THREATENED MEDICINAL PLANTS OF SOUTH AFRICA: CASE OF THE FAMILY HYACINTHACEAE

Background: Traditional medicine plays a major role in the primary health care of many people living in rural areas. South Africa is a home to over 30,000 species of higher plants and 3,000 of these species have been found to be used in traditional medicine across the country. South African medicinal plants are decreasing at an alarming rate as a result of over exploitation. Today many medicinal plants face extinction but detailed information is lacking. The purpose of this paper was to review current and proposed cultivation strategies that could be used to improve plant conservation statuses, livelihoods of the people involved in medicinal plant industry and sustainability of this industry. Methods: In this review, emphasis was on the members of Hyacinthaceae family and the species Siphonochilus aethiopicus (Schweinf) B.L. Burtt (Zingiberaceae), which are some of the most traded and used in traditional herbal medicine. Detailed literature search was conducted on the current strategies that are being used for the cultivation of medicinal and food crops and a conceptual analysis of how technologies used for the cultivation of non-medicinal crops could be adopted for cultivation of medicinal plants in Africa. Siphonochilus aethiopicus was used as a case study to demonstrate the potential of using alternative cultivation strategy such as hydroponics in the cultivation of medicinal plants. Results: The results showed that hydroponics has the potential to improve plant growth. In conclusion, evidences suggest that there is potential for growth in the medicinal plant industry if optimum cultivation technologies such as hydroponics are implemented despite the perception that Africans have an ingrained traditional preference of wild harvested plants, on the contrary many Africans have no issues with cultivated medicinal plants

EFFICACY OF VEGETABLE OILS AGAINST DRY BEAN BEETLES Acanthoscelides obtectus

Acanthoscelides obtectus (Say) is a major pest of stored dry beans ( Phaseolus vulgaris L.) and other legumes world wide. The objective of this study was to assess the efficacy of castor ( Ricinus communis L.) and cottonseed ( Gossypium hirsutum ) oils against A. obtectus on stored dry beans under laboratory conditions. Castor and cottonseed oils at 0, 3, 4.5, 6, 7.5 and 9 ml kg-1 were tested against A. obtectus. All bioassays were conducted at 28 \ub1 1 \ub0C and 65 \ub1 5% relative humidity, and mortality recorded after 24, 48, 72, 96 and 120 hr of exposure. After the 120 hr mortality count, all the adults were removed and the vials were maintained at the same conditions for 35 days to assess progeny production. Mortality of A. obtectus significantly (P<0.05) increased with increase in dose of oil treatments and exposure interval. After 120 hr of exposure, mortalities were 99.1 and 74.1% at the highest dose (9 ml kg-1) with castor oil and cottonseed oil, respectively. The lowest LC50 value of 2.95 ml kg-1 and complete suppression in progeny production were achieved on beans treated with castor oil at 9 ml kg-1. However, in all treatments, the percentage of progeny reduction was more than 80%. In conclusion, results indicate that vegetable oils have great potential for A. obtectus control.Acanthoscelides obtectus (Say) est un important ravageur des haricots secs et autres l\ue9gumineuses stock\ue9es \ue0 travers le monde. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer l\u2019efficacit\ue9 des huiles de ricin ( Ricinus communis L.) et coton ( Gossypium hirsutum ) contre A. obtectus peste de haricots secs dans des conditions de laboratoire. L\u2019huile de Ricin et l\u2019huile de coton \ue0 0, 3, 4, 5, 6, 7.5 et 9 ml kg-1 ont \ue9t\ue9 test\ue9s contre A. obtectus. Tous les essais biologiques ont \ue9t\ue9 effectu\ue9s \ue0 28 \ub1 1 \ub0C et 65 \ub1 5% h.r. et de la mortalit\ue9 a \ue9t\ue9 enregistr\ue9e 24, 48, 72, 96 et 120 heures apr\ue8s exposition. Apr\ue8s 120 hr, tous les adultes ont \ue9t\ue9 retir\ue9s et les flacons ont \ue9t\ue9 maintenus dans les m\ueames conditions pendant 35 jours pour \ue9valuer l\u2019effet des huiles sur la production et la descendance. La mortalit\ue9 des A. obtectus a augment\ue9 de fa\ue7on significative (P<0.05) avec l\u2019augmentation de la dose de traitements et le temps d\u2019exposition. Apr\ue8s 120 heures d\u2019exposition, les mortalit\ue9s \ue9taient de 99,1 et 74,1% \ue0 la dose la plus \ue9lev\ue9e (9 ml kg-1) avec de l\u2019huile de ricin et l\u2019huile de coton, respectivement. La plus basse valeur de concentration l\ue9tale 50 (CL50) de 2,95 ml kg-1 et une suppression compl\ue8te de la production de la descendance ont \ue9t\ue9 r\ue9alis\ue9es sur des graines trait\ue9es \ue0 l\u2019huile de ricin \ue0 9 ml kg-1. Cependant, dans tous les traitements, le pourcentage de r\ue9duction de la descendance \ue9tait sup\ue9rieur \ue0 80%. En conclusion, les r\ue9sultats indiquent que les huiles v\ue9g\ue9tales ont un grand potentiel pour le contr\uf4le A. obtectus

High aboveground carbon stock of African tropical montane forests

Tropical forests store 40–50 per cent of terrestrial vegetation carbon1. However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests2. Owing to climatic and soil changes with increasing elevation3, AGC stocks are lower in tropical montane forests compared with lowland forests2. Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4 megagrams of carbon per hectare (95% confidence interval 137.1–164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network4 and about 70 per cent and 32 per cent higher than averages from plot networks in montane2,5,6 and lowland7 forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa8. We find that the low stem density and high abundance of large trees of African lowland forests4 is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to help to guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse9,10 and carbon-rich ecosystems

High above-ground carbon stock of African tropical montane forests

Tropical forests store 40–50 per cent of terrestrial vegetation carbon1. However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests2. Owing to climatic and soil changes with increasing elevation3, AGC stocks are lower in tropical montane forests compared with lowland forests2. Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4 megagrams of carbon per hectare (95% confidence interval 137.1–164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network4 and about 70 per cent and 32 per cent higher than averages from plot networks in montane2,5,6 and lowland7 forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa8. We find that the low stem density and high abundance of large trees of African lowland forests4 is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to help to guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse9,10 and carbon-rich ecosystems

In vitro investigation of the toxic effects of extracts of Allium sativum bulbs on adults of Hyalomma marginatum rufipes and Rhipicephalus pulchellus

The toxic effects of the extracts of Allium sativum (Garlic) were evaluated against adults of Hyalomma marginatum rufipes and Rhipicephalus pulchellus using three types (Types A, B and C) of contact toxicity bioassays. A. sativum bulbs were extracted with acetone, ethanol and dichloromethane (DCM) solvents. Among these three solvents, it is the DCM extract of A. sativum that appears to have anti-tick activity. In the Type A contact toxicity bioassay, DCM extracts of A. sativum demonstrated a high acaricidal bioactivity against H. m. rufipes with 100 % of ticks killed in less than an hour, and toxicity persisted to the second day. A weak acaricidal activity of aqueous extracts of A. sativum was observed in the Type B contact toxicity bioassay. In the Type C contact toxicity bioassay, a concentration of 24 % w/v of DCM extracts of garlic in sunflower oil (Helianthus annuus) had killed 100% of H. m. rufipes (LC50= 5.9 % w/v) and R. pulchellus (LC50 = 10.3 % w/v) by 24 hours post-treatment of ticks. The results obtained from this study suggest that DCM extract of A. sativum is a potential source of novel acaricidal agents

Isolation of anti-Candida albicans compounds from Markhamia obtusifolia (Baker) Sprague (Bignoniaceae)

AbstractAn increase in clinical cases of Candidiosis globally as well as fungal resistance to drugs prompted the search for novel anti-Candida albicans agents from plant sources. Leaf extracts of Markhamia obtusifolia were screened for activity against C. albicans in vitro. An acetone extract obtained following serial exhaustive extraction contained mainly the active components with at least four active zones on the bioautogram. Bioassay guided fractionation of this extract led to the isolation of three compounds which inhibited the growth of three C. albicans strains. Based on spectroscopy studies (NMR and MS), the compounds were identified as 3β-hydroxyurs-12-en-28-oic acid, ursolic acid (1) 3β, 19α-dihydroxyurs-12-en-28-oic acid, pomolic acid (2) and 2β, 3β, 19α -trihydroxy-urs-12-en-28-oic acid, 2-epi-tormentic acid (3). The most active compound was 3β, 19α-dihydroxy-12-ursen-28-oic acid (2) with a minimum inhibitory concentration (MIC) value of 12.5 µg/mL for C. albicans isolated from dog and 25.0 µg/mL for C. albicans from cat and ATCC 90028 at 24 h following incubation. However, at 48 h of incubation MICs were >400 µg/mL for all the three compounds isolated. This study indicated that M. obtusifolia could be a potential source of active principles against C. albicans

Exploring the notion of knowing, doing and being in the Teaching

Exploring the notion of knowing, doing and being in the Teaching Development Programme (TDP) through the frame of activity theory Research in Innovation, Teaching and Learning Conference – RITAL 2012, Cape Town, 11 December 201