Tan Eddie T T, Al Jassim Rafat, D'Arcy Bruce R, Fletcher Mary T
Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland, Health and Food Sciences Precinct , Coopers Plains, Queensland 4108, Australia.
Food Technology Programme, School of Industrial Technology, Faculty of Applied Sciences, Universiti Teknologi MARA , 40450 Shah Alam, Selangor, Malaysia.
J Agric Food Chem. 2017 Aug 30;65(34):7528-7534. doi: 10.1021/acs.jafc.7b02492. Epub 2017 Aug 18.
The known accumulation of the hepatotoxin indospicine in tissues of camels and cattle grazing Indigofera pasture plants is unusual in that free amino acids would normally be expected to be degraded during the fermentation processes in these foregut fermenters. In this study, in vitro experiments were carried out to examine the degradability of indospicine of Indigofera spicata by camel and cattle foregut microbiota. In the first experiment, a 48 h in vitro incubation was carried out using foregut fluid samples that were collected from 15 feral camels and also a fistulated cow. Degradability of indospicine ranged between 97% and 99%, with the higher value of 99% for camels. A pooled sample of foregut fluids from three camels that were on a roughage diet was used in a second experiment to examine the time-dependent degradation of indospicine present in the plant materials. Results indicated that camels' foregut fluids have the ability to biodegrade ∼99% of the indospicine in I. spicata within 48 h of incubation and produced 2-aminopimelamic acid and 2-aminopimelic acid. The time-dependent degradation analysis showed rapid indospicine degradation (65 nmol/h) during the first 8-18 h of incubation followed by a slower degradation rate (12 nmol/h) between 18 and 48 h. Indospicine degradation products were also degraded toward the end of the experiment. The results of these in vitro degradation studies suggest that dietary indospicine may undergo extensive degradation in the foregut of the camel, resulting in trace levels after 48 h. The retention time for plant material in the camel foregut varies depending on feed quality, and the results of this study together with the observed accumulation of indospicine in camel tissues suggest that, although indospicine can be degraded by foregut fermentation, this degradation is not complete before the passage of the digesta into the intestine.
已知骆驼和牛食用槐蓝属牧草植物后，其组织中会积累肝毒素吲哚西平，这一现象不同寻常，因为在前肠发酵动物的发酵过程中，游离氨基酸通常会被降解。在本研究中，进行了体外实验，以检测骆驼和牛的前肠微生物群对穗花槐蓝中吲哚西平的降解能力。在第一个实验中，使用从15头野生骆驼和一头装有瘘管的奶牛采集的前肠液样本进行了48小时的体外培养。吲哚西平的降解率在97%至99%之间，骆驼的降解率较高，为99%。在第二个实验中，使用来自三头以粗饲料为食的骆驼的前肠液混合样本，来检测植物材料中吲哚西平随时间的降解情况。结果表明，骆驼的前肠液能够在培养48小时内将穗花槐蓝中约99%的吲哚西平进行生物降解，并产生2-氨基庚二酸和2-氨基庚二酸。随时间的降解分析表明，在培养的前8至18小时内，吲哚西平迅速降解（65 nmol/h），随后在18至48小时之间降解速度较慢（12 nmol/h）。在实验结束时，吲哚西平降解产物也被降解。这些体外降解研究的结果表明，日粮中的吲哚西平可能在前肠中经历广泛降解，48小时后会残留微量。植物材料在骆驼前肠中的停留时间因饲料质量而异，本研究结果以及在骆驼组织中观察到的吲哚西平积累表明，尽管吲哚西平可通过前肠发酵降解，但在食糜进入肠道之前，这种降解并不完全。
