The data given in the literature published during 1976-1986 Table!. concerning antimicrobial activities of essential oils are treated from an experimental point of view and with regard to a possible practical application. Attention is paid to four factors which are important when testing essential oils: the assay technique; the growth medium; the microorganism; the essential oil.

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From Tabernaemontana chippii root bark, forty-five alkaloids were isolated; thirty-four were fully characterized by means of their spectral data and/or co-tlc; eight alkaloids were new, four of them being 3-hydroxy derivatives of known dimeric voacamine type alkaloids. Most of the twenty-six known alkaloids belonged to the corynanthean, ibogan, or bisindole classes. The structures of eleven other alkaloids--all minor--were only partially elucidated, most of them being new alkaloids. All the dimeric alkaloids were shown to possess strong antimicrobial activity against gram-positive bacteria and moderate to weak activity against gram-negative bacteria.

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Fifty-three essential oils were tested against five micro-organisms (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans) using the agar overlay technique. The essential oils were randomly selected and not on the basis of a supposed activity. It was found that all oils showed an activity against at least one micro-organism, and that substantial activities against P. aeruginosa were scarce. Combined activities against C. albicans, the Gram-positive bacteria and E. coli, and an activity against C. albicans were most often observed. Secondly a combined activity against C. albicans, B. subtilis and S. aureus was found. The differences between the inhibition zones were too small for a differentiation of the antimicrobial activities of the essential oils. A correlation matrix shows the relationships of the micro-organisms as to the activity patterns of the essential oils. High correlations were found for all the micro-organisms, except for P. aeruginosa.

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The antibacterial, antifungal and anti-yeast activities of ethanolic extracts of 19 different Tabernaenontana species have been screened by means of the agar diffusion test, 18 species showed activity against gram-positive bacteria, 14 species against gram-negative bactena, 5 species against, yeast and 6 species against, fungus. From most of the plants various parts have been examined, the root bark and stem bark showing the greatest activity. The antiamoebic activity of 15 species was assessed, three species showing significant activity at 0.5 mgI ml. Only two of the 14 species examined for antiviral activity showed significant activity against a single virus.Part 6 in the series "Pharmacognostical studies of Tabernaemontana species". For part 5 see reference (1)

The composition of the phthalide mixture of the essential oil from roots of Levisticum officinale Koch was investigated. The phthalide mixture was analyzed by combining separation methods - GLC, LSC and TLC - and subsequently using spectroscopic methods - IR, MS and NMR. E- and Z-butylidenephthalide, E- and Z-ligustilide, senkyunolide and validene-4,5-dihydrophthalide were found to be present; isosenkyunolide and propylidenephthalide were tentatively identified. The influence of the isolation procedure on the composition of the phthalide mixture was tentatively studied by comparison of mixtures isolated by solvent extraction and hydrodistillation respectively.