Antimicrobial activities of essential oils from Southern Africa against selected bacterial and fungal organisms

In the present study, essential oils from four plants including Melissa officinalis, Mentha piperita,  Pelargonium graveolens and Leucosidea sericea, traditionally used to treat infectious diseases were  tested for antimicrobial activity against seven Gram-positive bacteria, eight Gram-negative bacteria and six yeast species (Candida spp. and Cryptococcus neoformans) using the agar diffusion method. The  minimum inhibitory concentrations (MIC) of the oils were determined by the microdilution technique. The killing kinetics of the oils was further evaluated against specific bacterial and fungal organisms. Both  antifungal and antibacterial activities were observed from the essential oil of P. graveolens and M.  peripeta against bacterial and fungal strains tested in the present study with the MIC values ranging from 0.95 to 7.5 mg/ml against the bacterial isolates and 0.24 to 7.50 mg/ml 'against the fungal isolates. The oils of P. graveolens were fungicidal to all the yeast isolates tested in the present study with minimum fungicidal concentration (MFC) values ranging from 0.12 to 7.50 mg/ml while the essential oil from M. piperita was fungicidal to one of the six yeast isolates tested with the smallest MFC of 0.48 mg/ml against Candida tropicalis. Essential oils from P. graveolens were able to kill 90% of the P. aeruginosa cells within three hours. The present study has revealed the antimicrobial activity of P. graveolens and M. piperita and indicated that essential oils are promising sources of natural products with potential antimicrobial activity. These results will guide the selection of some plant species for further pharmacological and phytochemical analysis. These results also support the use of essential oils to treat microbial infections and could be used as pharmaceuticals as well as preservatives in the food industry.Key words: Medicinal plants, essential oils, antibacterial activity, antifungal activity, time-kill activity

The chemical composition and biological activities of essential oil from the fresh leaves of Schinus terebinthifolius from Zimbabwe

In the present study, the essential oil from the fresh leaves of Schinus terebinthifolius was extracted using the hydrodistillation method. The oil yield obtained was 0.65%. Gas chromatography and mass spectroscopy (GC-MS) analysis of the essential oil showed that the major constituents of the essential oil were sabinene, -pinene, -phellandrene, -pinene, terpinene-4-ol, trans--ocimene and myrcene. Using the hole-plate diffusion testing method, the essential oil exhibited potent antibacterial activity against Yersinia enterocolitica, Pseudomonas aeruginosa, Escherichia coli, Acinetobacter calcoaceticus, Bacillus subtilis, Klebsielia pneumoniae and Bacillus subtilis with at least 58% inhibitioncompared to the positive control. The mycelium growth inhibition method was used for anti-fungal testing. The essential oil exhibited activity against Aspergillus flavus with 58% inhibition, Candida albicans with 49.8% inhibition and Aspergillus niger with 48.7% inhibition. The -carotene, acetone and linoleic acid method was used to assess the antioxidant activity of the essential oil. The essential oil showed anti-oxidant activity of 13.1 mm mean zone of colour retention representing 72.7% activitycompared to the positive control (ascorbic acid). This is the first study on S. terebinthifolius collected from sub-saharan Africa indicating the presence of trans--ocimene in the essential oil and its strong antibacterial activity against Y. enterocolitica and P. aeruginosa as well as moderate antifungalactivities of the plant

Analysis of a gum from the exudates of Dichrostachys cinerea (L.) Wight & Am

Only little research is currently underway on gums from African plants, yet Africa imports a lot of gums for pharmaceutical and food industries. This study was aimed to investigate the rheological properties, and the moisture and ash contents of the isolated gum resins from Dichrostachys cinerea. The gum from this plant exhibited low shear stress even at high concentrations of the gum. The moisture content obtained was 15.8 ± 0.3%, which was rather too high and would only be suitable for formulations that need to remain moisturized. The gum from this plant had little ash content (2.59 ± 0.01%). The gum from D. cinerea exhibited low shear stress at high concentrations, while the gum was profoundly affected by the addition of ions. In conclusion, this gum has potential as a product for the cosmetic, pharmaceutical and food industries. Further studies are needed to identify the phytoconstituents in the gum as well as toxicity studies.Key words: Gum, exudates, Dichrostachys cinerea, rheology, moisture

Serum progesterone as an indicator of cyclic activity in post-partum goat does

___________________________________________________________________________________ Abstract The aim of this trial was to assess post-partum ovarian activity of the does of two South African goat breeds from their serum progesterone concentrations. Between seven and 100 days post-partum, does from the Boer goat breed and an indigenous rural goat type were allocated to two nutritional treatments within breed. One group per breed received a concentrated diet in an intensive feeding programme. The other group per breed was subjected to a low level of nutrition through the grazing of the natural pasture in an extensive (veld) grazing system. Blood samples were collected weekly from five does per breed per treatment. Serum progesterone concentrations were determined using a Gamma Coat TM [128] progesterone radioimmunoassay kit (Sorin Diagnostics, France). Large variations in serum progesterone concentrations were recorded within and between breeds and nutritional regimens. Irrespective of breed, in the extensive groups subjected to the low level of nutrition, mean peak serum progesterone concentrations never exceeded 0.2 ng/mL. This suggests that throughout the experimental period, ovarian activity remained low in the extensive groups. It was concluded that nutritional regimen plays a significant role in ensuring high ovarian activities. Furthermore, the higher mean serum progesterone levels in the Boer goat indicate an earlier and higher oestrous activity, compared to the indigenous does. __________________________________________________________________________________

Factors affecting smallholder farmers' participation in agro-processing industry

The aim of the study was to identify smallholder farmers participating in agro-processing and factors influencing their choice of participation. The study was conducted in Gauteng Province on a randomly purposive selected sample of 102 smallholder farmers. Data was collected through a structured questionnaire that was administered face-to-face to respondents. A probit regression model was used to determine factors influencing farmers� participation in agro-processing. The results show that only 19% of the sampled respondents are participating in the agro-processing industry of Gauteng Province. The results also revealed that factors such as educational level, land tenure, agro-processing training and information have a positive influence on agro-processing participation. Yet, distance to market and off-farm income negatively influence the decision to participate in agro-processing. However, there are challenges that need to be addressed in order for them to participate to their potential (i.e. lack of access to infrastructure, transport, poor knowledge on agro-processing norms and standards, poor finance and high cost of production). The study recommended for development of strategies that could realistically increase access of friendly investment capital to potential smallholder farmers to start their own small-scale agro-processing businesses, intensification of awareness of farmers on micro-financing institutions, and building local agro-processing plants. Keywords: Agro-processing industry; Smallholder; Probit regression; Challenge

Factors affecting smallholder farmers' participation in agro-processing industry

The aim of the study was to identify smallholder farmers participating in agro-processing and factors influencing their choice of participation. The study was conducted in Gauteng Province on a randomly purposive selected sample of 102 smallholder farmers. Data was collected through a structured questionnaire that was administered face-to-face to respondents. A probit regression model was used to determine factors influencing farmers� participation in agro-processing. The results show that only 19% of the sampled respondents are participating in the agro-processing industry of Gauteng Province. The results also revealed that factors such as educational level, land tenure, agro-processing training and information have a positive influence on agro-processing participation. Yet, distance to market and off-farm income negatively influence the decision to participate in agro-processing. However, there are challenges that need to be addressed in order for them to participate to their potential (i.e. lack of access to infrastructure, transport, poor knowledge on agro-processing norms and standards, poor finance and high cost of production). The study recommended for development of strategies that could realistically increase access of friendly investment capital to potential smallholder farmers to start their own small-scale agro-processing businesses, intensification of awareness of farmers on micro-financing institutions, and building local agro-processing plants. Keywords: Agro-processing industry; Smallholder; Probit regression; Challenge

Biological activity and phytoconstituents of essential oil from fresh leaves of Eriosema englerianum

Essential oil was extracted from fresh leaves of Eriosema englerianum by hydrodistillation and its major phytoconstituents determined by GC-MS. The major phytoconstituents were O-cymene, terpinolene and ascaridole with a yield of 0.28%. Antimicrobial activity of the oil was tested against nine human bacterial pathogens and three opportunistic fungi (Candida albicans, Aspergillus niger and Aspergillus flavus). The essential oil showed anti-oxidant activity with mean zone of colour retention of14.4 mm and good antibacterial and antifungal activities. Results of present study revealed that the fresh leaves of E. englerianum yield essential oil which contains medicinal properties

Socio-economic determinants of rural household food expenditure: A quantile regression analysis

This paper provides an analysis of factors that influence rural household expenditure on food using a quantile regression analysis. The objective was to investigate if there are any relationships to discern between household expenditure on food and a number of other socio-economic factors in addition to household income and household size as stipulated in Engel�s law. The results indicate that indeed there are relationships that could be discerned between household food expenditure and gender, education, occupation, household income, number of people depending on household income, gender distribution by age groups and number of livestock sales per annum. However, household income has a relatively smaller effect in magnitude as compared to the rest of these factors. Furthermore, the results show that the relationships differ along the quantiles. In other words, some factors had a significant and higher effect in the lower quantile compared to the higher quantile. On the basis of such results, the study suggests that tailor-made interventions should be considered in the development initiatives that are targeting rural households as different factors affect these households differently

Socio-economic determinants of rural household food expenditure: A quantile regression analysis

This paper provides an analysis of factors that influence rural household expenditure on food using a quantile regression analysis. The objective was to investigate if there are any relationships to discern between household expenditure on food and a number of other socio-economic factors in addition to household income and household size as stipulated in Engel�s law. The results indicate that indeed there are relationships that could be discerned between household food expenditure and gender, education, occupation, household income, number of people depending on household income, gender distribution by age groups and number of livestock sales per annum. However, household income has a relatively smaller effect in magnitude as compared to the rest of these factors. Furthermore, the results show that the relationships differ along the quantiles. In other words, some factors had a significant and higher effect in the lower quantile compared to the higher quantile. On the basis of such results, the study suggests that tailor-made interventions should be considered in the development initiatives that are targeting rural households as different factors affect these households differently

Factors affecting extension workers in their rendering of effective service to pre and post-settled farmers in government initiated and supported farming small, micro and medium enterprises

http://www.sabinet.co.za/abstracts/agri/agri_v38_a1.htm