Antioxidant activity and total phenolic content of fresh and cured rhizomes of Curcuma longa and Etlingera philippinensis

The search for effective natural antioxidants has been increasing nowadays due to human health concern. Further investigation of the Zingiberaceae plants such as Etlingera philippinensis, a Philippine endemic plant, and Curcuma longa (turmeric) is key towards alleviating this concern. The present work aimed to provide fundamental information on the total antioxidant activity (TAA), total phenolic content (TPC), and curcumin content of the ethanolic extracts of the fresh and cured rhizomes of C. longa and E. philippinensis. Healthy and fresh rhizomes of E. philippinensis were collected from Kibawe, Bukidnon, while C. longa were from Musuan, Bukidnon, Philippines. TAA determination was done using phosphomolybdenum method, while TPC and curcumin content using spectrophotometric method. Results showed that the TAA of fresh and cured rhizomes of C. longa were significantly higher than those of fresh and cured rhizomes of E. philippinensis. The TPC of fresh and cured rhizomes of C. longa were significantly higher than those of fresh and cured rhizomes of E. philippinensis. Significantly higher curcumin content was also observed in the rhizomes of C. longa as compared to that in the fresh and cured rhizomes of E. philippinensis. Generally, the ethanolic extracts of the cured rhizomes of E. philippinensis and C. longa exhibited higher TAA, TPC, and curcumin content than the fresh one. TAA, TPC, and curcumin were significantly correlated with each other. It can thus be concluded that E. philippinensis could also be a source of valuable curcumin.