NOVEL ANTIOXIDANT PEPTIDES FROM THE CAMEL MILK HYDROLYSATES U.J. Ishimov, Asrorov A.M, J.F. Ziyavitdinov Institute of Bioorganic Chemistry, Academy of Sciences Republic of Uzbekistan, Tashkent e-mail: uchkunishimov@gmail.com
Milk peptides have strong biological activities. Camel milk protein composition is
different from those in cow, buffalo, sheep, goats, donkey and mare based on casein and
raw protein proportion. In the present study, camel milk proteins were hydrolyzed using
trypsin. The digested camel milk samples were then fractionated and further their
antioxidant activities were determined using 2,2-diphenyl-1- picrylhydrazyl (DPPH)
and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS
+
). Antioxidant
activity test guided-fractionation allowed isolation of the three antioxidant peptides
using ultrafiltration (3000 Da membrane), gel filtration chromatography, and RP-HPLC.
Camel milk was defatted by centrifugation at 10 000 rpm for 15 min using a high-
speed centrifuge. Skimmed milk protein was hydrolyzed with trypsin enzyme under
optimal conditions for 4 hours. The yield of isolated peptides made 82%. Camel milk
peptides were fractionated and purified using a C18 Agilent column (ZORBAX 300SB-
C18 25.0 cm × 9.4 mm, 5 μm; USA). Elution was monitored with an ultraviolet (UV)
detector at 224 nm. The amino acid sequence and molecular weight of the separated
peptide fractions were determined on an Agilent Technologies 6530B Chip-HPLC-Q-
TOF mass spectrometer. The obtained mass spectra were interpreted using Mass COT
and Spectrum Mill programs. As a result of chromato-mass spectrometric studies, the
following fragment peptides were identified: F-1 - RLDGQGRPRVWLGR, F-2 -
TPDNIDIWLGGIAEPQVKR and F-3 - VAYSDDGENWTEYRDQGAVEGK with
MW 1665.94, 2122.13 and 2489.09 Da, respectively. The amino acid sequence search
in databases showed that the peptides were novel.
The DPPH and ABTS
+
scavenging activities of three individual peptides (F-1, F-2,
and F-3) were determined. IC
50
values on DPPH were 1.9 for F-1, 1.2 for F-2, 0.6
mg/mL for F-3. Results on ABTS
+
made 2.4, 1.8 and 0.9 mg/mL respectively. F-3
exhibited higher DPPH and ABTS scavenging activity than other fractions.