International Journal of Biological Macromolecules 104 (2017) 189–196 Contents lists available at ScienceDirect International Journal of Biological Macromolecules j ourna l h o mepa ge: www.elsevier.com/locate/ijbiomac Characterization of keratin microparticles from feather biomass with potent antioxidant and anticancer activities Swati Sharma a , Arun Gupta a,∗ , Syed Mohd S.T. Chik a , Chua Geek Kee a , Bhupendra M. Mistry b , Doo H. Kim c , Gaurav Sharma d a Faculty of Chemical Engineering and Natural Resources, Universiti Malaysia Pahang, Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia b Department of Food Science and Biotechnology, Dongguk University-Seoul, Ilsandong-gu, Goyang-si, Gyeonggi-do 410-820, Republic of Korea c Department of Bioresources and Food Science, College of Life and Environmental Sciences, Konkuk University, Seoul, Republic of Korea d School of Chemistry, Shoolini University, Solan 173212, Himachal Pradesh, India a r t i c l e i n f o Article history: Received 26 April 2017 Received in revised form 2 June 2017 Accepted 3 June 2017 Keywords: Chicken feather Keratin Micro-particles Anti-oxidant Anti-cancerous Iso-electric point a b s t r a c t In the present study chicken feathers were hydrolyzed by chemical treatment in alkaline conditions. The pH value of feather hydrolyzed solution was amended accordingly the iso-electric precipitation. Two types of keratin microparticles KM1, KM2 were synthesized under acidic conditions at 3.5 and 5.5 pH respectively. The synthesized keratin microparticles possessed uniform and round surface by scanning electron microscopy (SEM). The thermal degradation of microparticles were examined by ther- mogravimetry (TGA). Fourier transform infrared spectroscopy (FTIR) revealed that the extracted keratin retained the most of protein backbone. The microparticles were screened for their in vitro anticancer activities by SRB bioassay towards HeLa, SK-OV-3 and A549 cancer cell lines. Futhermore, their cytotox- icity towards healthy cell lines was analyzed having Malin Darby canine kidney (MDCK) cell lines along with in vitro antioxidant activity using DPPH and ABTS methods KM1 and KM2 showed 200.31 ± 1.01 and 139.73 ± 0.94, 214.16 ± 0.29 and 153.92 ± 0.61, 328.92 ± 3.46 and 200.33 ± 2.48 g/mL of IC 50 levels against HeLa, SK-OV-3, and A549 cell lines, respectively. Moreover, KM1 and KM2 demonstrated signifi- cant antioxidant potency with IC 50 levels 13.15 and 9.02 g/mL as well as 8.96 and 5.60 g/mL in DPPH and ABTS radical scavenging bioassay, respectively. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Feathers are a regular, renewable and natural stuff produced in abundance. Approximately 5 million tons of feather biomass is being generated annually from poultry farms [1,2] which leads to serious solid waste hazards [3]. The chicken feathers are the most troublesome waste product of the poultry industry [4]. Consider- ing the high protein content (90%) [1], it could provide an excellent source of amino acids for animal feed [5], biocomposites [6] and for numerous other industrial applications [7,8]. Keratin is one of the most abundant biopolymers and is available from a variety of sources like hairs, nails, feather, wool, horn-hoof etc. [9–14]. Thus, due to serious environmental concern, these bio-based materials can be used to replace petrochemicals and can be applicable in chemical, pharmaceutical industries and tissue engineering too. Keratin consists a chain of small amino acids with molecular weight approximately 10,500 Da [15]. It has -helix,  sheet or ran- ∗ Corresponding author. E-mail address: arungupta10@gmail.com (A. Gupta). dom, unordered macrostructure. Particularly, keratin from chicken feathers mainly consist of -sheet and little amount of -helices and loops [16,17] and showed high percentage of amino acids such as alanine, glycine, serine, cystine and valine, but lower fraction of methionine, tryptophan and lysine [18]. The composition of amino acid may vary and depends on the source of keratin extracted [9]. Keratin is widely used in the pharmaceutical, cosmetic, med- ical, and biotechnological industry. It can be easily converted into porous foam of different shapes, sponges, microfibers coatings, mats, gels, and materials of high molecular weight. Various techniques were used for extraction of keratin like reduction, oxidation and processing in ionic liquids [19–21]. Also, 2-mercaptoethanol was used as a thiol supplier which cleave the disulfide bonds without any alternation in the primary chain [22]. The sodium sulfide based extraction of keratin by dissolv- ing chicken feather is an efficient and economically favorable method which provide sufficient yield and also retained the sec- ondary structure of protein [23]. The feather protein also has potent http://dx.doi.org/10.1016/j.ijbiomac.2017.06.015 0141-8130/© 2017 Elsevier B.V. All rights reserved.