25-Methoxylprotopanaxadiol derivatives and their anti-proliferative activities

(20R)-25-Methoxyl-dammarane-3β,12β,20-triol (25-OCH₃-PPD) is a dammarane-type sapogenin showing anti-proliferative potential. In our study, two series of analogs substituted at the C-3 or C-3 and C-12 positions with fatty acids were prepared conveniently. The cytotoxic activity of these compounds was evaluated using four different human tumor cell lines (A549, Hela, HT-29 and MCF-7) and a normal cell line (IOSE144). As compared with 25-OCH₃-PPD, compounds 1a, 1b, 2a and 2b showed better anti-proliferative activities against all tumor cell lines and all the derivatives, with low toxicities in the normal cell line. Compound 1a (C-3 monoformiate) exhibited the strongest activity with the IC₅₀ value of 5.2 μM towards HT29 cells. The results indicated that the difference in the substituents may affect the anti-proliferative activity of the compounds. The longer the side chain of 25-OCH₃-PPD is, the lower the anti-proliferative activity would be. This information may be useful for evaluating the structure–activity relationship of other dammarane-type sapogenins and for development of novel antineoplastic agents.     

Novel dammarane-type sapogenins from Panax ginseng berry and their biological activities

Three new dammarane-type sapogenins (1, 3, and 5) together with two known ones (2 and 4) were isolated from the total hydrolyzed saponins extracted from Panax ginseng berry. Their structures were elucidated using a combination of 1D and 2D ¹H and ¹³C NMR spectra and mass spectroscopy as 20(R)-25-methoxyl-dammarane-3β,12β,20-triol (1), 20(R)-25-methoxyl-dammarane-3β,6α,12β,20-tetrol (2), 20(R)-20-methoxyl-dammarane-3β,12β,25-triol (3), 20(R)-20,25-dimethoxyl-dammarane-3β,12β-diol (4), and (12R,20S,24S)-20,24-; 12,24-diepoxy-dammarane-3β-ol (5). Their antitumor activities were evaluated in six human cancer cell lines. The novel compounds 1 and 3 showed significant cytotoxic activity against the six cell lines. The IC₅₀ values of 3 against HepG2, Colon205, and HL-60 were the lowest (8.78, 8.64, and 3.98 μM, respectively). Compounds 1 and 20(S)-25-OCH₃-PPD, which are a pair of configuration isomers, showed a 10- to 100-fold greater growth inhibition than ginsenoside-Rg₃ (an anti-cancer clinical agent in China). The data presented here may be useful for the development of novel anti-cancer agents.     

Microbial transformation of acetyl-11-keto-β-boswellic acid and their inhibitory activity on LPS-induced NO production

The capabilities of 20 strains of fungi to transform acetyl-11-keto-β-boswellic (AKBA) were screened. And biotransformation of AKBA by Cunninghamella blakesleana AS 3.970 afforded five metabolites (1–5), while two metabolites (6, 7) were isolated from biotransformation of Cunninghamella elegans AS 3.1207. The chemical structures of these metabolites were identified by spectral methods including 2D NMR and their structures were elucidated as 7β-hydroxy-3-acety-11-keto-β-boswellic acid (1), 21β-dihydroxy-3-acety-11-keto-β-boswellic acid (2), 7β,22α-dihydroxy-3-acety-11-keto-β-boswellic acid (3), 7β,16α-dihydroxy-3-acety-11-keto-β-boswellic acid (4), 7β,15α-dihydroxy-3-acety-11-keto-β-boswellic acid (5); 7β,15α,21β-trihydroxy-3-acety-11-keto-β-boswellic acid (6) and 15α,21β-dihydroxy-3-acety-11-keto-β-boswellic acid (7). All these products are previously unknown. Their primary structure–activity relationships (SAR) of inhibition activity on LPS-induced NO production in RAW 264.7 macrophage cells were evaluated.     

3,4-Seco-spirostane sapogenins with cytotoxic activity from Allium umbilicatum boiss

Two new sapogenins, named seco-umbilicagenins A and B (1 and 2), possessing a new chemical structure based on a 3,4-seco-spirostane skeleton, were isolated from Allium umbilicatum Boiss. The chemical structures of seco-umbilicagenins A and B were established through a combination of extensive spectroscopic analysis, mainly nuclear magnetic resonance spectroscopy and mass spectrometry, and chemical methods as (2S,25R)-2,5α,6β-trihydroxy-3,4-seco-spirosta-3,4-dioic acid (1) and (2S,25R)-2,4,5α-trihydroxy-6-oxo-3,4-seco-spirostan-3-oic acid (2). Interestingly, the isolated compounds exhibited cytotoxic activity on J-774, murine monocyte/macrophage, and WEHI-164, murine fibrosarcoma, cell lines. To the best of our knowledge this is the first time that 3,4-seco-spirostane sapogenins are isolated from natural sources, being this skeleton obtained by synthetic modification of intact sapogenins.     

Microbial transformation of glycyrrhetinic acid derivatives by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741

Glycyrrhetinic acid (GA), the major bioactive pentacyclic triterpene aglycone of licorice root, was known to play a vital role in anti-ulcer, anti-depressant, anti-inflammatory, and anti-allergic. In this study, we semi-synthesized five GA derivatives by a series of chemical reactions. They were selected as substrates for the biotransformation and yielded thirteen metabolites by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741. Their structures were identified on the basis of extensive spectroscopic methods and nine of them were found for the first time. Two main types of reactions, regio- and stereo-selective hydroxylation and glycosylation, especially in the unactivated C-H bonds including C-11, C-19 and C-27, were observed in the biotransformation process, which greatly expand the chemical diversities of GA derivatives. All compounds were tested for their inhibitory effects on nitric oxide (NO) generation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Among them, olean-12-ene-3β,7β,15α,19α,30-pentol (16) and olean-12-ene-3β,7β,15α,27,30-pentol (17) showed significant inhibitory effect with IC₅₀ values of 0.64 and 0.07 μM, respectively.     

Hydrogenolysis of benzylidene acetals: synthesis of benzyl 2,3,6,2′,3′,4′-hexa-O-benzyl-β-cellobioside, -maltoside,and -lactoside,benzyl 2,3,4,2′,3′,4′-hexa-O-benzyl-β-allolactiside,and benzyl 2,3,6,2′,3′,6′-hexa-O-benzyl-β-lactoside

Hydrogenolysis of benzyl penta-O-benzyl-4′,6′-O-benzylidene-β-cellobioside (4), -maltoside (5), and -allolactoside (16) with LiAlH₄-AlCl₃ gave only the corresponding derivatives having HO-6′ free, in yields of 55, 78, and 90%, respectively. The main product of the hydrogenolysis of benzyl penta-O-benzyl-4′,6′-O-benzylidene-β-lactoside (6) also had HO-6′ free, but the isomer having HO-4′ free was also isolated. The role of the C-1 substituent in the galactose moiety in the direction of benzylidene ring-cleavage is discussed.     

Biotransformation of dianabol with the filamentous fungi and β-glucuronidase inhibitory activity of resulting metabolites

Biotransformation of the anabolic steroid dianabol (1) by suspended-cell cultures of the filamentous fungi Cunninghamella elegans and Macrophomina phaseolina was studied. Incubation of 1 with C. elegans yielded five hydroxylated metabolites 2–6, while M. phaseolina transformed compound 1 into polar metabolites 7–11. These metabolites were identified as 6β,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (2), 15α,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (3), 11α,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (4), 6β,12β,17β-trihydroxy-17α-methylandrost-1,4-dien-3-one (5), 6β,15α,17β-trihydroxy-17α-methylandrost-1,4-dien-3-one (6), 17β-hydroxy-17α-methylandrost-1,4-dien-3,6-dione (7), 7β,17β,-dihydroxy-17α-methylandrost-1,4-dien-3-one (8), 15β,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (9), 17β-hydroxy-17α-methylandrost-1,4-dien-3,11-dione (10), and 11β,17β-dihydroxy-17α-methylandrost-1,4-dien-3-one (11). Metabolite 3 was also transformed chemically into diketone 12 and oximes 13, and 14. Compounds 6 and 12–14 were identified as new derivatives of dianabol (1). The structures of all transformed products were deduced on the basis of spectral analyses. Compounds 1–14 were evaluated for β-glucuronidase enzyme inhibitory activity. Compounds 7, 13, and 14 showed a strong inhibition of β-glucuronidase enzyme, with IC₅₀ values between 49.0 and 84.9 μM.     

SIRT1 activator isolated from artificial gastric juice incubate of total saponins in stems and leaves of Panax ginseng

Panax ginseng as a traditional Chinese medicine has been extensively used for the treatment of many diseases, especially in prolonging life and anti-tumor. Dammarane-type triterpenoids from P. ginseng have diverse beneficial effects and their chemical structures can be modified in the gastrointestinal tract after oral administration. In this paper, the dammarane-type triterpenoids were isolated from artificial gastric juice incubate of total saponins in the stems and leaves of P. ginseng through column chromatographic methods and their chemical structures were determined based on spectral data. Two new dammarane-type triterpenoids named ginsenotransmetins B (1) and C (2), along with twenty-nine known compounds (3–31), were obtained. All 31 compounds isolated were investigated for their activities of SIRT1 using SIRT1 fluorometric drug discovery assay kit. Among them, compounds 11, 17, 18, 20, 23, 24, 28, and 29, which were found to be potential as SIRT1 activators, exhibited significant stimulation of SIRT1 activity. The results showed that these compounds may be considered to be a useful medicinal resource for prolonging life and anti-tumor. In addition, the results were helpful to explain the longevity effect of ginseng from the new field of view.     

New derivatives of ursolic acid through the biotransformation by Bacillus megaterium CGMCC 1.1741 as inhibitors on nitric oxide production

Microbial transformation of ursolic acid (1) by Bacillus megaterium CGMCC 1.1741 was investigated and yielded five metabolites identified as 3-oxo-urs-12-en-28-oic acid (2); 1β,11α-dihydroxy-3-oxo-urs-12-en-28-oic acid (3); 1β-hydroxy-3-oxo-urs-12-en-28, 13-lactoe (4); 1β,3β, 11α-trihydroxyurs-12-en-28-oic acid (5) and 1β,11α-dihydroxy-3-oxo-urs-12-en-28-O-β-d-glucopyranoside (6). Metabolites 3, 4, 5 and 6 were new natural products. Their nitric oxide (NO) production inhibitory activity was assessed in lipopolysaccharide (LPS) – stimulated RAW 264.7 cells. Compounds 3 and 4 exhibited significant activities with the IC₅₀ values of 1.243 and 1.711 μM, respectively. A primary structure-activity relationship was also discussed.     

Microbial transformation of bavachin by Absidia coerulea

Microbial transformation of bavachin (1), one of the major bioactive components of Psoralea corylifolia L., was performed by using Absidia coerulea. Three oxidized metabolites were obtained in the biotransformation of 1, and their structures were elucidated as bavachinone A (2), (2S)-4′-hydroxy-6,7-[(R)-2-(1-hydroxy-1-methylethyl)-2,3-dihydrofurano]flavanone (3), and (2S)-4′,7-dihydroxy-6-(2,3-dihydroxy-3-methylbutyl)flavanone (4) based on the spectroscopic analyses. Among them, metabolites 3 and 4 were new compounds. The biotransformation study suggested that 1 was fully oxidized to its metabolites within 5 days. Thus, biotransformation by A. coerulea can be used as a promising method for oxidation of bavachin.     

Bioactive oleanane-type saponins from the rhizomes of Anemone taipaiensis

Investigation of the n-BuOH extract of the rhizomes of Anemone taipaiensis led to the isolation of five new oleanane-type triterpenoid saponins (1–5), together with seven known saponins (6–12). Their structures were determined by the extensive use of ¹D and ²D NMR experiments along with ESIMS analyses and acid hydrolysis. The aglycone of 1, 2 and 4 was determined as siaresinolic acid, which was reported in this genus for the first time. The cytotoxicities of the saponins 1–12, prosapogenins 4a, 5a, 10a–12a and sapogenins siaresinolic acid (SA), oleanolic acid (OA), hederagenin (HE) were evaluated against five human cancer cell lines, including HepG2, HL-60, A549, HeLa and U87MG. The monodesmosidic saponins 6–8, 5a, 10a–12a and sapogenins SA, OA, HE exhibited cytotoxic activity toward all cancer cell lines, with IC₅₀ values ranging from 2.25 to 57.28 μM. Remarkably, the bisdesmosidic saponins 1–4 and 9 showed selective cytotoxicity against the U87MG cells.     

Some observations on the selective benzoylation of maltose and its derivatives

Benzoylation of β-maltose monohydrate (2) with 10 mol. equiv. of benzoyl chloride in pyridine at ?40° gave 1,2,6-tri-O-benzoyl-4-O-(2,3,4,6-tetra-O-benzoyl-α-D-glucopyranosyl)-β-D-glucopyranose (5) in 87% yield, without the need for column chromatography. Similarly, benzoylation of 2 with 8 mol. equiv. of reagent afforded the octabenzoate 5, and the 1,2,6,2′,3′,6′-hexabenzoate 11 in 3%, 79%, and 12% yield, respectively. Methyl 2,6,2′,3′,4′,6′-hexa-O-benzoyl-β-maltoside (10) was directly isolated as a crystalline monoethanolate in 83% yield, from the reaction mixture obtained by the benzoylation of methyl β-maltoside monohydrate (8) with 8.9 mol. equiv. of reagent. Benzoylation of 8 with 7 mol. equiv. of reagent produced 10 and the 2,6,2′,3′,6′-pentabenzoate 16 in 71% and 23% yield, respectively. The order of reactivity of the hydroxyl groups in methyl 4′,6′-O-benzylidene-β-maltoside towards benzoylation is HO-2, HO-6>HO-2′ ≈ HO-3′>HO-3. Benzoylation of methyl β-cellobioside (33) with 7.9 mol. equiv. of reagent gave the heptabenzoate and the 2,6,2′,3′,4′,6′-hexabenzoate 36 in 56% and 27% yield, respectively. Compounds 5, 16, and 36 were transformed into 4-O-α-D-glucopyranosyl-D-allopyranose, methyl 4-O-α-D-galactopyranosyl-β-D-allopyranoside, and methyl 4-O-β-D-glucopyranosyl-β-D-allopyranoside, respectively, by sequential sulfonylation, nucleophilic displacement, and O-debenzoylation.     

Triterpene glycosides from red ginseng marc and their anti-inflammatory activities

Three new triterpene glycosides ursan-3β,19α,22β-triol-3-O-β-d-glucopyranosyl (2′→1″)-β-d-glucopyranoside (1), ursan-3α,11β-diol-3-O-α-d-glucopyranosyl-(6′→1″)-α-d-glucopyranosyl-(6″→1‴)-α-d-glucopyranosyl-(6‴→1‴′)-α-d-glucopyranoside (2) and lanost-5,24-dien-3β-ol-3-O-β-d-glucopyranosyl-(6′→1″)-β-d-glucopyranosyl-(6″→1‴)-β-d-glucopyranoside (3), together with one known compound were isolated and identified from the marc of red ginseng. Their structures were elucidated by spectroscopic data analysis. Compounds (1–3) were investigated for anti-inflammatory effects using the RAW 264.7 macrophage cell line. In the cell proliferation assay, lipopolysaccharide stimulation decreased cell proliferation of RAW 264.7 macrophage cells, but the suppression of cell proliferation was significantly protected by treatment with compounds 2 and 3. Compounds 2 and 3 had a suppressive effect on the production of nitric oxide (NO), and they inhibited mRNA expression of proinflammatory mediators such as inducible nitric oxide synthase, and cyclooxygenase-2, and proinflammatory cytokines such as two interleukins and tumor necrosis factor-α. These findings suggest that compounds 2 and 3 have potential anti-inflammatory activities.     

Syntheses and pharmacokinetic evaluations of four metabolites of 2-(4-(2-((1H-benzo[d]imidazol-2-yl)thio)ethyl)piperazin-1-yl)-N-(6-methyl-2,4-bis-(methylthio)pyridin-3-yl)acetamide hydrochloride [K-604], an acyl-CoA:cholesterol O-acyltransferase-1 inhibitor

We synthesized and identified four metabolites of acyl-coenzyme A:cholesterol O-acyltransferase (ACAT)-1 inhibitor, K-604 (1). Two of the metabolites M1 and M2, were prepared from 1 using a combination reagent of hydrogen peroxide and sodium tungstate with either phosphoric acid or trifluoroethanol as the solvent to control the regioselectivity. Upon exposure of 4b to tert-butyl hypochlorite at −78 °C, the monosulfoxidation afforded synthetic intermediate of M3 in excellent yield. The efficient synthesis of M4 was established. The in vitro metabolic study exhibited a high clearance value (720 μL/min/mg protein) of 1 using human liver microsomes. We orally administered a single dose of 10 mg/kg of 1 to monkeys because the in vitro metabolic patterns are quite similar. Fortunately, the drug concentration of 1 was much higher than those of M1, M2, M3 and M4.     

Microbial hydroxylation and glycosylation of pentacyclic triterpenes as inhibitors on tissue factor procoagulant activity

To discover new inhibitors on tissue factor procoagulant activity, 20 pentacyclic triterpenes were semi-synthetized through microbial transformation and assayed on the model of human THP-1 cells stimulated by lipopolysaccharide. In the biotransformation two types of reactions were observed, regio-selective hydroxylation and glycosylation. The bioassay results showed that most of tested compounds were significant effective on this model and two of the biotransformation products 23-hydroxy-28-O-β-d-glucopyranosyl betulinic acid (3d) and 28-O-β-d-glucopyranosyl oleanic acid (1a) exhibited most potential activities with the IC₅₀ values of 0.028, 0.035 nM respectively. The preliminary structure and activity relationship analysis revealed that the aglycones with single free hydroxyl group on the skeleton (1, 1j) were less effective than that with more free hydroxyl groups (1d, 1f, 2), mono-glycosylation can significantly enhance their inhibitory effects. Our findings also provide some potential leading compounds for tissue factor-related diseases, such as cancer and cardiovascular diseases.     

Biotransformation of naringin and naringenin by cultured Eucalyptus perriniana cells

The biotransformation of naringin and naringenin was investigated using cultured cells of Eucalyptus perriniana. Naringin (1) was converted into naringenin 7-O-β-d-glucopyranoside (2, 15%), naringenin (3, 1%), naringenin 5,7-O-β-d-diglucopyranoside (4, 15%), naringenin 4′,7-O-β-d-diglucopyranoside (5, 26%), naringenin 7-O-[6-O-(β-d-glucopyranosyl)]-β-d-glucopyranoside (6, β-gentiobioside, 5%), naringenin 7-O-[6-O-(α-l-rhamnopyranosyl)]-β-d-glucopyranoside (7, β-rutinoside, 3%), and 7-O-β-d-gentiobiosyl-4′-O-β-d-glucopyranosylnaringenin (8, 1%) by cultured cells of E. perriniana. On the other hand, 2 (14%), 4 (7%), 5 (13%), 6 (2%), 7 (1%), naringenin 4′-O-β-d-glucopyranoside (9, 4%), naringenin 5-O-β-d-glucopyranoside (10, 2%), and naringenin 4′,5-O-β-d-diglucopyranoside (11, 5%) were isolated from cultured E. perriniana cells, that had been treated with naringenin (3). Products, 7-O-β-d-gentiobiosyl-4′-O-β-d-glucopyranosylnaringenin (8) and naringenin 4′,5-O-β-d-diglucopyranoside (11), were hitherto unknown.     

Antioxidant and antiproliferative activity of glycosides obtained by biotransformation of xanthohumol

The biotransformation of xanthohumol (1), a prenylated chalcone isolated from hops by selected fungi, was investigated. Microbial regioselective glycosylation at the C-4′ position led to xanthohumol 4′-O-β-d-glucopyranoside (2) and xanthohumol 4′-O-β-d-(4′′′-O-methyl)-glucopyranoside (3). The subsequent cyclization of 2 resulted in isoxanthohumol 7-O-β-glucopyranoside (4). The structures of the products were identified based on spectroscopic methods. The biological activity of isolated metabolites has been evaluated. Compared to xanthohumol (1), metabolite 2 is a better 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger, while 2 and 3 have stronger antiproliferative activity against the human HT-29 colon cancer cell line.     

Inhibitory effects of ginseng sapogenins on the proliferation of triple negative breast cancer MDA-MB-231 cells

Because of poor prognosis, clinical treatment of triple-negative (TN) breast cancer remains the most challenging factor in cancer treatment. Extensive research into alternative cancer therapies includes studying the naturopathic effects of the medicinal herb ginseng. This study investigates the anti-neoplastic properties of ginseng sapogenins and the derivatives: (1) (20(S)-protopanaxadiol (PPD), (2) 20(S)-protopanaxatriol), (3) (20(S)-dihydroprotopanaxadiol, and (4) 20(S)-dihydroprotopanaxatriol). These compounds were found to prevent the proliferation of MDA-MB-231 human breast cancer cells. PPD was the most potent inhibitor, exhibiting an IC₅₀ (5.87 μM) comparable to that of the chemotherapeutic drug taxol. Furthermore, PPD induced dose-dependent cleavage of caspase-8, caspase-3, and PARP in MDA-MB-231 cells. Thus, we propose that PPD acts as anti-cancer agent by stimulating caspase-dependent apoptosis in breast cancer cells.     

Synthesis and biological activity of 2-hydroxynicotinoyl-serine-butyl esters related to antibiotic UK-3A

Novel 2-hydroxynicotinoyl-serine-butyl esters have been synthesized. Three-step reactions from l-serine by esterification with n-butanol, amidation with 2-hydroxynicotinic acid and esterification with the corresponding carboxylic acids gave AD-1, AD-2 and AD-3. The toxicity level of esters were determined by Brine shrimp assay, and antibiotic activity was tested against Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Candida albicans. AD-3 showed greater activity as a growth inhibitor of B. subtilis and S. aureus compared to Antimycin A₃.     

Fungal metabolites of xanthohumol with potent antiproliferative activity on human cancer cell lines in vitro

Xanthohumol (1) and xanthohumol D (2) were isolated from spent hops. Isoxanthohumol (3) was obtained from xanthohumol by isomerisation in alkaline solution. Six metabolites were obtained as a result of transformation of xanthohumol (1) by selected fungal cultures. Their structures were established on the basis of their spectral data. One of them: 2″-(2′′′-hydroxyisopropyl)-dihydrofurano-[4″,5″:3′,4′]-4′,2-dihydroxy-6′-methoxy-α,β-dihydrochalcone (6) has not been previously reported in the literature. The antioxidant properties of hops flavonoids and xanthohumol derivatives were investigated using the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method. The effects of these compounds on proliferation of MCF-7, PC-3 and HT-29 human cancer cell lines were determined by the SRB assay. With the exception of one metabolite, all tested compounds showed antiproliferative activity against the tested human cancer lines. α,β-Dihydroxanthohumol (4), obtained through the biotransformation of xanthohumol, showed higher antiproliferative activity against MCF-7 human breast carcinoma cell line than cisplatin, a widely used anticancer therapeutic agent, and a comparably high activity against PC-3 human prostate cancer cell line.