Evaluation on Antimicrobial Activity of Psoraleae semen Extract Controlling the Growth of Gram-Positive Bacteria

Sejeong Kim1,2, Soomin Lee1,2, Heeyoung Lee1,2, Jimyeong Ha1,2, Jeeyeon Lee1,2, Yukyung Choi1,2, Hyemin Oh1,2, Joonbae Hong3, Yohan Yoon1,2,*, Kyoung-Hee Choi4,5,*
Author Information & Copyright
1Department of Food and Nutrition, Sookmyung Women's University
2Risk Analysis Research Center, Sookmyung Women's University
3Test & Research Department, Consumer Safety Center, Korea Consumer Agency
4Department of Oral Microbiology, College of Dentistry, Wonkwang University
5Institute of Biomaterials-Implant, Wonkwang University
*Corresponding authors Kyoung-Hee Choi College of Dentistry, Wonkwang University, Iksan 54538, Korea Tel: +82-63-850-6911 Fax: +82-63-850-6911 E-mail: Yohan Yoon Department of Food and Nutrition, Sookmyung Women's University, Seoul 04310, Korea Tel: +82-2-2077-7585 Fax: +82-2-710-9479 E-mail:

Copyright © 2017, Korean Society for Food Science of Animal Resources. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Feb 08, 2017 ; Revised: Jun 21, 2017 ; Accepted: Jul 04, 2017

Published Online: Aug 31, 2017


This study investigated bacterial growth-inhibitory effect of 69 therapeutic herbal plants extracts on 9 bacterial strains using a disc diffusion assay. Especially, the antimicrobial activity of Psoraleae semen, which showed different activity on pathogenic Gram-positive and Gram-negative bacteria, was evaluated by MIC (minimal inhibition concentration) and biofilm formation assay. The effect of Psoraleae semen extract on bacterial cell membranes was examined by measurement of protein leakage (optical density at 280 nm) and scanning electron microscope (SEM). No clear zone was formed on discs containing Gram-negative bacteria, but Gram-positive bacteria exhibited clear zones. The MICs of Psoraleae semen extract were 8 μg/mL for Streptococcus mutans, and 16 μg/mL for Enterococci and Staphylococcus aureus. In addition, biofilm formation was inhibited at concentration 8-16 μg/mL. Protein leakage values and SEM images revealed that cell membranes of Gram-positive bacteria were impaired following exposure to the extract. Further, the extract inhibited the growth of Listeria monocytogenes in sausages. These results indicate that Psoraleae semen extract could be utilized as a natural antimicrobial agent against Gram-positive bacteria.

Keywords: antibacterial activity; natural antimicrobials; therapeutic herbal plants


For last decades, abuse of antibiotics has increased the prevalence of antibioticresistant bacteria, resulting in significant problems to human health (Fani et al., 2007). Therefore, investigation into new antibacterial agents is required. Currently, there are negative perceptions regarding synthetic additives, and natural materials are attractive as alternative antimicrobial agents because of their limited effects on the environment and their low toxicity to human cells(Kaya et al., 2008). Various lifeforms, including microorganisms, plants, and animals, have been investigated to identify novel antimicrobial agents that possess these favored characteristics (Guliani et al., 2007; Yoon and Choi, 2010).

Plant-derived extracts, which are biodegradable and ready available, are known to possess antimicrobial activity against bacteria, yeast, and mold. Furthermore, they contain various antimicrobial components and phytochemicals, including alkaloids, terpenes, essential oils, and phenols. Therefore, plant-derived compounds are considered to be valuable sources of potential novel antimicrobial agents (Liu et al., 2007). For instance, a mixture of lemon and cherry powder was effective at inhibiting Clostridium perfringens growth in frankfurters and ham (Jackson et al., 2011), and an extract from the stem bark of Irvingia gabonensis, known as African mango, also showed antimicrobial activity on various bacteria such as Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus at concentrations of 75-160 μg/mL (Kuete et al., 2007).

Psoraleae semen is the seed of natural herb Psoralea corylifolia L. (Shim et al., 2009). It has been used in traditional Asian medicine, and it has been proved that they have many pharmacological effects including anti-angiogenesis, anti-cancer, and promoting bone formation (Hwang et al., 2013; Xiong et al., 2003). Extract of the plant contains many useful compounds such as bakuchiol, bavachinin, corylin, corylifolin, isopsorlen, psoracorylifols, psoralen, and psoralidin (Wong and Rabiem, 2010). In particular, bakuchiol was found to inhibit growth of Helicobacter pylori (Zaide et al., 2009), and Yoon and Choi (2012) reported that among various therapeutic herbal extracts, Psoraleae semen had a considerable antilisterial effect. Nevertheless, the antimicrobial effect of this extract on other important pathogenic bacteria remains to be determined.

In the present study, various therapeutic herbal plant extracts were screened for antimicrobial activity, and one of them, Psoraleae semen was evaluated as an antimicrobial agent in in vitro and in sausages for application in food, and its effect on bacterial cells was observed by measuring protein leakages and observing a scanning electron microscope (SEM).

Materials and Methods

Preparation of therapeutic herbal plant extracts

Sixty-nine of herbal plant extract powder were acquired from New Natural Material Bank of Korea National Research Resources (Korea) (Table 1). The powder was produced by heating 70% ethanol extraction, followed by vacuum evaporation of the filtrate. A liquid stock was made by dissolving the extract powder in 100% dimethyl sulfoxide (DMSO; Sigma, USA) to give a final concentration of 50 mg/mL.

Table 1. Therapeutic herbal extracts (50 mg/mL) used in this study and their antimicrobial activities against Gram-positive and Gram-negative bacteria
Number of NNMBS Name of extracts Scientific name of extracts Gram-negative bacteria Gram-positive bacteria

NNMBS4 Gaehyuldeng Spatholobi caulis *3 * * * * * * * *
NNMBS7 Gosam Sophorae radix * * * * * * * * *
NNMBS10 Ildangui Angelicae radix * * * * * * * * *
NNMBS13 Mogua Chaenomelis fructus * * * * * * * * *
NNMBS16 Baekduong Pulsatillae radix * - * * * * * * *
NNMBS19 Baeksunpi Dictamni radicis Cortex * - * - * * * * *
NNMBS22 Baekji Angelicae dahuricae Radix * * * * * * * * *
NNMBS25 Bokbunja Rubi fructus §
NNMBS31 Sansuyu Corni fructus * * * * * * * * *
NNMBS34 Sanglyuk Phytolaccae radix * * * * * * * * *
NNMBS37 Sangbaekpi Mori radicis Cortex * * * * * * *
NNMBS40 Sansimja Mori fructus * * * * * * * * *
NNMBS42 Aeyub Artemisiae argyi Herba * * * * * * * * *
NNMBS45 Youngsil Rosae fructus * * * * * * * * *
NNMBS48 Omija Schizandrae fructus * - * * * * * * *
NNMBS51 Obaeja Galla rhois § *
NNMBS54 Oyak Linderae radix * * * * * * * *
NNMBS60 Wonji Polygalae radix * * * * * * * * *
NNMBS63 Yukyongjong Cistanchis gerba * * * * * * * * *
NNMBS66 Baekjakyak Paeoniae radix * * * * * * * * *
NNMBS69 Chunlyunja Meliae fuctus * * * * * * * * *
NNMBS72 Taeksa Alismatis rhizoma * * * * * * * * *
NNMBS75 Panlamgun Indigo rulverata Levis * * * * * * * * *
NNMBS78 Jeukhasuo Polygoni multiflori Radix * * * * * * * * *
NNMBS81 Dansam Salviae miltiorrhizae Radix * * * * * * * *
NNMBS84 Yongdam Gentianae scabrae Radix * * * * * * * * *
NNMBS87 Jagun Lithospermi radix * * * * * * * *
NNMBS90 Kunjihwang Rehmanniae radix * * * * * * * * *
NNMBS92 Hyunsam Scrophulariae radix * * * * * * * * *
NNMBS94 Hwanggum Scutellariae radix * * * * * * * *
NNMBS97 Gunkang Zingiberis rhizoma * * * * * * * * *
NNMBS100 Daehwang Rhei rhizoma * * * * * * * * *
NNMBS103 Sungma Cimicifugae rhizoma * * * * * * * * *
NNMBS105 Jimo Anemarrhenae rhizoma * - * * * * * * *
NNMBS108 Chunkung Cnidii rhizoma * * * * * * * * *
NNMBS111 Chunma Gastrodiae rhizoma * * * * * * * * *
NNMBS114 Hyangbuja Cyperi rhizoma * * * * * * * *
NNMBS117 Hyunhosaek Corydalis tuber * * * * * * * * *
NNMBS120 Hwanglyun Coptidis rhizoma * * * * * * * *
NNMBS123 Kyulmyungja Cassiae semen * * * * * * *
NNMBS126 Binlangja Arecae semen * * * * * * * *
NNMBS129 Yukdugu (Nutmeg) Myristicae semen * * * * * * * *
NNMBS132 Chajunja Plantaginis semen * - * - * * * * *
NNMBS135 Kugija Lycii fructus * * * * * * * *
NNMBS141 Sancho Zanthoxyli fructus * * * * * * * * *
NNMBS144 Yunkyo Forsythiae fructus * - - - * * * * *
Download Excel Table

Table 1. Therapeutic herbal extracts (50 mg/mL) used in this study and their antimicrobial activities against Gram-positive and Gram-negative bacteria
Number of NNMBS Name of extracts Scientific name of extracts Gram-negative bacteria Gram-positive bacteria

NNMBS147 Osuyu Evodiae fructus * - * * * * * *
NNMBS150 Ikjiin Alpiniae fructus * * * * * * * * *
NNMBS156 Jinpi Aurantii nobilis Pericarpium * - * * * * * *
NNMBS159 Chija Gardeniae fructus * * * * * * * * *
NNMBS163 Umyanggwak Epimedii herba * * * * * * * * *
NNMBS166 Ikmocho Leonuri herba * * * * * * *
NNMBS172 Duchung Eucommiae xortex * * * * * * * * *
NNMBS175 Mokdanpi Moutan xortex Radicis - * *
NNMBS178 Ogapi Acanthopanacis cortex * * * * * * * * *
NNMBS179 Hwangbaek Phellodendri cortex * * * * * * * *
NNMBS182 Hubak Magnoliae cortex * * * * * * * * *
NNMBS188 Kumunwha Lonicerae flos * * * * * * * * *
NNMBS191 Hagocho Prunellae spica * * * * * * * * *
NNMBS203 Jiyu Sanguisorba officinalis Linne - -
NNMBS209 Bogolji Psoraleae semen * * * * *
NNMBS212 Sasangja Torilis fructus * * * * * * * * *
NNMBS215 Omae Mume fructus * * * * * * * * *
NNMBS220 Jiguja Hoveniae semen cum Fructus * * * * * * * *
NNMBS222 Jilyuja Tribuli fructus * * * * * * * *
NNMBS225 Chogwa Amomi tsao-ko Fructus * * * * * * * *
NNMBS229 Chodugu Alpiniae kotsumadaii Semen * * * * * * * * *
NNMBS231 Sangkisaeng Loranthi rtamulus * * * * * * * *
NNMBS234 Injinho Artemisiae capillaris Herba * * * * * * * *

NNMBS: Standard sample from new natural materials bank.

2AB, Acinetobacter baumannii ATCC19606; BT, Burkholderia thailandensis E264; KP, Klebsiella pneumoniae ATCC25306; PA, Pseudomonas aeruginosa PAO1; SE, Salmonella enterica serovar Derby ATCC6960; EFS, Enterococcus faecalis ATCC35038; EFM, Enterococcus faecium ATCC19434; SA, Staphylococcus aureus ATCC25923; SM, Streptococcus mutans ATCC25175.

3-, not determined; *, no clear zone; †, <10 mm; ‡, 10 mm-12 mm; §, >12 mm.

Download Excel Table

Bacterial strains and media

The following bacterial strains were used in this study; Gram-negative bacteria (Acinetobacter baumannii ATCC 19606, Burkholderia thailandensis E264, Klebsiella pneumoniae ATCC25306, Pseudomonas aeruginosa PAO1, Salmonella enterica serovar Derby ATCC6960) and Grampositive bacteria (E. faecalis ATCC35038, Enterococcus faecium ATCC19434, S. aureus ATCC25923, Streptococcus mutans ATCC25175), and brain heart infusion (BHI, Becton, Dikinson and Company, USA) broth was used as the bacterial growth medium.

Disc diffusion assay

Each bacteria was activated and subcultured in BHI broth, and incubated at 37°C until they were grown to mid-logarithmic phase. The bacteria were mixed with 3 mL of BHI medium containing 0.8% agar to obtain an optical density of 0.1 at 600 nm (OD600), and the mixtures were overlaid on BHI agar plates. After solidifying the agar under room temperature, the paper discs (6 mm in diameter) containing 3 μL of the extract (50 mg/mL) were placed on the agar plates. After 24 h incubation at 37°C, the diameters of inhibition zones were measured.

Determination of MICs

The minimum inhibitory concentration (MIC) of Psoraleae semen extract on bacterial growth was determined using the two-fold broth micro-dilution method (NCCLS, 1997). Briefly, each bacterial strain was subcultured and was grown to mid-logarithmic growth phase in BHI broth. The bacterial cells were diluted in BHI broth to an optical density of 0.01 at 600 nm. An equal volume of the bacterial diluent was added to each well on the 96-well plate containing 100 μL of the serially-diluted Psoraleae semen extract (0-256 μg/mL). The 96-well plates were incubated at 37°C for 24 h, and the MICs were determined by measuring OD600 using a spectrophotometer (Sunrise, Tecan, Austria).

Biofilm assay

Biofilm formation experiment was performed by referring to the protocol provided by Loo et al. (2000). Bacterial cells were prepared and treated with Psoraleae semen extract following the method used to determine the MIC. Each bacterial culture was incubated in a 96-well plate containing Psoraleae semen extract (0-32 μg/mL) at 37°C for 24 h. The suspensions were carefully discarded, and the biofilm formed on the surface of the well plate was stained using 200 μL of crystal violet (1%; v/v). The stained cells were rinsed twice with 300 μL of PBS, followed by solubilizing the cells in 200 μL of 95% ethanol, and the degree of biofilm formation was determined by measuring the OD575 with a spectrophotometer.

Protein leakage measurement

Subcultured bacterial cells were suspended in phosphate buffered solution (PBS, pH 7.4; 0.2 g of KH2PO4, 1.5 g of Na2HPO4, 8.0 g of NaCl, and 0.2 g of KCl in 1 L of distilled water) for adjusting OD600 to 0.7. The bacterial cells were exposed to 2×MIC of Psoraleae semen extract or equal volume of DMSO for 1 h. After centrifugation, protein leakage was determined by measuring optical density of the cell supernatants using a spectrophotometer (Biophotometer, Eppendorf, Germany) at OD280. Values were calibrated with control group treated in PBS instead of cultured cells, and relative ratio (OD280 of bacterial cell exposed to the extract/OD280 of bacterial cell exposed to DMSO) was calculated.

Scanning electron microscopy

Bacteria were incubated in BHI broth containing a glass slide to allow bacterial cells to adhere to the glass slide. Adherent cells were exposed to 2×MIC of Psoraleae semen extract in PBS, and the bacterial cells that had been treated with DMSO at the same volume as Psoraleae semen extract, were used as a negative control (Bereksi et al., 2002). After pre-fixing the treated cells in 1.8% glutaraldehyde solution (Sigma, USA), they were washed using distilled water. The bacterial cells were post-fixed with 2% osmium tetra oxide (Sigma, USA), followed by washing and dehydrating sequentially in 25, 50, 75, 90, and 100% ethanol. Bacterial cells were platinum-coated using a sputter coater 108 auto (Cressington Scientific Instruments Ltd., England) and then observed under field emission SEM (JEOL Ltd., JSM-7600F, Japan).

Statistical analysis

The experiments were replicated twice with six samples in each replication. The results were analyzed by the mixed model procedure of SAS® version 9.2 (SAS Institute, USA). Mean comparisons for the fixed effect were performed with the pairwise t-test, and significance was determined at alpha = 0.05.

Evaluation of antimicrobial activity in sausages

Inoculum for sausage contamination was prepared as follows. Two strains of Listeria monocytogenes (sausage isolate) cells identified and provided by Korea Consumer Agency (Korea) were incubated in BHI broth. The cultures were centrifuged at 1,912 g and 4°C for 15 min. The cell pellet was washed with PBS and resuspended in PBS. Sausage formulation was prepared by mixing lean pork (58.5%), pork fat (19.5%), NaCl (1.2%), sodium phosphate (0.3%), isolated soy protein (0.5%), spice (0.4%), and ice water (19.5%) using a blender (HR1372, Phillips, China). Ten grams of homogenized formulations were transferred into a 6-well plate, and were boiled at 80°C in a waterbath for 40 min, followed by cooling. Psoraleae semen extract (final concentration: 2×MIC) or same volume of DMSO was spread on the sausage samples, and the samples were dried. The sausages were inoculated with L. monocytogenes inoculum to obtain 2 Log CFU/g. During storage at 4°C, L. monocytogenes growth was determined by plating sausages samples on Palcam agar on day 0, 5, and 10.

Results and Discussion

In a previous study, Psoraleae semen exhibited antimicrobial activity against L. monocytogenes, and it was suggested that the herb has potential to be used as an antibacterial agent (Yoon and Choi, 2012). This preliminary evaluation was further progressed and the effect was assessed against an extended range of pathogens such as Enterococci, S. aureus and Salmonella Derby in the present study. In addition, antimicrobial activities of 69 herbal plant extracts on various pathogens including Gram-positive and Gram-negative bacteria were tested using a disc diffusion assay. Among them, only five extracts (Rubi fructus, Galla rhois, Moutan xortex Radicis, Sanguisorba officinalis Linne, and Psoraleae semen) were effective for inhibiting more than three different bacteria (Table 1). Rubi fructus inhibited growth of all bacterial strains tested in this study. Interestingly, there were no clear zones formed on the disc containing Psoraleae semen extract against any Gram-negative bacteria, but obvious clear zones (7-13 mm) were observed against Gram-positive bacteria such as S. mutans, E. faecium, E. faecalis, and S. aureus (Table 1). This contrary result observed against Gram-positive and Gram-negative bacteria in the presence of Psoraleae semen might be caused by the structural dissimilarity of the cell wall between them (Henie et al., 2009). Low permeability against lipophilic solutes and good adaptability of outer membrane is the key of resistance in Gram-negative bacteria (Plesiat and Nikaido, 1992). For example, Gram-negative bacteria have outer membranes, which may prevent the extract used in this study from exerting its antimicrobial activity. However, further study is necessary to elucidate the antimicrobial mechanisms of this extract against Gram-negative bacteria.

The antimicrobial effect of Psoraleae semen extract was further assessed by MIC determination for Gram-positive bacteria, which were susceptible to Psoraleae semen extract. As a result, S. mutans ATCC25175 exhibited no visible growth at 8 μg/mL, and E. faecalis ATCC35038, E. faecium ATCC19434, and S. aureus ATCC25923 exhibited no growth at 16 μg/mL (Fig. 1). Yim et al. (2013) also found that the MIC of Psoraleae semen extract was 625 μg/mL for E. faecalis and 156 μg/mL for S. mutans. This discrepancy may be due to use of different fractions of the extract for the experiment. Yim et al. (2013) used a water-soluble fraction of Psoraleae semen, whereas our group used total extract, which contains both water-soluble and water-insoluble fractions. Yoon and Choi (2012) suggested that the water-insoluble fraction of Psoraleae semen exhibits higher antimicrobial activity than the water-soluble fraction. Psoraleae semen extract contains bakuchiol in water-insoluble fraction, which has been known to have antimicrobial activity on various oral bacteria (Katsura et al., 2001), as Yoon and Choi (2012), and Yim et al. (2013) suggested that it may be a major compound responsible for the antimicrobial activity of Psoraleae semen against the bacteria.

Fig. 1. Minimum inhibition concentration of Psoraleae semen extract on Streptococcus mutans ATCC25175 (a), Enterococcus faecalis ATCC35038 (b), Enterococcus faecium ATCC19434 (c), and Staphylococcus aureus ATCC25923 (d).
Download Original Figure

Biofilm is a collection of bacterial cells that form on surfaces in reaction to stressful environmental conditions, and biofilm formation is of concern in various areas including food safety, dental health, and medicine (Loesche, 1986). In this study, the effect of Psoraleae semen extract on biofilm formation was investigated. Biofilm formation of S. mutans ATCC25175 and S. aureus ATCC25923 was inhibited when the extract was present at concentrations greater than 8 μg/mL, and it was significantly decreased when concentrations exceeded 16 μg/mL in E. faecalis ATCC35038 (Fig. 2). S. mutans biofilms, namely plaque, are responsible for dental diseases like caries (Loesche, 1986), and S. aureus and E. faecalis biofilms are a problem in the food industry and medical devices (Hood and Zottola, 1995). Thus, our results indicate that Psoraleae semen extract may be of potential use for the inhibition of biofilm formation by these bacterial strains.

Fig. 2. Biofilm formation of Streptococcus mutans ATCC25175 (a), Enterococcus faecalis ATCC35038 (b), and Staphylococcus aureus ATCC25923 (c) after exposure of Psoraleae semen extract.
Download Original Figure

The effects of antimicrobial agents on bacterial cell structures and membranes have been widely used to investigate the mode of action of natural antimicrobial agent (Leela and Satirapipathkul, 2011). In this study, protein leakage induced by cell membrane damage was measured, and the membranes were observed by SEM analysis following exposure to Psoraleae semen. In case of Gram-positive bacteria (E. faecalis and E. faecium), values of OD280 were increased in extract-treated cells, compared to non-treated cells (relative ratios = 3.17 and 3.07 in E. faecalis and E. faecium, respectively). This result suggests that exposure of the extract to the bacterial cells induce membrane damage, resulting in leakage of intracellular proteins. Whereas, relative ratio of OD280 (= 1.57) was relatively low in Salmonella Typhimurium, a Gram-negative bacteria (Fig. 3). Further, SEM images showed that the membranes of Gram-positive bacteria, such as E. faecalis, E. faecium, and S. aureus cells have been damaged by the treatment of Psoraleae semen extract, whereas no damage was observed in Sal. Typhimurium (Fig. 4). Taken together, antibacterial activity of Psoraleae semen extract on Gram-positive bacteria seems to be attributed to this membrane damage-mediated action, but Sal. Typhimurium possessing outer membrane, which contributes to homeostasis and adaptability, avoids membrane injury by the extract. Although S. aureus is gram-positive bacteria, protein leakage was not observed in this species. This can be explained by two possible reasons as follows. First, longer incubation time may have been required for inhibition of the S. aureus growth. Briefly, MIC against S. aureus was determined after 24 h, whereas protein leakage by the extract was observed only after 1 h treatment, which can be too short to induce the effects on S. aureus compared to the other bacteria. Second, structural difference of the bacteria probably causes discrepant outcome. S. aureus cell wall is solubilized by lysostaphin, unlike the ones of other Gram-positive bacteria can be solubilized by lysozyme (Navarre and Schneewind, 1999).

Fig. 3. Relative ratio of OD280 in bacterial cells exposed to 2×MIC of Psoraleae semen extract to the one exposed to same volume of DMSO in ST (Salmonella Typhimurium NCCP 10812), EFS (Enterococcus faecalis ATCC35038), EFM (Enterococcus faecium ATCC19434), and SA (Staphylococcus aureus ATCC25923).
Download Original Figure
Fig. 4. Bacterial cell membrane of Salmonella Typhimurium NCCP10812 (A), Enterococcus faecalis ATCC35038 (B), and Enterococcus faecium ATCC19434 (C), observed by scanning electron microscope following exposure to DMSO (a; negative control) or Psoraleae semen extract (b).
Download Original Figure

A Gram-positive bacterial pathogen L. monocytogenes usually contaminates livestock products such as ham and sausages, and can grow at low storage temperature. Our research group previously demonstrated that Psoraleae semen extract (named bogolgi) had antibacterial effects on this pathogen in in vitro environment (Yoon and Choi, 2012). Subsequently, current study investigated this antimicrobiacl activity of Psoraleae semen extract on livestock products-originated L. monocytogenes in sausages at refrigeration temperature. As a result, the growth of L. monocytogenes was impeded in the sausages treated with the extract, compared to the ones treated with DMSO as a negative control on day 10 at 4°C (Fig. 5). This result may suggest that Psoraleae semen extract could be applied to control L. monocytogenes growth in processed meat products. Although Psoraleae semen extract exhibits these antimicrobial activities, it was also reported that high dosage of psoralens, the component of Psoraleae semen could induce phototoxicity (Wu et al., 2005). Thus, further study is necessary to find appropriate conditions and procedure to use Psoralea semen extract as food antimicrobial.

Fig. 5. Growth of Listeria monocytogenes in sausages with Psoraleae semen extract (opened circle) or DMSO (closed circle) after incubation at 4°C for 10 d.
Download Original Figure

In conclusions, Rubi fructus, Galla rhois, Moutan xortex Radicis, Sanguisorba officinalis Linne, and Psoraleae semen have antimicrobial activity against various pathogenic bacteria. Among them, Psoraleae semen extract could be used as a natural antimicrobial to control the growth of Gram-positive bacteria including Enterococci, S. aureus, and L. monocytogenes.


This work was supported by the Wonkwang university in 2016.



Bereksi N., Gavini F., Benezech T., Faille C. Growth, morphology and surface properties of Listeria monocytogenes Scott A and LO28 under saline and acid environments. J. Appl. Microbiol. 2002; 92:556-565.


Fani M. M., Kohanteb J., Dayaghi M. Inhibitory activity of garlic (Allum sativum) extract on multidrug-resistant Streptococcus mutans. J. Indian Soc. Pedod. Prev. Dent. 2007; 25:164-168.


Guliani A., Pirri G., Nicoletto S. F. Antimicrobial peptides: An overview of a promising class of therapeutics. Cent. Eur. J. Biol. 2007; 2:1-33.


Henie E. F. P., Zaiton H., Suhaila M. Bacterial membrane disruption in food pathogens by Psidium guajava leaf extracts. Int. Food Res. J. 2009; 16:297-311.


Hood S. K., Zottola E. A. Bioflms in food processing. Food Control. 1995; 6:9-18.


Hwang J. H., Rha S. J., Cho J. K., Shin T. S., Kim M. Y., Kim J. D. Psoraleae semen extract inhibits angiogenesis and adipogenesis. Biotechnol. Bioproc. Eng. 2013; 18:942-949.


Jackson A. L., Kulchaiyawat C., Sullivan G. A., Sebranek J. G., Dickson J. S. Use of natural ingredients to control growth of Clostridium perfringens in naturally cured frankfurters and hams. J. Food. Prot. 2011; 74:417-424.


Katsura H., Tsukiyama R. I., Suzuki A., Kobayashi M. In vitro antimicrobial activities of bakuchiol against oral microorganisms. Antimicrob. Agents Chemother. 2001; 45:3009-3013.


Kaya I., Yigit N., Benli M. Antimicrobial activity of various extracts of Ocimum Basilicum L. and observation of the inhibition effect on bacterial cells by use of scanning electron microscopy. Aft. J. Trad. CAM. 2008; 5:363-369.


Kuete V., Wabo G. F., Ngameni B., Mbaveng A. T., Metuno R., Etoa F. X., Ngadjui B. T., Beng V. P., Meyer J. J. M., Lall N. Antimicrobial activity of the methanolic extract, fractions and compounds from the stem bark of Irvinia gabonensis (Ixonanthaceae). J. Ethnopharmacol. 2007; 114:54-60.


Leela T., Satirapipathkul C. Studies on the antibacterial activity of quercus infectoria galls. Int. Con. Biosci. Biochem. Bioinform. (IPCBEE). 2011; 5:410-414.


Liu C. S., Cham T. M., Yan C. H., Chang H. W., Chen C. H., Chuan L. Y. Antibacterial properties of Chinese herbal medicines against nosocomial antibiotic resistant strains of Pseudomonas aeruginosa in Taiwan. Am. J. Chinese Med. 2007; 35:1047-1060.


Loesche W. J. Role of Streptococcus mutans in human dental decay. Microbiol. Rev. 1986; 50:353-380.


Loo C. Y., Corliss D. A., Ganeshkumar N. Streptococcus gordonii biofilm formation: identification of genes that code for biofilm phenotypes. J. Bacteriol. 2000; 182:1374-1382.


Navarre W. W., Schneewind O. Surface proteins of Gram-positive bacteria and mechanisms of their targeting to the cell wall envelope. Microbiol. Mol. Biol. Rev. 1999; 63:174-229.


NCCLS (National Committee for Clinical Llaboratory Standards) Performance standards for antimicrobial disk susceptibility tests: Approved standard M2-A7. Wayne: PA: USA 1997


Plesiat P., Nikaido H. Outer membranes of gram-negative bacteria are permeable to steroid probes. Mol. Microbiol. 1992; 6:1323-1333.


Shim S. H., Kim Y., Lee J. Y., Song D. G. Aldose reductase inhibitory activity of the compounds from the seed of Psoralea corylifolia. J. Korean Soc. Appl. Biol. Chem. 2009; 52:568-572.


Wong R. W. K., Rabiem A. B. M. Effect of Buguzhi (Psoralea corylifolia fruit) extract on bone formation. Phytother. Res. 2010; 24:155-160.


Wu F., Wang A. F., Zhou Y., Zhou T. S., Jiang H. L., Fang Y. Z. Determination of psoralen and isopsoralen in traditional Chinese medicines by capillary zone electrophoresis with amperometric detection. Chromatographia. 2005; 61:157-160.


Xiong Z., Wang D., Wu Y., Li F. Osteoblastic differentiation bioassay and its application to investigating the activity of fractions and compounds from Psoralea corylifolia L. Int. J. Phamaceutic. Sci. 2003; 58:925-928.


Yim N. H., Jung Y. P., Cho W. K, Kim T., Kim A., Im M., Ma J. Y. Screening of aqueous extracts of medicinal herbs for antimicrobial activity against oral bacteria. J. Integr. Med. 2013; 2:18-24.


Yoon Y., Choi K. H. Identification of inhibitory effect on Streptococcus mutans by oleanolic acid. J. Life Sci. 2010; 3:321-325.


Yoon Y., Choi K. H. Antimicrobial activities of therapeutic herbal plants against Listeria monocytogenes and the herbal plant cytotoxicity on Caco-2 cell. Lett. Appl. Microbiol. 2012; 55:47-55.


Zaide S. F., Yamada K., Kadowaki M., Usmanghani K., Sugiyama T. Bactericidal activity of medicinal plants, employed for the treatment of gastrointestinal ailments, against Helicobacter pylori. J. Ethnopharmacol. 2009; 121:286-291.