Phytochemical analysis and evaluation of the inhibitory effect of the Cunila lythrifolia Benth aerial parts on abdominal pain and some digestive enzymes

Ethnopharmacology relevance

Cunila lythrifolia Benth. (Lamiaceae) commonly named “poleo de monte” is a Mexican plant known since pre-Hispanic times because of the properties of its aerial parts to treat respiratory and gastrointestinal conditions, for postpartum care, and as an aphrodisiac.

Aim of the study

To obtain preclinical evidence of the pharmacological properties of C. lythrifolia on abdominal pain and some digestive enzymes, as well as its chemical composition.

Material and methods

The preclinical safety of a decoction was evaluated by the Lorke method in mice. The antinociceptive effect was assessed using the acetic acid-induced writhing test in mice, and the mechanism of action was explored by the co-administration of naloxone. Additionally, the inhibition of the lipase and α-amylase was carried out using a colorimetric assay to calculate the percentage of inhibition. The isolation of specialized metabolites was carried out using chromatographic techniques, and characterization was established with MS, NMR, and chiroptical analysis. The volatile components of the aerial parts were identified by GC–MS analysis of the essential oils, and by HSPM coupled with GC−MS. An analytical method by UHPLC was validated under the guidelines of the ICH, for the quantification of 1.

Results

The LD₅₀ of the aqueous extract is higher than 5 g/kg. The decoction and the essential oil have an antinociceptive effect at 100 and 10 mg/kg, respectively. The essential oil was active against the lipase enzyme (96−76 % of inhibition). The isolated compounds from the decoction were linarin (1), 7-O-[2-O-acetyl-β-D-glucopyranosyl-(1 → 2)-[α-L-rhamnopyranosyl-(1 → 6)]-β-D-glucopyranoside] (2), lithospermic acid (3), rosmarinic acid (4), and citrusin C (5). Compound 1 showed an antinociceptive effect at 316 mg/kg. A UHPLC method was validated for the quantification of 1 in three different batches. The volatiloma analysis revealed that menthofuran (10), β-caryophyllene (22), spathulenol (31), and caryophyllene oxide (32) are the major constituents in the aerial parts. (±)−cunildone (27) a new menthofuran derivative was isolated from the essential oil of the fresh aerial parts.

Conclusion

The results of these studies demonstrate the preclinical safety and validate the traditional use of C. lythrifolia as an antinociceptive agent. Contribute to the chemical identification of the species and to the quality control and establish a method for quantitative analysis of the plant. Overall promoting the rational use and quality control of C. lythrifolia.