compounds, ibogaine (2) coronaridine (3), heyneanine (4), voacangine hydroxyindolenine (5) and coronaridine hydroxyindolenine (6), were also isolated.

A new quinazolinedione alkaloid from the fruits of Evodia officinalis.

A new quinazolinedione alkaloid, wuchuyuamide IV (1) was isolated from the fruits of Evodia officinalis.1 showed moderate cytotoxicity against Hela and HT1080 cell lines.

[Study on chemical constituents in rhigome of Ervatamia hainanensis].

OBJECTIVE: To investigate the chemical constituents of the rhizome of Ervatamia hainanensis. METHOD: The solvent extraction and silica column chromatography were used to separate the chemical constituents, and their structures were identified by physico chemical properties and spectra analysis. RESULT: Twelve compounds were isolated and their structures were identified as voacangine (1), ibogaine (2), ibogamine (3), coronaridine (4), 19-heyneanine (5), 19-epi-heyneanine (6), 3-hydroxyl coronaridine (7), coronaridine hydroxyindolenine (8), 3-(2-oxopropyl) coronaridine (9), vobasine (10), alpha-amyrin (11), alpha-amyrin acetate (12). CONCLUSION: Compounds 1, 2, 6, 11 and 12 were first found from this plant.

Comparative analysis of the chemical profile of wild and cultivated populations of Corydalis saxicola by high-performance liquid chromatography.

Studies on the simultaneous determination and chemical fingerprinting of alkaloids in Corydalis saxicola Bunting. (Yanhuanglian) were performed for authentication purposes. Ninety samples prepared from different parts of C. saxicola, including whole plants, roots, stems, leaves and flowers, from wild and cultivated populations, were submitted to quantitative determination and fingerprint analysis. Five major alkaloids, namely, tetradehydroscoulerine, dehydroapocavidine, dehydroisoapocavidine, coptisine and dehydrocavidine, were quantitatively analysed by reversed-phase HPLC with acceptable recoveries (>98.2%). Chemical fingerprinting of C. saxicola was established and involved 11 markers. The results indicated that there were no obvious differences between the chemical profiles of wild and of cultivated C. saxicola populations, and that the mean alkaloid contents of the five marker compounds in cultivated populations were significantly higher than those of the wild plants. The highest content of total alkaloids (up to 28.8 mg/g) was found in roots of C. saxicola. The total alkaloids of the leaves were approximately 50% of those of roots, suggesting that the leaves may be employed as an alternative source of alkaloids. Chemical fingerprints and quantitative HPLC analysis will have a positive impact on the conservation and cultivation of this medicinal plant.

A new bisxanthone from Hypericum japonicum.

A new bisxanthone, named jacarelhyperols D (1), was isolated from the whole plant of Hypericum japonicum. Its chemical structure was elucidated as 6-[1',5',6'-trihydroxy-2''-(alpha-hydroxy-alpha-methyl)ethyl-3'',4''-dihydrofuran (2'',3'',3',4') xanthone-3''-oxyl]-1,3,5-trihydroxy-xanthone on the basis of spectroscopic analysis.

[Studies on the separation and purificaton of pumiloside from Nauclea officinalis by macroreticular resin].

OBJECTIVE: To investigate the technological parameters and the process for separation and purification of pumiloside (PML) from Nauclea officinalis Pierrc ex Pitard by macroreticular resin. METHODS: PML was extracted by hot water, and the content of PML was determinated by HPLC method. The static capacity absorption, static elution ratios of five types of resin were studied respectively, and were compared to evaluate their absorption and desorption effect to PML. And then the absorption capacity, elution solution and elution volume of the AB-8 resin were researched to set up the optimum separation process for PML. Finally, PML was recrysallized from MeOH and identified by spectra analysis. RESULTS: The AB-8 resin had the best absorptive and separative properties to PML. The dynamic absorption ratio was 2.44 mg/g. The applicable process was as follows: the water extracted solution of Nauclea officinalis flow through the resin column repeatedly, after being eluted with 6BV of distilled water, the resin column was eluted with 4BV 30% ethanol, the 30% ethanol fraction was combined and the solvent was recovered in vacuum. The precipitation was filtered and recrysallized from MeOH to give pure PML. The yield of PML was 75.1%, and the product purity was up to 99.5%. CONCLUSION: AB-8 resin shows better comprehensive absorption property. It can be used for separation and purification of PML from Nauclea officinalis successfully.

Saponins from Polygala japonica and their effects on a forced swimming test in mice.

Five new triterpenoid saponins, polygalasaponins E (1), F (2), G (3), H (4), and J (5), along with eight known ones (6-13), were isolated from the aerial parts of Polygala japonica. Their structures were established by chemical and spectroscopic means. Forced swimming tests on mice showed that saponins 1 and 4 significantly reduce the immobility status by 58.1% and 51.3% at a dosage of 100 mg/kg administrated orally once daily for 5 days, respectively.

Antifungal activities and action mechanisms of compounds from Tribulus terrestris L.

Antifungal activity of natural products is being studied widely. Saponins are known to be antifungal and antibacterial. We used bioassay-guided fractionation to have isolated eight steroid saponins from Tribulus terrestris L., which were identified as hecogenin-3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-8), tigogenin-3-O-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-9), hecogenin-3-O-beta-D-glucopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-10), hecogenin-3-O-beta-D-xylopyranosyl (1-->3)-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-11), tigogenin-3-O-beta-D-xylopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-galactopyranoside (TTS-12), 3-O-[beta-D-xylopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-[alpha-L-rhamnopyranosyl (1-->2)]-beta-D-galactopyranosyl]-26-O-beta-D-glucopyranosyl-22-methoxy-(3beta,5alpha,25R)-furostan-3,26-diol (TTS-13), hecogenin-3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-14), tigogenin-3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-xylopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (TTS-15). The in vitro antifungal activities of the eight saponins against five yeasts, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis and Cryptococcus neoformans were studied using microbroth dilution assay. In vivo activity of TTS-12 in a Candida albicans vaginal infection model was studied in particular. The results showed that TTS-12 and TTS-15 were very effective against several pathogenic candidal species and Cryptococcus neoformans in vitro. It is noteworthy that TTS-12 and TTS-15 were very active against Candida albicans (MIC(80) = 10 and 2.3 microg/mL) and Cryptococcus neoformans (MIC(80) = 1.7 and 6.7 microg/mL). Phase contrast microscopy showed that TTS-12 inhibited hyphal formation, an important virulence factor of Candida albicans, and transmission electron microscopy showed that TTS-12 destroyed the cell membrane of Candida albicans. In conclusion, TTS-12 has significant in vitro and in vivo antifungal activity, weakening the virulence of Candida albicans and killing fungi through destroying the cell membrane.