PHARMACOGNOSTIC SPECIFICATIONS AND ANTIMICROBIAL ACTIVITIES OF HOUTTUYNIA CORDATA

Abstract

Houttuynia cordata Thunb. (Plu-Klao) is a perennial plant that belongs to Saururaceae Family. Fresh leaves of H. cordata are popular vegetable eaten with main course in the northern region of Thailand and all parts were used for immune stimulization. The aims of this study were to investigate the pharmacognostic specifications, analyses of the content of quercetin and volatile oil chemical constituents of H. cordata whole plants. H. cordata were collected from 12 different locations in Thailand. The results demonstrated the content of loss on dying, total ash, acid insoluble ash, water-soluble extractive value, ethanol- soluble extractive value, moisture and volatile oil content as 7.22 ±0.34, 14.31±0.15, 4.11±0.36, 14.17±1.03, 4.69±0.48, 11.70±1.18, 0.08±0.01 % by dried weight, respectively. The macroscopic and microscopic characteristics were illustrated in detail. Thin layer chromatographic fingerprints of ethanolic extract were performed using toluene: ethyl acetate: methanol: formic acid (5: 5: 3: 2) as mobile phase and visualization under daylight, UV 254 nm, UV 366 nm and staining with natural product–polyethylene glycol reagent. Quercetin contents in 12 ethanolic extracts were determined by TLC-densitometry and TLC image analysis using imageJ software. Both methods were valid and reliable according to ICH guideline. The quantitative analysis revealed that quercetin contents in most extracts were less than the limit of quantitation except only one source which was found to be 0.0049 g/g crude drugs by TLC densitometry and 0.0031 g/g crude drugs by TLC image analysis. H. cordata volatile oil was extracted by hydrodistillation. At least 30 chemical constituents of volatile oil were identified by GC/MS. The major constituents were decanoic acid (40.40±27.21%), 2-undecanone (26.43±14.54%) and myrcene (19.21±15.09%). The volatile oil was investigated for antimicrobial activity by agar diffusion assay and broth microdilution assay and was shown positive against gram positive bacteria (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Kocuria rhizophila, Straphylococcus epidermidis) and fungi (Candida albicans, Saccharomyces cerevisiae).