Cancers of all types are among the four main non-communicable diseases, a category of diseases responsible for 38 million yearly deaths worldwide. Although various medical procedures including surgery, immunotherapy, radiation therapy, hormone therapy, stem cell transplant and chemotherapy have been used for decades in the treatment and control of cancer, current survival rates suggest that more definitive and effective treatment strategies are warranted. This work provides a succinct summary of the various methods used for producing anticancer peptides and protein hydrolysates from food sources, their modes of action, as well as descriptions of their antitumour properties in cellular and animal models. Although the mechanisms by which protein hydrolysates and peptides exert antitumor and antiproliferative effects are not entirely elucidated, there is evidence pointing to antioxidative function as an important predictor of their anticancer property.

The aim of this work was to produce wonderful cola protein hydrolysate fractions with in vitro antioxidant properties coupled with blood pressure-reducing ability when orally administered to spontaneously hypertensive rats (SHRs). Wonderful cola protein isolate (WCI) was hydrolyzed with pancreatin to produce a hydrolysate (WCH), which was subjected to ultrafiltration separation using 1, 3, 5, and 10 kDa molecular weight cut-off membranes to obtain < 1, 1–3, 3–5 and 5–10 kDa peptide fractions, respectively. The < 1 and 1–3 kDa fractions had higher contents of arginine when compared to the 3–5 and 5–10 kDa peptides. The WCH and < 1 kDa peptide fraction had significantly (p < 0.05) better DPPH radical scavenging (55–67%) and metal chelation (83–93%) activities but lower hydroxyl radical scavenging power (10–32%) than the WCI (46, 46 and 63%, respectively). The < 1 kDa had significantly (p < 0.05) higher in vitro inhibition (80%) of angiotensin converting enzyme (ACE) activity while the 5–10 kDa was the most active inhibitor (90%) of renin activity. All peptide fractions so produced had better systolic and diastolic blood pressure-lowering effects than WCH and WCI. However, the < 1 kDa fraction produced significantly (p < 0.05) stronger systolic (−33 mmHg) and diastolic (−30 mmHg) blood pressure reductions 6 h after oral gavage to SHRs. Thus, wonderful cola proteins contain encrypted bioactive peptides that may be used to formulate antioxidant and antihypertensive products.

The antihypertensive effects of aqueous polyphenol-rich extracts of Amaranthusviridis (AV) and Telfairiaoccidentalis (TO) leaves in spontaneously hypertensive rats (SHR) were investigated. The dried vegetable leaves were extracted using 1:20 (leaves: water, w/v) ratio for 4 h at 60 ℃. Results showed significantly (P < 0.05) higher polyphenol contents in TO extracts (80–88 mg gallic acid equivalents, GAE/100 mg) when compared with the AV (62–67 mg GAE/100 mg). Caffeic acid, rutin and myricetin were the main polyphenols found in the extracts. The TO extracts had significantly (P < 0.05) higher in vitro inhibition of angiotensin I-converting enzyme (ACE) activity while AV extracts had better renin inhibition. Oral administration (100 mg/kg body weight) to SHR led to significant (P < 0.05) reductions in systolic blood pressure for the AV (−39 mmHg after 8 h)and TO (−24 mmHg after 4 and 8 h).The vegetable extracts also produced significant (P < 0.05) reductions in diastolic blood pressure, mean arterial blood pressure and heart rate when compared to the untreated rats. Thus both the AV and TO leaf extracts have the potential to be used as antihypertensive agents, especially the AV, which produced persistent long-lasting effect over a 24 h period.