A. Baerheim Svendsen

Tabernaemontana L. (Apocynaceae): A review of its taxonomy, phytochemistry, ethnobotany and pharmacology☆

The taxonomy, phytochemistry, ethnobotany, and pharmacology of the genus Tabernaemontana L. (Apocynaceae) is reviewed. The genus is currently being revised taxonomically; most of the segregate genera are being reunited with it and the number of species that will ultimately be recognized will probably be about 100. All the names encountered in the chemical and ethnobotanical literature have been evaluated as far as possible, and a list is presented of the recognized species and their synonyms. The biogenesis and classification of the indole alkaloids found in Tabernaemontana species is set out and some problems in the determination of their stereochemistry are discussed. To facilitate access to the information, three lists have been compiled: the alkaloids in alphabetical order; the alkaloids in order of increasing molecular weight; and the alkaloids grouped according to their biogenetic classification, together with the species and plant part(s) in which they are known to occur. Biogenetic and chemotaxonomic aspects are briefly considered. A table of the non-alkaloidal constituents is also included. The ethnobotany of individual Tabernaemontana species is outlined and an overall assessment made. Likewise, information on the pharmacology of crude extracts and individual alkaloids from Tabernaemontana species has been assembled and appraised.

Antimicrobial activities of essential oils

The testing of essential oils for antimicrobial activities is reviewed with respect to various possible applications. Consideration is given to the screening for antimicrobially active oils or constituents, for disinfecting or antiseptic properties and for food conserving properties. The role of essential oils in biological interactions and their potential as therapeutic agents are also discussed.

Screening for antimicrobial activity of some essential oils by the agar overlay technique

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 againstP. aeruginosa were scarce. Combined activities againstC. albicans, the Gram-positive bacteria andE. coli, and an activity againstC. albicans were most often observed. Secondly a combined activity againstC. albicans, B. subtilis andS. 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 forP. aeruginosa.

Anthraquinones as phytoalexins in cell and tissue cultures of Cinchona spec.

The addition of autoclaved mycelia of Aspergillus niger and the known phytopathogenic fungus Phytophtora cinnamomi to cultured cells of Cinchona ledgeriana Moens. caused a marked increase in the anthraquinone content of the plant cells. This finding in combination with the antimicrobial activity of the anthraquinones isolated from calli of Cinchona pubescens Vahl. led to the conclusion that anthraquinones are phytoalexins.

Antimicrobial activities of some ocimum species grown in rwanda

The essential oils of four Ocimum species grown in Rwanda, i.e. O. canum, O. gratissimum, O. trichodon and O. urticifolium (synonym O. suave) including some chemotypes, were screened for antimicrobial activities. Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Trichophyton mentagrophytes var. interdigitale were used as test organisms. Different techniques were applied in the screening, such as the biogram and agar overlay techniques and a dilution technique yielding maximum inhibitory dilution (MID) values. Also some growth curves were determined. Although the results obtained by the diffusion techniques were rather different for some of the oil samples, all samples were found to be antimicrobially active.

Anthraquinones in callus cultures of Cinchona ledgeriana

Abstract From callus cultures of Cinchona ledgeriana seven known anthraquinones, purpurin, anthragallol-1,2-dimethylether, anthragallol-1,3-dimethylether, rubiadin, 1-hydroxy-2-hydroxymethylanthraquinone, 1-hydroxy-2-methylanthraquinone and morindone-5-methylether (or 1,7-dihydroxy-8-methoxy-2-methylanthraquinone), and eight new anthraquinones, 5,6-dimethoxy-1-(or -4-)hydroxy-2-(or -3-)hydroxymethylanthraquinone, 5-methoxy-2-(or -3-)methyl-1,4,6-trihydroxyanthraquinone, 2-hydroxy-1,3,4-trimethoxyanthraquinone, 4-methoxy-1,3,5-trihydroxyanthraquinone, 1,4-dimethoxy-2,3-methylenedioxyanthraquinone, 1,3-dihydroxy-4-methoxyanthraquinone, 1,3-dihydroxy-2,5-dimethoxyanthraquinone and 2,5-(or 3,5-)dihydroxy-1,3,4-(or -1,2,4-)trimethoxyanthraquinone have been isolated.

Screening of antimicrobial activity of some plants belonging to the Apocynaceae and Loganiaceae

A review is given of the literature on the antimicrobial activity of various indole alkaloids. The data are briefly discussed. A screening was performed of a series of plants belonging to the indole alkaloid rich plant families Apocynaceae and Loganiaceae, 25 materials representing 14 Apocynaceae species and 54 materials representing 41 Strychnos species were investigated. No activity against the yeast or the fungus, used as test organisms was found. A number of extracts showed activity against the gram-positive test organisms, 4 species showed activity against gram-negative bacteria.

Antimicrobially active alkaloids from Tabernaemontana pachysiphon

Abstract Twenty-three alkaloids and five steroids and triterpenes have been isolated and identified from the root bark and stem bark of a Nigerian Tabernaemontana pachysiphon . The following bases have not previously been obtained from this species: isositsirikine, 16-epiisositsirikine, normacusine B, 16-epiaffinine, anhydrovobasindiol, tubotaiwine, ibogaline, isovoacangine, voacamine, lochnericine, 3 R -hydroxyconopharyngine, 3 S -hydroxyconopharyngine and 11-demethylconoduramine, the last three being new alkaloids. The dimeric indole alkaloids and 3 R/S -hydroxyconopharyngine were shown to possess strong antibacterial activity against Gram-positive bacteria and the dimers against Gram-negative bacteria also.

The essential oil of Ducrosia anethifolia (DC.) Boiss. Chemical composition and antimicrobial activity.

The essential oil from herb ofDucrosia anethifolia (DC.) Boiss., growing wild in Iran, was investigated by LSC, GLC and GC-MS. The oil consisted mainly of aliphatic compounds. α-Pinene, myrcene and limonene were main components of the hydrocarbons present in the oil, whilen-decanal,n-dodecanal,n-decanol,trans-2-dodecenal, andcis-chrysanthenyl acetate were the major oxygen-containing constituents.The oil and the main oxygen-containing aliphatic components showed a remarkable antimicrobial activity against gram-positive bacteria, a yeast, and some dermatophytes.

Induction of triterpene biosynthesis by elicitors in suspension cultures of Tabernaemontana species.

Treatment of suspension cultures of some Tabernaemontana species (Apocynaceae) with elicitors (e.g. cellulase, Candida albicans) result in a rapid de novo production of antimicrobial active triterpenes. The triterpenes are identified as ursene carboxylic acid derivatives. These triterpenes are not produced by an elicited cell suspension culture of Catharanthus roseus, another Apocynaceae.