Vol.:(0123456789) 1 3 Journal of Food Measurement and Characterization https://doi.org/10.1007/s11694-020-00663-2 ORIGINAL PAPER Multifunctional hydrolysates from kenaf (Hibiscus cannabinus L.) seed protein with high antihypertensive activity in vitro and in vivo Nurul Dhania Zaharuddin 1  · Mohamad Arif Hanaf 1  · Chay Shyan Yea 1  · Farah Salina Hussin 1  · Shehu Muhammad Auwal 2  · Mohammad Zarei 3  · Shahrul Razid Sarbini 4  · Wan Zunairah Wan Ibadullah 1  · Roselina Karim 5  · Nazamid Saari 1 Received: 11 March 2020 / Accepted: 14 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Kenaf (Hibiscus cannabinus L.) seed is an underutilized protein-rich resource considered as a by-product of the kenaf fber processing industry. Its high protein content (34%) makes it a promising candidate as a source of bioactive protein hydro- lysates. In this study, the potential of enzymatically hydrolyzed kenaf seed protein to generate multifunctional bioactive peptides was evaluated. Kenaf seed protein concentrate was hydrolyzed using four diferent proteolytic enzymes (papain, alcalase, bromelain, and favourzyme) at their respective optimum pH and temperature. The choice of enzyme afected the bioactivities to a certain degree as KSPH were shown to possess high ACE inhibitory activity and low-to-moderate DPP-IV and antioxidant activity. Papain KSPH showed the highest ACE inhibitory activity with 95% inhibition compared to other enzymatic hydrolysates, and therefore was chosen for further investigation of its antihypertensive activity. Papain KSPH was profled for its hydrophobicity by RP-HPLC and revealed that the majority of late-eluting fractions exerted the highest ACE inhibitory activity. Spontaneously hypertensive rats showed a decrease of approximately 18–46 mmHg in their systolic blood pressure (BP) from 0 to 24 h after oral administration of papain KSPH at dosages of 100 mg/kg, 300 mg/kg, and 500 mg/ kg. However, the efect was not dose-dependent. As a novel protein source, future research should aim to demonstrate the safety of kenaf seed protein and its hydrolysates, and validate its bioactivity through human intervention trials. Overall, kenaf seed protein has the potential to generate antihypertensive hydrolysates with multifunctional bioactivities as part of a functional food ingredient. Keywords Kenaf seed · Protein hydrolysate · Multifunctional bioactivity · Antihypertensive · Spontaneously hypertensive rat Introduction The growing world population has provoked an increased urgency in fnding novel solutions to address food security issues. This is compounded by the threat of non-commu- nicable diseases (NCD), including diabetes, cardiovascular diseases, and cancer, responsible for up to 71% of deaths worldwide [1]. While the problem lies partly with how food is manufactured and marketed, the solution may come in the form of food themselves [2, 3]. There’s a growing body of evidence that certain bioactive components from food possess benefcial physiological efects that can help to ame- liorate the efect of NCDs. Bioactive protein hydrolysates generated from enzymatic hydrolysis of protein substrates have shown potential as functional food ingredients [4]. Functional food ingredients produced from underutilized * Nazamid Saari nazamid@upm.edu.my 1 Department of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 2 Department of Biochemistry, Faculty of Basic Medical Sciences, Bayero University Kano, P.M.B 3011, Kano, Nigeria 3 Department of Food Science and Technology, School of Industrial Technology, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia 4 Department of Crop Science, Faculty of Agricultural and Food Sciences, Universiti Putra Malaysia Bintulu Campus, Jalan Nyabau, 97008 Bintulu, Sarawak, Malaysia 5 Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia