Myung Kyung, Manthey John A, Narciso Jan A
Citrus and Subtropical Products Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 600 Ave. S, N.W., Winter Haven, FL 33881, USA.
Appl Microbiol Biotechnol. 2008 Mar;78(3):401-7. doi: 10.1007/s00253-007-1326-9. Epub 2008 Jan 10.
Furanocoumarins (FCs) in grapefruit are involved in the "grapefruit/drug interactions" in humans, in which the FCs inhibit the intestinal cytochrome P450 3A4 (CYP 3A4) activity responsible for metabolizing certain prescribed medications. These interactions have adversely affected the grapefruit industry and have led a need to develop a process to remove the FCs from grapefruit juice (GFJ) in a manner that retains much of the original juice sensory attributes. In our experiments, grapefruit juice was incubated with Aspergillus niger, and the compositional changes in hydroxycinnamates, flavonoid glycosides, and the FCs were monitored. Many of the FCs and 7-geranyloxycoumarin were efficiently taken up by the fungal tissue, whereas no uptake occurred with the polar hydroxycinnamates, flavonoid glycosides, and a few of the polar FCs. This biosorption was also observed with autoclaved A. niger, indicating that the uptake of non-polar FCs by the fungal hyphae was due to adsorption rather than metabolism. The binding of the FCs to autoclaved fungus was complete within 4 h, and the level of binding was proportional to the amount of autoclaved fungal hyphae used. This removal of the FCs from GFJ led to a reduced inhibition of CYP 3A4 activity in in vitro assays by both GFJ and GFJ extracts.
葡萄柚中的呋喃香豆素（FCs）会引发人体中的“葡萄柚/药物相互作用”，其中FCs会抑制负责代谢某些处方药的肠道细胞色素P450 3A4（CYP 3A4）的活性。这些相互作用对葡萄柚产业产生了不利影响，因此需要开发一种从葡萄柚汁（GFJ）中去除FCs的方法，同时保留原果汁的大部分感官特性。在我们的实验中，将葡萄柚汁与黑曲霉一起培养，并监测羟基肉桂酸酯、黄酮苷和FCs的成分变化。许多FCs和7-香叶氧基香豆素被真菌组织有效吸收，而极性羟基肉桂酸酯、黄酮苷和一些极性FCs则未被吸收。在经过高压灭菌的黑曲霉中也观察到了这种生物吸附现象，这表明真菌菌丝对非极性FCs的吸收是由于吸附而非代谢。FCs与经过高压灭菌的真菌的结合在4小时内完成, 且结合水平与所用的经过高压灭菌的真菌菌丝量成正比。从GFJ中去除这些FCs导致GFJ及其提取物在体外试验中对CYP 3A4活性的抑制作用降低。
