Exploring the Potential of Subcritical Water Extraction for Zerumbone and the Antioxidant Activity of Zingiber Zerumbet Rhizome

Abstract

Traditional extraction methods for obtaining bioactive compounds from the rhizome of Zingiber zerumbet are associated with long extraction times and the use of hazardous organic solvents, posing significant health and environmental risks. In this study, a modern approach was used in which the fresh rhizome of Z. zerumbet was extracted by subcritical water extraction (SWE). Zerumbone concentration and antioxidant activity of the extract generally increase with longer extraction time. The highest zerumbone concentration (57.278 ± 6.066 mg/g) was obtained at an extraction time of 25 minutes with a crude concentration of 10 mg/mL. However, the antioxidant activity value (92.234 ± 3.132 %) was highest at an extraction time of 10 minutes, slightly higher than the value at 25 minutes (89.489 ± 1.913 %) at the same concentration. The IC50 values decreased significantly with longer extraction times, indicating an increased antioxidant potential. The 25 minutes extraction showed a robust IC50 value of 0.041 ± 0.022 mg/mL, indicating a strong 50 % inhibition of free radicals. Statistical analysis showed no significant differences in zerumbone concentration (p = 0.930) and antioxidant activity (p = 0.851) between the different extraction times and extract concentrations. Correlation analysis showed a bidirectional relationship between zerumbone concentration and antioxidant activity (R2 = 0.9316, r = 0.703), indicating a moderate to strong relationship. The consistent trends in this study support SWE as an effective method for extracting fresh rhizomes, yielding extracts with significant zerumbone concentration and antioxidant activity. Due to the large sample size (N = 36), this study was credible and provides valuable insights for various industries, including pharmaceuticals, dietary supplements, food, and natural health products.