Frank Sporer

Synergistic properties of the terpenoids aromadendrene and 1,8-cineole from the essential oil of Eucalyptus globulus against antibiotic-susceptible and antibiotic-resistant pathogens.

The aim of the present study was to investigate the chemical composition of the essential oil of the fruits of Eucalyptus globulus and to examine the potential application of the fruit oil against multidrug-resistant bacteria. GLC/MS analysis in the fruit oil showed that aromadendrene was the main compound followed by 1,8-cineole and globulol. The three most abundant components of the fruit oil were also tested individually against microorganisms. In addition, the synergistic effects of combinations of the major constituents (aromadendrene and 1,8-cineole) of the fruit oil were also investigated. All Gram-positive bacteria were susceptible to the fruit oil with different degrees of susceptibility as determined by microdilution method. The oil exerted a marked inhibition against multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) Enterococcus faecalis. The results indicated that aromadendrene might be responsible for the antimicrobial properties, whereas 1,8-cineole and globulol exhibited low activities. The checkerboard assay demonstrated that combinations of 1,8-cineole and aromadendrene reduce the MIC in most cases in an additive way, whereas the time-kill assay indicates a synergistic effect.

Anthraquinones in Rheum palmatum and Rumex dentatus(Polygonaceae), and phorbol esters in Jatropha curcas(Euphorbiaceae) with molluscicidal activity against the schistosome vector snails Oncomelania,Biomphalaria, and Bulinus

Hot water extracts of Rheum palmatum and Rheum dentatus (from China) showed molluscicidal activity against the snails Oncomelania hupensis, Biomphalaria glabrata and Bulinus globosus which are vectors of Schistosoma japonicumS. mansoni and S. haematobium respectively. Activity was correlated with anthraquinones which were identified by HPLC: rhein and chrysophanol‐anthron were most active (>50% dead snails after 2 days in a 0.03% solution). Molluscicidal activity was intermediate with Rheum‐emodin and physcion and was not detectable with cinnamic acid or Aloe‐emodin. The snail O. hupensis tended to be more sensitive for several compounds than B. glabrata Extracts of Jatropha curcas seeds (from Mali) showed molluscicidal activity against both B. glabrata and O. hupensis the latter being the more sensitive snail. The activity was associated with phorbol esters extracted from Jatropha oil. Of the pure phorbol esters tested, 4β‐phorbol‐13‐decanoate killed both snail species at a concentration of 0.001% (10 p.p.m). As Jatropha is locally grown in Mali for other purposes, it might potentially be exploited for schistosomiasis control.

Antibacterial activity of essential oils from Eucalyptus and of selected components against multidrug-resistant bacterial pathogens

Context: Eucalyptus globulus Labill (Myrtaceae) is the principal source of eucalyptus oil in the world and has been used as an antiseptic and for relieving symptoms of cough, cold, sore throat, and other infections. The oil, well known as ‘eucalyptus oil’ commercially, has been produced from the leaves. Biological properties of the essential oil of fruits from E. globulus have not been investigated much. Objective: The present study was performed to examine the antimicrobial activity of the fruit oil of E. globulus (EGF) and the leaf oils of E. globulus (EGL), E. radiata Sieber ex DC (ERL) and E. citriodora Hook (ECL) against multidrug-resistant (MDR) bacteria. Furthermore, this study was attempted to characterize the oils as well as to establish a relationship between the chemical composition and the corresponding antimicrobial properties. Materials and methods: The chemical composition of the oils was analyzed by GLC-MS. The oils and isolated major components of the oils were tested against MDR bacteria using the broth microdilution method. Results: EGF exerted the most pronounced activity against methicillin-resistant Staphylococcus aureus (MIC ~ 250 µg/ml). EGF mainly consisted of aromadendrene (31.17%), whereas ECL had citronellal (90.07%) and citronellol (4.32%) as the major compounds. 1,8-cineole was most abundant in EGL (86.51%) and ERL (82.66%). Discussion and conclusion: The activity of the oils can be ranked as EGF > ECL > ERL ~ EGL. However, all the oils and the components were hardly active against MDR Gram-negative bacteria. Aromadendrene was found to be the most active, followed by citronellol, citronellal and 1,8-cineole.

Chemical composition and biological activity of the essential oil obtained from Bupleurum marginatum (Apiaceae).

Objectives Bupleurum marginatum is a herb indigenous to the southern and southwestern part of China. It is widely used in many Chinese prescriptions. We aimed to investigate the chemical composition, antioxidant, anti‐inflammatory, antimicrobial and in‐vitro cytotoxic activity of the hydrodistilled and extracted essential oil from B. marginatum to validate some of its ethnopharmacologial uses.

Biological activity of the essential oil of Kadsura longipedunculata (Schisandraceae) and its major components

Objectives  The aim was to determine the chemical composition of the essential oil of Kadsura longipedunculata and the biological activity of the oil and its major components.

Sequestration of phorbolesters by the aposematically coloured bug Pachycoris klugii (Heteroptera: Scutelleridae) feeding on Jatropha curcas (Euphorbiaceae).

Summary. The phorbol ester DHPB has been detected in 5th instars and adults of Pachycoris klugii which feed on Jatropha curcas, a producer of phorbol esters with mollusc-, insect-, and vertebrate toxicity. DHPB from Pachycoris activates protein kinase C (PKC) which appears to be the main molecular target for phorbol esters. Phorbol esters of J. curcas exhibit a wide range of acute toxic effects in vertebrates and insects. It is therefore likely that the sequestration of DHPB, which would explain the aposematic colouration of the bugs, confers chemical protection to P. klugii against vertebrate predators.

Antimicrobial activity of a traditionally used complex essential oil distillate (Olbas(®) Tropfen) in comparison to its individual essential oil ingredients.

Plant extracts and essential oils have been widely studied and used as antimicrobial agents in the last decades. In our study we investigated the antimicrobial activities of Olbas(®) Tropfen (in the following named Olbas), a traditionally used complex essential oil distillate, in comparison to its individual essential oil ingredients. Olbas (10 g) consists of three major components such as peppermint oil (5.3 g), eucalyptus oil (2.1 g), and cajuput oil (2.1 g) and of two minor constituents like juniper berry oil (0.3 g) and wintergreen oil (0.2 g). The composition of Olbas and the five individual essential oils were characterized by GLC-MS. According to GLC-MS analysis 1,8-cineol is the main component of the complex essential oil distillate followed by menthol and menthone. The minimum inhibitory and minimum microbicidal concentrations of Olbas and each of the single essential oils were evaluated in 17 species/strains of bacteria and fungi. Time-kill assay was performed to compare the microbicidal activity of Olbas and peppermint oil during several time intervals. Olbas displayed a high antimicrobial activity against all test strains used in this study, among them antibiotic resistant MRSA (methicillin-resistant Staphylococcus aureus) and VRE (vancomycin-resistant Enterococcus). Its antimicrobial activity was comparable to that of peppermint oil which was the most potent one of all individual essential oils tested. In the time kill assay Olbas as well as peppermint oil demonstrated similar microbicidal activities. Based on its wide antimicrobial properties Olbas can be a useful agent for the treatment of uncomplicated infections of skin and respiratory tract.

Carlina Oxide – A Natural Polyacetylene from Carlina acaulis (Asteraceae) with Potent Antitrypanosomal and Antimicrobial Properties

Carlina acaulis (Asteraceae) has a long history of medicinal use in Europe due to its antimicrobial properties. The strong activity of Carlina oxide, themain compound of the essential oil of C. acaulis against two MRSA strains, Streptococcus pyogenes, Pseudomonas aeruginosa, Candida albicans, and C. glabrata was confirmed. A strong and selective activity against Trypanosoma brucei brucei with an IC₅₀ of 1.0 μg/mL and a SI of 446 compared to human HeLa cells was recorded. The selective toxicity of Carlina oxide makes it a promising lead compound for the development of drugs to treat African trypanosomiasis and multiresistant gram-positive bacteria.

Variations of the chemical composition and bioactivity of essential oils from leaves and stems of Liquidambar styraciflua (Altingiaceae).

This study aimed to evaluate the variations of the chemical composition and bioactivity of essential oils of Liquidambar styraciflua L. (Altingiaceae) collected in different seasons.

Physicochemical properties of harpagoside and its in vitro release from Harpagophytum procumbens extract tablets.

The objective of this investigation was to characterize the active-component harpagoside of Harpagophytum extract from a physico-chemical perspective and to determine its in-vitro release from tablets according to DAB 1996. It was found that both pure harpagoside and harpagoside in Harpagophytum extract have an octanol-water distribution coefficient of approximately 4 which is neither dependent on temperature nor on pH. The mean harpagoside content in Harpagophytum tablets of Batch 9102 was 16.4 mg (S.D. 0.2; S.E. 0.03). Related to a tablet weight of 365 mg (100%), this corresponds to a haragoside content of 4.5% (S.D. 0.049; S.E. 0.006). On average the tablets disintegrate after 18 +/- 3 minutes (mean +/- SD). The tablets taken from Batch 9102 released the active component harpagoside well, with a t50 of 13.5 min, a t90 of 23 min and a t95 of 25 min in relation to 16.5 mg of harpagoside per dose. Harpagoside content decreased by about 10% in artificial gastric fluid within a period of 3 hours and remained stable in artificial intestinal fluid for a period of 6 hours.