G. Prinsloo

Cichorium intybus: Traditional Uses, Phytochemistry, Pharmacology, and Toxicology

The genus Cichorium (Asteraceae) is made up of six species with major geographical presence in Europe and Asia. Cichorium intybus, commonly known as chicory, is well known as a coffee substitute but is also widely used medicinally to treat various ailments ranging from wounds to diabetes. Although this plant has a rich history of use in folklore, many of its constituents have not been explored for their pharmacological potential. Toxicological data on C. intybus is currently limited. This review focuses on the economic and culturally important medicinal uses of C. intybus. Traditional uses, scientific validation, and phytochemical composition are discussed in detail.

Commercially Important Medicinal Plants of South Africa: A Review

There is a growing interest in natural plant-based remedies as a source for commercial products. Around 80% of the South African population use traditional medicines to meet their primary health care needs; however, only a few South African medicinal plants have been exploited to their full potential in terms of commercialization. The opportunity for bioprospecting of plant compounds for novel pharmaceuticals remains largely untapped. Certain renowned medicinal plants of international acclaim including buchu and rooibos are currently contributing to local enterprise; however, other exciting opportunities exist for commonly used plants which have not yet reached the international arena. This paper focuses on the key research and development contributions of 10 commercially important medicinal plants of South Africa. Traditional uses, scientific validation, commercialisation developments, as well as both potential opportunities and setbacks are discussed.

A cardiac glucoside with in vitro anti-HIV activity isolated from Elaeodendron croceum.

Human immunodeficiency virus (HIV) affects more than 40 million people worldwide and more than 5 million in South Africa alone. There is no cure for the disease yet, and novel effective drugs need to be discovered to make any progress in combating the disease. Twelve extracts from indigenous South African plants were analysed, of which Elaeodendron croceum showed potent inhibition of transcription factors and a recombinant HIV strain in an MT-2 VSV-pseudotyped recombinant virus assay at 100 ng mL−1. Bioassay guided isolation of an ethanolic extract of E. croceum yielded a well-known digitoxigenin-glucoside as the only active compound. It showed significant inhibition (90%) at 0.2 µM. The in vitro toxicity of digitoxigenin-glucoside proved to be quite low, and its therapeutic index was 250. This observation indicates that digitoxigenin-glucoside could represent a potential pharmacophore for the treatment of HIV from natural sources.

The use of plants containing genotoxic carcinogens as foods and medicine

In many developing countries, populations rely on traditional medicine for primary health care, which have infiltrated commercial markets globally as natural remedies are generally regarded as safe. Traditional and natural remedies are adapted and expanded in commercial products and product ranges to provide alternatives for various diseases and illnesses. These products resemble very little of the traditional use and application and adverse effects are observed in several cases. Some of the herbs and botanical formulations therefore, are not as safe as are commonly contemplated. This paper discusses some plants that are used as food or medicine. These plants are known to contain chemical components that have been identified as genotoxic carcinogens. Often contradictory results are obtained with beneficial and adverse effects reported. The concentration, biotransformation and metabolism of these compounds, as well as the matrix effect, affect the outcome of these results, therefore not providing a clear picture of the risk associated with the use and consumption of these plants. This paper focuses on plants that are accepted as healthy, however contain compounds that are genotoxic and carcinogenic. We further highlight the risks in use of these plants where thorough studies have been conducted in various food and plant products.

In vitro bioassays to evaluate beneficial and adverse health effects of botanicals: promises and pitfalls

This review provides an update on the promises and pitfalls when using in vitro bioassays to evaluate beneficial and adverse health effects of botanicals and botanical preparations. Important issues addressed in the paper are: (i) the type of assays and biological effects available; (ii) false-positives, false-negatives and confounding factors; (iii) matrix and combination effects; (iv) extrapolation of in vitro data to the in vivo situation; (v) when (not) to use bioassays; and (vi) identification of active constituents. It is concluded that in vitro bioassays provide models to detect beneficial as well as adverse activities, but that linking these observations to individual ingredients and extrapolations to the in vivo situation is more complicated than generally anticipated.

Anti-HIV activity of southern African plants: Current developments, phytochemistry and future research

Abstract Ethnopharmacological relevance The African continent is home to a large number of higher plant species used over centuries for many applications, which include treating and managing diseases such as HIV. Due to the overwhelming prevalence and incidence rates of HIV, especially in sub-Saharan Africa, it is necessary to develop new and affordable treatments. Aim of the study The article provides an extensive overview of the status on investigation of plants from the southern African region with ethnobotanical use for treating HIV or HIV-related symptoms, or the management of HIV. The review also provide an account of the in vitro assays, anti-viral activity and phytochemistry of these plants. Materials and methods Peer-reviewed articles investigating plants with ethnobotanical information for the treatment or management of HIV or HIV-related symptoms from the southern African region were acquired from Science Direct, PubMed central and Google Scholar. The selection criteria was that (1) plants should have a record of traditional/popular use for infectious or viral diseases, HIV treatment or symptoms similar to HIV infection, (2) if not traditionally/popularly used, plants should be closely related to plants with popular use and HIV activity identified by means of in vitro assays, (3) plants should have been identified scientifically, (4) should be native to southern African region and (5) anti-HIV activity should be within acceptable ranges. Results Many plants in Africa and specifically the southern African region have been used for the treatment of HIV or HIV related symptoms and have been investigated suing various in vitro techniques. In vitro assays using HIV enzymes such as reverse transcriptase (RT), integrase (IN) and protease (PR), proteins or cell-based assays have been employed to validate the use of these plants with occasional indication of the selectivity index (SI) or therapeutic index (TI), with only one study, that progressed to in vivo testing. The compounds identified from plants from southern Africa is similar to compounds identified from other regions of the world, and the compounds have been divided into three groups namely (1) flavonoids and flavonoid glycosides, (2) terpenoids and terpenoid glycosides and (3) phenolic acids and their conjugated forms. Conclusions An investigation of the plants from southern Africa with ethnobotanical use for the treatment of HIV, management of HIV or HIV-related symptoms, therefore provide a very good analysis of the major assays employed and the anti-viral compounds and compound groups identified. The similarity in identified anti-viral compounds worldwide should support the progression from in vitro studies to in vivo testing in development of affordable and effective anti-HIV agents for countries with high infection and mortality rates due to HIV/AIDS.

The effects of season and water availability on chemical composition, secondary metabolites and biological activity in plants

AbstractPlants react towards changes in their environment, which can be a result of biotic or abiotic activities. Numerous studies have investigated the effects of abiotic stress on plants, and how it affects the primary as well as secondary metabolism. Generally it is accepted that plants react to environmental stress by increasing secondary metabolites. This is however a very broad and simplified explanation and often inaccurate. Various examples are provided where plants react positively, and often negatively towards seasonal variation and water availability, resulting in a lowering of certain secondary metabolites concentration, while others are increased. Furthermore species differences, cultivars and interaction of other environmental factors such as temperature complicates a simple conclusion from the effect of stress on plants. The differential expression of genes in different species and in different metabolic pathways ensures a complex and very specific reaction of a plant to environmental stress. Overall the paper provides support for a complex and intricate response system which differs for each plant species, and could be explained by understanding and studying the different metabolic pathways responsible for secondary metabolite production.

Identifying anti-HSV compounds from unrelated plants using NMR and LC–MS metabolomic analysis

IntroductionPlants have been used to treat various ailments and diseases, including viral infections. Often activity is reported after screening plants traditionally used, without identifying the active principles.ObjectivesThis study investigated the use of metabolomics to identify common compound groups or compounds from unrelated plants, but with similar reported biological activity. Plants with anti-viral activities against Herpes Simplex Virus (HSV), Cytomegalovirus (CMV) and Human Immunodeficiency Virus (HIV) were collected and analysed. A few non-active plants, with no reported anti-viral activity were included as control samples.Methods1H-NMR and LC–MS metabolomic analysis were conducted, to determine the chemical similarity between plants with similar activity using SIMCA and XCMS online.ResultsPlants with anti-HSV, anti-HIV and anti-CMV activity, presented specific clusters, with the non-active samples separating from the active samples. The anti-HSV group presented a clear contribution plot and chlorogenic acid was identified by NMR. LC–MS metabolomic analysis confirmed the NMR results and furthermore identified several chlorogenic acid isomers including the main substructures of chlorogenic acids.ConclusionMetabolomic analysis on unrelated plants with similar activity can be used to identify the active compound groups or compounds, thereby eliminating the need for screening of plants to determine biological activity, additionally providing information on possible active principles. The two analytical methods identified chlorogenic acids and its building blocks as common and important compounds within plants with anti-HSV activity. Intensified research on plants containing chlorogenic acids should be the focus of future research for development of accessible anti-HSV treatments.

The allelopathic effects of Amaranthus on seed germination, growth and development of vegetables

ABSTRACT Amaranthus is a versatile plant used as a food, but it is also a recognised weed due to its competitive ability. Amaranthus is very nutritious and preferred by rural communities as a leafy vegetable, but it also contains anti-nutritional components and there are reports of allelopathic activity. This study investigated the effects of Amaranthus on seed germination, and the effects of Amaranthus grown in pots and in the field on follow-up crops planted in the same soil. Extracts of the whole plant, stems, leaves, flowers and roots of Amaranthus exhibited severe inhibition of seed germination of vegetables, as well as of weed seeds of Conyza bonariensis. Significant allelopathic effects were observed on tomato seedlings in the pot experiment with reduced growth in two of the treatments. However, no significant effects were observed in any of the field trials. All of the Amaranthus extracts exhibited very high electrical conductivity (EC) value. In a dilution experiment, the diluted extracts exhibited lower EC values, with no or limited seed germination at concentrations higher than 3.12 mg ml−1 and corresponding EC value of 2.1 mS cm−1. The high EC values that were associated with the allelopathic effect, possibly resulted from allelochemicals in the plant, but these were not identified in this study. The origin and persistence of the allelopathic effect warrant further research to determine the risks for agricultural crops.

Estimation of Pelargonium sidoides root damage by Meloidogyne spp.

Pelargonium sidoides is a medicinal plant species indigenous to Southern Africa. Its roots are used for treating a variety of ailments in man and livestock. It is in great demand by local users and international pharmaceutical producers. Root-knot nematodes, Meloidogyne species, penetrate into the roots of plants in search of food and for reproduction locations, resulting in the formation of galls. They affect the plant’s ability to absorb water and nutrients. P. sidoides plants, grown as part of a fertilizer trial, showed susceptibility to root-knot nematodes. Fifteen plots were replicated three times in a randomized complete block design with different levels of nitrogen, phosphorus and potassium. Ten plants per treatment were harvested eight months after planting, with the aim of developing a root-knot nematode rating chart. Each root system was assessed and ranked on a class of 0 to 10, with 0 representing no galls, 5 representing 50% infestation and 10 representing severe infestation. Meloidogyne incognita and Meloidogyne javanica were identified in the root samples. The sampled roots showed more than 50% infestation. It is recommended that the soil should be analyzed and treated accordingly, before planting P. sidoides to avoid root damage by root-knot nematodes.