Metabolism of kalopanaxsaponin K by human intestinal bacteria and antirheumatoid arthritis activity of their metabolites

The intramolecular self-assembly of bidesmosidic kalopanaxsaponins

The phenomena of intramolecular self-assembly of bidesmosidic kalopanaxsaponins was identified for the first time in this paper. NMR (1H-NMR, NOESY), transmission electron microscopy (TEM), and molecular dynamics (MD) simulation techniques were used to compare the spatial structures of bidesmosidic kalopanaxsaponins and monodesmosidic kalopanaxsaponins. The results showed that the bidesmosidic kalopanaxsaponins formed a clustered and twisted structure in space, whereas the monodesmosidic kalopanaxsaponins were in an extended state. This discovery confirmed the presence of intramolecular self-assembly in bidesmosidic kalopanaxsaponins.

Anticandidal Activity of Kalopanaxsaponin A: Effect on Proliferation, Cell Morphology, and Key Virulence Attributes of Candida albicans

Background

The pathogenicity of Candida albicans is attributed to various virulence factors including adhesion to the surface of epithelial cells or mucosa, germ tube formation, hyphal morphogenesis, development of drug resistant biofilms, and so on. The objective of this study was to investigate the effects of Kalopanaxsaponin A (KPA) on the virulence of C. albicans.

Methods

The effect of KPA on the virulence of C. albicans was characterized by an XTT reduction assay and fluorescent microscopic observation. The action mechanism was further explored using GC/MS system and BioTek Synergy2 spectrofluorophotometry. The cytotoxicity and therapeutic effect of KPA were evaluated by the Caenorhabditis elegans-C. albicans infection model in vivo.

Results

The minimum inhibitory concentration (MIC) of KPA was 8∼16 μg/mL for various genotypes of C. albicans. The compound was identified as having remarkable effect on the adhesion, morphological transition and biofilm formation of C. albicans. The results of fluorescent microscopy and GC/MS system suggested that KPA could promote the secretion of farnesol by regulating the expression of Dpp3 and decrease the intracellular cAMP level, which together inhibited morphological transition and biofilm formation. Notably, KPA showed low toxicity in vivo and a low possibility of developing resistance.

Conclusion

Our results demonstrated that KPA had remarkable efficacy against C. albicans pathogenicity, suggesting that it could be a potential option for the clinical treatment of candidiasis.

Current knowledge and development of hederagenin as a promising medicinal agent: a comprehensive review

Hederagenin (HG) is a pentacyclic triterpenoid that exists in many plants in the form(s) of sapogenin or saponins. This review highlights the pharmacokinetics, pharmacological activities, mechanisms of action, and safety of HG using literature and patents from the last 50 years to collate information on this compound as a promising medicinal agent. This review also looks at the development of related derivatives of HG with increased efficacy and lower toxicity. HG is quickly absorbed in the gastrointestinal tract with a short elimination half-life, and can cross the blood-brain barrier and rapidly distribute into cerebrospinal fluid. HG has been shown to possess a wide range of pharmacological activities, including anti-tumor, anti-inflammatory, anti-depressant, anti-neurodegenerative, anti-hyperlipidemia, anti-diabetic, anti-leishmanial, and anti-viral activity. In particular, the extensive anti-tumor activity indicates that HG has the potential to be a highly effective chemotherapy agent. Recently, in the search for more active compounds as potential pharmaceuticals, structural modification of the triterpene scaffold of HG at the C-3, C-12, C-13, C-23, and C-28 positions, has resulted in compounds that exhibited greater potency than HG itself. However, the low bioavailability and moderate hemolysis effect of HG may limit its clinical application. The cause of the observed toxic effects in some animals, including dogs, cats, cattle, goats, and horses also needs to be explained. Future studies of HG focusing on extending the half-life, improving bioavailability, enhancing pharmacological activity, as well as decreasing or avoiding hemolysis by structural modification or formulation design could potentially accelerate HG from the preclinical to clinical research phase.

Methyl syringate, a TRPA1 agonist represses hypoxia-induced cyclooxygenase-2 in lung cancer cells

BACKGROUND

We have previously found that methyl syringate is a specific and selective agonist of the human transient receptor potential channel ankyrin 1 (TRPA1) and suppresses food intake and gastric emptying in imprinting control region mice. Because TRPA1 has been implicated in inflammatory responses, and inflammation and tumorigenesis are stimulated by the cyclooxygenase-2 (COX-2)/prostaglandin E2 pathway in hypoxic cancer cells.

PURPOSE

This study examined the effects of methyl syringate on hypoxia-induced COX-2 in human distal lung epithelial A549 cells.

STUDY DESIGN

The effect of the methyl syringate on suppression of hypoxia-induced COX-2 in A549 cells were determined by Western blot and/or quantitative real-time polymerase chain reaction. The anti-invasive effect of methyl syringate was evaluated on A549 cells using matrigel invasion assay.

RESULTS

Methyl syringate suppressed hypoxia-induced COX-2 protein and mRNA expression and promoter activity and reduced hypoxia-induced cell migration and invasion and secretion of vascular endothelial growth factor. These effects were antagonized by a TRPA1 antagonist, implying their mediation by the TRPA1 pathway.

CONCLUSION

Together, these results indicate that methyl syringate inhibits the hypoxic induction of COX-2 expression and cell invasion through TRPA1 activation. These findings suggest that methyl syringate could be effective to suppress hypoxia-induced inflammation and indicate an additional functional effect of methyl syringate.

Kalopanaxsaponin A Exerts Anti-Inflammatory Effects in Lipopolysaccharide-Stimulated Microglia via Inhibition of JNK and NF-κB/AP-1 Pathways

Microglial activation plays an important role in the development and progression of various neurological disorders such as cerebral ischemia, multiple sclerosis, and Alzheimer's disease. Thus, controlling microglial activation can serve as a promising therapeutic strategy for such brain diseases. In the present study, we showed that kalopanaxsaponin A, a triterpenoid saponin isolated from Kalopanax pictus, inhibited inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and tumor necrosis factor (TNF)-α expression in lipopolysaccharide (LPS)-stimulated microglia, while kalopanaxsaponin A increased anti-inflammatory cytokine interleukin (IL)-10 expression. Subsequent mechanistic studies revealed that kalopanaxsaponin A inhibited LPS-induced DNA binding activities of NF-κB and AP-1, and the phosphorylation of JNK without affecting other MAP kinases. Furthermore, kalopanaxsaponin A inhibited the intracellular ROS production with upregulation of anti-inflammatory hemeoxygenase-1 (HO-1) expression. Based on the previous reports that JNK pathway is largely involved in iNOS and proinflammatory cytokine gene expression via modulating NF-κB/AP-1 and ROS, our data collectively suggest that inhibition of JNK pathway plays a key role in anti-inflammatory effects of kalopanaxsaponin A in LPS-stimulated microglia.

Kalopanaxsaponins A and B isolated from Kalopanax pictus ameliorate memory deficits in mice

The stem-bark of Kalopanax pictus (KP, family Araliaceae), which contains triterpenoid saponins, has been shown to exhibit anticarcinogenic, antiinflammatory, antirheumatoid and antidiabetic activities. In a preliminary study, a KP methanol extract demonstrated acetylcholinesterase activity in vitro and memory enhancement in scopolamine-treated mice. Therefore, we isolated acetylcholinesterase inhibitors, kalopanaxsaponins A and B, from a KP butanol (BuOH) fraction, measured acetylcholinesterase activity in vitro, and investigated their memory-enhancing effects in a passive avoidance test, Y-maze test and Morris water maze test. These constituents inhibited acetylcholinesterase activity and significantly reversed scopolamine-induced deficits. They also increased brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding (p-CREB) protein expression but reduced TNF-α increased by scopolamine. Based on these findings, kalopanaxsaponins A and B may ameliorate memory deficits by inhibiting acetylcholinesterase activity and inducing BDNF and p-CREB expression.

The Stem Bark of Kalopanax pictus Exhibits Anti-inflammatory Effect through Heme Oxygenase-1 Induction and NF-κB Suppression

Background

The stem bark of Kalopanax pictus (KP) has been used in traditional medicine to treat rheumatoidal arthritis, neurotic pain and diabetes mellitus in China and Korea. In this study, the mechanism responsible for anti-inflammatory effects of KP was investigated.

Methods

We examined the effects of KP on NO production, nitric oxide synthase (iNOS) and HO-1 expression, NF-κB, Nrf2 and MAPK activation in mouse peritoneal macrophages.

Results

The aqueous extract of KP inhibited LPS-induced NO secretion as well as inducible iNOS expression, without affecting cell viability. KP suppressed LPS-induced NF-κB activation, phosphorylation and degradation of IκB-α, phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK). Furthermore, KP induced HO-1 expression and Nrf2 nuclear translocation.

Conclusion

These results suggest that KP has the inhibitory effects on LPS-induced NO production in macrophages through NF-κB suppression and HO-1 induction.

19Alpha-hydroxyursane-type triterpenoids: antinociceptive anti-inflammatory principles of the roots of Rosa rugosa

To search for antiinflammtory 19alpha-hydroxyursane-type triterpenoids, the MeOH extract of the roots of Rosa rugosa (Rosaceae) was fractionated. The active fraction of the EtOAc extract was hydrolyzed in alkaline solution to give a hydrolyzed fraction. Both extracts showed antiinflammatory/antinociceptive action in acetic acid-induced writhing and hot plate testing and in a carrageenan-induced paw edema model in mice and rats. Repeated chromatography of the EtOAc extract on both silica gel and octadecylsilane columns led to the isolation of kaji-ichigoside F1 (1, euscaphic acid 28-O-glucoside) and rosamultin (2, tormentic acid 28-O-glucoside). The hydrolyzed fraction was also subjected to silica gel column and octadecylsilane column chromatography to produce euscaphic acid (3) and tormentic acid (4). The potencies were observed in the following order: 4>3>2>1. These results suggest that 19alpha-hydroxyursane-type triterpenoids are responsible for the antiinflammatory/antinociceptive action of R. rugosa roots.

Pharmacological studies of the aqueous extract of Sapindus trifoliatus on central nervous system: possible antimigraine mechanisms

The aqueous extract of pericarp of fruits of Sapindus trifoliatus (ST) Linn., family Sapindaceae was evaluated for its potential effects on central nervous system in mice. The extract at doses 20 and 100 mg/kg, i.p. significantly (p < 0.001) reduced the spontaneous locomotor activity and at 100 mg/kg, increased the thiopental-induced sleeping time. In rota-rod motor co-ordination test, ST at 100 mg/kg, i.p. significantly (p < 0.05-0.01) reduced the endurance time. Further ST exhibited no protection against maximal electroshock (MES)- and pentylenetetrazole (PTZ)-induced convulsions in mice. In receptor radioligand binding studies, ST exhibited affinity towards dopaminergic, alpha-adrenergic and muscarnic receptors. The findings suggest that, ST may possess principles with potential neuroleptic properties.

Antinociceptive and Anti-Inflammatory Effects of the Saponin and Sapogenins Obtained from the Stem of Akebia quinata

The stem of Akebia quinata Decasisne (Lardizabalaceae) has been used to treat urinary tract inflammatory disease. It has been reported that saponins in medicinal plants may act as bioactive components after biodegradation to sapogenins in the gastrointestinal tract. To find the active components, we obtained the methanol (MeOH) extract from A. quinata stems and fractionated this extract into CHCl(3), butanol (BuOH), and H(2)O fractions. A saponin-containing BuOH fraction was refluxed in an acidic solution to yield the hydrolyzed fraction. Silica gel column chromatography separated kalopanaxsaponin A (1) from the BuOH fraction, and oleanolic acid (2) and hederagenin (3) were obtained from the hydrolyzed fraction. The antinociceptive effect was tested by hot plate-writhing and tail-flicks methods using mice, and the anti-inflammatory effect was assayed using carrageenan-induced rat edema against the following samples: the MeOH extract of A. quinata stems, its fractions, the isolated saponin, kalopanaxsaponin A, and the sapogenins hederagenin and oleanolic acid. The MeOH extract exhibited antinociceptive/anti-inflammatory effects by oral administration of 100 and 250 mg/kg doses, indicating that the MeOH extract has an antinociceptive/anti-inflammatory activity. The BuOH fraction (crude saponin) also significantly exhibited those bioactivities. Treatments with 10 and 30 mg/kg perorally of these two sapogenins produced significant antinociceptive/ anti-inflammatory effects in the rat, suggesting that the sapogenins may act as resultant active compounds. Compounds 2 and 3 inhibited dye leakage into the peritoneal cavity induced by acetic acid, and the latter was more active than the former. The anti-inflammtory effects were further supported by the reduction of carrageenan-induced lipid peroxidation and hydroxy radical content in serum. These results suggest that the antinociceptive/anti-inflammatory properties of the stem of A. quinata can be attributed to the sapogenins oleanolic acid and hederagenin.

Structure-activity relationship of oleanane disaccharides isolated from Akebia quinata versus cytotoxicity against cancer cells and NO inhibition

In order to further determine the nature of structure-activity relationship on the cytotoxicities of saponins with 1-->2 and 1-->3 linkages of disaccharides, we isolated guaianin N, collinsonidin, kalopanaxsaponin A and hederoside D(2) as disaccharides, and patrinia glycoside B-II as a trisaccharide, from the n-BuOH extract of Akebia quinata (Lardizabalaceae). Complete acid hydrolysis of the extract afforded oleanolic acid (1) and hederagenin (2). By sulforhodamine B (SRB) assay, kalopanaxsaponin A containing an alpha-L-rhap-(1-->2)-alpha-L-arap moiety exhibited distinctly higher cytotoxicity (IC(50) 1.8-2.7 microg/ml) against all of the tested cell lines than the other saponins (IC(50), 4-8 microg/ml). These results suggest that the alpha-L-rhap-(1-->2)-alpha-L-arap moiety has a unique structural significance in terms of its cell biochemistry, compared to those oleanane glycosides with other sugar linkages. On the other hand, kalopanaxsaponin A exhibited a significant inhibitory effect on nitric oxide production by lipopolysaccharide (LPS)-activated macrophage 264.7, whereas other saponins had weaker activities.

Antinociceptive and Antiinflammatory Effects of Niga-ichigoside F1 and 23-Hydroxytormentic Acid Obtained from Rubus coreanus

As an attempt to search for bioactive natural constituents exerting antinociceptive and antiinflammatory activities, we examined the potency of the extract of Rubus coreanus fruits by the activity-guided fractionation. The EtOAc- and BuOH fraction and those alkaline hydrolysates showed significant antinociceptive effects as assessed by writhing-, hot plate- and tail flicks tests in mice and rats as well as antiinflammatory effect in rats with carrageenan-induced edema. BuOH extract was subjected to column chromatography to obtain a large amount of niga-ichigoside F(1) (1,23-hydroxytormentic acid 28-O-glc), which was again hydrolyzed in NaOH solution to yield an aglycone 23-hydroxytormentic acid (1a). The aglycone, 23-hydroxytormentic acid, was much more potent in both antinociceptive and antiinflammatory tests than the glycoside, niga-ichigoside F(1). The antiinflammatory effects of these compounds were further supported by the reduction of carrageenan-induced lipid peroxidation and hydroxyl radical in serum. These results suggested that 23-hydroxytormentic acid might be an active moiety of niga-ichigoside F(1) present in R. coreanus.