In Vitro Multi-Bioactive Potential of Enzymatic Hydrolysis of a Non-Toxic Jatropha curcas Cake Protein Isolate

Abstract

The Jatropha curcas cake, a protein-rich by-product of biofuel production, was the subject of our study. We identified and quantified the ACE inhibitory, antioxidant, and antidiabetic activities of bioactive peptides from a Jatropha curcas L. var Sevangel protein isolate. The protein isolate (20.44% recovered dry matter, 38.75% protein content, and 34.98% protein yield) was subjected to two enzyme systems for hydrolysis: alcalase (PEJA) and flavourzyme (PEJF), recording every 2 h until 8 h had passed. The highest proteolytic capacity in PEJA was reached at 2 h (4041.38 ± 50.89), while in PEJF, it was reached at 6 h (3435.16 ± 59.31). Gel electrophoresis of the PEJA and PEJF samples showed bands corresponding to peptides smaller than 10 kDa in both systems studied. The highest values for the antioxidant capacity (DPPH) were obtained at 4 h for PEJA (56.17 ± 1.14), while they were obtained at 6 h for PEJF (26.64 ± 0.52). The highest values for the antihypertensive capacity were recorded at 6 h (86.46 ± 1.85) in PEJF. The highest antidiabetic capacity obtained for PEJA and PEJF was observed at 6 h, 68.86 ± 8.27 and 52.75 ± 2.23, respectively. This is the first report of their antidiabetic activity. Notably, alcalase hydrolysate outperformed flavourzyme hydrolysate and the cereals reported in other studies, confirming its better multi-bioactivity.

Keywords: Jatropha curcas; alcalase; antidiabetic; antihypertensive; antioxidant; bioactive peptides; flavourzyme.

Figure 1

Peptide separation by Tris-Tricine-SDS-PAGE in a protein extract of Jatropha hydrolyzed with alcalase (A) and a protein extract of Jatropha hydrolyzed with flavourzyme (B). STD: peptides standard. Hydrolysis time (0–8 h). On the left side of A and B, the molecular mass range of the peptides is observed from 2 to 50 KDa. The blue lines indicate the bands detected in each lane of the electrophoresis gel. The peptide zones of interest in this study are in the range of 2–10 KDa.

Figure 2

Antioxidant activity by FRAP (A) and DPPH (B) methods with alcalase and flavourzyme of hydrolysates of a protein extract of Jatropha curcas L. var. Sevangel. Results are expressed in 100 mL as mean ± standard error. FRAP: ferric-reducing antioxidant power; DPPH: 2,2-diphenyl-1-picrylhydrazyl hydrolysis time (0–8 h). This figure shows that the alcalase system had higher antioxidant activity than the flavourzyme system at all hydrolysis times, especially at 6 h for DPPH and 4 h for FRAP.

Figure 3

Electropherogram profile at 0 h, 2 h, 4 h, 6 h, and 8 h in Jatropha protein extract hydrolyzed with alcalase. STD: peptide standard. The green area in the figure represents the molecular weight concentration of the peptides; for more information see the Data Availability Statement. This figure shows an increase in the concentrations of various peptides ≤ 10 KDa for the initial time (0 h).

Figure 4

Electropherogram profile at 0 h, 2 h, 4 h, 6 h, and 8 h in Jatropha protein extract hydrolyzed with flavourzyme. STD: peptide standard. The green area in the figure represents the molecular weight concentration of the peptides; for more information see the Data Availability Statement. This figure shows an increase in the concentrations of various peptides ≤ 10 KDa for the initial time (0 h).