Prenylated cinnamate and stilbenes from Kangaroo Island propolis and their antioxidant activity

► A novel cinnamic acid derivative and six novel prenylated stilbenes were isolated from Kangaroo Island propolis. ► Seventy five percent of the total phenolics of Kangaroo Island propolis were prenylated stilbenes. ► High level of O- and C-prenylation were present in Kangaroo Island propolis. ► Kangaroo Island propolis showed a stronger DPPH free radical scavenging activity than Brazilian green propolis.