Oleanane Triterpenoids with Inhibitory Activity against NFAT Transcription Factor from Liquidambar formosana

Abstract

The transcription factor called the "nuclear factor of activated T cells" (NFAT) is a cytoplasmic protein that is activated by the stimulation of the cell surface receptors coupled to Ca 2ϩ mobilization. The Ca 2ϩ activated phosphatase, calcineurin, dephosphorylates this NFAT protein, and promotes their nuclear translocation and activation.1) However, the excessive activation of NFAT provokes immunopathological reactions including autoimmunity, transplant rejection and inflammation.2) Therefore, it is expected that modulating the NFAT transcription factor will be useful in treating immune diseases. A high-affinity calcineurin-binding peptide 3) and 3,5-bis(trifluoromethyl)pyrazoles 4) were reported to be regulators of the NFAT transcription factor. Recently, lignans were isolated from Schisandra chinensis 5) and phthalides and an acetylene component were isolated from Cnidium officinale, 6) which are substances for regulating the NFAT transcription factor isolated from several medicinal plants.In an ongoing study for screening regulators from medicinal plants, potent activity was found in the MeOH extract of the Liquidambar formosana fruit (Hamamelidaceae) which has been used as an analgesic, diuretic and anticonvulsant in Oriental medicine. 7) Four oleanane triterpenoids which had not been reported as NFAT transcription factor regulators were isolated by activity-guided fractionation from this plant. Herein, we report the inhibitory activity of these compounds against the NFAT transcription factor. RESULTS AND DISCUSSIONThis study forms part of an ongoing study screening several medicinal plants for inhibitory activity against NFAT transcription factor. The results showed that the MeOH extract of L. formosana exhibited high activity (IC 50 : 4.67Ϯ0.61 mg/ml). The MeOH extract of L. formosana was suspended in water and consecutively partitioned with hexane, EtOAc and BuOH. The EtOAc fraction exhibited strong activity (IC 50 : 4.31Ϯ0.33 mg/ml), and activity-guided separation yielded four oleanane triterpenoids, liquidambaric acid (1), oleanolic acid (2), 3a-acetoxy-25-hydroxy-olean-12-en-28-oic acid (3), and lantanolic acid (5), as shown in Fig. 1. Of these compounds, compound 3 exhibited the strongest inhibitory activity against the NFAT transcription factor (IC 50 : 4.63Ϯ0.22 mM). However, the activity of 3 (IC 50 : 2.38 mg/ml) was similar to that of the EtOAc fraction. This fact indicates that other strong inhibitors may be present in minor constituents of the EtOAc fraction. Compound 5, which was isolated for the first time from L. formosana, showed moderate inhibitory activity against the NFAT transcription factor (IC 50 : 12.62Ϯ0.17 mM). However, compounds 1 and 2 did not have any inhibitory activity with IC 50 values over 50 mM (cell viability: Ͻ65%). From the structure activity relationship, compounds 1 and 2, which lack one oxy methylene group at C-25, had weak activity (IC 50 : Ͼ50 mM) on the NFAT transcription factor (Table 1). However, compounds 3 and 5 with this group at C-25 exhibited high inhibitor...

Oleanolic acid and related derivatives as medicinally important compounds

“…Four oleanane triterpenoids were isolated and identified to be liquidambaric acid, oleanolic acid, 3 alpha-acetoxy-25-hydroxy-olean-12-en-28-oic acid and lantanolic acid. Of these compounds, 3 alpha-acetoxy-25-hydroxy-olean-12-en-28-oic acid (IC 50 : 4.63 microM) and lantanolic acid (IC 50 : 12.62 microM) exhibited strong inhibitory activity against the NFAT transcription factor [15].…”

“…The plants were Beta vulgaris L. (Suger Beet,Chenopodiaceae) [5], Kochiae fructus [6], Kochia scoparia Schrad, Momordica cochinchinensis Spreng.) [7], Tiarella polyphylla [8], Clerodendranthus spicatus [9], Perilla frutescens [10], Glechoma hederaceae [11], Olea europaea [12,13], Couepia polyandra [14], Liquidambar formosana [15], Pistacia terebinthus galls [16], Rosmarinus officinalis L. [17], Crataegus pinnatifida Bunge [18], Luffa cylindricall [19], Rosa woodsii, (leaves), Prosopis glandulosa (leaves and twigs), Phoradendron juniperinum (whole plant), Syzygium claviflorum (leaves), Hyptis capitata (whole plant), Ternstromia gymnanthera (aerial part) [20], Plantago major [21] and Ludwigia octovalvis [22]. A number of oleanolic acid derivatives have been prepared.…”

“…Oleanolic acid glycosides (41)(42)(43)(44)(45) showed gastrointestinal transit accelerating activity. Three oleanane type triterpene (15)(16)(17) showed significant cytotoxicity against two human tumor cell lines. These derivatives have attracted considerable interest due to there biological activity.…”

Clinically useful anticancer, antitumor, and antiwrinkle agent, ursolic acid and related derivatives as medicinally important natural product

“…2α-hydroxyursolic acid (7)(8)(9)(10)(11)(12)(13), showed higher antiproliferative activity toward HepG2 cancer cells. Four ursolic type triterpene (14)(15)(16)(17), showed a marked anti-inflammatory effect on 12-O -tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice.…”

New Inhibitor against Nuclear Factor of Activated T Cells Transcription from Ribes fasciculatum var. chinense

“…24,25) For assay, 100 ml of cells (1ϫ10 4 cells/well) were incubated with 50 ml of sample and 50 ml of stimulator at 37°C for 18 h. The reaction mixture was centrifuged and 100 ml of supernatant were heated at 65°C for 1 h. The heated sample was incubated with 50 ml of SEAP buffer and 50 ml of substrate at 37°C for 4 h. After incubation of the reaction mixture, optical density was measured at 405 nm. Inhibitory activity on NFAT transcription factor was expressed as percent inhibition of the control and statistical significance was evaluated by Students's t-test.…”