Anna K. Jäger

Isolation of the major germination cue from plant-derived smoke

A highly active, heat stable, long lasting compound, 3- methyl-2H-furo[2,3-c]pyran-2-one (1), that stimulates seed germination was isolated from plant-derived smoke water using bioactivity-guided fractionation. The identification of this natural molecule, the major germination cue from smoke, should now rapidly lead to a more comprehensive understanding of the role of smoke as a promoter of seed germination.

Flavonoids and the CNS.

Flavonoids are present in almost all terrestrial plants, where they provide UV-protection and colour. Flavonoids have a fused ring system consisting of an aromatic ring and a benzopyran ring with a phenyl substituent. The flavonoids can be divided into several classes depending on their structure. Flavonoids are present in food and medicinal plants and are thus consumed by humans. They are found in plants as glycosides. Before oral absorption, flavonoids undergo deglycosylation either by lactase phloridzin hydrolase or cytosolic β-glucocidase. The absorbed aglycone is then conjugated by methylation, sulphatation or glucuronidation. Both the aglycones and the conjugates can pass the blood-brain barrier. In the CNS several flavones bind to the benzodiazepine site on the GABAA-receptor resulting in sedation, anxiolytic or anti-convulsive effects. Flavonoids of several classes are inhibitors of monoamine oxidase A or B, thereby working as anti-depressants or to improve the conditions of Parkinson’s patients. Flavanols, flavanones and anthocyanidins have protective effects preventing inflammatory processes leading to nerve injury. Flavonoids seem capable of influencing health and mood.

Review on plants with CNS-effects used in traditional South African medicine against mental diseases

The majority of the population in South Africa use traditional health care to treat various mental conditions. In this review, we present ethnobotanical information on plants used by the traditional healers in South Africa to treat mental illnesses, specifically epilepsy, depression, age-related dementia and debilitative mental disorders. Details of the recent scientific studies conducted on some of these plants are reviewed. Extracts of Searsia chirindensis, Cotelydon orbiculata and Leonotis leonurus have shown in vivo anticonvulsant activity. Extracts from Searsia dentata and Searsia pyroides showed spontaneous epileptiform discharge in mouse cortical slices, and acted as NMDA-receptor antagonists. Apigenin, amentoflavone and agathisflavone with affinity to the benzodiazepine site on the GABA(A)-receptor were isolated from Searsia pyroides. Naringenin with affinity to the GABA(A)-benzodiazepine receptor was isolated from Mentha aquatica. Agapanthus campanulatus, Boophone disticha, Mondia whitei and Xysmalobium undulatum exhibited antidepressant-like activity in three in vivo models for depression. Amaryllidaceae alkaloids with activity to the serotonin transporter were isolated from Boophone disticha. The alkaloid mesembrine, which act as a serotonin reuptake inhibitor, was isolated from Sceletium tortuosum. Investigations of plants used to treat age-related dementia and debilitative mental disorders lead to the isolation of a number of Amaryllidaceae alkaloids with acetylcholinesterase inhibitory activity from Boophone disticha and Crinum species. Extracts of Mentha aquatica, Gasteria croucheri, Ruta graveolens and Scotia brachypetala inhibited MAO-B. Naringenin was isolated from Mentha aquatica as a MAO inhibitor. Only a small number of the more than 300 southern African plant species reported to treat or affect the CNS have been scientifically evaluated. Very few of the active compounds have been isolated and identified.

Isolation of the MAO-inhibitor naringenin from Mentha aquatica L.

AIMS OF THE STUDY To isolate the compound(s) responsible for the MAO-inhibitory activity. MATERIALS AND METHODS Six extracts of varying polarity of Mentha aquatica L. were tested in a photometric peroxidase linked MAO bioassay. The 70% ethanol extract had highest inhibitory activity. (S)-Naringenin was isolated from the extract by bioassay guided fractionation on VLC and preparative TLC. The structure of the compound was determined by (1)H, (13)C and (13)C-DEPT NMR and optical rotation. RESULTS The IC(50) values for MAO inhibition by naringenin were 342+/-33 microM for the rat liver mitochondrial fraction, 955+/-129 microM for MAO-A and 288+/-18 microM for MAO-B. CONCLUSIONS The content of naringenin in Mentha aquatica might explain its use in traditional medicine for depression-like conditions.

Can phylogeny predict chemical diversity and potential medicinal activity of plants? A case study of amaryllidaceae

BackgroundDuring evolution, plants and other organisms have developed a diversity of chemical defences, leading to the evolution of various groups of specialized metabolites selected for their endogenous biological function. A correlation between phylogeny and biosynthetic pathways could offer a predictive approach enabling more efficient selection of plants for the development of traditional medicine and lead discovery. However, this relationship has rarely been rigorously tested and the potential predictive power is consequently unknown.ResultsWe produced a phylogenetic hypothesis for the medicinally important plant subfamily Amaryllidoideae (Amaryllidaceae) based on parsimony and Bayesian analysis of nuclear, plastid, and mitochondrial DNA sequences of over 100 species. We tested if alkaloid diversity and activity in bioassays related to the central nervous system are significantly correlated with phylogeny and found evidence for a significant phylogenetic signal in these traits, although the effect is not strong.ConclusionsSeveral genera are non-monophyletic emphasizing the importance of using phylogeny for interpretation of character distribution. Alkaloid diversity and in vitro inhibition of acetylcholinesterase (AChE) and binding to the serotonin reuptake transporter (SERT) are significantly correlated with phylogeny. This has implications for the use of phylogenies to interpret chemical evolution and biosynthetic pathways, to select candidate taxa for lead discovery, and to make recommendations for policies regarding traditional use and conservation priorities.

Neuroprotective and neurochemical properties of mint extracts.

Mints are aromatic plants with a tradition as medicinal remedies and culinary herbs. With the aim of investigating potential central nervous system (CNS) activities of traditional medicinal plants, four species and one hybrid of the genus Mentha (M. aquatica, M. longifolia, M. pulegium, M. suaveolens and M. × piperita) were selected. Methanolic extracts of the plants were tested for protective effects against hydrogen‐peroxide‐induced toxicity in PC12 cells, antioxidant activity (by ABTS and X/XO methods) and neurochemical properties (MAO‐A inhibition, AChE inhibition and affinity to the GABAA receptor). Mentha × piperita and Mentha aquatica produced significant (p < 0.05) protection of the PC12 cells against oxidative stress. All the plants exhibited antioxidant and MAO‐A inhibitory activities, M. × piperita being the most active. M. aquatica showed the highest affinity to the GABAA‐receptor assay. Results demonstrate that mints might have effect on the CNS. Copyright

The Need for Cultivation of Medicinal Plants in Southern Africa

Traditional medicine is an important part of healthcare in southern Africa. Most drugs are prepared from plants, all of which are collected from the wild. This has led to a large number of medicinal plants coming under severe threat and sustainable harvest is no longer a viable option. Therefore, a new strategy for developing these medicinal plants as commercial crops is needed. This could be both as an alternative crop for larger, commercial farms and for the small-scale farmer. Cultivation data need to be linked with pharmacological assessments of the crop during the development of protocols.

Effects of South African traditional medicine in animal models for depression

ETHNOPHARMACOLOGICAL RELEVANCE The four South African medicinal plants Agapanthus campanulatus (AC), Boophone distica (BD), Mondia whitei (MW) and Xysmalobium undulatum (XU) are used in traditional medicine to treat depression. AIM To evaluate the effect of ethanolic extracts of the plants in models for depression. MATERIALS AND METHODS The extracts were screened for affinity for the serotonin transporter (SERT) in the [(3)H]-citalopram-binding assay. The inhibitory potency of the extracts towards the SERT, the noradrenalin transporter (NAT) and the dopamine transporter (DAT) were determined in a functional uptake inhibition assay. Antidepressant-like effects of the extracts were investigated using the tail suspension test (TST) and the forced swim test in both rats (rFST) and mice (mFST). RESULTS All four plants showed affinity for SERT in the binding assay. AC and BD showed functional inhibition of SERT, NAT and DAT, MW affected SERT while XU showed no effect. BD showed significant effect in the TST and in the mFST/rFST, AC showed significant effect in mFST, MW showed significant effect in the rFST and XU showed significant effect in the mFST. CONCLUSION In this study we have demonstrated the antidepressant activity of four South African medicinal plants in vitro and in vivo, supporting their rational use in traditional medicine.

Isolation of immunomodulatory triterpene acids from a standardized rose hip powder ( Rosa canina L.)

A previously published systematic review and a metaanalysis have concluded that the consumption of standardized rose hip powder (Rosa canina L.) can reduce pain in osteoarthritis patients. Synovial inflammation has been suggested to play an important role in the pathogenesis of osteoarthritis and mainly to involve infiltration of the synovial membrane by macrophages. Therefore, the immunomodulatory effect of standardized rose hip powder of Rosa canina L. was investigated and active principles isolated using the Mono Mac 6 cell line as a model for human macrophages. Treatment of Mono Mac 6 cells with the residue of a crude dichloromethane extract of rose hip powder significantly and concentration dependently inhibited the lipopolysaccharide induced interleukin‐6 release. Through bioassay‐guided fractionation the immunomodulatory effect of the dichloromethane extract was correlated to a mixture of three triterpene acids; oleanolic acid, betulinic acid and ursolic acid (IC50 21 ± 6 µm). Further studies revealed that only oleanolic acid and ursolic acid, but not betulinic acid, could inhibit the lipopolysaccharide induced interleukin‐6 release from Mono Mac 6 cells when tested separately. Combination of either oleanolic acid or ursolic acid with betulinic acid enhanced the immunomodulatory effect of the two triterpene acids. Copyright

MAO-A inhibitory activity of quercetin from Calluna vulgaris (L.) Hull.

AIM OF THE STUDY This study investigated MAO-A inhibitory activity of methanol extract of Calluna vulgaris (L.) Hull., which traditionally has been used as a nerve calming remedy. MATERIALS AND METHODS A methanolic extract of Calluna vulgaris was partitioned against heptane, ethyl acetate and water. The three fractions were tested in a photometric peroxidase linked MAO-A bioassay. The ethyl acetate phase showed the highest MAO-A inhibitory activity. Quercetin was isolated by VLC through bioassay-guided fractionation and purified by re-crystallisation. The structure was elucidated by LC-MS and (1)H NMR. RESULTS The IC(50)-value for MAO-A inhibition by quercetin was 18+/-0.2 microM in an assay where the IC(50)-value for MAO-A inhibition by clorgylin was 0.2+/-0.02 microM. CONCLUSION The content of quercetin in Calluna vulgaris might explain the reported nerve calming effect of the plant.