No description available.

Peppermint dry weight biomass was higher in Verona (8119 kg/ha) than in Stoneville (6115 kg/ha). Overall both, oil content and yield were higher in bud formation stage than flowering stage. The levels of major essential oil constitutes were (-)-menthol 26 – 30 %, (-)-menthone 14 – 21 %, (+)-menthofuran 5 – 11 %, and eucalyptol 3 – 4 % of total essential oil content at flowering stage. Menthone content and its yield were higher at first cut; however, (+)-menthofuran content and its yield were higher at the second cut at bud formation. Although N fertilizers at rate 80 kg/ha did not affect essential oil content and yield at cut 1, N rate at 80 + 80 kg/ha increased oil yield at cut 2.

No description available.

Abstract A study on the essential oil chemistry and microbiological activity of South African indigenous medicinal plants with the aim of establishing a scientific rationale for their anti-infective properties was undertaken. For the purpose of this study, nine medicinal aromatic plants were selected. The hydrodistilled essential oil was analyzed by gas chromatography combined with mass spectrometry (GC-MS) and various techniques were used to document the antimicrobial activity. Disc diffusion studies on Myrothamnus flabellifolius indicated highest activities against the fungal test organisms Cryptococcus neoformans and Aspergillus niger with radial inhibition zones of 8 mm and 10 mm respectively. The highest antimicrobial activity noted in the minimum inhibitory concentration (MIC) assay was for C. neoformans (2 mg/mL). Time-kill studies demonstrated the death kinetic progression on M. flabellifolius essential oils where the killing rate was greatest for Candida albicans. Osmitopsis asteriscoides, a plant used traditionally for cuts and swellings showed highest disc diffusion antimicrobial efficacy against Staphylococcus aureus (3 mm) and C. neoformans (3 mm). The MIC study indicated highest susceptibilities (4 mg/mL) for Escherichia coli and Staphylococcus epidermidis. Death kinetics for the three organisms studied demonstrated that the killing rate was greatest for C. albicans. The role of the two major constituents (1,8-cineole and (-)-camphor) act synergistically to enhance antimicrobial activity. Disc diffusion assays undertaken on Artemisia afra showed highest activity against Candida tropicalis (5 mm). In the MIC assay the highest susceptibility was against Serratia odorifera (4 mg/mL). Time-kill assays on Artemisia afra showed a concentration dependent bactericidal activity, with evidence that the major constituents independently and in combination were not responsible for the overall activity of the plant. Lippia javanica, a plant used to treat coughs, colds and bronchitis, indicated highest susceptibility against the respiratory pathogen Klebsiella pneumoniae (5 mm) with the disc diffusion assay. The MIC assay indicated highest susceptibilities (4 mg/mL) against C. neoformans and E. coli. Death kinetic assays for three test organisms showed that the killing rate was the greatest for K. pneumoniae. The time-kill study for L. javanica in combination with A. afra demonstrated that the oils in combination act synergistically against K. pneumoniae. The antimicrobial activity of the essential oils and extracts were determined for Helichrysum cymosum subsp. cymosum where the extracts demonstrated at least a six times greater MIC efficacy than the essential oils. Using column chromatography, the antimicrobially active compound was isolated from H. cymosum subsp. cymosum and identified as helihumulone. The traditional use of plants as a treatment for infectious diseases is not always restricted to a single part of the plant as was noted in the study on Croton gratissimus var. subgratissimus, where the leaf, bark and root extracts were investigated singularly and combined in various ratios to establish possible interaction. The MIC and fractional inhibitory concentration (FIC) results indicated variable efficacies for the plant combinations. The greatest synergistic profile was noted for C. neoformans in the leaf and root combination (MIC 0.4 mg/mL and FIC of 0.4). Further isobologram combination studies were thereafter conducted on varying ratios of leaf and root extracts, indicating greatest synergy for Bacillus cereus, Enterococcus faecalis, C. albicans and C. neoformans. While seasonal variation had very little impact on the MIC results obtained from Heteropyxis natalensis, the ratio of the two major compounds (1,8-cineol and limonene) fluctuated on a monthly basis. Moderate antimicrobial activity (3.0-16.0 mg/mL) was found for most pathogens with higher sensitivities for C. neoformans. The geographical variation of H. natalensis essential oil indicated similar profiles for Gauteng, Nelspruit and Waterberg samples. The Lagalametse sample, however, showed distinct variation both chemically and microbiologically where efficacy was higher than in all other samples. The impact of the enantiomeric configuration was investigated for limonene in combination with 1,8- cineole with (+/-)-limonene in combination with 1,8-cineole having the most significant synergistic ratios against Pseudomonas aeruginosa. The antimicrobial activities of the non-volatile and volatile fractions of Tarchonanthus camphoratus and Plectranthus grandidentatus, singularly and in combination demonstrated that the volatile constituents contribute to the total efficacy of the plant. Isobologram representation of the combination of various ratios of T. camphoratus and P. grandidentatus essential oil and non-volatile extracts devoid of essential oils present a predominant synergistic profile for all pathogens studied. A comparative study on five indigenous oils (M. flabellifolius, O. asteriscoides, H. natalensis, A. afra and L. javanica) was undertaken with five popular commercial oils (Lavendula angustifolia, Thymus vulgaris, Melaleuca alternifolia, Mentha piperita and Rosmarinus officinalis). The highest antimicrobial activity was noted for Thymus vulgaris in the MIC assay, followed by M. flabellifolius, O. asteriscoides and M. alternifolia. With the time-kill assay, M. flabellifolius showed the most rapid cidal effect against all three pathogens tested. The comparative evaluation of commercial essential oils with indigenous oils validated the use of South African aromatic plants for their anti-infective properties.

The aim of this study was to evaluate the behavioural effects of inhaled bergamot, geranium and a combination of these oils in three novelty evoked tests of anxiety. Sixty adult Hooded Rats (Rattus norvegicus), with 10 rats randomly assigned to one of the 6 test groups; three essential oil treated groups, and three control groups. The essential oil groups consisted of bergamot, geranium and a combined group, i.e. the combination of bergamot and geranium oil. The control groups consisted of the odour and vehicle control, with the anxiolytic drug diazepam as a positive control. The behaviour of rats was assessed on the elevate-plus maze, open-field and social interaction test. Diazepam increased open arm entries and the time spent in the open arms, decreased time spent in closed arms and increased the number of head-dips and unprotected stretch-attends in the EPM. In the open-field diazepam increased immobility time, decreased ambulation, increased grooming activity and reduced the amount of time spent exploring the arena. Similarly, diazepam decreased the frequency of separations, sniffs, follows, crawls, passive and active interactions with test partners in the social interaction test. Bergamot, geranium and the combination of the two oils increased total arm entries in the elevated-plus maze. Bergamot increased locomotion and exploratory behaviour in open-field and decreased contact latency and increased passive and active interaction between the rat pairs in the social interaction test. Geranium decrease immobility and increase the time spent rearing in the open-field and also increased active interaction, i.e. partner sniffing and decreased the amount of time the rat pairs spent apart in the social interaction test. The combination of bergamot and geranium oil increased locomotion and the time spent in Zone2, and also increased exploratory behaviour, i.e. the frequency and duration of rears in the open-field. In the social interaction test, contact latency was shortened and active and passive interactions between rat pairs were increased by the combination of essential oils. The present study established that bergamot, geranium, and the combination of the two oils had a stimulating effect in the elevated-plus maze and an anxiolytic effect in the open-field and social interaction tests when inhaled. Furthermore the study also demonstrated that the combining of the oils had a potentiating effect on the anxiolytic properties of the single oils.

The Burkholderia cepacia complex (Bcc) are a group of closely related species known for their intrinsic multidrug resistance, large multipart genomes and ability to infect people with cystic fibrosis. The clinical relevance of the Bcc and their large multipart genomes make the study of their essential genes of broad interest. Essential genes are those required for survival in standard laboratory conditions this makes them potential targets for novel antibiotics against a group of species where few existing antibiotics are effective. Furthermore, while essential gene studies have been carried out in a number of bacterial species, only one of these species had multiple chromosomes and none had a genome as large as the Bcc. In my research I identified essential genes in B. cenocepacia K56-2, a member of the Bcc, by using transposon mutagenesis to deliver a rhamnose inducible promoter randomly into the genome and screening for a conditional growth (CG) phenotype. The utility of the CG mutant library was confirmed by showing that, when grown in suboptimal concentrations of rhamnose, only mutants that under-expressed the target of the antibiotic were hypersensitive. The CG mutant library included transposon insertions upstream from widely conserved, well-characterized essential genes suggesting that the system is capable of recovering essential gene mutants. A number of genes with either no or mixed records of essentiality in other microorganisms were also recovered. Among these was one of the three electron transfer flavoproteins (ETFs) in B. cenocepacia. The ETFs are a family of proteins found in a large number of eukaryotic, archaeal and bacterial species, which are required for the metabolism of specific substrates or for symbiotic nitrogen fixation in some bacteria. Despite these non-essential functions, high throughput screens have identified ETFs as putatively essential in several species. I showed that ETF expression is required for both viability and growth both on complex media and on media containing a variety of single carbon sources. Furthermore, cells depleted of ETF were determined to be nonviable and the morphologic shape of the cells changed from short rods to small spheres. In depth studies of essential genes are only possible for organisms with sequenced genomes. Of the 18 named species that currently comprise the Bcc, only 7 have been sequenced limiting the possibility of cross species comparative genomics. Therefore, I have assembled the first draft genomes of B. contaminans isolates, a species that has emerged as the dominant Bcc species recovered from the CF populations of Argentina and Spain. Identifying and characterizing essential genes in the Bcc, and sequencing additional Bcc species for comparative genomics are important first steps in understanding these clinically important bacteria. / February 2016

Abstract Aims: Due to the emergence of multi-drug resistance, alternatives to conventional antimicrobial therapy are needed. This study aims to investigate the in vitro pharmacological interactions between essential oils (considered valuable as natural therapeutic treatments) and conventional antimicrobials (ciprofloxacin ⁄ amphotericin B) when used in combination. Methods and Results: Interactions of the essential oils (Melaleuca alternifolia, Thymus vulgaris, Mentha piperita and Rosmarinus officinalis) when combined with ciprofloxacin against Staphylococcus aureus indicate mainly antagonistic profiles. When tested against Klebsiella pneumoniae the isobolograms show antagonistic, synergistic and additive interactions depending on the combined ratio. The R. officinalis ⁄ ciprofloxacin combination against K. pneumoniae displayed the most favourable synergistic pattern. The interactions of M. alternifolia (tea tree), T. vulgaris (thyme), M. piperita (peppermint) and R. officinalis (rosemary) essential oils with amphotericin B indicate mainly antagonistic profiles when tested against Candida albicans. Conclusion: While a number of interactions show complete antagonism, others show varied (synergistic, additive and ⁄ or antagonistic) interactions, thus the efficacy is dependent on the ratio in which the two components co-exist. Significance and Impact of the Study: The predominant antagonistic interactions noted here, suggests that some natural therapies containing essential oils should be used with caution when combined with antibiotics.

Abstract The contribution of the volatile constituents to the overall antimicrobial efficacy of the medicinal plant Tarchonanthus camphoratus was considered, where different extraction techniques were applied to yield four fractions. These comprised of the essential oil prepared by hydrodistillation, non-volatile constituents prepared by extraction of plant material remaining in the distilling apparatus (having no or negligible volatile constituents), and extracts prepared from fresh and dried plant material having both volatile and non-volatile constituents. The antimicrobial activities of the non-volatile and volatile fractions of T. camphoratus singularly (MIC method) and in combination (isobologram ratio method) demonstrated that the volatile constituents play an integral role in the total antimicrobial efficacy of the plant. The MIC values for the essential oils of T. camphoratus ranged from 1.5 to 16.0 mg/ml depending on the pathogen studied. With the exception of studies on Klebsiella pneumoniae, the non-volatile fraction devoid of volatile constituents displayed higher antimicrobial efficacies (2.0–4.0 mg/ml). When the volatile and non-volatile fractions were combined, increased efficacy was mostly noted with the dried plant material mostly showing a higher antimicrobially-active profile. Synergistic interactions were further validated by the isobologram studies on the combination of non-volatiles with essential oil.

Heteropyxis natalensis (Heteropyxidaceae) is traditionally used to treat respiratory disorders, and as a decongestant and antimicrobial agent. The seasonal variation of the hydrodistilled essential oil was investigated. Three trees in the Johannesburg Botanical Garden (Gauteng) indicated similar chemical profiles with fluctuation in the levels of the two major constituents (1,8-cineole and limonene). Little variation between the antimicrobial activity of seasonally collected samples was documented, with standard deviations of ±0.3 to ±3.3 depending on the pathogen studied. Moderate antimicrobial activity (3.0–16.0 mg/ml) was noted for most pathogens tested with Cryptococcus neoformans exhibiting the highest sensitivity (2.0–3.0 mg/ml). The chemogeographical variation of the oil composition from five of the seven distinct localities studied all contains 1,8-cineole and limonene as major constituents. The antimicrobial study of these samples indicated little variability between localities (standard deviation of ±0.5 to ±3.8). As observed in the seasonal variation study, C. neoformans displayed the highest sensitivity (0.5–2.0 mg/ml). One oil sample (Lagalametse), was distinctly different both chemically and microbiologically.

No description available.