李 國雄 ノースカロライナ大学, 薬学部, 教授
HASHIMOTO Fumio Kagoshima University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (70244142)
NATAO Tsuneatsu Fukuoka University, Faculty of Pharmaceutical Sciences, Assistant Professor, 薬学部, 助手 (90180455)
OKABE Hikaru Fukuoka University, Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (10078678)
季 國雄 ノースカロライナ大学, 薬学部, 教授
LEE Kuo-Hsiung University of North Carolina at Chapel Hill, School of Pharmacy, Professor
A series of lupane-type triterpenoic acid derivatives were synthesized and evaluated for their inhibitory activity against HIV-1 replication in acutely infected H9 cells, based on the fact that betulinic acid (1) and dihydrobetulinic acid (9) were identified as anti-HIV agents. Among the derivatives, 3-O-(3 ', 3 '-dimethylsuccinyl)-betulinic acid (3) and 3-O-(3 ', 3 '-dimethyl-succinyl)-dihydrobetulinic acid (11) both demonstrated extremely potent inhibitory activity with EC_<50> values of< 0.00035 muM.They exhibited remarkable in vitro therapeutic index (TI.) values of >20,000 and >14,000, respectively. 3-O-(3', 3'-Dimethylglutaryl)-betulinic acid and -dihydrobetulinic acid(12), 3-O-diglycolyl-betulinic acid and -dihydrobetulinic acid and 3-O-glutaryl- betulinic acid were also potent inhibitors of HIV replication with ED_<50> values ranging from 0.01 to 0.0023 muM and T.I.values from 1,017 to 2,344. In addition, compounds 1 1 and 12 are also active against HLV replica-tion in a monocy
te cell line and n peripheral blood mononuclear cells (PBMCs). Our in vitro assay indicated that these compounds are not inhibitors on HIV- 1 reverse transcriptase, whereas they inhibited syncytia formation completely in a concentration range of 20 - 40 mug/mL.However, 3-O-(2', 2'-dimethylsuccinyl)-betulinic acid (2) was also found to be an inhibitor of HIV-induced membrane fusion with IC_<100> value of 20mutg/mL, though it displayed significantly lower anti-HIV activity than foregoing compounds with ED_<50> value of 2.7 muM and T.l. values of 5.9. This observation indicated that another mechanism(s) of action other than inhibition of syncytia formation could be involved in the anti-HIV activity shown by these compounds. Compound 3 was not active in the MAGI assay, suggesting that it inhibit HIV replication at a late stage of the viral life cycle, such as after viral protein synthesis.
On the other hand, oleanolic acid was identified as an anti-HIV principle from several plants, including Rosa woodsii (leaves), Prosopis glandulosa (leaves and twigs), Phorodendron juniperinum (whole plant), Syzygium claviflorum (leaves), Hyptis capitata (whole plant), and Terniroemia gymnanthera (aerial part). It inhibited HIV- 1 replication in acutely infected H9 cells with an EC_<50> value of 3.7 muM, and inhibited H9 cell growth with an IC_<50> value of 47.8 muM [therapeutic index (T.I.) 12.8]. Pomolic acid, isolated from R.woodsii and H.capitata, was also identified as an anti-HIV agent (EC_<50> 3.0 muM, T.I.16.6). Although ursolic acid did show anti-HIV activity (EC_<50> 4.4 muM), it was slightly toxic (IC_<50> 14.3 muM, T.I.3.3). Based on these results, we examined anti-HLV the activity of oleanolic acid- or pomolic acid-related triterpenes isolated from several plants. In addition, we previously demonstrated that derivatives of betulinic acid, isolated from the leaves of S.claviflum as an anti-HIV principle, exhibited extreme potent anti-HIV activity. Accordingly, we prepared derivatives of oleanolic acid, and evaluated their anti-HIV activity. Among the oleanolic acid derivatives, 3-O-(3', 3'-dimethylsuccinyl)-oleanolic acid demonstrated most potent anti-HIV activity, with an EC_<50> value of 0.00086 muM and a T.I.value of 22,400.
Though ursolic acid is slightly toxic against H9 cells, it shows similar level of anti-HIV acitivity to that of oleanolic acid. In addition, the structure of ursolic acid is closely correlated with oleanolic acid and betulinic acid, hence it is regarded as a potential lead for anti-HIV agent. Therefore, similar modification of ursolic acid, and evaluated their anti-HIV activities. 3-O-diglycoryl-uroslic acid demonstarated relatively potent anti-HIV activity with an EC_<50> value of 0.31 muM and a T.I.value of 155.5. Hoever, anti-HJV activities for other derivatives, including 3,3-dimethysuccinyl derivative, were not potent as corresponding betulinic acid and oleanolic acid derivatives. Less