Rare sesquiterpenes from South African Pteronia species

The genus Pteronia consists of approximately 80 species which are widely distributed in southern Africa. The essential oils isolated from the aerial parts of eleven species, analyzed by GC-MS varied both qualitatively and quantitatively. In Pteronia pallens, Pteronia empetrifolia and Pteronia flexicaulis uncommon sesquiterpenes such as presilphiperfolol-7-ene, 7-α-(H)-silphiperfol-5-ene, 7-β-(H)-silphiperfol-5-ene, α-campholene aldehyde, silphiperfol-5-ene, cameroonan-7-α-ol, silphiperfol-7-β-ol, presilphiperfolan-9-α-ol and presilphiperfolan-8-ol (a major compound in P. pallens) were identified. Cluster analysis based of the chemical composition of the oils revealed that individual plants of Pteronia camphorata collected in the same population had similar oil profiles with a high correlation coefficient (S_corr ≈ 0.98). Similarly, the essential oil composition of P. pallens collected from two distinct localities also showed high levels of congruency (S_corr ≈ 0.99).     

High performance thin layer chromatography as a method to authenticate Hoodia gordonii raw material and products

Hoodia gordonii which contains the perceived active molecule, P57, is a plant used in many weight loss products that are highly susceptible to adulteration due to increased public demand and limited availability. Rapid and simple methods for authentication and confirmation of the presence of P57 are desirable for the quality control of H. gordonii raw material and products. High performance thin layer chromatography (HPTLC) analysis of several H. gordonii raw material samples collected from different locations as well as weight loss products was carried out on silica gel plates and developed in a mobile phase of toluene:chloroform:ethanol (40:40:12.5 v/v/v). Liebermann–Burchard (LB) reagent was used as derivatising agent since it is specific for glycosides and triterpenes (such as P57) and the plates were viewed under UV light at 365 nm. This method produced good separation of the compounds in complex mixtures with well-defined bands including that of the P57 band (R_f 0.42), which was confirmed by liquid chromatography coupled to mass spectrometry (LC–MS) after preparative thin layer chromatography (TLC). All the HPTLC results obtained for the H. gordonii raw materials and products were confirmed with quantitative LC–MS analyses, which confirmed the qualitative reliability of the HPTLC method. The HPTLC method was used successfully to develop a chemical fingerprint for authentication and reliable confirmation of the presence of P57 in H. gordonii raw material and products.     

Application of vibrational spectroscopy in the quality assessment of Buchu oil obtained from two commercially important Agathosma species (Rutaceae)

Quality assessment of natural raw materials and derived consumer products is often done using conventional analytical techniques such as liquid and gas chromatography which are expensive and time consuming. This paper reports on the use of vibrational spectroscopy techniques as possible alternatives for the rapid and inexpensive assessment of the quality of ‘buchu oil’ obtained from two South African species; Agathosma betulina and Agathosma crenulata belonging to the Rutaceae family. Samples of A. betulina (55) and A. crenulata (16) were collected from different natural localities and cultivation sites in South Africa. The essential oil was obtained by hydrodistillation and scanned on Near infrared (NIR), mid infrared (MIR) and Raman spectrometers. The spectral data obtained was processed using chemometric techniques and orthogonal partial least squares discriminant analysis (OPLS-DA) was used to clearly differentiate between A. betulina and A. crenulata. The OPLS-DA technique also proved to be a useful tool to identify wave regions that contain biomarkers (peaks) that contributed to the separation of the two species. The three spectroscopy techniques were also evaluated for their ability to accurately predict the percentage composition of seven major compounds that occur in A. betulina ‘buchu’ oil. Using GC–MS reference data, calibration models were developed for the MIR, NIR and Raman spectral data to predict/profile the major compounds in ‘buchu oil’. A comparison of the three spectroscopy techniques showed that MIR together with PLS algorithms produced the best model (R²X = 0.96; R²Y = 0.88 and Q²Ycum = 0.85) for the quantification of six of the seven major oil constituents. The MIR model showed high predictive power for pseudo-diosphenol (R² = 0.97), isomenthone (R² = 0.97), menthone (R² = 0.90), limonene (R² = 0.91), pulegone (R² = 0.96) and diosphenol (R² = 0.85). These results illustrate the potential of MIR spectroscopy as a rapid and inexpensive alternative to predict the major compounds in buchu oil.     

The application of high-throughput AFLP's in assessing genetic diversity in Fusarium oxysporum f. sp. cubense

Fusarium oxysporum f. sp. cubense (Foc) is responsible for fusarium wilt of bananas. The pathogen consists of several variants that are divided into three races and 21 vegetative compatibility groups (VCGs). Several DNA-based techniques have previously been used to analyse the worldwide population of Foc, sometimes yielding results that were not always consistent. In this study, the high-resolution genotyping method of AFLP is introduced as a potentially effective molecular tool to investigate diversity in Foc at a genome-wide level. The population selected for this study included Foc isolates representing different VCGs and races, isolates of F. oxysporum f. sp. dianthi, a putatively non-pathogenic biological control strain F. oxysporum (Fo47), and F. circinatum. High-throughput AFLP analysis was attained using five different infrared dye-labelled primer combinations using a two-dye model 4200s LI-COR automated DNA analyser. An average of approx. 100 polymorphic loci were scored for each primer pair using the SAGA^MX automated AFLP analysis software. Data generated from five primer pair combinations were combined and subjected to distance analysis, which included the use of neighbour-joining and a bootstrap of 1000 replicates. A tree inferred from AFLP distance analysis revealed the polyphyletic nature of the Foc isolates, and seven genotypic groups could be identified. The results indicate that AFLP is a powerful tool to perform detailed analysis of genetic diversity in the banana pathogen Foc.     

Genetic diversity analysis in sorghum germplasm as estimated by AFLP, SSR and morpho-agronomical markers

A comparison of the different methods of the estimation of genetic diversity is important to evaluate their utility as a tool in germplasm conservation and plant breeding. Amplified fragment length polymorphism (AFLP), microsatellites or SSR and morphological traits markers were used to evaluate 45 sorghum germplasm for genetic diversity assessment and discrimination power. The mean polymorphism information content (PIC) values were 0.65 (AFLPs) and 0.46 (SSRs). The average pairwise genetic distance estimates were 0.57 (morphological traits), 0.62 (AFLPs) and 0.60 (SSRs) markers data sets. The Shannon diversity index was higher for morphological traits (0.678) than AFLP (0.487) and SSR (0.539). The correlation coefficients obtained by the Mantel matrix correspondence test, which was used to compare the cophenetic matrices for the different markers, showed that estimated values of genetic relationship given for AFLP and SSR markers, as well as for morphological and SSR markers were significantly related (p <0.001). However, morphological and AFLP data showed non-significant correlation (p >0.05). Both data sets from AFLP and SSR allowed all accessions to be uniquely identified; two accessions could not be distinguished by the morphological data. In summary, AFLP and SSR markers proved to be efficient tools in assessing the genetic variability among sorghum genotypes. The patterns of variation appeared to be consistent for the three marker systems, and they can be used for designing breeding programmes, conservation of germplasm and management of sorghum genetic resources.     

The Use of Morphological and AFLP Markers in Diversity Analysis of Linseed

Different methods of genetic diversity measures could give better judgment of differentiating important accessions for growers, germplasm curators and plant breeders. Data of 60 accessions of linseed, mainly from Ethiopia, were used to assess their genetic diversity, employing morphological and amplified fragment length polymorphism (AFLP) methods. Analyses of genetic distance, principal components and clusters showed the presence of a wide range of diversity among the studied accessions. The mean for genetic distance estimates of the entire 1770 pairwise accessions was 0.6684 for morphology, while that of AFLP was 0.5734. These genetic distances varied from zero to one for morphology in contrast to 0.29 to 0.71 of the AFLP. Morphological and AFLP based clusters and their accompanying analyses showed different hierarchical patterns of genetic diversity among the accessions. Despite their disparity, the two diversity measures were found independently useful for assessing the degree of relatedness and the overall patterns of genetic variation among the analysed linseed accessions.     

Heterozygous mutations in SIX3 and SHH are associated with schizencephaly and further expand the clinical spectrum of holoprosencephaly

Schizencephaly (SCH) is a clinically and etiologically heterogeneous cerebral malformation presenting as unilateral or bilateral hemispheric cleft with direct connection between the inner and outer liquor spaces. The SCH cleft is usually lined by gray matter, which appears polymicrogyric implying an associated impairment of neuronal migration. The majority of SCH patients are sporadic, but familial SCH has been described. An initial report of heterozygous mutations in the homeobox gene EMX2 could not be confirmed in 52 patients investigated in this study in agreement with two independent SCH patient cohorts published previously. SCH frequently occurs with additional cerebral malformations like hypoplasia or aplasia of the septum pellucidum or optic nerve, suggesting the involvement of genes important for the establishment of midline forebrain structures. We therefore considered holoprosencephaly (HPE)-associated genes as potential SCH candidates and report for the first time heterozygous mutations in SIX3 and SHH in a total of three unrelated patients and one fetus with SCH; one of them without obvious associated malformations of midline forebrain structures. Three of these mutations have previously been reported in independent patients with HPE. SIX3 acts directly upstream of SHH, and the SHH pathway is a key regulator of ventral forebrain patterning. Our data indicate that in a subset of patients SCH may develop as one aspect of a more complex malformation of the ventral forebrain, directly result from mutations in the SHH pathway and hence be considered as yet another feature of the broad phenotypic spectrum of holoprosencephaly.     

Health benefits of chromones: common ingredients of our daily diet

Phytochemistry Reviews - Chromones are naturally occurring phenolic compounds that are universally present in a healthy human diet. To date, thousands of chromone derivatives, including chromone...     

The role of host traits, season and group size on parasite burdens in a cooperative mammal

The distribution of parasites among hosts is often characterised by a high degree of heterogeneity with a small number of hosts harbouring the majority of parasites. Such patterns of aggregation have been linked to variation in host exposure and susceptibility as well as parasite traits and environmental factors. Host exposure and susceptibility may differ with sexes, reproductive effort and group size. Furthermore, environmental factors may affect both the host and parasite directly and contribute to temporal heterogeneities in parasite loads. We investigated the contributions of host and parasite traits as well as season on parasite loads in highveld mole-rats (Cryptomys hottentotus pretoriae). This cooperative breeder exhibits a reproductive division of labour and animals live in colonies of varying sizes that procreate seasonally. Mole-rats were parasitised by lice, mites, cestodes and nematodes with mites (Androlaelaps sp.) and cestodes (Mathevotaenia sp.) being the dominant ecto- and endoparasites, respectively. Sex and reproductive status contributed little to the observed parasite prevalence and abundances possibly as a result of the shared burrow system. Clear seasonal patterns of parasite prevalence and abundance emerged with peaks in summer for mites and in winter for cestodes. Group size correlated negatively with mite abundance while it had no effect on cestode burdens and group membership affected infestation with both parasites. We propose that the mode of transmission as well as social factors constrain parasite propagation generating parasite patterns deviating from those commonly predicted.