Antioxidant Activity of Mahang Leaves from Post-Coal Mining Revegetated Areas in East Kalimantan

Abstract Coal is of great importance to Indonesia’s foreign exchange and the income sharing of East Kalimantan. However, its environmental effects, such as soil acidification, are causing problems. Reclamation measures entail using pioneer plants like Mahang trees or Macaranga tanarius, renowned for their therapeutic benefits in restoring vegetation. Nevertheless, the pharmacological characteristics of these plants are contingent upon soil factors. This study aimed to assess the antioxidant properties of Mahang leaves extracts obtained from a forest that has undergone post-coal mining, in addition to analyzing the soil characteristics. The antioxidant activity was evaluated using the DPPH radical scavenging test. Post-coal mining soil contained elevated levels of heavy metal concentrations. However, the DPPH radical scavenging test of Mahang leaves extract indicated significant antioxidant activity. Overall, non-toxic soils in forests that have undergone post-coal mining indicate an abundance of soil nutrients available for the growth of medicinal plants such as Mahang. The revegetation demonstrates the effectiveness of the land recovery process, which has resulted in thriving vegetation after ten years of revegetation.