As the popularity of organic food especially fresh vegetables is increasing, it is a common practice to replace chemical fertilizers by manure which leads to high bacterial contamination. Some essential oils such as Thymus vulgaris (thyme) and Ocimum basilicum (basil) oils reduce spoilage flora and foodborne pathogens when used in washing water. This information prompted us to search for effective essential oils from Thai spices for vegetable washing products. Seven out of nine essential oils; fingerroot (Boesenbergia pandurata (Roxb.) Schltr.), galanga (Alpinia galanga (L.) Willd.), holy basil (Ocimum tenuiflorum L.), makrut leaf, makrut peel (Citrus hystrix DC.), sweet basil (O. basilicum L.), and turmeric (Curcuma longa L.) oils showed antibacterial activity. The active components were identified by thin layer chromatography (TLC) bioautography, preparative TLC, and gas chromatography-mass spectrometry. The results indicated that the active components were major components of the oils. The essential oils exhibited higher potency than their active components suggesting that the whole essential oils were more suitable than the pure compounds for product development.
Context: Citrus hystrix de Candolle (Rutaceae), an edible plant regularly used as a food ingredient, possesses antibacterial activity, but there is no current data on the activity against bacteria causing periodontal diseases. Objective: C. hystrix essential oil from leaves and peel were investigated for antibiofilm formation and mode of action against bacteria causing periodontal diseases. Materials and methods: In vitro antibacterial and antibiofilm formation activities were determined by broth microdilution and time kill assay. Mode of action of essential oil was observed by SEM and the active component was identified by bioautography and GC/MS. Results and discussion: C. hystrix leaves oil exhibited antibacterial activity at the MICs of 1.06 mg/mL for P. gingivalis and S. mutans and 2.12 mg/mL for S. sanguinis. Leaf oil at 4.25 mg/ mL showed antibiofilm formation activity with 99% inhibition. The lethal effects on P. gingivalis were observed within 2 and 4 h after treated with 4 Â MIC and 2 Â MIC, respectively. S. sanguinis and S. mutans were completely killed within 4 and 8 h after exposed to 4 Â MIC and 2 Â MIC of oil. MICs of tested strains showed 4 times reduction suggesting synergistic interaction of oil and chlorhexidine. Bacterial outer membrane was disrupted after treatment with leaves oil. Additionally, citronellal was identified as the major active compound of C. hystrix oil. Conclusions: C. hystrix leaf oil could be used as a natural active compound or in combination with chlorhexidine in mouthwash preparations to prevent the growth of bacteria associated with periodontal diseases and biofilm formation.
Dolichandrone serrulata (DC.) Seem flowers are widely used as vegetables in northern and eastern Thailand. Biological studies of the methanolic extract of these flowers have shown promising antioxidant activity. Biological-guided separation of D. serrulata flowers yielded six compounds, identified as hallerone, protocatechuic acid, rengyolone, cleroindicin B, ixoside, and isomaltose. This is the first report on hallerone, protocatechuic acid, rengyolone, cleroindicin B, and isomaltose in D. serrulata. Protocatechuic acid was the most potent scavenger of 2,2-diphenyl-l-picrylhydrazyl and hydroxyl radicals with IC 50 values of 25.6 ± 0.6 and 29.6 ± 0.4 M, respectively. Hallerone and rengyolone showed moderate scavenging action on superoxide radicals and inhibited H 2 O 2 induced reactive oxygen species production in HEK-293 cell. In addition, the other isolated compounds showed weak activity.
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