Thanaka stem bark powder was supplied by Ever Glory Co.
Ltd. (Bangkok, Thailand). Fresh bark was obtained from over
10-year old plants cultivated in the Eastern region of Burma
(see 1H NMR spectrum of its crude methanol extract in the
supplementary information). The bark was then grounded into
100–300 micrometer powder. Three kilograms of bark powder
were extracted by sequential extraction at room temperature with
hexane, dichloromethane, ethyl acetate and methanol, respectively,
each at 9 l volume. In addition, 3 l of 85% (v/v) aqueous
ethanol and distilled water extracts were obtained by the separate
maceration of one kilogram of stem bark powder. Each extract
was then filtered and evaporated under reduced pressure to yield
six different dried crude extracts.