Leucosidea Research Articles

Chemical profiling and inhibitory effects of selected South African plants against phytopathogenic bacteria and fungi of tomato

Soilborne pathogens are economically important, causing great losses in agricultural production globally. The high cost and toxicity of antibiotics, coupled with the development of drug-resistant bacteria, has awakened interest in finding alternative methods of plant-pathogen control. This study aimed to screen extracts of selected plants against phytopathogenic bacteria and fungi that infect tomatoes, and to profile their chemical constituents. The antimicrobial activity of acetone, water and dichloromethane: methanol (DCM/MeOH = 1:1) extracts from leaves of ten plants was examined against five phytopathogenic bacterial strains and one fungal strain using a serial microplate dilution method to determine the minimal inhibitory concentration (MIC) values. Gas chromatography-mass spectrometry (GC–MS) was used for profiling constituents in the acetone and DCM/MeOH extracts. The MIC values indicated weak antibacterial activity of all the water extracts against tested bacterial strains. Acetone and DCM/MeOH extracts of Leucosidea sericea and Searsia lancea had very good to outstanding antibacterial activity against most of the tested bacteria with MIC values ranging between 19.5 and 78 µg/mL. All extracts were not active against Fusarium spp. except for the acetone extract of Cotyledon orbiculata and the water extract of Leonotis leonurus which inhibited the growth of F. oxysporum with MIC = 39 and 97.5 µg/mL after 24 h, with further incubation resulting in MICs of 156 and 469 µg/mL respectively. The GC–MS analysis of the acetone and DCM/MeOH extracts indicated the major peaks of 9-octadecenamide, (Z)-, octadecanoic acid and dodecanamide which were present in almost all the extracts. The 9-octadecenamide was found to be the most highly concentrated compound in most extracts. Leucosidea sericea and S. lancea, therefore, contain bioactive compounds that may be used as broad-spectrum antimicrobials against phytopathogenic bacteria and fungi.

Community Perceptions on the Transformation of a high-altitude Grassland Through Invasion by Leucosidea sericea at Vuvu, South Africa

We assessed perceptions of Leucosidea sericea, a woody plant that is increasing in density such that it may threaten rangelands among agro-pastoralists whose livelihoods rely on livestock (56%) and crop farming (36%) in Vuvu, Eastern Cape, South Africa. Using semi-structured questionnaires, we asked 198 respondents about the spread of the species in the last few decades, and its impact on the availability of graze for livestock. Responses indicated that L. sericea started spreading in the 1950s, with marked increases in 2011–2020, particularly in the mountainous areas used for grazing as well as by rivers and village residences. Respondents suggested that livestock were the main biological agent of seed dispersal, and livestock ownership had increased dramatically in recent years, with a preference for sheep (a minimum of 120 per household). Overall, respondents indicated that L. sericea encroachment negatively affected their community.

Assessing habitat suitability for selected woody range-expanding plant species in African mountains under climate change

Social-ecological systems in mountains are sensitive to the effects of climate change and are being affected at rates faster than other terrestrial habitats. We need to know which species are likely to be “winners” and which are likely to be “losers” in the context of climate change. This study evaluated the current and predicted future habitat suitability of selected range-expanding woody plant species (Acacia dealbata, Leucosidea sericea, Vernonanthura phosphorica) in African mountains under climate change. These species are representative of range-expanding plants, which have the potential to affect ecosystem services. Future average temperature is projected to decline in African mountains whereas global mean temperatures are projected to increase. Climate-change models may not be capturing dynamics in the climate of African mountains, possibly due to a lack of representative climate data used in calibrating these models. Although only climate variables were assessed, potential species distribution results were considered accurate according to model evaluation metrics, and some static factors thought to influence species distribution were strongly coupled to climate. Vernonanthura phosphorica and A. dealbata are likely to spread under climate change. The extent of habitat suitable for L. sericea is predicted to decline under climate change. An improved understanding of climate change in mountain systems through better representation of mountain climates in climate-change models could enhance the accuracy of species distribution models.

The effect of phenological stages, pruning and harvesting time on vegetative growth (biomass yield) and antibacterial activity of Leucosidea sericea

The effect of phenological stages, pruning and harvesting time on vegetative growth (biomass yield) and antibacterial activity of <i>Leucosidea sericea</i>

Possible range expansion of the Karoo Prinia Prinia maculosa into the range of the Drakensberg Prinia Prinia hypoxantha in the eastern Free State

Possible range expansion of Karoo Prinia Prinia maculosa observed within the range of Drakensberg Prinia P. hypoxantha north east of Harrismith in the eastern Free State. An Karoo Prinia individual was captured and ringed at Mnt Everest Nature Reserve, Harrismith on 3 November 2021 in Leucosidea sericea bush on mountain slope of Mooihoekkop. On 4 November 2021 the net site were moved to the Mnt Everest hilly slope and a Drakensberg Prinia was captured and ringed. Both species were also photographed and submitted to the Biodiversity Development Institure Virtual Museum (VM 19170 &amp; 19171). The ocurrence and new distribution records of Karoo Prinias within the range of Drakensberg Prinias north of Harrismith is discussed.

South African medicinal plants screened against Pseudomonas aeruginosa

Background: Pseudomonas aeruginosa is amongst the three high-ranking pathogens on the World Health Organization’s global priority list of antibiotic-resistant bacteria. The list highlights research priorities in drug discovery and development.Aim: This study aimed to provide a detailed account of efforts by researchers to find anti-P. aeruginosa compounds from South African medicinal plant species during the period 2000–2020.Method: Various online research and journal databases were used to obtain information relating to South African medicinal plants and P. aeruginosa.Results: During the study period (2000–2020), only 31 studies reported on the antibacterial properties of South African medicinal plants against the pathogen. Given that P. aeruginosa is a serious cause of morbidity and mortality worldwide, it was interesting to note that none of the published reports were dedicated solely to the pathogen. Furthermore, only one study included the antibiotic-resistant mutants of the pathogen as a test organism. Over 150 plant species belonging to 78 families were screened against the bacterium. Barringtonia racemosa, Croton megalobotrys, Erythrina caffra, Leucosidea sericea, Maesa lanceolata, Morella serrata and Trichilia emetica exhibited potent anti-P. aeruginosa properties (minimum inhibitory concentration [MIC] ˂ 0.1 mg/mL). Plumbagin, a compound isolated from the leaves of Aristea ecklonii demonstrated promising activities (MIC = 0.008 mg/mL) against the bacterium. Essential oils extracted from some plants demonstrated noteworthy antibacterial synergistic effects (fractional inhibitory concentration index [FICI] ˂ 0.5) when used in pairwise combinations with conventional antibiotics.Conclusion: Overall, empirical evidence presented in the scantly available literature suggests that novel anti-P. aeruginosa agents could be developed from South African herbal extracts.

Phytochemical Profiling and Isolation of Bioactive Compounds from Leucosidea sericea (Rosaceae).

In the study, ultraperformance liquid chromatography–quadrupole time-of-flight–mass spectrometry analysis of Leucosidea sericea leaf and stem extracts led to the identification of various classes of compounds. Further chromatographic purifications resulted in the isolation of 22 compounds that consisted of a new triterpenoid named leucosidic acid A (1), an acetophenone derivative 2, a phloroglucinol derivative 3, three chromones 4–6, seven pentacyclic triterpenoids 7–13, a phytosterol glucoside 14, a flavonoid 15, and seven flavonoid glycosides 16–22. Nineteen of these compounds including the previously undescribed triterpenoid 1 are isolated for the first time from L. sericea. The structures of the isolated compounds were assigned based on their high-resolution mass spectrometry and nuclear magnetic resonance data. Some of the isolated triterpenoids were evaluated for inhibitory activity against α-amylase, α-glucosidase, and pancreatic lipase. Of the tested compounds, 1-hydroxy-2-oxopomolic acid (7) and pomolic acid (13) showed higher potency on α-glucosidase than acarbose, which is used as a positive control in this study. The two compounds inhibited α-glucosidase with IC50 values of 192.1 ± 13.81 and 85.5 ± 6.87 μM, respectively.

Evaluation of antioxidant activity of extracts from Leucosidea sericea

Summary Introduction: Leucosidea sericea finds applications in the treatment of herpes and HIV. Objective: The aim of the current study was to evaluate the antioxidant activity and determine the total flavonoid contents (TFCs) and total phenolic contents (TPCs) of hexane, chloroform, ethyl acetate, acetone and methanol crude extracts obtained from leaves and stem-bark of L. sericea. Methods: Maceration and hot solvent extraction methods were used to obtain various crude extracts. DPPH and ferric reducing power assays were used to evaluate the antioxidant activity. Colorimetric aluminium chloride and Folin-Ciocalteu methods were used to determine the TFCs and TPCs, respectively. Results: The methanol leaf extract showed highest radical scavenging activity of 82.00±0.93% at a concentration of 3000 µg/ml followed by ethyl acetate leaf extract and methanol stem-bark extract with 79.40±5.21 and 75.16±1.15%, respectively. Acetone stem-bark extract showed highest ferric reducing power of 0.539±0.004 at 700 nm at a concentration of 100 µg/ml followed by hexane leaf extract and hexane stem-bark extract with 0.474±0.014 and 0.437±0.013 at 700 nm, respectively. Ethyl acetate stem-bark extract showed highest TFCs of 655.6±0.1111 mg QE/g of DW of the extract followed by acetone stem-bark extract with 450.0±0.00711 mg QE/g of DW of the extract. Acetone stem-bark extract showed highest TPCs of 891.9±0.657 mg TAE/g of the DW of extract followed by methanol stem-bark extract with 878.3±0.029 mg TAE/g of DW of the extract. Conclusion: The antioxidant activity of various solvent extracts from leaves and stem-bark of L. sericea was evaluated. L. sericea could be a source of potent antioxidants.

English

A battery of short-term in vitro assays for apoptosis and/or cell cycle arrest, cytotoxicity, genotoxicity and antigenotoxicity are used to screen and establish the efficacy of medicinal plants. This study evaluated three concentrations (0.1, 0.2 or 0.4 mg/ml) of methanolic leaf extracts of Artemisia afra and Leucosidea sericea and their individual mixtures with Ethyl methanesulfonate (EMS) (0.15 mg/ml) for induction of those end points using the in vivo Allium cepa assay. Cytotoxicity was measured by the mitotic index, genotoxicity was expressed as the number of aberrant mitotic cells per 100 mitotic cells and modulatory effect (ME) was calculated as: ME = (B - C) - (A - C) / (A - C) and the value, positive or negative, indicated the number of units of the mutagen-induced genotoxicity (A) that equaled the mixture-induced genotoxicity (B). The three concentrations of A. afra extract tested did not induce cell cycle arrest and were not cytotoxic. The 0.4 mg/ml concentration and its mixture with EMS were genotoxic. The concentrations of L. sericea extract tested did not induce cell cycle arrest, were not cytotoxic nor genotoxic to the A. cepa root tip cells. The mixture of either 0.2 or 0.4 mg/ml L. sericea extract with EMS was genotoxic. The mixture of 0.4 mg/ml L. sericea extract with EMS was significantly more (ME = 4.40>2) genotoxic than EMS alone. Leaf extracts of A. afra and L. sericea lacked cell-cycle arrest activity, were non-toxic but lacked antigenotoxic activity against EMS-induced genotoxicity. High concentrations of A. afra were genotoxic whereas high concentrations of L. sericea interacted synergistically with EMS. Chromosomal abnormalities observed included sticky chromosomes, c-mitosis, chromosome largards, chromosome fragments, anaphase and telophase bridges. Key words: Anti-genotoxicity, cell cycle arrest, safety of medicinal plants of Lesotho.

The potential of surface renewal for determining sensible heat flux for indigenous vegetation for a first-order montane catchment

ABSTRACT Eddy covariance (EC) systems are expensive and not financially viable in a budget-restricted hydrological monitoring network. The surface renewal (SR) method is a cheaper alternative that requires a reduced fetch, but is currently dependent on EC for calibration. SR methods not requiring calibration (surface renewal 2 (SR2) and surface renewal dissipation theory (SRDT)) have been used but are not widely tested over indigenous vegetation. The aim of this research was to test the SR approach as a viable alternative to EC for the estimation of sensible heat flux (H) over indigenous vegetation (Leucosidea sericea) in a montane catchment for unstable periods. For both summer (7 d) and winter (9 d) campaigns, the three SR methods showed a good relationship with the EC method for the estimation of H. Overall, the SRDT method was the most viable alternative to EC and produced acceptable estimates of H over an indigenous vegetation canopy in a montane catchment.

Middle Stone Age wood use in Rose Cottage Cave South Africa: Evidence from charcoal identifications

Here we present charcoal identifications for Rose Cottage Cave, Eastern Free State, from layers dated between about 96,000 and 35,000 years ago (~96 and ~35 ka ago). We then suggest plant community types that might have been established in the area in warm Marine Isotope Stage 5 (MIS5) versus cooler MIS4/MIS3 phases. The hypothesis is that frost-tender plants should occur in warm phases while hardy Leucosidea sericea, Protea spp. and Erica spp. should be more common during cooler phases more recent than ~74 ka ago. Leucosidea sericea thrives under moist conditions and its presence in late MIS4 and in several MIS3 layers at Rose Cottage implies that the area may have been moister than many other sites in the interior of southern Africa, thereby making it attractive for occupation. The charcoal identifications at ~96 ka ago included taxa like Buddleja salvifolia that need somewhat warmer conditions than taxa such as Leucosidea sericea. Taxa diversity based on the charcoal identifications is generally low at the site throughout the Middle Stone Age, but the vegetation from relatively warm MIS5 seems more diverse than that of MIS4 and MIS3. Some taxa identified, for example, Calodendrum capense, Leucosidea sericea, Erica caffra and Protea caffra no longer grow near the cave although they are commonly found in other parts of eastern South Africa.

Biosynthesis, Characterization, and Biological Activities of Procyanidin Capped Silver Nanoparticles.

In this study, procyanidin dimers and Leucosidea sericea total extract (LSTE) were employed in the synthesis of silver nanoparticles (AgNPs) and characterized by ultraviolet-visible (UV-Visible) spectroscopy, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and dynamic light scattering (DLS) techniques. AgNPs of about 2–7 nm were obtained. DLS and stability evaluations confirmed that the AgNPs/procyanidins conjugates were stable. The formed nanoparticles exhibited good inhibitory activities against the two enzymes studied. The IC50 values against the amylase enzyme were 14.92 ± 1.0, 13.24 ± 0.2, and 19.13 ± 0.8 µg/mL for AgNPs coordinated with LSTE, F1, and F2, respectively. The corresponding values for the glucosidase enzyme were 21.48 ± 0.9, 18.76 ± 1.0, and 8.75 ± 0.7 µg/mL. The antioxidant activities were comparable to those of the intact fractions. The AgNPs also demonstrated bacterial inhibitory activities against six bacterial species. While the minimum inhibitory concentrations (MIC) of F1-AgNPs against Pseudomonas aeruginosa and Staphylococcus aureus were 31.25 and 15.63 µg/mL respectively, those of LSTE-AgNPs and F2-AgNPs against these organisms were both 62.50 µg/mL. The F1-AgNPs demonstrated a better bactericidal effect and may be useful in food packaging. This research also showed the involvement of the procyanidins as reducing and capping agents in the formation of stable AgNPs with potential biological applications.

Green Synthesis of Gold Nanoparticles Capped with Procyanidins from Leucosidea sericea as Potential Antidiabetic and Antioxidant Agents

In this study, procyanidins fractions of dimers and trimers (F1–F2) from the Leucosidea sericea total extract (LSTE) were investigated for their chemical constituents. The total extract and the procyanidins were employed in the synthesis of gold nanoparticles (Au NPs) and fully characterized. Au NPs of 6, 24 and 21 nm were obtained using LSTE, F1 and F2 respectively. Zeta potential and in vitro stability studies confirmed the stability of the particles. The enzymatic activity of LSTE, F1, F2 and their corresponding Au NPs showed strong inhibitory alpha-amylase activity where F1 Au NPs demonstrated the highest with IC50 of 1.88 µg/mL. On the other hand, F2 Au NPs displayed the strongest alpha-glucosidase activity at 4.5 µg/mL. F2 and F2 Au NPs also demonstrated the highest antioxidant activity, 1834.0 ± 4.7 μM AAE/g and 1521.9 ± 3.0 μM TE/g respectively. The study revealed not only the ability of procyanidins dimers (F1 and F2) in forming biostable and bioactive Au NPs but also, a significant enhancement of the natural products activities, which could improve the smart delivery in future biomedical applications.

1H-NMR Metabolomics and LC-MS Analysis to Determine Seasonal Variation in a Cosmeceutical Plant Leucosidea sericea.

Leucosidea sericea is an evergreen shrub belonging to the Rosaceae family with previous studies that indicated that L. sericea extracts exhibited strong anti-bacterial properties against Propionibacterium acnes, showing potential as a cosmeceutical. The plant is traditionally used as a vermifuge, as an astringent and to treat conjunctivitis. Commercial production is, however, not possible as no information is available on cultivation and the effect of external environmental factors such as seasonal variation on the medicinal properties of the plant. Seasonal variation was investigated and it was found that significant differences were observed between the anti-acne (P. acnes) activity of plant material collected in different seasons. The best activity was found in winter with a mean minimum inhibitory concentration (MIC) of 5.20 μg mL–1 compared to spring at 26.04 μg mL–1. A 1H NMR-based untargeted metabolomic analysis was used to determine the differences in the chemical profiles of plant samples collected in different seasons. Principal component analysis (PCA) showed clear separation of the seasons and a supervised orthogonal partial least square discriminant analysis (OPLS-DA) was used to determine the compounds that differentiated the spring from the winter samples. The contribution plot indicated a strong positive association with the NMR regions from δ 1.2–1.6, 3.3–4.1, and 6.8–8.0 ppm indicative of a compound with an aromatic ring. Different LC-MS analyses were used in conjunction with a compound database, MAGMa and CSIFingerID, which led to the identification of the compound 2-(4-ethoxyphenyl)-5,6,7,8-tetramethoxy-4H-1-benzopyran-4-one and also confirmed the presence of tangeritin, rutin, quercetin glucoside, and kaempferol glucosides as well as several other compounds previously identified from the plant. This compound similar in structure to the anti-microbial flavonoid tangeritin, was only present in the winter samples. It is therefore recommended that seasonal variation be closely monitored during cultivation and commercial harvesting, and that winter is the preferred harvesting season to obtain the best anti-acne activity.

Ultrastructure changes induced by the phloroglucinol derivative agrimol G isolated from Leucosidea sericea in Haemonchus contortus

Plant extracts used for the treatment of helminth infections in sheep are an alternative to chemical anthelmintic drugs. Previous studies have reported the anthelmintic activity of acetone leaf extracts of Leucosidea sericea. For this study, we evaluate the ultrastructure changes induced by the acetone leaf extract of L. sericea and the component agrimol G (AG) that was isolated for the first time on adult haemonchus parasites. Adult haemonchus parasites harvested from sheep were incubated with the plant extract and AG for 3 h and evaluated by both scanning and transmission electron microscopy in comparison and in combination with albendazole or ivermectin. In all cases the method of evaluation shows ultrastructural changes, with albendazole inducing mitochondrial damage and ivermectin inducing muscle degeneration, both as previously described. Incubation with the plant extract and AG resulted in the formation of numerous non-membrane bound multi-vesicular like bodies and evenly spread disruptions/erosion in the epicuticle. Combining AG with ivermectin or albendazole resulted in an absence of effect of AG. Based on the structural changes induced by AG, together with the absence of an effect in combination with ivermectin and albendazole would suggest a disrupted microtubular network. The latter does however require biochemical confirmation.

Developing propagation methodology for Leucosidea sericea, a species with cosmeceutical application using cuttings and seeds

Developing propagation methodology for <i>Leucosidea sericea,</i> a species with cosmeceutical application using cuttings and seeds

Identification and characterization of potential bioactive compounds from the leaves of Leucosidea sericea

Ethnopharmacological relevanceLeucosidea sericea is a southern African tree used for treating different diseases including microbial infections and inflammatory-related conditions. Aim of the studyTo isolate and identify the chemicals in Leucosidea sericea which possibly account for the diverse therapeutic effects of the species. Materials and methodsLeaf material was extracted using 20% methanol and subsequently partitioned with different solvents (hexane, dichloromethane, ethyl acetate and butanol). Resultant fractions were subjected to bioactive (antimicrobial)-guided isolation and the structural elucidation was conducted using NMR (1D and 2D) spectroscopic methods. Given the broad uses of Leucosidea sericea in traditional medicine, the extract, fractions and isolated compounds were evaluated in five (5) biological assays in vitro (antimicrobial, antioxidant, acetylcholinesterase (AChE) and anti-inflammatory inhibition as well as cytotoxicity effect). ResultsAs the most active fractions, from ethyl acetate yielded 5,7-dihydroxychromone (1); 1-hydroxy-2-oxopomolic acid (2); 3,5,7,3´,4´-pentahydroxyflavone (3) and Tiliroside (4). For the first time, these four (4) compounds were isolated from leaves of Leucosidea sericea. These aforementioned compounds demonstrated broad-spectrum antibacterial activity (1.95–125 µg/mL) and noteworthy antifungal (3.9–250 µg/mL) potential. In addition to its noteworthy antimicrobial activity, compound 3 also demonstrated significant antioxidant (EC50 = 14 µg/mL in DPPH assay) and anti-inflammatory (inhibited the level of ELAM by approximately 36% and decreased also the viability of endothelial cells) activities in vitro. Overall, AChE inhibition activity and cytotoxic response was generally weak for the extracts, fractions and isolated compounds. ConclusionThe pool of chemicals in Leucosidea sericea were enriched with the isolation and identification of four (4) compounds obtained from the leaf extract. Among these compounds, the significant antimicrobial activity of compound 3 provides strong evidence that support the use of Leucosidea sericea for microbial-related infections in folk medicine.

Bark and wood anatomy of Leucosidea and Cliffortia (Sanguisorbeae, Rosaceae)

The wood and bark structure of Leucosidea sericea and two species of Cliffortia, the South African members of the tribe Sanguisorbeae (Rosaceae) are described. These two genera share few anatomical traits (the presence of schizo-rhexigenous intercellular spaces in the cortex, almost exclusively simple perforation plates, small alternate intervessel pits, etc.) with other Rosaceae. However, Leucosidea shows a distinct storied structure of the secondary phloem and wood as well as stratification of the secondary phloem, with conductive elements and nonsclerified crystalliferous axial parenchyma arranged into alternating bands. These conditions are recorded for the first time for the family Rosaceae. In contrast to Leucosidea, two species of Cliffortia show neither storied structure of secondary phloem and xylem, nor stratification of secondary phloem.

Seasonal variation and anti-bacterial activity of Leucosidea sericea

Seasonal variation and anti-bacterial activity of Leucosidea sericea

Establishing the effects of phloroglucinol derivatives isolated from Leucosidea sericea on the ultrastructure of Haemonchus contortus, using electron microscopy

Plant extracts used for the treatment of helminth infections in animals are an alternative to chemical anthelmintics. Previous studies have reported the anthelmintic activity of acetone leaf extracts of Leucosidea sericea. However the mechanisms of action remain unknown. The aim of this study was to determine through scanning and transmission electron microscopy the effect of the acetone leaf extract of L. sericea and two phloroglucinol derivatives on the ultrastructure of Haemonchus contortus. A positive drug control treatment using albendazole and ivermectin was included. The main changes identified were the alteration and destruction of the cuticle, changes to the hypodermis, vacuoles within the cytoplasm, cytoplasmic degradation, cellular swelling and in a few cases, some abnormality within the mitochondria. The control for albendazole and ivermectin had the expected destruction of internal architecture and paralysis respectively. The lesions seen were probably due to bioactive plant metabolites and the route of entry. The possible mode of action is direct as it depends on contact between the bioactive plant metabolite and Haemonchus contortus.