|摘要: ||香蕉廣泛生長在熱帶和亞熱帶國家，已被應用在治療潰瘍性結腸炎、糖尿病及高血壓等疾病，但目前對於香蕉之生理活性成份尚無完整研究，因此本研究利用水、甲醇、正己烷等三種不同極性溶劑萃取香蕉(Musa sapientum L.)果肉與果皮中富含多醣、多酚以及精油等成分，於體外模式下進行免疫調節和抗發炎之功能評估，並進一步利用具有免疫調節與抗發炎潛力之萃取物以直接添加或免疫療法方式探討其對前列腺癌PC-3與乳腺癌MCF-7細胞株細胞凋亡之影響。|
在探討香蕉不同萃取物對雌鼠初代脾臟細胞Th1/Th2免疫反應之影響方面，結果顯示，香蕉果肉粗多醣(banana sarcocarp polysaccharide, BSP)具有調節免疫使傾向Th1免疫平衡之潛力；在以LPS刺激脾臟細胞發炎模式下，香蕉果皮正己烷萃取物(banana peel n-hexane extracts, BPHE)具有抗發炎潛力；在單獨添加或以LPS刺激腹腔巨噬細胞發炎模式下，香蕉不同萃取物中，以BPHE最具有抗發炎潛力。BPHE在預防與治療模式下對腹腔巨噬細胞促發炎與抗發炎細胞激素分泌之影響，顯示在治療模式下BPHE具有降低細胞激素分泌之趨勢，推測BPHE可能具有免疫抑制特性。以膠體過濾(gel filtration)分析BSP，顯示BSP中含有兩個主要成份(fraction-1, F1與fraction-2, F2)，分析BSP中總醣與總蛋白質組成比例，顯示F1和F2皆為蛋白多醣(proteo-polysaccharide)成分，分別以膠體過濾和高效分子篩層析儀(high performance size-exclusion chromatography, HPSEC)測定分子量，F1與F2分子量分別為>37,000 kD (F1)與3.4 kDa (F2)，以HPLC-UV測定單醣組成，發現F1以甘露糖含量最高(53.2%)，F2以葡萄糖含量最高(94.0%)。探討已純化F1與F2對初代脾臟細胞Th1/Th2免疫反應之影響，結果顯示，F1具有調節免疫反應使傾向Th1免疫平衡之潛力；F2則具有使傾向Th2免疫平衡之潛力；整體效果顯示，BSP中主要的免疫活性物質為F1。
Banana grown widely in tropical and subtropical countries, has been used for treatments of ulcerative colitis, diabetes and hypertension. However, the physiologically active ingredients in banana remain unclear. To unravel active immunomodulatory compounds in banana, components rich in polysaccharides, polyphenols and essential oils, were extracted from banana (Musa sapientum L.) using three different solvents with different polarity, including water, methanol, and n-hexane. The extracts were subjected to evaluate their immunomodulatory and anti-inflammatory functions in vitro. The active components were further selected to treat human prostate adenocarcinoma PC-3 cells and breast adenocarcinoma MCF-7 cells using direct addition or immunotherapy.
The effects of different banana extracts on Th1/Th2 immune responses were first investigated using mouse primary splenocytes. The results showed that banana sarcocarp polysaccharide (BSP) had potent potential to regulate Th1/Th2 immune responses toward Th1 immune balance. Banana peel n-hexane extracts (BPHE) inhibited lipopolysaccharide (LPS)-induced inflammatory in the splenocytes. BPHE showed the most anti-inflammatory potential among six different extracts using mouse peritoneal macrophages in the absence or presence of LPS. Furthermore, the effects of BPHE on cytokines secretion profile by peritoneal macrophages under specified preventive and curative experiments were assayed. BPHE inhibited both pro- and anti- inflammatory cytokine secretions by peritoneal macrophages in a specified curative experiment, suggesting that BPHE has an inhibitory property to immune responses. In adddition, BSP was purified using gel filtration with sepharose 6B gel, showing that there were two major components fraction-1 (F1) and fraction-2 (F2) in BSP. Both F1 and F2 were suggested proteo-polysaccharides based on their total sugar and protein composition ratios. The molecular weights of F1 and F2 were distributed at >37,000 kDa and 3.4 kDa, respectively, estimated using gel filtration and high performance size-exclusion chromatography. The monosaccharide compositions showed that F1 and F2 were rich in mannose (53.2%) and glucose (94.0%), respectively, using HPLC-UV assay method. In comparison with isolated F1 and F2, F1 modulated Th1/Th2 immune balance toward Th1-inclination, but F2 toward Th2- inclination. We concluded that F1 was a major active component with an immunomodulatory property in BSP.
F1 and BPHE were further selected to treat PC-3 and MCF-7 cells using direct addition or immunotherapy. The effects of F1, BPHE and conditioned media of imuune cells cultured with F1 or BPHE on pro-/anti-apoptoic gene expression were determined. The results showed that BPHE direct addition and the conditioned medium of peritoneal macrophages cultured with BPHE, as well as the conditioned medium of splenocytes or peritoneal macrophages cultured with F1 increased pro- (Bax)/anti-apoptotic (Bcl-2) gene expression ratios of PC-3 cells.
Overall, F1 and BPHE from banana might induce apoptosis in PC-3 cells through direct action or immunotherapy to achieve anticancer effects.