New alternative treatments against Clostridioides difficile infection (CDI) are needed due to the substantial increase of CDI caused by hypervirulent isolates and the lack of effective traditional treatment. Therefore, both curcumin (CCM) and capsaicin (CAP) were tested for their ability to inhibit the toxin-producing activity of C. difficile RT 001, RT 126, and RT 084 cell-free supernatants (Tox-S) and C. difficile ATCC 700057 culture-filtrate. The MTT test was used to measure the viability of HT-29 cells after exposure to CCM, CAP, C. difficile Tox-S, and culture-filtrate at a range of doses. In addition, following exposure of HT-29 cells to C. difficile Tox-S and culture-filtrate, the anti-inflammatory and anti-apoptotic effects of CCM and CAP were evaluated.

We used RT-qPCR to determine the levels of BCL-2, SMAD3, NF-κB, TGF-β, and TNF-α gene expression in stimulated HT-29 cells. The vitality of HT-29 cells was significantly (P<0.05) decreased by Tox-S compared to untreated cells. Furthermore, tox-S-treated HT-29 cells saw reduced their BCL-2, SMAD3, NF-κB, and TNF-α gene expression levels (P<0.05) by both CAP and CCM. In addition, both CAP and CCM suppressed TGF-β gene expression in HT-29 cells after Tox-S stimulation, although the effects were not substantially different (P>0.05).

Their findings show that CCM and CAP can inhibit the inflammatory response and apoptotic consequences caused by Tox-S from a variety of clinical C. difficile strains in vitro. Natural components may have anti-toxin activity; however, more research is needed to fully understand the nature of this activity and any potential hazards it may pose in therapeutic settings.