Phytochemical and Toxicological Analyses of Herbal Mixtures Containing Hypericum perforatum and Melissa officinalis.

Objectives: This study aimed to formulate a novel herbal mixture of Hypericum perforatum (H) and Melissa officinalis (M) and evaluate its toxicity, microbial load, and phytochemical content.

Materials and methods: Total flavonoids were measured using the AlCl₃/NaNO₂ complex formation method and colorimetric assay. The quercetin content of the herbal mixture was determined by reverse-phase high-performance liquid chromatography. The in vitro and in vivo safety of the herbal formulations were analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and acute oral toxicity analysis in the rat model, respectively.

Results: The formulated extract (HM), compared with the standard rutin extract, had a total flavonoid content of 15.29 ± 0.64 mg rutin per mL sample. Reverse-phase high-performance liquid chromatography revealed a quercetin content of 0.187 mg/mL. Microbial tests for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella spp. were negative. Colony counts for total aerobic microbial and yeast and mold counts were 10 in each case. The MTT assay (with up to about 5% v/v HM extract) using the NIH/3T3 cell line revealed no cell toxicity in the range of concentrations tested. Acute oral toxicity was tested in the Wistar rat model, and the LD₅₀ was 695.2 ± 7.5 mg/kg. The dry weight of the HM extract was 38.1 mg/mL.

Conclusion: Preliminary results proved the safety of the HM herbal mixture, with its toxicity and microbial load within the limits of accepted guidelines allowable for use in clinical trials.