The Sambong plant was already medicine a long, long time ago.
My late grandmother, Juliana Colipapa, the "hilot" (midwife) for Catmon, Cebu, Philippines was already using it. The plant was used in infant baths. The water is boiled and the sambong leaf is added to the water. When it is warm, the infant is bathed.
When I had stomachache, my grandmother would ask me to chew young sambong leaves. The chewed leaves are also used in treating fresh wounds to stop the bleeding and heal the wound.
It is traditional medicine here in the Philippines.
I get the impression that our ancestors learned that Sambong is medicine from their olders involved in the healing arts.