摘要 |
Disclosed are compounds having the formula wherein R<SUP>1 </SUP>is hydrogen, an alkyl group, an aryl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aralkyl group, or -O, R<SUP>2 </SUP>is an alkyl group, an aryl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aralkyl group, or the pharmaceutically acceptable salt or ester thereof. Also disclosed are methods of using the compounds.
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