Study On The Chemical Composition And Antimicrobial Activity Of Essential Oils From Many Plants And The Bioactivity And Stability Of Bergenin

Essential oils obtained from 18 plant material were qualitatively and quantitatively analyzed by GC-MS. The antimicrobial activity of the oils of 18 plant material and pure samples (artemisia ketone, p-cymene, 1,8-cineole) was evaluated using disc paper and broth microdilution methods. The oils were analyzed by GC-MS with three different fused silica capillary columns (30 m×0.25 mm i.d.; film thickness 0.25 μm) of different polarities (DB-5, DB-1 and HP-innowax). Components were identified by comparison of their mass spectra with those of NIST'98 GC-MS library data of the GC-MS system and literature data, and further confirmed by comparison with the compounds elution order with their retention indices on semi-polar phases reported in the literature. Retention indices of the components were determined relative to the retention times of a series of n-alkanes with linear interpolation. At the same time, the paper deals with the separation and the identification of bergenin that is the component of Oreocharis acericula presenting the biologic activity, also includesits ability of eliminating O₂^-. and its stability and mechanism of the thermal dehydration.1 Essential oil GC-MS analysisThe experiment dealt with some plants such as Compositae, Umbelliferae, Aristolochiaceae, Magnoliaceae and Lauraceae, all the oils' contents of which wereabundant, the yield of the essential oil obtained from Litsea pungens was highest, up to5.55%. According to the result of the component analysis, terpenes were shown as the major group of compositions in the oils obtained from most experimental plants except Artemsia capillaries, capillene and 5-phenyl-l,3-pentadiyne were the main components in its oil.1.1 Monoterpenes were shown as the major group of compositions in the oils of Dendranthema indicum and its flowers, especially oxygenated monoterpenes were present in large percentage. The four components characterized two essential oils: 1,8-cineole (0.12%³0.41%), camphor (2.86%²3.52%), borneol (4.66%¹8.34%), germacrene D (1.08-12.67%).The essential oils of Artemisia were divided into four types basing on the change of the composition and content:I) type of Artemisia apiacea Hance: it includes A. apiacea, A. lavandulaefolia, A.sacrorum and A. lactiflora, the content of oxygenated monoterpenes were very high in their essential oils. 1,8-cineole (4.65%⁴1.80%), artemisia ketone (6.90%¹5.47%), artemisia alcohol (0.56%⁹.55%) and yomogi alcohol (0.86%⁹.35%) were the characterized components;II) type of A. annna: the essential oil mainly contained terpenes, for example,p-himachalene (11.52%), trans-cadia-l(6),4-diene (7.05%), p-farnesene (E-) (4.07%), caryophyllene(Z-) (5.76%) and p-cymene (4.98%);III) type of A. imponens: its oil mainly contained oxygenated terpenes such as vulgarone B (26.58%), 1,8-cineole (19.89%), camphor (7.91%) and a-cadinol (7.03%), in which vulgarone B was the particularly characterized component;IV) type of A. capillaries: benzene alkyne were the major group of compositions in theoil: capillene (43.64%) and 5-phenyl-l,3-pentadiyne (10.26%).The essential oil of Cacalia tangutica differed from the oils of the other congener plants, it contained terpenes: a-zingiberene (13.49%), germacrene D (10.76%), a-pinene (8.54%) and caryophyllene(Z-) (6.36%).1.2 The six essential oils of Umbelliferae were divided into three types basing on the change of the composition and content:I) Saposhnikovia divaricata and Peucedanum medicum, the content of monoterpeneswere very high in their oils, but the high-content components differed respectively, y-terpinene (24.43%), sabinene (11.15%), p-pinene (7.01%), caryophyllene (Z-)(6.56%) and terpene-4-ol (6.27%) were rich in the former o The latter oil mainly consisted of limonene (13.93%), p-mentha-2,4(8)-diene (9.19%) and a-pinene(5.58%).II ) Angelica pubescens and Cryptotaenia japonica, terpenes were their maincomponent in the oils, which shared the high-content components: germacrene D (4.09%¹6.20%), caryophyllene(E-) (7.36%¹2.57%), limonene (2.54%¹0.21%)and cc-pinene (1.21%⁹.17%).Ill) A. megaphylla and Osmorthiza aristata, their oils both contained large amount of sesquiterpenes, especially the amount of sesquiterpenes in the former one, up to 75.12%, although they were different in high-content component. The former oil was high abundant in caryophylIene(E-) (12.57%), a-selinene (8.35%), germacrene D (7.85%), p-selinene (6.71%) and p-famesene (E-) (6.26%). There wereEpi-a-bisabolol (18.25%), germacrene D (12.17%) and p-selinene (4.19%) in thelatter oil.1.3 Two essential oils of Aristolochiaceae differed a lot in the main components, Asarum caulescen was rich in p-pinene (6.64%⁴6.64%), germacrone (7.63%²0.72%), a-phellandrene (7.80%¹4.39%), 1,8-cineole (8.91%¹3.29%) and 2-carene (7.99%⁸.94%). Camphene (23.98%), borneol (6.82%), bomeol ramificaton 24.09% and selina-l,3,7(ll)-trien-8-onel0.24% occupied high percentage in the oil of Aristolochia debilis.1.4 The oil extracts of Iiicium henryi and L. pungens were in large amount, and both were colorless. But the components of those two oils were quite distinct from each other. In the former, 1,8-cineole (29.62%), a-pinene (4.86%), p-pinene (4.05%), a-terpineol (3.78%), terpene-4-ol (3.09%) and camphor (3.7%) were shown as the major group of compositions. The latter oil mainly contained carvone (29.36%), geraniol (25.36%),limonene (6.88%), P-citronellol (4.08%) and linalool (3.80%). The oil complexity demanded independent analyses on dissimilar stationary phase columns. By using apolar column, low-polarity column and polar column, and manycomponents could be found. The MS search routine used linear retention as a post filter and the identification of the unknowns was made more reliable.2 Antimicrobial activity of 15 essential oils and 3 pure samples ( artemisia ketone,p-cymene, 1,8-cineole)Fifteen essential oils tested antimicrobial activity in vitro. But the essential oils of A. annua and P. medicum were tested by using the agar disc diffusion method in virtue of lack of the oils (other oils were not examined the antimicrobial activity in vitro due to lack of the oils). The detailed analysis divided into three files according to the antibacterial activity from strong to weak.2.1 Analysis of the essential oil showing the strongest antimicrobial activityThe essential oil of L pungens showed the strongest antimicrobial activity and presented rather a broad antimicrobial spectrum. At the concentration of 0.31².5 mg/ml, it exhibited very strong antimicrobial activity against all the microorganisms tested, particularly against clinical isolated strains. The range of MBC against clinical isolated strains was fromO.31 mg/ml to 0.61 mg/ml.2.2 Analysis of the essential oil showing the very strong antimicrobial activityAt the concentration of 0.63¹0.00mg/ml, the oil of/, henryi Diels exhibitedrather strong antimicrobial activity against all the microorganisms tested. At the concentration of 1.25⁵.00mg/m it exhibited rather strong antimicrobial activity against clinical isolated strains.At the concentration of 0.16²0.00mg/ml, the oil of A. capillaries exhibited rather strong antimicrobial activity against all the microorganisms tested, especially against the gram-positive bacteria and yeasts. The bactericidal activity of this oil was stronger against two yeasts than other oils. All the results of MBC against Staphylococcus aureus CCTCC AB91053, S. aureus CCTCC AB91118, H. anomala and Candida sp. Were 0.16mg/ml. This oil showed the most effective on S. saprophyticus, the result of MIC was 0.02mg/ml.The oil of A. sacrorum exhibited rather effective against gram-positive bacteria, gram-negative bacteria and yeasts except Salmonella typhi. The fact that at the concentration of 0.31².50mg/ml, it showed the bactericidal activity against clinicalisolated strains was worth the whistle.2.3 Analysis of the essential oil showing the stronger antimicrobial activityThe oil of A. imponens had a strong effect on the gram-positive bacteria and yeasts, and strongest effect on S. aureus CCTCC AB91053, with MBC up to 0.04mg/ml, followed by Enterococcusfaecalis, S.saprophyticu, whose MIC&MBC are both 0.16mg/ml. However, it had no effect on E. coli CCTCC AB91107. The result of MBC against H. anomala was 0.31mg/ml, and the one of MIC against Candida sp was 0.08mg/ml.At the concentration of 0.16⁵.00mg/ml, the oil of C. tangutica had bactericidal activity against the other microorganisms except B. subtilis and E. coli CCTCC AB90054 against which the oil had no inhibitory effect. It showed very strong effect on P. mirabilis which belonged to the gram-positive bacteria. The results of MIC&MBC were both 0.63mg/ml.Both oils of S. divaricata and A. megaphylla had effect on the gram-positive bacteria, gram-negative bacteria and yeasts. For example, the former oil had obvious effect on C.freundill which was the gram-negative bacterium, while the results of MIC&MBC were both 0.63mg/ml. However, the latter oil had no activity against E. faecalis the gram-positive bacterium.The activity of the oil of C. japonica was the more effective on the gram-positive bacteria and yeasts. The oil exhibited the strongest effect on Candida sp., and the resultof MIC was 0.04mg/mL followed by S. aureus. It had no activity against the threegram-negative bacteria.2.4 Analysis of the essential oil showing the moderately strong antimicrobial activity The oil of A. debili had good activity against the gram-positive bacteria,particularly B. subtilis, the result of MIC was 0.16mg/ml. It had a generic activity against the yeast. It showed no bactericidal activity against S. typhi and P. mirabilis and had no inhibitory effect on E. coli and K. pneumoniae.In general, the oils of D. indicum, air-dried flowers of C. indicum and pre-processed flowers of C. indicum showed better effect on the gram-positive bacteria and yeasts. The oil of air-dried flowers had best effect on E. coli clinically isolated strains (the results of MIC&MBC were 0.39mg/ml) and had no activity against S. cescerevisiae, E. faecalis. In addition, the other two oils had best antimicrobial activityagainst S. saprophyticus, the results of MBC were0.78 mg/ml fP 1.25 mg/mlrespectively.The oil of A. apiacea showed a little stronger bactericidal activity against the gram-positive bacteria, had best bactericidal activity against E.faecalis (the results of MIC&MBC both were 0.63 mg/ml), and exhibited no activity against many gram-negative bacteria.The oil of A. laxandulaefolia exhibited the strongest antimicrobial activity against the gram-positive bacteria, the range of MBC was from0.63 mg/ml to 5.00mg/ml, had a generic activity against the epiphyte. It had no activity against three gram-negative bacteria: S. typhi, E. coli, E. cloacae.The oils of fresh and air-dried rootstock of A. caulescen exhibited the stronger antimicrobial activity against the gram-positive bacteria and yeasts, showed the weaker bactericidal activity against all the microorganisms tested. In general, the activity of the oil of fresh rootstock was weaker than the one of air-dried rootstock .2.5 Analysis of antimicrobial activity of A. annua and P. medicum oils (only theresults of DD)The two oils was better effective on the gram-positive bacteria, and had a generic activity against the epiphyte. The essential oil of A. annua had no activity against B. subtilis and S. typhi. The essential oil of P. medicum had no inhibitory activity against E. coli CCTCC AB90054 and E. cloacae.2.6 Analysis of antimicrobial activity of artemisia ketone, p-cymene, 1,8-cineole With comparison of the antimicrobial ability of three sample (artemisia ketone,p-cymene, 1,8-cineole), artemisia ketone exhibited the strongest activity, especially showed the strongest antimicrobial activity against S. saprophyticus, and the result of MBC was 0.01mg/ml.l,8-Cineole showed the higher inhibitory effect against the epiphytes, and the results of MIC&MBC are 0.31 mg/ml. p-Cymene exhibited the weakest activity in all.From the analysis of the compositions of the essential oils and the results of antimicrobial activity, it was shown that the major components were concluded to be responsible for bacteriostatic activity. The high-content components showing the anti-epiphyte activity(l,8-cineole and vulgarone B), which were in the essential oil ofA. imponens. Although the essential oils showed the strong anti-epiphyte activity, with comparison in the landscape orientation of the oils' main components obtained from A. capillaries, A.sacrorum, C.tangutica and C.japonica which exhibited significant anti-epiphyte activity, the antimicrobial activity had nothing to do with the bases clearly and directly. Therefore in fact it was possible that the antimicrobial effect presented is the result of that some components might be involved in some type of synergism with the others. It was obvious to fine that with comparison of the antimicrobial effect of the oils and samples.3 Study of bergenin3.1 Bergenin was separated from the plant of O. acericula by TLC, and qualitatively analysed by UV spectrophotometry and HPLC. The elementary judgement is that Bergenin exists in this plant and its content is lower.3.2 The stability and ability of anti-oxygen free radicals of bergeninThe ability of anti-oxygen free radicals of bergenin was determined by the classical methods of Mcord et al. and Beauchamp et al. The result shows that bergenincan eliminate O27 effectively, and the ability in the illuminaton-lactoflavm system is higher than in the Xanthine-oxidase-cytochrome C system. The data obtained by the method of cycle volt-ampere shows that bergenin is more stable in the acidic environment than the neutral one, and is easy to be attacked by NO and oxidated.3.3 The non-isothermal decomposition kinetics of ephedrine hydrochloridum, tinidazole, idoxuridine and several kinds of anti-inflammation drugs were studied by TG-DTG techniques, The pissible decomposition kinetic function was suggested and kinetic parameters were obtained.