After stirring, the sample was centrifuged at 18,000 g for 4 min at 4 C and the supernatant was filtered through PVDF 0.45 mm membrane (Millipore Corporation, Bedford, MA, USA).
After stirring, the sample was centrifuged at18,000 g for 4 min at 4 C and the supernatant was filteredthrough PVDF 0.45 mm membrane (Millipore Corporation, Bedford,MA, USA).