天然抗菌素材の開発研究(第1報) : ホソバヤマジソMosla chinensis Maxim.の抗菌性と成分
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概要
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In order to screen for natural antimicrobial compounds, we carried out halo tests using filter paper disks against ten species of microorganisms at 500mg/ml of extracts obtained from about two hundred plants. Although most extracts were effective against bacteria, the methanol extract of Mosla chinensis Maxim. (Hosoba-yamajiso in Japanese. Labiatae) proved highly inhibitory against not only bacteria but also yeast and fungi (Table 1). Partitioning between H_2O and three successive solvents, hexane, CHCl_3 and EtOAc, and MIC testing against twenty-three species of microorganisms revealed the hexane fraction to exhibit the strongest antimicrobial activity. That is, the MIC values with this fraction were found at the lowest concentration and comparison of the diameter of zone inhibition at the same concentration, demonstrated the hexane fraction to exert the greatest effects against almost all species of microorganisms. Plants of Labiatae, especially such as Thymus, Origanum and Satureja used as spices and food additives, contain essential oils, whose constituents such as thymol, carvacrol and eugenol are known to posess antimicrobial activity. A comparison of antimicrobial activities using the MIC test showed that the methanol extract of M. chinensis was more inhibitory against all soecies of microorganisms than that of Th. vulgaris. In addition, thymol exhibited a wide spectrum of antimicrobial activities, similar to these for M. chinensis (Table 2). Hexane fractions from the leaves, stems, flowers and roots of M. chinensis collected during June to August, were analyzed by GLC in order to determine their volatile constituents, and thymol was detected in all fractions. The content of thymol in leaves, 4.43-13.03% was overwhelmingly higher than in other parts, and maximum levels were observed in leaves collected in August (Table 3). Furthermore, antimicrobial activities of extracts determined by MIC testing were proportional to the tymol content. In conclusion, constituents of the hexane fraction containing essential oils, are the main factors responsible for antimicrobial activity of M. chinensis. The results further suggest the participation of thymol in inhibitory effects against microorganisms.
- 日本食品化学学会の論文
- 1997-12-31