Effect of Lactiplantibacillus plantarum fermentation on the in-vitro antioxidant and angiotensin I-converting enzyme-inhibitory properties of turmeric, coriander, cumin, and red chili pepper suspensions

In this study, we investigated the effects of lactic acid fermentation by the selected strains of Lactiplantibacillus plantarum on the antioxidant and angiotensin I-converting enzyme (ACE)inhibitory properties of four popular spice suspensions, namely turmeric (Curcuma longa), coriander (Coriandrum sativum), cumin (Cuminum cyminum), and red chili pepper (RCP) (Capsicum annuum). Among these, the RCP suspension exhibited the most significant positive changes following fermentation with L. plantarum Tennozu-SU3, whereby the total phenolic content, antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl and O2- scavenging), and rabbit lung ACEinhibitory activity were increased. The fermented RCP suspension was then fractionated via ultrafiltration. The 10-30 kDa fraction was speculated as the component that increased antioxidant and ACE-inhibitory activities of RCP. Moreover, although the ACE-inhibitory effect of the RCP suspension on rabbit lung ACE was significantly increased after fermentation (41 folds), this was not observed in murine organs (lungs, kidneys, and testes) or on recombinant human ACE. Our findings suggest that the inhibitory effect of fermented RCP suspension on the rabbit lung ACE was not extended to ACE from other animals, including humans.

Automated summary

This study examined the effects of lactic acid fermentation by selected strains of Lactiplantibacillus plantarum on the antioxidant and ACE-inhibitory properties of four popular spice suspensions. Among them, the RCP suspension showed the most significant positive changes, with an increase in total phenolic content, antioxidant capacity, and ACE-inhibitory activity. The fractionation of the fermented RCP suspension revealed that the 10-30 kDa fraction was responsible for the increased activities. However, the enhanced ACE-inhibitory effect observed in rabbit lung ACE did not extend to ACE from other animals or recombinant human ACE.