Objective: To investigate chemical constituents and new antimicrobial agents among essential oils from the rhizomes of Curcuma aeruginosa(C.aeruginosa)Roxb.,Curcuma glans K.Larsen&J.Mood and Curcuma cf.xanthorrhiza Roxb. Methods: The essential oils were obtained by hydro-distillation and analyzed by gas chromatography/mass spectroscopy.Agar-well diffusion assay was used to study the anti-microbial activity and also broth-micro dilution techniques were examined for minimum inhibitory concentration (MIC)against four bacterial strains and yeast. Results: The gas chromatography/mass spectroscopy analysis showed monoterpenes predominantly(88.53%)in the rhizome oil of Curcuma cf.xanthorrhiza.Sesquiterpenes (50.10%) was the most abundant component in the essential oil of C. glans, while monoterpenes(45.55%)and sesquiterpenes(45.81%)were found in C.aeruginosa with a significant amount. The major components of C. aeruginosa were characterized as camphor (29.39%) and germacrone (21.21%). Germacrone (15.76%),β-pinene (9.97%) and camphor (9.96%) were found as major compounds in the rhizome oils of C. glans while α-terpinolene (24.86%) and p-cymen-7-ol(12.17%) were found as major compo-sitions in Curcuma cf.xanthorrhiza.The essential oils were tested against four bacterial strains and yeast.As a result,the rhizome oil of C.aeruginosa exhibited potent activity against Staphylococcus aureus [inhibition zone (21.94 ± 0.24) mm, MIC 125 μg/mL], Bacillus cereus [inhibition zone (20.83 ± 0.36) mm, MIC 125 μg/mL], and Candida albicans[inhibition zone(11.60 ± 0.30)mm,MIC 250 μg/mL]. Conclusions: The essential oils from three Curcuma species possessed greater activity against the gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) than gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The results suggest that the essential oils from the fresh rhizome of Curcuma spp. might be a po-tential source of natural antimicrobial substances.

Traditional medicine uses a multitude of plants to create medicinal formulations, some of which show antiviral properties that may be of benefit in treating emerging viral diseases, including Covid-19. Lanna, an ancient Kingdom in Northern Thailand, with a thriving culture that continues to this day and has a rich history of traditional medicine using local plants that is still practiced today. To find potential antiviral medicinal candidates, we examined ancient manuscripts, interviewed traditional healers practicing today, and inventoried current traditional medicines to catalogue 1400 medicinal formulations used in Lanna traditional medicine. We then narrowed this list to find those traditionally used to treat diseases that in their original use and descriptions most likely map to those we know today to be viral diseases. We identified the plants used in these formulations to create a list of 64 potential antiviral herbal candidates drawn from this ancient Lanna wisdom and matched these to the scientific literature to see which of these plants had already been shown to possess antiviral properties, generating a list of 64 potential antiviral medicinal candidates from Lanna traditional medicine worth further investigation for treating emerging viral diseases.

Objective: To determine the chemical composition, as well as the antioxidant, antityrosinase and antibacterial activities of essential oils obtained from some Apiaceous and Lamiaceous plants collected in Thailand. Methods: The essential oils of the specified spices and aromatic herbs were obtained by hydro-distillation, and their chemical constituents were analyzed by gas chromatography/mass spectrometry. Antioxidant assays were based on the scavenging effects of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radicals as well as the lipid oxidation inhibition of ß-carotene bleaching by linoleic acid. Tyrosinase enzyme inhibition was evaluated by the dopachrome method. Broth microdilution technique was performed for the purposes of studying microbial growth inhibition against the isolated bacterial strains. Results: The essential oils of Elsholtzia stachyodes, Coleus amboinicus (I) and Trachyspermum ammi presented a high degree of potency in DPPH, ABTS and ß-carotene bleaching assays. The Trachyspermum ammi oil, which mainly contained thymol (49.04%) and p-cymene (22.06%), proved to be the most effective in terms of antibacterial activity. The major compositions of Coleus amboinicus (I) were carvacrol (51.57%), y-terpinene (18.04%) and p-cymene (7.81%); while thymol (43.76%) and y-terpinene (24.61%) were identified as the major components of Elsholtzia stachyodes oil, with p-cymene (6.73%) being identified as a minor constituent. Moreover, Cuminum cyminum oil containing cuminaldehyde (49.07%) and Elsholtzia communis oil composed with geranial (44.74%) and neral (35.27%) as the major components displayed a specific ability for the inhibition of the mushroom tyrosinase enzyme. Conclusions: The results indicated that these bioactive essential oils obtained from indigenous herbs are of significant interest as alternative raw materials in food, cosmetic and medicinal products.

Objective To investigate chemical constituents and new antimicrobial agents among essential oils from the rhizomes of Curcuma aeruginosa (C. aeruginosa) Roxb., Curcuma glans K. Larsen & J. Mood and Curcuma cf. xanthorrhiza Roxb. Methods The essential oils were obtained by hydro-distillation and analyzed by gas chromatography/mass spectroscopy. Agar-well diffusion assay was used to study the anti-microbial activity and also broth-micro dilution techniques were examined for minimum inhibitory concentration (MIC) against four bacterial strains and yeast. Results The gas chromatography/mass spectroscopy analysis showed monoterpenes predominantly (88.53%) in the rhizome oil of Curcuma cf. xanthorrhiza. Sesquiterpenes (50.10%) was the most abundant component in the essential oil of C. glans, while monoterpenes (45.55%) and sesquiterpenes (45.81%) were found in C. aeruginosa with a significant amount. The major components of C. aeruginosa were characterized as camphor (29.39%) and germacrone (21.21%). Germacrone (15.76%), β-pinene (9.97%) and camphor (9.96%) were found as major compounds in the rhizome oils of C. glans while α-terpinolene (24.86%) and p-cymen-7-ol (12.17%) were found as major compositions in Curcuma cf. xanthorrhiza. The essential oils were tested against four bacterial strains and yeast. As a result, the rhizome oil of C. aeruginosa exhibited potent activity against Staphylococcus aureus [inhibition zone (21.94 ± 0.24) mm, MIC 125 μg/mL], Bacillus cereus [inhibition zone (20.83 ± 0.36) mm, MIC 125 μg/mL], and Candida albicans [inhibition zone (11.60 ± 0.30) mm, MIC 250 μg/mL]. Conclusions The essential oils from three Curcuma species possessed greater activity against the gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) than gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The results suggest that the essential oils from the fresh rhizome of Curcuma spp. might be a potential source of natural antimicrobial substances.