Phytochemicals and Physiological Activities of Sweetpotato (Ipomoea batatas L.) Leaves Processed via Full Fermentation

全發酵甘藷葉茶之植化素與生理活性分析

Ya-Lin Lee(李雅琳) ； Che-Lun Huang(黃哲倫) ； Tzu-Huan Hung(洪子桓) ； Wei-Ting Liu(劉威廷) ； Su-Yue Lin(林素月) ； Chiu-Hua Chen(陳秋樺) ； Yi-Han Ho(何奕漢) ； Ying-Fu Lee(李穎甫) ； Chung-En Tseng(曾崇恩)

《台灣農業研究》 Volume 74 Issue 1 (2025/03) Pp. 11-23

https://doi.org/10.6156/JTAR.202503_74(1).0002

Abstracts

Two cultivars of leafy sweetpotato (Ipomoea batatas L.), 'Purple Leaf' (PL) and 'Fancy Leaf' (FL), were mixed (at a ratio of 2 : 1) and processed to produce a full-fermented leaf tea (FFLT). Two harvests of the leafy tissues were collected to study their bioactive phytochemicals and physiological activities. The first harvest was conducted in the winter (collected on 2021/11/16), and the second was in the autumn (2022/09/01). The materials of the former were divided into leaf blade and petiole portions. Extracts with room-temperature distilled water (ddH_2O) were conducted to examine the total phenolics and flavonoids contents, and the reducing power was analyzed to reveal their antioxidative activities. Results showed that the nutritional values of the leaf blade tissues were much higher than those of the petioles. The FFLT samples made from both harvests were prepared with boiling ddH_2O and showed similar reducing power. In contrast, the flavonoid content of the harvest in the autumn was 1.7 times that of the winter, but the latter was slightly higher in the phenolic content than the former. The physiological activity was studied with the FFLT prepared from the second harvest, and its raw material of the leaf tea (RMLT) was also extracted with boiling ddH_2O for comparison. Results showed that both FFLT and RMLT extracts exhibited anti-inflammatory activity by reducing nitric oxide (NO) production; however, the latter increased TNF-α production (a detrimental response), while the former did not. In inhibiting protein glycation, both extracts showed effectiveness, with the FFLT being more effective than the RMLT. These results suggest that the full-fermentation manufacturing process converts certain phytochemicals in sweetpotato leaves to enhance their bioactivity, thereby making the resulting leaf tea a potential food with improved health benefits.

Keywords

Leafy sweetpotato ； Total phenolics ； Total flavonoids ； Anti-inflammation ； Anti-glycation

Parallel abstracts

採用2種葉用甘藷品種「紫葉」（'Purple Leaf'; PL）、「彩葉」（'Fancy Leaf'; FL）取其葉片（2:1比例）混合製成一種全發酵葉茶（full-fermented leaf tea; FFLT）。兩批試驗原料分別採集於2021年冬天（11月16日）與2022年秋天（9月1日）。第一批冬天材料將樣品區分為葉片與葉柄，以室溫之蒸餾水萃取其植化素，進行總酚與黃酮類化合物含量分析，並分析其還原力以探討其抗氧化能力，結果顯示葉片營養成分高於葉柄。比較此二批原料製成的葉茶，以沸騰熱蒸餾水萃取其植化素，結果顯示其還原力相近，然而第二批秋天採收製成的葉茶中，黃酮類化合物含量為冬天（第一批原料）葉茶的1.7倍，但是總酚含量則是後者略高。葉茶生理活性的研究，是使用第二批採收的秋天材料，並以葉茶生原料（raw material of leaf tea; RMLT）做為比較；同樣以沸騰熱蒸餾水萃取生原料，分析結果顯示FFLT與RMLT均具有抑制一氧化氮（nitric oxide; NO）產生的抗發炎效果，但是後者有增加TNF-α產生的發炎反應，而前者則沒有。針對抑制蛋白質醣化的效果，分析顯示兩者均有效，但FFLT勝於RMLT。由這些結果推測，此全發酵製程使甘藷葉中的某些植化素轉變，從而提升其生理活性，使葉茶成為一種具潛力的健康食物。

Parallel keywords

葉用甘藷 ； 總酚 ； 黃酮類化合物 ； 抗發炎 ； 抗醣化