Antimicrobial activity of Angocin® Anti-Infekt N, a combination of nasturtium (Tropaeoli majoris herba) and horseradish (Armoraciae rusticanae radix)

Abstract

Aims: Angocin® Anti-Infekt N (Repha, Langenhagen, Germany) is a native preparation comprised of the haulm of nasturtium (N) and the root of horseradish (H). The active ingredients are isothiocyanates that are cleaved from precursors (glucosinolates) after oral intake. Clinical trials have shown that this drug is effective for treatment of urinary and upper respiratory tract infections [1]. Objective: Antimicrobial susceptibility testing of the preparation. Methods: A gas-test was used to investigate the antimicrobial activity of the volatile mustard oils that are released by the preparation. Gently dried and ground N and H were applied to the lids of Mueller Hinton-agar plates (ratio of 2.5:1) and mixed with sterile H2O. Amounts of 3.31mg N/1.25mg H to 400mg/160mg were tested in 65mm, amounts of 200mg/80mg up to 1200mg/480mg in 95mm plates. Various clinically relevant bacterial species were tested (20 isolates each). The organisms were plated onto the agar plates and placed above the test substances. The plates were sealed with tape and incubated at 37° C for 92h. Colony forming units were counted after 24h and 92h, and the MIC90 was determined for each bacterial species. Susceptibilities were checked by use of synthetic mustard oils and with agar- and broth dilution methods. Results: H. influenzae: MIC90 50mg N/20mg H, M. catarrhalis: 100mg/40mg, E. coli: 400mg/160mg, P. aeruginosa: 400mg/160mg, P. vulgaris 400mg/160mg, MSSA and MRSA 400mg/160mg, S. pyogenes 400mg/160mg, S. pneumoniae 400mg/160mg, K. pneumoniae 1000mg/400mg. Conclusion: A broad in vitro antibacterial activity was found against both, gram-negative and gram-positive bacteria, including MRSA and P. aeruginosa. Given that one capsule of the preparation contains 200mg N/80mg H and that the advised daily intake averages out at 15–25 capsules, clinical efficacy can be explained.