Volatiles from vegetative organs of the palaeoendemic resurrection plants Ramonda serbica Panc. and Ramonda nathaliae Panc. et Petrov

Medicinal compounds, chemically and biologically characterised from extracts of Australian Callitris endlicheri and C.glaucophylla (Cupressaceae): used traditionally in Aboriginal and colonial pharmacopoeia

ETHNOPHARMACOLOGICAL SIGNIFICANCE

Callitrisendlicheri and C.glaucophylla were highly valued by Australian Aboriginal people for use in medicinal applications. Pine needles were prepared using modalities of either smoking or topical preparations, requiring either aqueous or lipophilic extraction into animal fat. Extracts treated various ailments consistent with pathogenic infection, or other topical or tracheal ailments not clearly elucidated in ethnopharmacological records.

AIM OF THE STUDY

Here we aim firstly to investigate antimicrobial activities of both smoke, essential oil and solvent extracts and secondly to chemically characterise significant volatile compounds potentially related to medicinal or antimicrobial activities.

MATERIALS AND METHODS

Essential oils were produced using traditional hydrodistillation of pine needles collected from Callitrisendlicheri and C.glaucophylla. From the same material, solvent extracts were produced separately, using acetone and methanol, and then smoke extracts were produced with separate methods described herein, using fresh needles. All extracts were screened for antimicrobial activity against a range of bacterial organisms and sporicidal activity against pathogenic fungi (Trichophytonmentagrophytes, T.interdigitalis and T.rubrum).

RESULTS

Essential oils produced only modest antibacterial activity and the Callitris endlicheri essential oil had moderate antifungal activity. Smoke extracts demonstrated considerable broad spectrum antimicrobial activity, but solvent extracts demonstrated more selective activity against Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and the yeast Candida albicans. Chemical character of essential oils was consistent with previous studies; however, solvent and smoke extracts from fresh needles produced high concentrations of potentially medicinal abietane diterpenes, specifically pisiferal, pisiferol and ferruginol; well known from Japanese species with demonstrated bioactivity.

CONCLUSION

The occurrence of these diterpenes and other phenolics, in conjunction with significant antimicrobial activities from the various extracts, is in alignment with the use of Australian Callitris species in Aboriginal medicinal practice.

Caryophyllene-Rich Essential Oil of Didymocarpus Tomentosa: Chemical Composition and Cytotoxic Activity

The essential oil from the leaves of Didymocarpus tomentosa was extracted by hydrodistillation and analyzed by GC/FID and GC/MS. Twenty five constituents amounting to 81.6% of the oil were identified. The leaf oil contained 78.7% sesquiterpenes and 2.9% monoterpenes. The leaf essential oil of D. tomentosa is a unique caryophyllene-rich natural source containing β-caryophyllene, caryophyllene oxide, α-humulene and humulene oxide. The cytotoxic activity of the oil was determined by the BSLT using shrimp larva and the MTT assay using HeLa tumor cell line. The oil showed significant cytotoxic activity with LC50 and IC50 values of 12.26 and 11.4 μg/mL, respectively. This is the first report on the chemical composition and cytotoxic activity of the essential oil of D. tomentosa.

The most frequently encountered volatile contaminants of essential oils and plant extracts introduced during the isolation procedure: fast and easy profiling

INTRODUCTION

Unfortunately, contaminants of synthetic/artificial origin are sometimes identified as major constituents of essential oils or plant extracts and considered to be biologically active native plant metabolites.

OBJECTIVE

To explore the possibility of early recognition and to create a list of some of the most common semi-volatile contaminants of essential oils and plant extracts.

METHODOLOGY

Detailed GC and GC-MS analyses of the evaporation residues of six commercially available diethyl ethers and of a plastic bag hydrodistillate were performed. Average mass scans of the total ion chromatogram profiles of the analysed samples were performed.

RESULTS

Almost 200 different compounds, subdivided into two groups, were identified in the analysed samples: (i) compounds that could be only of a synthetic/artificial origin, such as butylated hydroxytoluene and o-phthalic acid esters, i.e. requiring exclusion from the list of identified plant constituents; (ii) compounds possibly of synthetic and/or natural plant origin, i.e. compounds derived from the fatty acid metabolism or products of anaerobic intracellular/microbial fermentation. Average mass scans of the total ion chromatogram profiles provide meaningful and convenient information on uncovering important solvent-derived contamination.

CONCLUSION

A database of the most common semi-volatile contaminants of essential oils and plant extracts has been generated that provides information on the likelihood of rejection or acceptance of contaminants as possible plant constituents. The suggested average mass scan approach enables fast and easy profiling of solvents, allowing even inexperienced researchers to pinpoint contaminants.

Chemical composition and screening of the antimicrobial and anti-oxidative activity of extracts of Stachys species

GC and GC/MS analyses of the diethyl ether and ethyl acetate extracts obtained from the aerial parts of Stachys germanica subsp. heldreichii (Boiss) Hayek, Stachys iva Griseb., Stachys plumosa Griseb. and Stachys scardica Griseb., Balkan peninsula endemics, were performed. One hundred and seventy-nine constituents, accounting for 88.8-98.1% of the total composition of the extracts, were identified. The common feature of the diethyl ether extracts was the high content of terpenoids and fatty acidderived compounds, while the common feature of the ethyl acetate extracts was the prevalence of fatty acid-derived compounds. A disk diffusion method was used for the evaluation of the antimicrobial activities of the extracts against a panel of microorganisms (bacteria: Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella enteritidis; fungi: Aspergillus niger and Candida albicans). The total antioxidant capacity of the extracts was evaluated by the phosphomolybdenum method. The preliminary bioassay results indicated that the diethyl ether extract of S. plumosa could be a possible source of antioxidant and antimicrobial compounds.