儲存期間啤酒花萃取物之抗氧化及對痤瘡桿菌抗菌之影響

Abstract

啤酒花廣泛用於啤酒釀造過程中賦予啤酒苦味以及特殊香氣。研究指出啤酒花中苦味酸化合物葎草酮 (humulone)、蛇麻酮 (lupulone)，以及多酚類化合物等活性成分，具有抗菌、抗發炎、抗氧化、抑制癌細胞增生等功效。尋常性痤瘡 (acnevulgaris) 俗稱青春痘，是一種常見的皮膚疾病，而痤瘡桿菌 (Propionibacterium acnes, P. acnes) 對尋常性痤瘡形成扮演著相當重要的角色。啤酒花中活性成分的穩定性相當重要，但這些成分易受光、溫度、氧氣的影響而劣化。為促使啤酒花能獲得更廣泛之應用，故本研究欲探討以不同酒精濃度 (55%、75%、95%) 萃取之啤酒花萃取物 (hops ethanol extracts,HEE)，及以超臨界流體萃取之啤酒花浸膏對痤瘡桿菌之抑菌效果，並探討啤酒花萃取物在儲存期間之抗痤瘡桿菌與抗氧化活性的變化，萃取物分別儲存於室溫 (25°C) 及冷藏 (4°C) 環境下 3 個月，藉此評估啤酒花應用在皮膚保健產品上的潛力。研究結果顯示，不同啤酒花萃取物對痤瘡桿菌皆有良好抑菌及殺菌效果，且以啤酒花浸膏殺菌效果最佳，抑制 P. acnes 生長的最小抑制濃度 (MIC) 和最小殺菌濃度 (MBC) 為 2 μg/ml 和 4 μg/ml。而儲存試驗結果顯示，經過 3 個月儲藏後，95%酒精萃取之啤酒花萃取物及啤酒花浸膏之抗菌及抗氧化活性較穩定，抗氧化力分別下降 0.06%、15.28%，而 55%酒精萃取之啤酒花萃取物，抗氧化力下降 38.43%，其抗菌及抗氧化活性有明顯下降的現象 (P < 0.05)，透過低溫儲存可減緩其下降趨勢。因此，未來欲利用啤酒花進行產品開發，可選擇較安定的啤酒花浸膏或 95%啤酒花酒精萃取物來進行，尚需注意其儲存環境，以確保其效用。

Hops, the female inflorescences of the hop plant (Humulus lupulus L.), are widely used in the brewing industry to add bitterness and aroma to beer. Hops have attracted a great deal of attention as a source of small molecules such as humulone, lupulone and xanthohumol with potential for beneficial effects on antibacterial,antiinflammatory, antioxidation and antiproliferation. Propionibacterium acnes (P. acnes) play important roles in common skin disease of acne vulgaris. The stability of the constituents of hops has been great important. However, hop constituents are quite unstable and sensitive to heat, light, and oxygen. In addition, oxidation and degradation occurring during the storage period reduce the active ingredients content and antibacterial activity. In order to increase application of hops, the aim of this work is to evaluate antibacterial activity of the hops extracts obtained under various extract conditions, and their antibacterial and antioxidant activity changes during storage period. Thus, in this work, hops extracts made with various ethanol concentrations (55%, 75%, 95%) and CO2 hops extract were stored at different temperatures (4°C / 25°C) for three months to study their antibacterial activity against P. acnes and antioxidant activity changes during storage period. The results showed that CO2 hops extract and 95% hops ethanol extract exhibited higher antibacterial and antioxidant activities than other hops extracts and remained stable after three months storage. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of CO2 hops extract was 2 μg/ml and 4 μg/ml, respectively. The 55% hops ethanol extract showed a significant decrease in antibacterial and antioxidant activities after storage, but the activities can be improved by storage at a lower temperature. These results suggested that the CO2 hops extract and 95% hops ethanol extract are more suitable for skin care products and the storage environment should be noticed to ensure quality of the extracts.