Capillin is a naturally occurring organic compound with the chemical formula C12H8O.

The structure contains acetophenone and a polyyne (pentadiynyl) portion, conjugated together as an ynone.

[1] The substance was initially isolated from Artemisia capillaris in 1956.

It has strong antifungal activity, and it is possibly antitumoral.

Capillin exhibits cytotoxic activity and could cause apoptosis of certain human tumor cells.