Chemical Composition and Antibacterial Activity of the Essential Oil of Centella asiatica. Growing in South Africa

ABSTRACT

In South Africa, Centella asiatica. (L.) Urb is used traditionally for the treatment of various diseases. Analyses of the essential oil of this medicinal plant revealed 11 monoterpenoid hydrocarbons (20.20%), nine oxygenated monoterpenoids (5.46%), 14 sesquiterpenoid hydrocarbons (68.80%), five oxygenated sesquiterpenoids (3.90%), and one sulfide sesquiterpenoid (0.76%). α.-Humulene (21.06%), β.-caryophyllene (19.08%), bicyclogermacrene (11.22%), germacrene B (6.29%), and myrcene (6.55%) were the predominant constitutes. The essential oil extract exhibited a broad spectrum of antibacterial activities against Gram-positive (Bacillus subtilis, Staphylococcus aureus.) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Shigella sonnei.) organisms.     

Correlation Between Chemical Composition and Antifungal Activity of the Essential Oils of Eight Cinnamomum. Species

Abstract

Fourteen essential oils hydrodistilled from eight Cinnamomum. (Lauraceae) species (C. pubescens. Kochummen, C. impressicostatum. Kosterm, C. microphyllum. Ridl., C. scortechinii. Gamb., C. rhyncophyllum. Miq., C. cordatum. Kosterm, C. zeylanicum. Blume, and C. mollissimum. Hook f.) were examined for their antifungal activity against six dermatophytes (Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Microsporum canis, M. gypseum., and M. audouini)., one filamentous fungi (Aspergillus fumigatus.), and five strains of yeasts (Candida albicans, C. glabrata, C. tropicalis, C. parapsilosis., and Crytococcus neoformans.) by using the broth microdilution method. The antifungal activities of 13 standard compounds that are prevalent constituents in Cinnamomum. oils were also investigated in an effort to correlate the effectiveness of the oils with those of the components of the oils. The chemical composition of the oils was analyzed by GC and GC-MS. Most of the oils showed moderate to strong activity against the fungi. Among the oils, the leaf and bark oils of C. zeylanicum. showed the highest activity against all the fungi with MIC values of 0.04 to 0.63 μ g μ L^{? 1}. Other oils that gave a strong inhibition on fungal growth were the leaf oil of C. cordatum. and bark and twig oils of C. pubescens. and C. impressicostatum.. Cinnamaldehyde, which was the most abundant component of the bark oil of C. zeylanicum., showed the strongest activity against all the fungi studied. Based on the results of the assay on standard samples, it may be that the high levels of cinnamaldehyde, eugenol, geraniol, benzyl benzoate, and methyl cinnamate in the oils and in combination with the minor components is responsible for the high antifungal activity of the oils.     

Antifungal Activity of the Essential Oils of Nine Zingiberaceae Species

The rhizome oils of nine Zingiberaceae species [Zingiber officinale Rosc., Z. cassumunar Roxb., Z. zerumbet Smith, Curcuma aeruginosa Roxb., C. mangga Valeton and van Zyp, C. xanthorrhiza Roxb., Kaempferia galanga Linn., Alpinia galanga Swartz and Boesenbergia pandurata (Roxb.) Schlecht] were investigated for their antifungal activities against five dermatophytes (Trichophyton mentagrophytes, T. rubrum, Microsporum canis, M. nanum and Epidermophyton floccosum), three filamentous fungi (Aspergillus niger, A. fumigatus and Mucor sp.) and five strains of yeast (Saccharomyces cerevisiae, Cryptococcus neoformans, Candida albicans, Ca. tropicalis and Torulopsis glabrata). The antifungal testing was carried out by using the broth microdilution and the disc gel diffusion methods. Amongst the essential oils studied, only the oil of B. pandurata was effective against all the fungi, exhibiting the lowest MIC values of 0.63µgµl -1 to Mucor sp., 1.25µgµl -1 to both A. niger and A. fumigatus, and 2.5µgµl -1 to both T. rubrum and E. floccosum, and the highest inhibition zone diameter of 20.6mm against S. cerevisiae. The essential oil of K. galanga showed selective toxicity against A. fumigatus with a MIC value of 0.63µgµl -1, while the essential oils of Z. officinale and Z. cassumunar exhibited high activity against the yeasts (11.7-15.7mm). The chemical composition of the active essential oils was investigated by GC and GC-MS.     

Antibacterial Activity of Essential Oils from Palmarosa, Evening Primrose, Lavender and Tuberose

Essential oils extracted from flower petals of palmarosa (Cymbopogon martini), evening primrose (Primula rosea), lavender (Lavandula angustifolia) and tuberose (Polianthus tuberosa) were tested for their antibacterial activities against gram-positive and gram-negative bacteria. Different concentrations of each essential oil ranging from 10-100% were tested. Both gram-positive and gram-negative bacteria were found susceptible to the studied flower essential oils. With increase in concentration of essential oil, increase in zone of inhibition was observed thus dose-dependent response was clear for each essential oil. Essential oil extracted from Cymbopogon martini showed the highest activity against both gram positive and gram negative bacteria among the tested essential oils.     

闽产罗勒油化学成分的研究

用气相色谱－质谱－计算机联用分析技术研究罗勒油的化学成分,以OV－101石毛细管柱共分离出42个峰,鉴定出其出其中的37个化学成分,占总挥发油的98．95％。     

Antinociceptive and Anti-inflammatory Activities of Seven Endemic Verbascum Species Growing in Turkey

The leaves, flowers, and whole aerial parts of Verbascum L. (Scrophulariaceae) species have been used to treat respiratory problems, eczema, and other types of inflammatory skin conditions in traditional Turkish medicine. Moreover, they have also been widely used as a folk medicine to produce a soothing and anti-inflammatory effect on the urinary tract. In order to evaluate their folkloric use, both antinociceptive and anti-inflammatory activities of seven endemic Verbascum species [V. chionophyllum Hub.-Mor., V. cilicicum Boiss., V. dudleyanum (Hub.-Mor.) Hub.-Mor., V. latisepalum Hub.-Mor., V. pycnostachyum Boiss. & Heldr., V. salviifolium Boiss., V. splendidum Boiss.] were investigated. Antinociceptive activity was investigated via p-benzoquinone–induced writhing test, and the anti-inflammatory activity was studied using carrageenan-induced hind paw edema, PGE₂-induced hind paw edema, and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema models in mice. The methanol extracts of the flowers of V. chionophyllum and V. pycnostachyum, and the aerial parts of V. latisepalum and V. salviifolium, displayed significant antinociceptive and anti-inflammatory activity at 200 mg/kg oral dose without inducing any apparent acute toxicity or gastric damage. On the other hand, extracts from the rest of the species did not show any remarkable anti-inflammatory and antinociceptive activity. Results of the current study support the continued and expanded use of these plant species employed in Turkish folk medicine.     

Effect of Selected Essential Oils and Pure Compounds on Saprolegnia parasitica

Saprolegnia parasitica Coker is the main agent of saprolegniosis, one of the most important causes of economic losses in the fish farming industry, affecting all developmental stages. In this work the activity of some essential oils are compared with the activity of their isolated chemical constituents (alcohols, aldehydes, ketones, phenols, and hydrocarbons) to evaluate molecular classes active against S. parasitica. This suggests potential new products to use against saprolegniosis. Sixteen commercial essential oils and 37 pure constituents were tested against a strain of Saprolegnia parasitica from cutaneous lesions of Perca fluviatilis Linnaeus, using a continuously agitated broth technique that allows both the Minimum Inhibitory Concentration (MIC) and the Minimum Lethal Concentration (MLC) to be evaluated. It was possible to evaluate the efficacy of each essential oil against S. parasitica in relation to its specific composition and the efficacy of its main constituents. Carvacrol (MIC of 50?ppm and a MLC of 100?ppm) and p-cymene (MIC and MLC = 200?ppm) are the main constituents of Origanum vulgare L. and Thymus vulgaris L. (MIC = 100?ppm, MLC = 200?ppm) and are the primarly responsible for the efficacy of these two essential oils against S. parasitica. The structure of the constituents was also evaluated in relation to their activities against S. parasitica. Besides monoterpenic aromatic compounds, the acyclic mono- and sesquiterpenic primary alcohols and aldehydes seem to be the most active compounds. The open chain alcohol 1-decanol [CH₃-(CH₂)₈-CH₂-OH] proved to be the most active agent with a MLC = 50?ppm.     

Chemical constituents and antimicrobial activities of the essential oils from Sedum pallidum var. bithynicum and S. spurium grown in Turkey

Chemical compositions of the essential oil of Sedum pallidum Bieb. var. bithynicum (Boiss.) and S. spurium Bieb. (Crassulaceae) from Turkey were investigated by GC-MS, and antimicrobial activity of the oil samples were assessed against Gram-positive/negative bacteria and yeast-like fungi. Thirty-eight and thirty-five components were identified in the essential oils and the main components of these species were found to be caryophyllene oxide from S. pallidum var. bithynicum and hexahydrofarnesyl acetone from S. spurium in the ratios of 12.8% and 15.7%, respectively. The isolated essential oils of the plants showed low antimicrobial activity against Gram-negative/positive bacteria and yeast-like fungi, having the MIC values of 500-2000?μg/mL. Antibacterial activity was not observed against Bacillus cereus.     

Physicochemical Characterization and Antioxidant Activity of Essential Oils of Guggul (Commiphora wightii) Collected from Madhya Pradesh

The present study reports physicochemical characterization and antioxidant activity of essential oils extracted from guggul (Commiphora wightii) exudates collected from different places in Madhya Pradesh, India. The guggul exudates were hydrodistilled for 3-4 h in Clevenger apparatus. The oil obtained was dried over anhydrous Na₂SO₄ and stored at 4° until testing. Before extraction of oils from the exudates, their % moisture and tristimulus values of the colors namely L (white-black), a (green-red) and b (blue-yellow) were determined. Physicochemical characterization of the extracted oils was carried out to determine their solubility, yield%, acid value (mg/KOH/g), saponification value (mg/KOH/g), ester value, iodine value (g/g), peroxide value (mEq/kg) and Fourier transformed infrared analyses. The storage-effect on the % moisture and tristimulus values of the colors of guggul exudates as also the % oil yield and physicochemical parameters of the essential oils extracted from them, were studied using three different packaging materials viz., local plastic, low density polyethylene (200 G) and high density polyethylene (200 G). The antioxidant potential of extracted oils was evaluated by free radical scavenging activity using 1,1-diphenyl-2-picryl hydrazyl assay.     

蜡梅不同部位精油化学成分分析及其体外抑菌活性研究

目的 研究蜡梅Chimonanthus praecox（Linn.）Link根、叶、果皮中精油的化学组成及其抑菌活性。方法 采用气相色谱-质谱联用（GC-MS）技术对水蒸气蒸馏法提取的蜡梅根、叶、果皮精油进行成分分析,并分别采用肉汤二倍稀释法和菌丝生长法测试蜡梅不同部位精油对细菌和病原真菌的抑制活性。结果 鉴定了蜡梅根精油中的37种成分、蜡梅叶精油中的48种成分、蜡梅果皮精油中的38种成分,蜡酶不同部位精油中具有相同的化合物15种,分别占各部位精油总量的84.05%,36.83%,64.46%。抑菌实验结果表明蜡梅不同部位精油对受试菌均有不同强度的抑制作用。结论 蜡梅根精油对革兰氏阳性菌和病原真菌具有较强的抑菌活性,抑菌谱较广,且该精油含有多种生物活性成分,具有较高的药用价值及开发前景。     

芸香挥发油GC-MS分析及其生物活性研究

目的研究芸香挥发油的化学成分、抑菌活性和对HepG2细胞、NCI-H460细胞增殖的抑制作用。方法采用水蒸气蒸馏法（SD）提取挥发油,通过气相色谱-质谱联用技术（GC-MS）分析芸香挥发油的化学成分,同时采用纸片法测定其抑菌活性和MTT法观察芸香挥发油对肝癌HepG2细胞和肺癌NCI-H460细胞增殖的抑制作用。结果从芸香挥发油共鉴定出21种成分,主要为2-十一酮（46.15%）,其次是2-壬酮（27.01%）及2-十三醇乙酸酯（12.73%）;抗菌实验显示,芸香挥发油对金黄色葡萄球菌、白色葡萄球菌、表皮葡萄球菌、乙型链球菌有较强的抑菌活性;对肝癌HepG2细胞和肺癌NCI-H460细胞的增殖也有抑制作用,48 h的作用强于24 h,IC50分别为23.21μg.mL-1和21.87μg.mL-1。结论芸香挥发油可作为一种潜在的天然抗菌和抗肿瘤药物的来源。     

Chemical composition and in vitro antimicrobial activity of essential oil of Rhynchosia heynei,an endemic medicinal plant from Eastern Ghats of India

Rhynchosia heynei Wt. & Arn. (Fabaceae) is an endemic medicinal plant found in the forests of Eastern Ghats of India. The essential oil obtained from the leaves by steam distillation was studied for antimicrobial activity and chemical characterization. The essential oil exhibited a broad spectrum of antimicrobial activity on eight bacterial and three fungal strains. The essential oil was characterized chemically using gas chromatography with flame ionization detector. The majority of the components of the essential oil of R. heynei are oxygenated terpenes, such as, terpineol, camphene hydrate, germacrene-D, humulene, and linalool. etc.     

Effects of Essential Oils and Extracts from Certain Thymus. Species on Swimming Performance in Mice

Abstract

The effect of the methanol extracts and essential oils from the aerial parts of Thymus fallax. Fisch. & C.A. Mey. (Lamiaceae), T. kotschyanus. Boiss. et Hohen., and T. pubescens. Boiss. et Kotschy ex Celak on mouse swimming performance were studied using different doses. On the basis of our findings, the methanol extracts and oils shortened remarkably the immobility period during the forced swimming test in comparison with negative control and exhibited a dose-dependent antidepressant activity. The duration of immobility observed via the essential oils was less than that via the extracts in these experiments. The results of tests showed that the extracts and oils of T. fallax. had more antidepressant activity than T. kotschyanus. and T. pubescens..     

Antioxidant Activity of the Essential Oils of Different Parts of Juniperus communis. subsp. hemisphaerica. and Juniperus oblonga.

Abstract

The essential oils of different parts of Juniperus communis. subsp. hemisphaerica. (Presl) Nyman (Cupressaceae) and Juniperus oblonga. M. B. were examined for their potential radical scavenging activity. The compositions of the essential oils of these plants were studied qualitatively and quantitatively by GC and GC-MS. The main components of the essential oils as well as positive controls were subjected to antioxidant testing. A rapid evaluation for antioxidants, using two TLC screening methods, showed that all tested oils and their main components have antioxidant activity. The abilities of the volatile oils to act as nonspecific donors for hydrogen atoms for electron were checked in the diphenylpicrylhydrazyl (DPPH) assay. In the DPPH assay, the strongest effect among the essential oils was measured for the oil of leaves of male J. communis. subsp. hemisphaerica. at a concentration of 4 µL/mL (24.0%) In the deoxyribose degradation assay, the essential oils, pure components, and positive controls were tested at different concentrations. Most of the tested compounds showed some antioxidant effects. The fruit oil of J. oblonga. has the strongest effect among the tested volatile oils.

The deoxyribose assay was modified in three different ways to assess whether the oils exhibited site-specific effects. The results of the current study, which demonstrate the DPPH scavenging activity of the essential oils of the of leaves of male J. communis. subsp. hemisphaerica. and the OH radical scavenging effects of the fruit oil of J. oblong. suggest the use of these two essential oils in very low concentrations for preserving food materials.     

Essential oil of croton nepetaefolius and its main constituent, 1,8-cineole, block excitability of rat sciatic nerve in vitro

1. The effects of the essential oil of Croton nepetaefolius (EOCN) and its major constituent, 1,8-cineole, on the compound action potential (CAP) of nerve were investigated. 2. Experiments were performed in sciatic nerves dissected from Wistar rats, mounted in a moist chamber and stimulated at a frequency of 0.2 Hz, with electric pulses of 100 micros duration at 20-40 V. Evoked CAP were displayed on an oscilloscope and recorded on a computer. The CAP control parameters were as follows: peak-to-peak amplitude 8.1 +/- 0.6 mV (n = 15); conduction velocity 83.3 +/- 4.2 m/s (n = 15); chronaxie 58.0 +/- 6.8 msec (n = 6); and rheobase 2.8 +/- 0.1 V (n = 6). 3. Lower concentrations of EOCN (100 and 300 microg/mL) and 1,8-cineole (153 and 307 microg/mL; i.e. 1 and 2 mmol/L, respectively) had no significant effects on CAP control parameters throughout the entire recording period. However, at the end of 180 min exposure of the nerve to the drug, peak-to-peak amplitude was significantly (P < 0.05) reduced to 27.4 +/- 6.7 and 1.7 +/- 0.8% of control values by 500 and 1000 microg/mL EOCN, respectively (n = 6), and to 76.5 +/- 4.4, 70.0 +/- 3.9 and 14.8 +/- 4.1% of control values by 614, 920 and 1227 microg/mL (i.e. 4, 6 and 8 mmol/L) 1,8-cineole, respectively (n = 6). Regarding conduction velocity, at the end of the 180 min exposure period, this parameter was significantly reduced to 85.8 +/- 7.3 and 48.7 +/- 12.3% (n = 6) of control values by 500 and 1000 microg/mL EOCN, respectively, and to 86.4 +/- 4.5 and 76.1 +/- 5.2% (n = 6) by 920 and 1227 microg/mL 1,8-cineole, respectively. Chronaxie and rheobase were significantly increased by the higher concentrations of both EOCN and 1,8-cineole. 4. It is concluded that EOCN and its main constituent 1,8-cineole block nerve excitability in a concentration-dependent manner, an effect that was totally reversible with 1,8-cineole but not with EOCN. This suggests that other constituents of EOCN, in addition to 1,8-cineole, may contribute to the mediation of this effect of EOCN.     

A new isopimarane-type diterpene and a new natural atisane-type diterpene from Excoecaria agallocha

From the woods of Excoecaria agallocha, a new isopimarane-type diterpene, 3α,11β-dihydroxy-ent-isopimara-8(14),15-dien-2-one (1) and a new natural atisane-type diterpene, 16β-hydroxy-ent-atisan-3-one (2) were isolated together with three known compounds, ribenone (3), ent-labda-8(17),13E-diene-3β,15-diol (4), and ent-3β-hydroxybeyer-15-ene-2,12-dione (5). Their structures were determined by spectral data and x-ray crystallography evidence.     

The effects of 8-OH-DPAT on medulllary 5-HT neurons and sympathetic activity in baroreceptor-denervated animals

The effects of the 5HT_1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on medullary 5-hydroxytryptamine (5-HT) neuronal firing and inferior cardiac sympathetic nerve activity were simultaneously determined in baroreceptor-denervated cats. 5-HT neuronal firing was inhibited by 50% at a 1 μg/kg i.v. dose of 8-OH-DPAT in the baroreceptor-denervated animal. Unit firing was completely inhibited by a 3 μg/kg dose. In contrast, 8-OH-DPAT inhibited inferior cardiac nerve activity between 10 and 100 μg/kg i.v. A similar relationship between the 8-OH-DPAT-induced inhibition of 5-HT unit activity and sympathetic nerve activity was observed in sham-operated control animals. These data suggest that the sympatholytic effects of 8-OH-DPAT cannot be explained on the basis of an autoreceptor effect of the drug.     

Effects of vinpocetine on cyclic nucleotide metabolism in vascular smooth muscle

A novel vasodilating agent, vinpocetine (14-ethoxycarbonyl-(3α, 16α-ethyl-14, 15-eburnamenine) inhibits Ca²⁺-dependent phosphodiesterase, selectively, among the three forms of cyclic nucleotide phosphodiesterase identified in the rabbit aorta. The concentration of vinpocetine producing 50% inhibition of Ca²⁺-dependent phosphodiesterase activity was approximately 21 μM, both in the presence and absence of Ca²⁺-calmodulin (CaM). Increasing the concentration of CaM in the presence of Ca²⁺ did not prevent vinpocetine-induced inhibition of Ca²⁺-dependent phosphodiesterase, thereby indicating that vinpocetine inhibited the enzyme by interacting with the enzyme and not with CaM. To determine the influence of vinpocetine-induced inhibition of Ca²⁺-dependent phosphodiesterase on cyclic nucleotide metabolism in vascular smooth muscle, cyclic nucleotide levels in isolated rabbit aortic strips were also investigated. Addition of vinpocetine produced dose-dependent increases in only the cyclic GMP levels and there was no significant effects on the cyclic AMP levels. These results provide pharmacological evidence that Ca²⁺-dependent phosphodiesterase mainly hydrolyzes cyclic GMP in vascular smooth muscle. Vinpocetine may induce vascular relaxation by increasing cyclic GMP contents in vascular smooth muscle through selective inhibition of Ca²⁺-dependent phosphodiesterase.