Allelopathic potential of Arctotis arctotoides (L.f.) O. Hoffm aqueous extracts on the germination and seedling growth of some vegetables

Aqueous shoot and root extracts of Arctotis arctotoides were tested for their allelopathic properties on cabbage, carrot, tomato and spinach seed germination and seedling growth. The addition of the two extracts at 8 and 10 mg ml-1 resulted in the highest germination inhibitions. The shoot extract at 10 mg ml-1 inhibited cabbage, carrot, tomato and spinach seed germination by 79.1, 75.6, 82.0 and 46.0%, respectively while the root extracts at the same concentration had inhibitions of 66.0, 64.0, 64.7 and 42.1%, respectively on each of the vegetables. The decreases in the radicle growth of the four targets were highest in 10 mg ml-1 of the shoot extract with cabbage, carrot, tomato and spinach having 95.3, 98.9, 92.9 and 87.6%, respectively. Considerable reductions also occurred in the plumule length of all the seedlings. The present study has demonstrated the inhibitory properties of the shoot and root aqueous extracts of A. arctotoides on the germination and seedling growth of the four vegetables.Key words: Arctotis arctotoides, allelopathy, germination, seedling growth, vegetable seeds

Antibacterial and antioxidant activities of hydroalcoholic stem bark extract of Schotia latifolia Jacq

AbstractObjectiveTo investigate the antibacterial and antioxidant activities of hydroalcoholic extract of Schotia latifolia (S. latifolia) bark commonly used in South Africa traditional medicine for the treatment of various ailments.MethodsThe antibacterial test and MIC was determined by using agar well diffusion and dilution methods respectively against eight strains of bacteria. The total phenol, proanthocyanidin and flavonoid contents of S. latifolia were assessed using standard methods. The antioxidant activity of the extract was evaluated using ferric reducing power and the free radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic-acid (ABTS), nitric oxide (NO), hydrogen peroxide (H2O2) and lipid oxidation (LO).ResultsThe antibacterial activity demonstrated an appreciable effect against all the gram positive bacteria at MIC between 0.016 and 10 mg/mL while that of gram negative bacteria was above 10 mg/mL. The plant extract exhibited high concentration of proanthocyanidin [(300.00±0.10) mg CE/g], followed by flavonoid [(12.46±0.04 mg) TE/g] and phenol [(11.06±0.03) mg QE/g] contents. Similarly, the extract at 0.5 mg/mL scavenges DPPH, ABTS, H2O2, LO and NO by 87.55%, 89.47%, 77.15%, 86.48% and 77.75% of the radicals respectively. The reducing power was also found to be concentration dependent.ConclusionsOur data suggest that S. latifolia extract has antibacterial and antioxidants activity and thus could be used as alternative therapy against antibiotic resistance bacteria and to prevent many radical related diseases

Evaluation of the polyphenolic contents and antioxidant properties of aqueous extracts of garlic, ginger, cayenne pepper and their mixture

Garlic (Allium sativum), Ginger (Zingiber officinale), and Cayenne Pepper (Capsicum fructences) are common culinary spices that are used singly or combined in the diet of many populations of the world and there is a long-held belief of their health-enhancing properties.  This study investigated the aqueous extracts each of garlic, ginger, cayenne pepper and a combination of the three for polyphenolic and antioxidant properties that might justify such claims. Aqueous extracts of garlic, ginger, pepper and a combination of the three was evaluated for polyphenolic and antioxidant activities using DPPH, ABTS, nitric oxide radical scavenging activities and reducing power assay. Each of the spice extracts showed high content of phenolics, flavonoids, flavonols and proanthocyanidin, with the pepper extract exhibiting the highest concentration of each polyphenol investigated. The antioxidant activities of the spices and their mixture was concentration dependent, though positively comparable with the standards used. Among the extracts, the mixture exhibited the highest antioxidant activity compared to the individual spices and standards probably due to a synergistic effect of combining the spices. The present study confirmed that the aqueous extracts of garlic, ginger and pepper exhibited significant polyphenolic content and antioxidant potentials. Also, that a mixture of the three spices potentially exhibits more powerful synergistic antioxidant activity than the individual spices, making a strong case for their combined use

Characteristics of pathogenic bacteria isolates associated with the gut and gill of molluscan shellfish, Eastern Cape, South Africa

Introduction: Infectious diseases attributable to the consumption of raw and lightly cooked molluscan shellfish are caused by bacterial agents that are associated either with human waste disposed into the ocean or those of marine origin. This has led to the increase in prevalence of bacterial diseases and microbial resistance to antibiotics. Method: Samples of P. perna were dissected and homogenized for bacterial isolation. Six bacteria were isolated, identified and evaluated for their antimicrobial susceptibility profiling. Results: The microbial counts obtained revealed significant differences in the pathogenic bacteria populations found in the gut and gill of Perna perna. The morphological characteristics of the isolates were found to be of different shapes. All the isolates were catalase and oxidase positive except Vibrio spp. which was negative to the latter. Chloramphenicol and ciprofloxacillin were the most effective antibiotics against all the isolates, each exhibiting 100% efficacy. The highest resistance to ampicilin was observed in Salmonella spp., Shigella spp., Listeria monocytogenes and Staphylococcus xylosus. Conclusions: The results revealed that marine habitats are reservoirs of bacterial pathogens and there is increased resistance to antibiotic therapy, thereby constituting risks to public health. Therefore, appropriate surveillance measures to safeguard the health of shellfish consumers’ should be established

Toxicity assessment of aqueous extract of Curtisia dentata (Burm.f) C.A. Sm: stem bark in male Wistar rats

Purpose: To investigate the acute and sub-acute toxicity effects of aqueous stem bark extract in male Wistar rats.Methods: For the acute toxicity study, a single dose of 5000 mg/kg body weight of the extract was orally administered to the animals by oral gavage and the rats thereafter were observed for mortality and toxicity signs for 14 days. In the sub-acute toxicity test, the graded doses (50, 100, and 200 mg/kg body weight) of the aqueous extract of CD were given to the animals once daily for 28 days. In each of the experiment, the food and water intake, body weight changes, relative organ weights, hematological, clinical biochemistry and histopathological parameters were evaluated.Results: In both the acute and sub-acute toxicity studies, CD did not show any visible signs of toxicity. There were also no significant differences (p > 0.05) between the control and CD-treated rats for all the investigated parameters; no obvious gross pathological features in the kidney, heart and liver of all the experimental animals were observed.Conclusion: The findings indicate that the extract is not toxic when administered at the tested doses and within the exposure period. Thus, the aqueous stem bark extract of CD may be adjudged relatively safe and pharmacologically non-toxic in Wistar rats.Keywords: Curtisia dentata, Hematopoietic, Histopathology, Toxicit

A Review of the Antidiabetic Activities of Ginger

Diabetes mellitus, a chronic metabolic disorder with major health care burden worldwide, is increasing, with 173 million adults being diabetic and over 8 million deaths recorded annually. Undesirable pathological conditions and high rates of secondary failure limit the use of current antidiabetic agents, thus, the need for more effective antidiabetic agents. Medicinal plants such as spices, rich in bioactive components that promote prevention and treatment of chronic conditions such as heart disease, cancer and Type-2 diabetes, are inexpensive with no side effects. The Zingiberaceae family, of which ginger is a member, consists of many species frequently cited for their antidiabetic and hypoglycemic properties. All important scientific literatures from 2000 to 2018 on the antidiabetic potentials of Zingiber officinale were evaluated. According to these studies, ginger exerts its antidiabetic effects through restorative effects on pancreatic β-cells, increasing insulin sensitivity, action and peripheral utilization of glucose. Other mechanisms include increased synthesis of hepatic glycogen through the enhancement of glycogen regulatory enzyme expression in the liver, inhibition of carbohydrate metabolizing enzymes, stimulation of pancreatic insulin release and inhibition of hepatic glucose production. Further studies, especially in humans are needed, more so, since ginger is one of the spices generally regarded as safe

Evaluation of Antidiabetic Activity and Associated Toxicity of Artemisia afra

Artemisia afra Jacq. ex Willd. is a widely used medicinal plant in South Africa for the treatment of diabetes. This study aimed to evaluate the hypoglycemic activity and possible toxicity effect of aqueous leaf extract of the herb administered at different dosages for 15 days in streptozotocin-induced diabetic rats. Administration of the extract at 50, 100, and 200 mg/kg body weight significantly (P<0.05) increased body weight, decreased blood glucose levels, increased glucose tolerance, and improved imbalance in lipid metabolism in diabetic rats. These are indications of antidiabetic property of A. afra with 200 mg/kg body weight of the extract showing the best hypoglycemic action by comparing favourably well with glibenclamide, a standard hypoglycemic drug. The extract at all dosages tested also restored liver function indices and haematological parameters to normal control levels in the diabetic rats, whereas the kidney function indices were only normalized in the diabetic animals administered with 50 mg/kg body weight of the extract. This investigation clearly showed that in addition to its hypoglycemic activity, A. afra may also protect the liver and blood against impairment due to diabetes. However, some kidney functions may be compromised at high dosages of the extract

In vivo Studies on Antidiabetic Plants Used in South African Herbal Medicine

Diabetes is one of the most common metabolic disorders worldwide. It is a major health problem with its frequency increasing every day in most countries. The disease is generally believed to be incurable; and the few orthodox drugs available to manage the disease are not readily affordable to the poor. Based on the historical success of natural products as antidiabetic agents and the ever increasing need for new antidiabetics, a number of South African medicinal plants have been evaluated for their antidiabetic properties. In this article, we review the major studies conducted based on ethnobotanical surveys carried out between 2005 and 2008 in South Africa on plants that are traditionally used for the treatment of diabetes. Overall, the results of the studies conducted confirmed the potential of South African medicinal plants in antidiabetic drug discovery and identified a number of promising taxa for further in vivo investigation as plant-based antidiabetic agents

The medicinal potential of Helichrysum Aureonitens

Plants have been used successfully for centuries by herbalists all over the world and especially in Africa, Asia and Latin America for the treatment of various human diseases. It has been estimated that 80% of people living in developing countries are almost completely dependent on traditional medical practices for their primary health care needs (Farnsworth 1990; Nwosu and Okafor 1995). Higher plants are known to be the main source of drug therapy in traditional medicine. Out of the 250 000 species of higher plants known to exist on earth, only a relative handful have been thoroughly investigated for their therapeutic values. Yet, in terms of the quantity consumed, the plant kingdom has yielded more than 25 % of the drugs used in prescriptive medicines today (Farnsworth 1988; Balick 1990). On the basis of global survey data it has been discovered that about 119 plant-derived chemical compounds of known structure are currently used as drugs or as biodynamic agents that affect human health. Less than a dozen of these are produced- commercially by synthesis or by simple chemical modification of the extracted active compounds; the remainder are extracted and purified directly from plants. These 119 useful drugs are obtained from only about 90 species of plants (Farnsworth et al. 1985; Farnsworth 1990). Considering the current rate of deforestation and concurrent loss of biodiversity throughout the world, there is an urgent need to examine the rest of the plant kingdom for new pharmaceutical compounds.Thesis (PhD)--University of Pretoria, 1994.Plant SciencePhDUnrestricte

Editorial: Medicinal Plants and Economic Development

No abstract available