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The essential oil obtained by hydrodistillation method from plants of three varieties Agastache aurantiaca, cultivated on the Republic of Belarus were investigated. Some morphobiometric parameters of plants 'Tango', 'Apricot Sprite' and 'Fragrant Delight' and oil yields were determined. Using the technique of gas-liquid chromatography essential oil components were identified and determined. The main components of the essential oil from 'Tango' and 'Fragrant Delight' plants were menton (~ 53 and ~ 65 v/v % respectively) and pulegon (~ 36 and ~ 25 v/v % respectively). The samples of 'Apricot' Sprite' essential oil were rich in isomentone (~ 46 v/v %) and pulegon (~ 41 v/v %). All tested essential oils contained (+)-menton and (+)-pulegon enantiomeric forms only. The antibacterial activity of dimethylsulfoxide and ethanolic essential oil solutions against Staphylococcus aureus, Salmonella alony, Bacillus subtilis, Clostridium sp., Escherichia coli Hfr H, Pseudomonas aeruginosa was proved. Ethanol solutions of essential oils at the concentrations 0.001–0.1 v/v % had significant bactericidal activity. A correlation between the composition of the essential oil and their antibacterial properties was established.

The steam distillation method was used to obtain samples of essential oil of some species of genus Agastache L. introduced in Belarus. More than 20 components have been identified and determined in the essential oils of Agastache pallidiflora ssp.neomexicana L., Agastache aurantiaca L., Agastache mexicana L., Agastache foeniculum L. by gas liquid chromatography.The quantitative composition of the samples of essential oils depends on the type of plant material. The main its components are limonene, 1.8-cineol, mentone, isomentone, methyl chavicol, methyeugenol. The main component of essential oils Agastache pallidiflora ssp. neomexicana L. и Agastache aurantiaca L is mentone (40–65 %). Essential oil Agastache foeniculum L. is enriched with pulegone and isomentone. Methyl chavicol and methyleugenol dominate in Agastache mexicana essential oil. Distribution of the enantiomers of limonene, menthone and pulegone are shown. Regardless of the plant species, the samples are optically pure in the (+)-pulegone. The nature of the distribution of the enantiomers of limonene and menthone is an individual characteristic of the studied Agastache L. essential oils.

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Hypericin was isolated from Diahyperon tincture for use as a standard sample. The chromatographic purity of the hypericin was confi rmed by high-performance liquid chromatography/mass spectrometry. Hypericin has the only chromatographic peak with a retention time of 23.10 min and gave a characteristic signal for the molecular ion [M -H + ]with m/z 504.05 in the mass spectrum. Electronic absorption spectra of Diahyperon tincture and the MeOH extract of Hyperici herba (Hypericum perforatum) showed characteristic hypericin bands at 550 and 590 nm and a band at 665 nm that was due to the presence of chlorophyll. It was shown that excitation of hypericin in Diahyperon tincture at λ ex = 470 nm gave an emission spectrum with characteristic hypericin bands at 593 and 640 nm while the emission spectrum of the MeOH extract of Hyperici herba showed the hypericin emission bands and a weak chlorophyll emission band at 670 nm. It was found that spectrophotometric and spectrofl uorimetric determinations of hypericin in Diahyperon tincture and in Hyperici herba gave similar results that were consistent with the standardized values of the hypericin content in the studied samples.