<jats:p> Three bases isolated from A. excelsum have been shown to be yohimbine, O-acetylyohimbine, and a previously unknown alkaloid C<jats:sub>22</jats:sub>H<jats:sub>26</jats:sub>N<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> (excelsinine), which is ascribed the structure and stereochemistry shown in formula VI.