The present study aimed to investigate the antibacterial activity of ethanolic Kaempferia parviflora extracts and the combined effects of the plant’s specific compounds with gentamicin against clinical strains of carbapenem-resistant Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. The minimal inhibitory concentrations (MIC) of gentamicin and Kaempferia parviflora extracts against the tested bacterial strains were determined by using broth microdilution. The combined effects of Kaempferia parviflora extract and gentamicin were investigated by using a checkerboard assay and expressed as a fractional inhibitory concentration index (FICI). Crude ethanolic extract of Kaempferia parviflora showed the lowest median values of MIC towards the tested isolates (n = 10) of these tested bacteria at doses of 64 µg/mL, compared to those of other Kaempferia extracts. Among the isolated compounds, only three compounds, namely 3,5,7-trimethoxyflavone, 3,5,7,3′4′-pentamethoxyflavone, and 5,7,4′-trimethoxyflavone, were identified by NMR structural analysis. According to their FICIs, the synergistic effects of gentamicin combined with 3,5,7,3′4′-pentamethoxyflavone were approximately 90%, 90%, and 80% of tested carbapenem-resistant Klebsiella pneumoniae (CRKP), Pseudomonas aeruginosa (CRPA), and Acinetobacter baumannii (CRAB), respectively. The present study concluded that 3,5,7,3′4′-pentamethoxyflavone extracted from Kaempferia parviflora potentiated the antibacterial action of gentamicin to combat bacterial resistance against the tested bacteria.

Vulvovaginal candidiasis (VVC) is the most common cause of vaginal discharge among women. The present study aimed to investigate the synergistic anticandidal effect of lactobacillus cultures supplemented with plant extracts. Among 600 isolates of lactic acid bacteria, 41 isolates exhibited inhibitory activity against Candida albicans ATCC10231. Six out of 41 cell-free supernatants demonstrated the most potent antibacterial and anticandidal activities. They also inhibited the clinical isolates of C. albicans, causing VVC and non-C. albicans. The synergistic effect between Lactobacillus crispatus 84/7 and Limosilactobacillus reuteri 89/4 was demonstrated by the lowest fractional inhibitory concentration index (FICI = 0.5). The synbiotic culture of bacterial combination, cultured with Jerusalem artichoke (H. tuberosus) extract, also exhibited the strongest inhibition against the tested C. albicans. Biofilm formation decreased after 12 h of incubation in the selected cell-free supernatants of this synbiotic culture. The anticandidal activity of crude extracts was lost after treatment with proteinase K and trypsin but not with heating conditions, suggesting that it may be a heat-stable substance. In conclusion, the combination of L. crispatus 84/7 and L. reuteri 89/4 with H. tuberosus may be a promising candidate for inhibiting Candida infection and biofilm formation, with the potential use as ingredients in vaginal biotherapeutic products.

Coconut oil-pulling therapy is used for maintaining oral health. The procedure has benefits for the prevention of oral disease, including dental caries, oral malodor, bleeding gums. However, virgin coconut oil (VCO) has unsatisfying oily taste. Therefore, coconut oil mouthwash (CoMW) was recently developed. This in vitro study aimed to evaluate the anti-inflammatory activity of coconut oil mouthwash consisting of 60% v/v virgin coconut oil (VCO), 30% v/v propylene glycol (PG), and 10% v/v distilled water on human gingival fibroblast (HGF) cells compared with the activity on murine macrophage (Raw 264.7) cells. The cytotoxicity of CoMW, 0.12% chlorhexidine gluconate (CHX), VCO, and PG was assessed. IC50 concentration of CoMW, CHX, and PG were 1:8 (v/v), 1:32 (v/v), and 1:16 (v/v), respectively. All tested concentrations of VCO had no impact on cell viability. Their anti-inflammatory effects of each IC50 concentration were further studied. Notably, the IC50 concentration of CHX also significantly inhibited nitric oxide production in lipopolysaccharide (LPS)- activated Raw 264.7 cells. Moreover, the IC50 concentrations of CoMW, VCO, PG, and CHX could suppress the interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) gene expressions in LPS-activated HGF cells, while also enhancing the cell migration of HGF cells as likely to the effect observed with the IC50 concentration of CHX. Wound healing ability of CoMW was also demonstrated after testing with a scratch assay. These findings indicated promising potential for coconut oil mouthwash as an effective agent in reducing inflammation and facilitating wound healing.

The present study was to investigate and identify the antimicrobial lactic acid bacteria against some gastrointestinal pathogens, to compare the activity between their synbiotic culture and bacteria culture alone, and to characterize the bacteriocins produced by the synbiotic culture of these isolates. Among 600 isolates of selected lactic acid bacteria, three isolates of Lactocaseibacillus paracasei subsp. paracasei, two of Latilactobacillus curvatus subsp. curvatus, and one of Lactiplantibacillus plantarum exhibited the antibacterial activities against four standard reference bacteria, and twelve clinical strains of food-poisoning bacteria especially Vibrio parahaemolyticus. The synbiotic culture of L. paracasei 9/5, L. curvatus 87/6 and L. plantarum 89/4 which are cultured with sweet corn, grand red bean, papaya, star fruit, nashi pear, and black ginger exhibited significant inhibitions to V. parahaemolyticus. Bacteriocin which was harvested from the synbiotic culture of L. curvatus 87/6 and nashi pear demonstrated the strongest activity to the tested bacteria. After partial purification, ultrafiltration, and ion exchange column chromatography, this bacteriocin was anionic with 40-80 kDa and pI at 4-5. Its antimicrobial activities significantly decreased at pH > 8.0, with trypsin and pepsin digestions as well as after heating at > 100°C. Analyzed with SDS-PAGE, the suspected bacteriocin band was detected in the increased intensity, lower intensity, and was not detected after harvested from the synbiotic culture, the bacterial culture alone, and only plant powder extract, respectively. It was concluded that the synbiotic culture of L. curvatus with some prebiotics could induce potent antimicrobial bacteriocin production. Keywords: Lactic acid bacteria, Prebiotics, Synbiotic, Bacteriocin, Vibrio parahaemolyticus Funding: The authors are thankful for the research funding provided by the Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.   Citation: Sookkhee, S., Kumsang, Y., and Boongum, S. 2022. Bacteriocin harvested from the synbiotic culture of selected lactic acid bacteria with various vegetables, cereals, fruits, medicinal and tuber plants: inhibition of Vibrio parahaemolyticus. CMUJ. Nat. Sci. 21(3): e2022050.  

Lactobacillus bacteriocin is an interesting compound playing a dual spermicidal/bacteriocidal role so that this compound can be developed as an agent that can be able to replace the unsafety chemical, nonoxynol-9. The present study aimed to investigate the antibacterial, sperm immobilization, and spermicidal activities of bacteriocins that were produced from vaginal lactobacilli. Nine of 932 cell-free supernatants exhibited potent antibacterial activities against the standard bacterial strains and the pathogenic Niesseria gonorrhoeae. Ion exchange-purified bacteriocins B84/7 F2 demonstrated the lowest minimum inhibitory concentration and the highest bacteriocin activity against the tested pathogens. The isolate B84/7 was then identified as Lactobacillus crispatus. The rapid killing activity was exerted within 15 minutes after being exposed to the tested bacteria, and also significantly inhibited the exponential growth of the tested pathogen. Among 48 semen of volunteers, the median time of sperm immobilization of ion-exchange purified B84/7 F2 bacteriocin (18.70 mg/mL) was 30.42 seconds. Within 60 seconds, spermicidal activities of the partial fractionated and ion-exchange purified B84/7 F2 at the undiluted concentration were 83.67 and 80.75%, respectively. Its activity will significantly decline at pH > 8.0 or after being treated with alkaline and proteolytic enzymes. Two peptide bands of this bacteriocin were 7.08, and 8.81 kDa after being detected on a tricine SDS-PAGE gel. In-depth characteristics of this bacteriocin should be further investigated regarding the mode of action and purification. These findings can be applied to develop as the protecting agent of sexually transmitted infections especially gonorrhea, and unwanted pregnancy.   Keywords: Antibacterial activity, Bacteriocins, Neisseria gonorrhoeae, Sperm immobilization, Spermicidal activity, Vaginal lactobacilli Citation: Sookkhee, S., Manonuek, S., Apichartpiyakul, C., and Sakonwasun, C. 2022. Antibacterial, sperm immobilization and spermicidal activities of bacteriocins produced by vaginal lactobacilli. CMU J. Nat. Sci. 21(1): e2022015.

Virgin coconut oil has been used for oil pulling, which helps to promote oral health and can inhibit oral fungi. Due to 15-20 minutes of rinsing time, oily taste, and instability of lately developed mouthwashes, this present study aimed to develop a mouthwash formula from virgin coconut oil with good stability and appropriate rinsing time to inhibit Candida albicans in biofilm. The formulation results showed that the mixed emulsifiers between tween 80 and span 80 at the ratio of 40:60 were appropriate to use as the mixed emulsifier of virgin coconut oil. After the formulation, seven mouthwash formulas including F5 (10:25:65), F21 (20:20:60), F36 (30:20:50), F49 (40:20:40), F59 (50:15:35), F67 (60:10:30) and F73 (70:5:25) which comprised the ratios among virgin coconut oil: mixed emulsifier: distilled water, respectively, exhibited the stable emulsion by using the lowest mixed emulsifier in each ratio. Results from the XTT assay at various exposure times demonstrated that a five-minute exposure with formula F73 exhibited the highest inhibitory activity against C. albicans biofilm with a significant difference compared to other formulas. To confirm the anticandidal activity, the F73 formula could inhibit the growth of C. albicans after enumerating the colonies with an exposure time of five minutes. It may be concluded that the appropriate virgin coconut oil mouthwash was formulated at the ratio of coconut oil: mixed emulsifier: distilled water at 70:5:25 and could inhibit C. albicans after five minutes of exposure. Keywords: Formulation, Coconut oil mouthwash, Mixed emulsifier, Candida albicans, Biofilm Funding: We are grateful for the research funding provided by the Faculty of Dentistry, Chiang Mai University, Chiang Mai, Thailand.   Citation: Chanpa, P., Owittayakul, D., Wanachantararak, P., Chaiyana, W., Sookkhee, S. 2023. Formulation of coconut oil mouthwash with mixed emulsifier and its growth inhibition of Candida albicans biofilms. Nat. Life Sci. Commun. 22(1): e20230 16.