Chiang Mai Journal of Science

     The fruit of Musa balbisiana (Tani banana) is an agricultural product that is not typically consumed due to its many seeds and small amount of flesh. However, studies have documented various biological activities, suggesting that this fruit could serve as a potential source of functional ingredients. This study produced M. balbisiana extract powder and investigated its cytoprotective effects against oxidative damage in an intestinal-like epithelial cell model in vitro. Unripe banana fruits were extracted using ultrasonic-assisted extraction, followed by spray drying to obtain a powder form. The non-digested extract (MBE) and digested extract (bioaccessible fraction; MBDE) were examined to determine their total phenolic content (TPC) and total antioxidant activities. For cytoprotection analysis, Caco-2 cells were cultured for 18 to 21 days to form an intestinal epithelium-like monolayer. The cell monolayers were then treated with MBE and MBDE (1000–5000 μg/ml) for 24 h, followed by H₂O₂ (5 mM) induction to induce oxidative stress. The cell viability, levels of intracellular reactive oxygen species (ROS), transepithelial electrical resistance (TEER), and interleukin-8 (IL-8) were determined. Results showed that MBDE at 5000 μg/ml resulted in 71.8% rescue of H₂O₂-induced cell death. The MBDE drastically decreased intracellular ROS levels by 6-fold compared to the H₂O₂-exposed cells. The MBDE significantly sustained the integrity of the cell monolayer, as demonstrated by the increasing TEER value, whereas IL-8 was not involved in this experimental condition. Findings suggested that the bioaccessible fraction of M. balbisiana fruit extract protected the intestinal epithelial-like cell monolayer from oxidative damage by ROS due to its antioxidant properties. Therefore, unripe fruit of M. balbisiana extract showed potential as a functional ingredient to increase antioxidant activity in the intestinal epithelium.