Huang B, et al. Nutr Res Pract. 2015 Feb;9(1):22-29. https://doi.org/10.4162/nrp.2015.9.1.22

Mentha plants containing over 25 species are aromatic perennial herbs. These species have been interested and widely used because of various clinical findings. Many volatile compounds facilitate environmental interactions such as protecting themselves from pathogens, parasites, and herbivores. Therefore, this study assessed comparison of volatile composition and antimicrobial activity from nine Mentha species. The composition of volatiles was investigated from the aerial parts of nine different Mentha species using gas chromatography-mass spectrometry (GC/MS). In addition, screened antimicrobial activities against six food borne pathogenic bacteria using extracts obtained these plants. 77 volatile compounds were identified in total and it included 13 monoterpenoids, 19 sesquiterpenoids, and others. In particular, monoterpenoids such as eucalyptol (9.35–62.16 %), (±)camphorquinone (1.50–51.61 %), and menthol (0.83–36.91 %) were mostly detected as major constituents in Mentha species. The ethanol extract of nine Mentha species showed higher activity compared to other solvent extracts (methanol, hexane, di ethyl ether). Among these nine Mentha species chocomint showed higher inhibition activity against all bacteria. It is concluded that monoterpenoids are mainly rich in Mentha plants. Moreover, most of extracts obtained from Mentha showed strong antimicrobial activity against bacteria. Of these, chocomint indicates the highest inhibition activity.

Japan's largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies

The goal of this study was to determine the rat lens aldose reductase-inhibitory effects of 95% ethanol extracts from the leaves of C. esculenta and, its organic solvent soluble fractions, including the dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc), n-butanol (BuOH) and water (H₂O) layers, using dl-glyceraldehyde as a substrate. Ten compounds, namely tryptophan (1), orientin (2), isoorientin (3), vitexin (4), isovitexin (5), luteolin-7-O-glucoside (6), luteolin-7-O-rutinoside (7), rosmarinic acid (8), 1-O-feruloyl-d-glucoside (9) and 1-O-caffeoyl-d-glucoside (10) were isolated from the EtOAc and BuOH fractions of C. esculenta. The structures of compounds 1–10 were elucidated by spectroscopic methods and comparison with previous reports. All the isolates were subjected to an in vitro bioassay to evaluate their inhibitory activity against rat lens aldose reductase. Among tested compounds, compounds 2 and 3 significantly inhibited rat lens aldose reductase, with IC₅₀ values of 1.65 and 1.92 μM, respectively. Notably, the inhibitory activity of orientin was 3.9 times greater than that of the positive control, quercetin (4.12 μM). However, the isolated compounds showed only moderate ABTS⁺ [2,29-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] activity. These results suggest that flavonoid derivatives from Colocasia esculenta (L.) Schott represent potential compounds for the prevention and/or treatment of diabetic complications.