Biofouling inhibition by Staphylococcus aureus extracts and their potential use for paints.

For the control of biofouling, some paints based on compounds that are toxic to marine organisms have been used. There is an intensive search for biodegradable solutions that are friendly to non-target organisms. Bacteria have been shown to be a source of compounds with antifouling potential. In this work, the antifouling activity of a strain of Staphylococcus aureus was evaluated. Extracts activity against biofilm-forming bacteria and the toxicity against Artemia franciscana were evaluated. The extracts were incorporated in a hard gel and a paint matrix, and they were exposed to the sea. In both the laboratory and field, we found that the compounds produced by S. aureus have antifouling activity. The non-toxicity of the tested extracts against Artemia franciscana nauplii suggests that the extracts obtained from S. aureus could have a low ecological impact over non-target organisms. Significant differences were found in the percentage of organisms cover in hard gels with extracts and control. After 90 days, important differences were also observed between the percentage of organisms cover of the paints that contained extracts and the control. Dichloromethane extract is the most effective for the inhibition or delay of the settlement of organisms For this reason, they could be used in matrices with different applications, such as in the shipping industry, aquaculture, or any other in which biofouling is a cause of inconvenience.

Identification and Assessment of Secondary Metabolites from Three Fungal Endophytes of Solanum mauritianum Against Public Health Pathogens.

Fungal endophytes, symbiotic microorganisms residing within plants, are renowned for producing bioactive secondary metabolites with diverse beneficial properties. We investigated the antimicrobial potential of fungal endophytes isolated from Solanum mauritianum, an invasive weed, against clinically significant bacterial pathogens. Selected fungal endophytes (Penicillium chrysogenum, Fusarium sp., and Paracamarosporium leucadendri) were isolated from the plant's leaves and fruits. Their crude extracts were tested against various referenced strains, such as Mycobacterium species (M. smegmatis ATCC 607 and M. bovis ATCC 27290), Staphylococcus aureus ATCC 6571, Bacillus subtilis ATCC 11774, Klebsiella species (K. pneumoniae ATCC 10031 and K. oxytoca ATCC 8724), Escherichia coli ATCC 10536, and Pseudomonas aeruginosa ATCC 10145, using the Kirby-Bauer disk diffusion method. Resazurin Microtiter Assay was used for the determination of the minimum inhibitory concentration. The chemical nature of the secondary metabolites in the crude extracts produced by fungal endophytes was evaluated using high-resolution liquid chromatography-mass spectrometry (LC-MS) using water and acetonitrile gradient. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS/MS) was employed for untargeted metabolomics. LC-QTOF-MS/MS identified 63 bioactive compounds across the three endophytes. P. chrysogenum had the highest activity against S. aureus and M. smegmatis (1.15 mg/mL and 0.02 mg/mL, respectively), while P. leucadendri demonstrated moderate activity against M. smegmatis (2.91 mg/mL) and E. coli (1.16 mg/mL). Fusarium sp. exhibited the broadest spectrum of antibacterial activity, with MIC values ranging from 0.03 mg/mL (B. subtilis) to 10 mg/mL (M. smegmatis). P. leucadendri produced 29 metabolites, Fusarium sp. had 23 identified metabolites, and a total of 11 metabolites were identified from P. chrysogenum. The fruits of the plant, accounting for 60%, appeared to be the most abundant in the endophyte diversity when compared to the stems and leaves. This study highlights the potential of fungal endophytes from S. mauritianum as a source of novel bioactive compounds, particularly against multidrug-resistant pathogens, contributing to the ongoing efforts to combat antimicrobial resistance.

Bioactive Molecules Derived from Plants in Managing Dengue Vector Aedes aegypti (Linn.).

Mosquitoes are the potential vectors of several viral diseases such as filariasis, malaria, dengue, yellow fever, Zika fever and encephalitis in humans as well as other species. Dengue, the most common mosquito-borne disease in humans caused by the dengue virus is transmitted by the vector Ae. aegypti. Fever, chills, nausea and neurological disorders are the frequent symptoms of Zika and dengue. Thanks to various anthropogenic activities such as deforestation, industrialized farming and poor drainage facilities there has been a significant rise in mosquitoes and vector-borne diseases. Control measures such as the destruction of mosquito breeding places, a reduction in global warming, as well as the use of natural and chemical repellents, mainly DEET, picaridin, temephos and IR-3535 have proven to be effective in many instances. Although potent, these chemicals cause swelling, rashes, and eye irritation in adults and children, and are also toxic to the skin and nervous system. Due to their shorter protection period and harmful nature towards non-target organisms, the use of chemical repellents is greatly reduced, and more research and development is taking place in the field of plant-derived repellents, which are found to be selective, biodegradable and harmless to non-target species. Many tribal and rural communities across the world have been using plant-based extracts since ancient times for various traditional and medical purposes, and to ward off mosquitoes and various other insects. In this regard, new species of plants are being identified through ethnobotanical surveys and tested for their repellency against Ae. aegypti. This review aims to provide insight into many such plant extracts, essential oils and their metabolites, which have been tested for their mosquitocidal activity against different life cycle forms of Ae. Aegypti, as well as for their efficacy in controlling mosquitoes.

A systematic review on phytochemicals for the treatment of dengue.

Dengue fever is prevalent in subtopic regions, producing mortality and morbidity worldwide, which have been of major concern to different governments and World Health Organization. The search of new anti-dengue agents from phytochemicals was assumed to be highly emergent in past. The phytochemicals have been used in wide distribution of vector ailments such as malaria. The demand of the phytochemicals is based on the medicines which are mostly considered to be safer, less harmful than synthetic drugs and nontoxic. This review mentions majorly about the phytochemicals potentially inhibiting dengue fever around the world. The phytochemicals have been isolated from different species, have potential for the treatment of dengue. Different crude extracts and essential oils obtained from different species showed a broad activity against different phytochemicals. The current studies showed that natural products represent a rich source of medicines toward the dengue fever. Furthermore, ethnobotanical surveys and laboratory investigation established identified natural plants species in the development of drug discovery to control the dengue fever.

Novel approach to combat antibiotic resistance: evaluation of some Armenian herb crude extracts for their antibiotic modulatory and antiviral properties.

AIMS: One of the strategies to combat antibiotic resistance can be the use of plant materials in combination with antibiotics, taking into account that phytochemicals can act as antibiotic resistance-modifying agents. This can give a second life to the traditional antibiotics. The aim was to evaluate antibiotic modulatory effect of crude extracts from Agrimonia eupatoria, Hypericum alpestre, Rumex obtusifolius and Sanguisorba officinalis herbs towards several commercial antibiotics using some Gram-positive and Gram-negative bacteria. METHODS: The antibiotic modulatory activity was tested by determining MICs of antibiotics in the absence and presence of plant crude extracts at subinhibitory concentrations. Antiviral potential of different extracts of tested plant materials was also explored by double overlay plaque assay. RESULTS: The tested plant crude extracts exhibited high modulatory activity towards used antibiotics. Particularly, high modulatory activity was observed with extracts of H. alpestre and R. obtusifolius. Many plant-antibiotic combinations induced the decrease in MICs of antibiotics up to ~fourfold indicating synergy. Moreover, the similar change was observed at both subinhibitory concentrations (MIC/2 and MIC/4) of the same plant crude extract. High anti-phage activity of plants with the exception of Lilium armenum against T4 phage of Escherichia coli C-T4 was also shown. CONCLUSIONS: Plant crude extract or commercial antibiotic combinations significantly increased the efficiency of antibiotics. Tested plant materials with exception of L. armenum have antiviral property. SIGNIFICANCE AND IMPACT OF THE STUDY: For the first time, antibiotic modulatory activity of tested herb extracts was shown, which could have potential in practical applications. Tested plant materials with exception of L. armenum could have prospective, as a source of new antiviral compounds.

Separation of three phenolic high-molecular-weight compounds from the crude extract of Terminalia Chebula Retz. by ultrasound-assisted extraction and high-speed counter-current chromatography.

This study presents an efficient strategy for separation of three phenolic compounds with high molecular weight from the crude extract of Terminalia chebula Retz. by ultrasound-assisted extraction and high-speed counter-current chromatography. The ultrasound-assisted extraction conditions were optimized by response surface methodology and the results showed the target compounds could be well enriched under the optimized extraction conditions. Then the crude extract was directly separated by high-speed counter-current chromatography without any pretreatment using n-hexane/ethyl acetate/methanol/water (1:7:0.5:3, v/v/v/v) as the solvent system. In 180 min, 13 mg of A, 18 mg of B, and 9 mg of C were obtained from 200 mg of crude sample. Their structures were identified as Chebulagic acid (A, 954 Da), Chebulinic acid (B, 956 Da), and Ellagic acid (C) by (1) H NMR spectroscopy.

Bioprospecting for secondary metabolites in the entomopathogenic bacterium Photorhabdus luminescens subsp. sonorensis.

Crude extracts of in vitro and in vivo cultures of two strains of Photorhabdus l. sonorensis (Enterobacteriaceae) were analyzed by TLC, HPLC-UV and LC-MS. Nine unique compounds with mass/charge ratios (m/z) ranging from 331.3 to 713.5 were found in MS analyses. Bioactivity of extracts was assessed on a selection of plant pathogens/pests and non-target species. Caborca strain extracts showed the highest activity against Helicoverpa zea (Lepidoptera: Noctuidae) neonates at all concentrations tested. Mortality ranged from 11% (at 10µg/ml) to 37% (at 40µg/ml). Strain CH35 extracts showed the highest nematicidal activity on Meloidogyne incognita (Tylenchida: Meloidogynidae) at 40µg/ml. Low to no nematicidal activity was observed against the non-target species Steinernema carpocapsae (Rhabditida: Steinernematidae) and Caenorhabditis elegans (Rhabditida: Rhabditidae). Caborca extracts exhibited a strong antibiotic effect on Pseudomonas syringae (Pseudomonadales: Pseudomonadacedae) at 40µg/ml, while both Caborca and CH35 extracts inhibited the growth of Bacillus subitillis (Bacillales: Bacillaceae) at 40µg/ml. All extracts strongly inhibited the growth of the fungus Fusarium oxysporum (Hypocreales: Nectriceae) but not that of Alternaria alternata (Pleosporales: Pleosporaceae). Contrastingly, a moderate to high inhibitory effect was denoted on the non-target biocontrol fungus Beauveria bassiana (Hypocreales: Clavivipitaceae).

Wild tomato leaf extracts for spider mite and cowpea aphid control.

Glandular trichomes on the leaves of wild tomato, L. hirsutum f. hirsutum Mull, also known as Solanum habrochaites (Solanaceae), synthesize and accumulate high levels of methyl ketones (MKs). L. hirsutum accession LA 407, having high concentration of MKs, was grown from seeds under greenhouse conditions. Four MKs (2-undecanone, 2-dodecanone, 2-tridecanone, and 2-pentadecanone) were screened for their toxicity to spider mites, Tetranychus urticae Koch and cowpea aphids, Aphis craccivora Koch. The objectives of this investigation were to: (1) develop a bioassay for testing MKs on spider mite and cowpea aphid mortality and (2) compare the efficacies of wild tomato leaf crude extracts and pure standard materials of MKs against spider mite and cowpea aphid mortality. Our results revealed that spider mites are most sensitive to 2-tridecanone (LC50 = 0.08 µmole cm(-2) of treated leaf surface) and least sensitive to 2-undecanone (LC50 = 1.5 µmole cm(-2) of treated leaf surface) 4 h after treatment. Similarly, 2-tridecanone caused greatest mortality (LC50 = 0.2 µmole cm(-2) of treated leaf surface), whereas 2-undecanone caused the lowest morality (LC50 = 0.48 µmole cm(-2) of treated surface) of cowpea aphid. We concluded that all MKs tested in this investigation are toxic to spider mites and aphids. 2-Tridecanone is more effective in killing mites and aphids compared to other MKs. Toxicity of crude extracts, prepared from the leaves of L. hirsutum accession LA 407, to spider mites and cowpea aphids revealed greater mortality compared to a combined mixture of MKs standard material (used at the same concentration as found on LA 407 leaves). This indicates that in addition to MKs, other unidentified compounds in LA 407 leaf extract also have pesticidal properties. Accordingly, leaf extracts of LA 407 could be explored in crop protection, and they might open a new area of MK formulations and discovery of biorational alternatives for pest control in agricultural fields.

In vitro antibacterial activity of Bersama abyssinica Fresen crude extract against representative Gram-positive and Gram-negative bacterial isolates.

BACKGROUND: Bersama abyssinica Fresen is a plant that is used in folk medicine for the treatment of mastitis and other infectious diseases. OBIECTIVE: The antibacterial activity of methanol crude extract of plant was evaluated against three common bacterial pathogens, including Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli and Pseudomonas aeruginosa). METHODS: The antibacterial activities and minimum inhibitory concentration of B. abyssinica crude extracts were evaluated using agar-well diffusion and broth dilution methods according to the National Committee for Clinical Laboratory Standards (NCCLS). RESULTS: A significant difference in the antibacterial activity of crude extracts was observed among different levels of concentration against tested isolates. A higher mean inhibition zone diameter was recorded in E. coli (29.2 ± 1.5 mm), followed by S. aureus (27.8 ± 1.1 mm) and P. aeruginosa (18.0 ± 0.7 mm) at a concentration of 100 mg/mL. The antibacterial activity of crude plant extract at 100 mg/mL was comparable with that of a standard antibiotic (27.6 ± 2.6) against S. aureus and E. coli isolates. The findings indicated that bacterial growth inhibition increased as the concentration of the crude extracts increased. E. coli and S. aureus isolates showed significantly higher susceptibilities to crude extracts than P. aeruginosa at all concentrations. The minimum inhibitory concentrations of extracts against S. aureus, E. coli and P. aeruginosa isolates were 0.78 mg/mL, 1.56 mg/mL and 1.56 mg/mL, respectively. CONCLUSIONS: All tested pathogenic bacterial species were susceptible to plant leaf extract and broad-spectrum activity against Gram-positive and Gram-negative bacteria. The study recommends further fractionation of the B. abyssinica plant that contributes to its antibacterial activity and understands the mode of action of this plant against bacteria and other microbes.

Biological Control of Severe Fungal Phytopathogens by Streptomyces albidoflavus Strain CARA17 and Its Bioactive Crude Extracts on Lettuce Plants.

Lettuce crop is an important horticultural crop of several Mediterranean countries, including Italy. The Italian region which is a major producer of lettuce crops is Apulia, where this crop is cultivated in open fields an in greenhouses. Since several microbial pathogens are responsible for important diseases found on lettuce produced in greenhouses, in this study, the experimental activities focused on the most severe fungal soilborne pathogens, i.e., Sclerotinia sclerotiorum and Athelia rolfsii. Their control is often performed with fungicides which cause public concern over the environment and human health. The main aims of this study were to determine the biocontrol efficacy of a Streptomyces strain in vitro and in vivo conditions on lettuce seedlings against Athelia rolfsii and Sclerotinia sclerotiorum as severe fungal soilborne pathogens through the application of its vegetative propagules and putative bioactive crude extracts via filtrate culture. The results obtained confirm a significant effectiveness of CARA17 strain to control the severity of both fungal soilborne pathogens during two different experiments: when it is used as vegetative propagules and as a culture filtrate containing putative bioactive metabolites in vitro and in vivo conditions. These preliminary results demonstrated that the actinomycetes CARA17 strain is valid as a biocontrol agent (BCA) against both the severe phytopathogens used in this study. The biocontrol action performed from the CARA17 strain is clearly and mainly due to the putative bioactive crude extracts produced, but further studies are necessary to identify which metabolites (polyphenols, terpenes, fatty acids, etc.) are produced from this Streptomyces strain.

Antibacterial potential and synergistic interaction between natural polyphenolic extracts and synthetic antibiotic on clinical isolates.

Emergence of antimicrobial resistance complicates treatment of infections by antibiotics. This has driven research on novel and combination antibacterial therapies. The present study evaluated synergistic antimicrobial activity of plant extracts and cefixime in resistant clinical isolates. Preliminary susceptibility profiling of antibiotics and antibacterial activity of extracts was done by disc diffusion and microbroth dilution assays. Checker-board, time-kill kinetics and protein content studies were performed to validate synergistic antibacterial activity. Results showed noteworthy quantities of gallic acid (0.24-19.7 µg/mg), quercetin (1.57-18.44 µg/mg) and cinnamic acid (0.02-5.93 µg/mg) in extracts of plants assessed by reverse-phase high performance liquid chromatography (RP-HPLC). Gram-positive (4/6) and Gram-negative (13/16) clinical isolates were intermediately susceptible or resistant to cefixime, which was used for synergistic studies. EA and M extracts of plants exhibited total synergy, partial synergy and indifferent characteristics whereas aqueous extracts did not show synergistic patterns. Time-kill kinetic studies showed that synergism was both time and concentration-dependent (2-8-fold decrease in concentration). Bacterial isolates treated with combinations at fractional inhibitory concentration index (FICI) showed significantly reduced bacterial growth, as well as protein content (5-62 %) as compared to extracts/cefixime alone treated isolates. This study acknowledges the selected crude extracts as adjuvants to antibiotics to treat resistant bacterial infections.

Duplex Real-Time PCR Assays for the Simultaneous Detection and Quantification of Botryosphaeriaceae Species Causing Canker Diseases in Woody Crops.

Woody canker diseases caused by fungi of the Botryosphaeriaceae family are producing increasing losses in many economically important woody crops, including almond. To develop a molecular tool for the detection and quantification of the most aggressive and threatening species is of main importance. This will help to prevent the introduction of these pathogens in new orchards and to conveniently apply the appropriate control measures. Three reliable, sensitive and specific duplex qPCR assays using TaqMan probes have been designed for the detection and quantification of (a) Neofusicoccum parvum and the Neofusicoccum genus, (b) N. parvum and the Botryosphaeriaceae family and (c) Botryosphaeria dothidea and the Botryosphaeriaceae family. The multiplex qPCR protocols have been validated on artificially and naturally infected plants. Direct systems to process plant materials, without DNA purification, allowed high-throughput detection of Botryosphaeriaceae targets even in asymptomatic tissues. These results validate the qPCR using the direct sample preparation method as a valuable tool for Botryosphaeria dieback diagnosis allowing a large-scale analysis and the preventive detection of latent infection.

Larvicidal proficiency of volatile compounds present in Commiphora wightii gum extract against Aedes aegypti (Linnaeus, 1762).

Aedes mosquitoes are the major cause of several vector-borne diseases in tropical and subtropical regions. Synthetic pesticides against these mosquitoes have certain limitations; hence, natural, eco-friendly, and safe larvicides obtained from plant resources are used to overcome these. In the present study, the larvicidal efficiency of Commiphora wightii against the fourth instar stage of the dengue fever mosquito Aedes aegypti (Linnaeus, 1762) was studied. The gum resin of C. wightii was collected using the borehole tapping method, and hexane extracts in different concentrations were prepared. The fourth-instar larvae were exposed to the extracts, and percent mortality, as well as LC20, LC50, and LC90, was calculated. Volatile compounds of the hexane gum extract were analyzed by Headspace GC/MS, and the sequence of the acetylcholine, Gamma-aminobutyric acid (GABA) receptor, and octopamine receptor subunit of A. aegypti was obtained. It was found that the hexane gum extract was toxic and lethal for larvae at different concentrations. Minimum mortality was observed at 164 µg mL-1 (10%/h), while maximum mortality was at 276 µg mL-1 (50%/h). The lethal concentrations LC20, LC50, and LC90 were 197.38 µg mL-1, 294.13 µg mL-1, and 540.15 µg mL-1, respectively. The GC/MS analysis confirmed the presence of diterpenes, monoterpenes, monoterpene alcohol, and sesquiterpenes in the gum samples, which are lethal for larvae due to their inhibitory activity on the acetylcholinesterase enzyme, GABA receptor, and octopamine receptor subunit. The use of commonly occurring plant gum for the control of mosquitoes was explored, and it was found that the gum of C. wightii had larvicidal activities and could be potentially insecticidal.

Influence of Lonicera japonica and Radix Puerariae Crude Extracts on the Fecal Microbiome and Nutrient Apparent Digestibility of Finishing Pigs.

This study aims to investigate the influence of adding Lonicera japonica (L. japonica) and Radix Puerariae crude extracts and their mixture to the diet of finishing pigs on their fecal microbes and nutrient apparent digestibility. A total of 72 healthy Duroc × Landrace × Yorkshire crossbred barrows without significant differences in body weight (93 ± 2 kg) were selected and randomly divided into four groups (18 in each group). Three replicate pens per group (six pigs per pen) were used, and two pigs were evaluated for each pen. The groups were fed the following diets: control group (CON), basic diet; chlorogenic acid group (CGA group), basic diet + 1 kg/ton L. japonica crude extract; Pueraria flavonoid group (PF group), basic diet + 1 kg/ton Radix Puerariae crude extract; and mix group (Mix group), basic diet + 0.5 kg/ton L. japonica crude extract + 0.5 kg/ton Radix Puerariae crude extract. The following results were obtained: (1) At the phylum level, Bacteroidetes, Firmicutes, Spirochaetes, Proteobacteria, Fibrobaeteres, and Kiritimatiellaeota were the main components of the fecal microbiota (top 5); the relative abundance of bacteria from phyla Firmicutes significantly increased in the Mix group than in the CON group (p < 0.05). At the genus level, Treponema_2, Rikenellaceae_RC9_gut_group, uncultured_bacterium_f_Lachnospiraceae, uncultured_bacterium_f_Prevotellaceae, and Prevotellaceae_NK3B31_group were the main components of the fecal microbiota (top 5); the relative abundance of bacteria from genus Lactobacillus significantly increased in the Mix group than in the CON group (p < 0.05). Chao1 and Ace counts were significantly higher in group CGA than in the CON group and group Mix (p < 0.05). The alpha and beta diversities and the relative abundance of fecal microbes were higher in all test groups than in the CON group. (2) The protein digestibility was significantly higher in the CGA and PF groups than in the CON group, and the TP digestibility was significantly higher in the CGA than in the CON and Mix groups (p < 0.05). In conclusion, Lonicera japonica and Radix Puerariae crude extract supplementation in the diet significantly changed fecal microbiota and improved the protein and TP digestibility of finishing pigs.

Crude extracts of an endophytic fungus attenuate the growth of pathogenic bacteria in aquaculture.

Background and Objectives: Endophytic fungi are believed to possess compounds as antibacterial agents. This study was designed to determine in vivo antibacterial activity of the crude extracts from Lasiodiplodia pseudotheobromae IBRL OS-64 against pathogenic bacteria. Materials and Methods: The qualitative and quantitative screenings were performed using agar plug and disk diffusion antimicrobial tests, respectively. Besides that, the MIC and MBC value of the extracts were determined using broth microdilution assay and morphological changes of the bacterial cells exposed to the extract were observed under Scanning Electron Microscope (SEM). Results: Agar plug diffusion assay revealed that V. parahaemolyticus ATCC 17802 and Exiguobacterium profundum IBRL MA6 were the most sensitive to the extract with the size of inhibition zones of 11 to ≤ 20 mm. The MIC and MBC values of the extract varied depending on the test bacteria. Observation through SEM revealed that the bacterial cells exposed to the extract experienced severe damage such as irregular shape with crumpled and shrunken cells which led to cell death. Conclusion: The data suggest that the crude extracts of L. pseudotheobromae IBRL OS-64 exert antibacterial activity against test bacteria and principally affect the cell wall in growing pathogenic bacterial cells.

Crude extracts activity of three selected medicinal plants from the Venda region against some pathogenic organisms.

Background: The emerging of antimicrobial resistance has become a problem as it is threatening public health worldwide. Objectives: To extract crude extracts from three different medicinal plants, test activity against Mycobacterium smegmatis, Staphylococcus aureus and Escherichia coli and screen for phytochemicals of those that showed activity against the targeted bacteria. Methods: KirkiaacuminataOliv., Dichrostachyscinerea (L.) Wight &Arn. and MimusopszeyheriSond. plants were collected at Thengwe area, Mafukani village, Limpopo Province, South Africa. The plant materials collected were extracted using four solvents. Antimicrobial screening was accomplished using the agar well diffusion method and the crude extracts that showed activity against the targeted organisms were screened for phytochemicals using different tests. Results: With all solvents used for extraction, methanol had a greater yield of 14.1% from Dichrostachyscinerea crude extracts. Kirkiaacuminata and Dichrostachyscinerea were medicinal plants that inhibited Mycobacterium smegmatis and Staphylococcus aureus at the lowest concentration of 2.5 mg/ml and 1.25 mg/ml. Conclusions: The results from this study show that the selected medicinal plants are active against Mycobacterium smegmatis and Staphylococcus aureus and their pharmacological properties can be further analyzed for the development of new drugs.

Bioprospecting of Helichrysum Species: Chemical Profile, Phytochemical Properties, and Antifungal Efficacy against Botrytis cinerea.

Variation in plant species and extraction solvents play a crucial role in the recovery of their bioactive compounds and antifungal efficacy. Thus, in this study, a comparative investigation was carried out using extraction solvents: 70% acetone and 95% ethanol to obtain crude aqueous extracts from Helichrysum odoratissimum and H. patulum. Crude aqueous extracts were screened using gas chromatography-mass spectrometry (GC-MS), to gain insight into their chemical composition. Phytochemical properties (total polyphenols (TP) and radical scavenging capacity via 2,2-diphenyl-1-picrylhydrazyl (DPPH)), and antifungal activity against Botrytis cinerea of the crude extracts were evaluated. Fungicide (Rovral® WP) and extraction solvents were used as controls. Variation in Helichrysum spp. and extraction solvent had influence on the chemical composition, phytochemicals, and antifungal activities. Metabolites such as γ-terpinene (≈0.1%), α-amorphene (≈0.6%) α-gurjunene (≈1.4%), ß-selinene (2.2-3.2%), γ-gurjunene (≈3.3%), and methyl cinnamate (≈20%) were detected only in extracts of H. patulum. Crude extract of H. odoratissimum using 70% acetone had the highest TP (19.3 ± 0.76 g GA 100 g-1), and DPPH capacity (13,251.5 ± 700.55 µmol Trolox g-1) compared to H. patulum (p ≤ 0.05). Ethanolic extracts of H. patulum showed highest antifungal efficacy (≈65%) against B. cinerea (p ≤ 0.05) compared to other crude extracts. This study showed that Helichrysum spp. differ in their potential as a source for bioactive compounds and antifungal treatments/formulations.

ANTIBACTERIAL EFFECTS OF SINGLE AND COMBINED CRUDE EXTRACTS OF SYNADENIUM GLAUCESCENS AND COMMIPHORA SWYNNERTONII.

Background: Synadenium glaucescens and Commiphora swynnertonii are among the reported plants used traditionally for treatment of bacterial infections. This study reports antibacterial effects of single and combined extracts from leaves, stem and root barks of Commiphora swynnertonii and Synadenium glaucescens. Materials and Methods: Plants were collected from Manyara and Njombe regions in Tanzania. Extraction was done using dichloromethane and methanol. The extracts were assessed for antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa). Minimum Inhibitory Concentrations (MIC) was determined by broth microdilution, while Fractional Inhibitory Concentration (FIC) indices were calculated from MIC values of combined extracts to determine combination effects. Results: Strong antibacterial activities were demonstrated by all extracts of S. glaucescens (MIC 0.011-0.375mg/mL) against Gram-positive bacteria and methanol extracts of C. swynnertonii (MIC 0.047-0.375mg/mL). Synergistic effect was observed when combining methanol extracts of C. swynnertonii stem bark with S. glaucescens leaves against S. aureus (∑FIC 0.5), Other synergistic effects were observed against E. faecalis with dichloromethane extracts of C. swynnertonii stem bark and S. glaucescens stem bark (∑FIC 0.5), and C. swynnertonii root bark and S. glaucescens root bark (FIC index 0.3). For the remaining combinations, mainly additive effects were observed. Conclusion: Synergistic effects on bacteria were observed by combining different plant parts of S. glaucescens and C. swynnertonii suggesting that it could be beneficial to combine such extracts when used for antibacterial purposes.

Secondary metabolites produced by endophytic fungi, Alternaria alternata, as potential inhibitors of the human immunodeficiency virus.

Antiretroviral treatment has significantly reduced human immunodeficiency virus infection and mortality. However, the current treatment regimen is limited by adverse side effects, the emergence of drug resistance, and the inability to eliminate viral reservoirs. Here, fifteen endophytic fungi were isolated from Sclerocarya birrea and Hypoxis plants. Crude extracts of Alternaria alternata (strain ID PO4PR1, PO4PR2, and PO2PL1) of the fifteen isolate's crude extracts showed anti-HIV-1 activity in TZM-bl cell line at inhibitory concentration (IC50) values ranging from 0.017 to 1.170 µg/ml. The three crude extracts also maintained the virus replication inhibition profile on PBMCs and CD4+ T cells at concentrations ranging from 0.3 to 50.2 ng/ml. Partial purification using the solid phase extraction and analysis with Gas Chromatography-Mass spectrophotometry showed a diverse profile. The bioactive compounds were identified based on peak area, retention time, similarity index. The major compounds from GC-MS analysis of A. Alternata revealed the existence of cyclotrisiloxane octamethyl (22.92%); Propaninitrile (16,67%); Pyrrolol[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methyl propyl) (10.42%); Silane, diethylethoxy(2-ethoxyethyloxy) (4.17%); Coumarin, 3,4-dihydro-4,5,7-trimethyl- 4,5,7-Trimethyl-2-chromanone (13.7%) and 1,2-Cyclobutanedicarbonitrile (2.08%) with previously reported biological activities such as antimicrobial, anti-inflammatory and antioxidant properties. Therefore, these bioactive compounds from A. alternata fungal endophytes could be repurposed as potential anti-HIV agents. This study showed the potential of endophytic fungi, Alternaria alternata from S. birrea, and Hypoxis species as producers of anti-HIV compounds.

Oilseed Extracts from Local Markets as Promising Coagulant Agents for Milk from Various Mammalian Species.

The aim of this study was to identify novel milk coagulants to be used in cheesemaking. For this purpose, aqueous extracts from safflower (Carthamus tinctorius), sunflower (Helianthus annuus), flax (Linum usitatissimum) and sesame (Sesamum indicum) seeds were tested for their caseinolytic (CA) and milk coagulating properties (MCA) in skim milk at temperatures of 25, 37, 50, 65 and 80 °C. The seed oil samples with the highest temperature ranges in regard to coagulation efficiency were then tested in cow, buffalo, goat and sheep milks and the MCA and curd yield (CY) parameters were measured at different temperatures. Due to their high milk coagulation efficiency (CE) in all types of milk and at different temperatures, the sesame and sunflower seed extracts proved to be particularly interesting and their CY parameters were similar to those obtained with animal rennet. Moreover, our results confirm that oilseed coagulants are capable of coagulating milk and can also be considered as potential animal rennet substitutes. This study provides valuable insights into the development of potential vegetable coagulants that could be used for various production processes aimed at specific target consumers.