Controlled release of Dextrin-conjugated growth factors to support growth and differentation of neural stem cells

An essential aspect of stem cell in vitro culture and in vivo therapy is achieving sustained levels of growth factors to support stem cell survival and expansion, while maintaining their multipotency and differentiation potential. This study investigated the ability of dextrin (~74,000 g/mol; 27.8 mol% succinoylation) conjugated to epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF; or FGF-2) (3.9 and 6.7% w/w protein loading, respectively) to support the expansion and differentiation of stem cells in vitro via sustained, controllable growth factor release. Supplementation of mouse neural stem cells (mNSCs) with dextrin-growth factor conjugates led to greater and prolonged proliferation compared to unbound EGF/bFGF controls, with no detectable apoptosis after 7 days of treatment. Immunocytochemical detection of neural precursor (nestin) and differentiation (Olig2, MAP2, GFAP) markers verified that controlled release of dextrin-conjugated growth factors preserves stem cell properties of mNSCs for up to 7 days. These results show the potential of dextrin-growth factor conjugates for localized delivery of bioactive therapeutic agents to support stem cell expansion and differentiation, and as an adjunct to direct neuronal repair

Fungicide Tolerance and Effect of Environmental Conditions on Growth of Trichoderma spp. with Antagonistic Activity Against Sclerotinia sclerotiorum Causing White Mold of Common Bean (Phaseolus vulgaris)

The present study was conducted to evaluate in vitro compatibility of commonly used agrochemicals as well as the effect of temperature, pH and salt on the growth of six Trichoderma spp. with antagonistic activity against S. sclerotiorum responsible for white mold of common bean. The results revealed that in dual culture, the mycelial growth inhibition of S. sclerotiorum ranged from 83.4 to 87.4 %25. The highest inhibition (87.4 %25) was obtained with isolate T. erinaceum It-58, while the lowest inhibition (83.4 %25) was caused by T. koningiopsis It-21. Except T. asperellum It-13, antagonistic fungi were able to fully colonized pathogen in five days reaching class I antagonism according to Bell scale. The maximum inhibition percentage of volatile (54.07 %25) and non-volatile compounds (68.89 %25) on pathogen was respectively caused by T. asperellum It-13 and T. harzianum P-11. Fungicides affect the growth of Trichoderma differently. No growth was observed while testing compatibility of T. asperellum It-13 and T. erinaceum It-58 with Mancozeb as well as T. asperellum It-13 and T. afroharzianum P-8 with Methyl thiophanate illustrating the absence of compatibility. The excellent growth rate of Trichoderma was found at temperature range of 25ndash%253B30˚C and pH range 4.5-5.5. Apart from T. asperellum It-13, all the isolates were able to grow at NaCl concentrations up to 1000 micro%253BM and were identified as superior salt-tolerant isolates

Antioxidant and Antifungal Activities of Cocoa Butter (Theobroma cacao), Essential Oil of Syzygium aromaticum and a Combination of Both Extracts against Three Dermatophytes

To contribute in the research of better drugs against dermatophytosis, we evaluated the antioxidant and antidermatophytic activities of cocoa butter, cloves essential oil, and a mixture of both extracts. The cocoa butter was obtained by boiling the cocoa paste. The essential oil extracted by hydrodistillation was chemically analysed by gas chromatography and gas chromatography coupled with mass spectrometry. The antioxidant activity was determined using the DPPH scavenging method, and  the antidermatophytic activity was evaluated using the agar dilution method. The essential oil, majoritary constituated by eugenol (87.62%), β-caryophyllene (5.88%), and β-bisabolene (4.41%), had an antiradical power (4.22 x 10-2) higher than that of BHT (4.00 x 10-3), like the cocoa butter and essential oil mixture (6.06 x 10-3). The essential oil was more active than the griseofulvin: it was fungicidal at 400 ppm against Trichophyton rubrum, and at 900 ppm against Microsporum gypseumand Trichophyton tonsurans. The cocoa butter activity was low, but the mixture with the essential oil had an important activity with inhibitory percentages of 78.69 %, 88.27 %, 91.20% against T. rubrum (at 400 ppm), T. tonsurans(at 900 ppm)and M. gypseum (at 900 ppm)respectively. Cloves essential oil and the mixture with cocoa butter can be used to formulate new drugs against dermatophytes.

Antagonistic fluorescent Pseudomonads: rhizobacteria with suppressive and plant growth promoting properties against Phytophthora colocasiae, the causal agent of taro leaf blight

Taro leaf blight caused by Phytophthora colocasiae affects plant health and is a major threat to taro culture in Cameroon. Chemical fertilizers used often harm the ecosystem. Plant growth-promoting rhizobacteria (PGPR) are better alternatives that increase plant growth promotion and suppress phytopathogens. In the present study, a total of 67 fluorescent Pseudomonas spp. was characterized by 17.91, 5.97, and 4.47% populations of P. fluorescens, P. chlororaphis, and P. putida, respectively, among the most represented. More than 36% of bacteria showed antagonistic potential through the production of both diffusible and volatile compounds. Some of them (03) exhibited antagonistic activity in dual culture against P. colocasiae with a diameter greater than 13 mm. These rhizobacteria produced a significant amount of siderophore, IAA, SA, HCN, protease, lipases, and cellulases. For the pot experiment, treatment by Pseudomonas significantly increased the enzymatic activity involved in the resistance of taro, such as peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL). The two antagonists also increased plant growth parameters of taro such as chlorophyll, plant height, shoot length, total leaf surface, fresh root biomass, and fresh leaf biomass. These findings showed that fluorescent Pseudomonas have an intriguing and undeniable potential in the fight against P. colocasiae, which could lead to the development of a biopesticide in the future

Effets de la salinite sur la croissance, la distribution ionique et l\'etat hydrique d\'une glycophyte tolerante: Gossypium hirsutum (Malvaceae)

No Abstract.Journal of the Cameroon Academy of Sciences Vol. 6 (3) 2006: pp. 167-17

Comparative essential oils composition and insecticidal effect of different tissues of Piper capense L., Piper guineense Schum. et Thonn., Piper nigrum L. and Piper umbellatum L. grown in Cameroon

This study compared the chemical composition of the essential oils obtained by hydrodistillation of different tissues of Piper capense, Piper guineense, Piper nigrum and Piper umbellatum grown in Cameroon. The GC and GC/MS analysis showed qualitative and quantitative differences between these oils. Oils from the fruits were rich in a-pinene (5.6 - 12.3%) and b-pinene (6.7 - 59.3%). The other major constituents were sabinene (14.7%) for P. capense, limonene (15.8%) and b-caryophyllene (20.8%) for P. guineense. The oil from the fruits of P. nigrum contained sabinene (11.2%), d-3-carene (18.5%),limonene (14.7%) and b-caryophyllene (12.8%) while that of P. umbellatum content linalool (14.4%) and (E)-nerolidol (10.0%) as major constituents. The essential oil obtained from the leaves of P. capense was largely composed of a-pinene (12.8%), -pinene (50.1%) and b-caryophyllene (12.4%). The most abundant constituents identified in the oil from the leaves of P. guineense were limonene (10.3%) and germacrene B (25.1%) while that from P. nigrum was characterized by its high amount of a-selinene (16.5%) and -selinene (14.6%). -pinene (10.8%), -caryophyllene (28.2%) and (E)-nerolidol (16.5%) were the quantitative important constituents of the essential oils from the leaves of P. umbellatum. Theoils from the lianas of P. guineense was rich in (Z, E)-a-farnesene (28.7%), limonene (19.7%) and myristicine (10.9%), while those from P. nigrum contained d-3-carene (14.4%) and -caryophyllene(36.0%). The oil from the stems of P. capense contained mostly a-pinene (14.3%) and -pinene (61.4%). The distillation of those from P. umbellatum did not produce any essential oil. Oils from the three fruits showed variable contact toxicity against Sitophilus zeamais with P. guineense being more toxic (LD50 =10.0 ± 0.3 ìl/g) than P. capense (LD50 = 16.1 ± 0.6 ìl/g) and P. nigrum (LD50 = 26.4 ± 1.5 ìl/g). Poudrox (5%) used as a standard insecticide exhibited 100% mortality

Propriétés antifongiques des huiles essentielles de quelques plantes du genre Aframomum du Cameroun contre Aspergillus flavus

La recherche d’alternatives aux moléules synthétiqes dans la lutte contre les moisissures est à l’origine de cette étude. Ainsi, les huiles essentielles (HE) des feuilles et graines de Aframomum daniellii, Aframomum melegueta et Aframomum latifolium et celles des coques de Aframomum latifolium du Cameroun ont été extraites par hydrodistillation. Leurs activités antifongiques contre Aspergillus flavus ont été évaluées par la méthode d’incorporation en milieu solide. Les résultats révèlent que l’huile essentielle la moins active est représentée par l’huile essentielle des graines de A. melegueta  et la plus active est représentée par celle des coques de A. latifolium à une concentration de 5000 ppm. L’analyse statistique par ANOVA à (

Cameroonian medicinal plants belonging to Annonaceae family: radical scavenging and antifungal activities

The free-radical scavenging activity of ethanolic and methanolic extracts of leaves, stems and roots of Annona muricata, Monodora tenuifolia, Uvaria comperei, Uvaria muricata and Xylopia africana was evaluated using DPPH and ORAC assays. Further, phytochemical analysis, total phenolic and total flavonoid contents were also determined. Moreover, the antifungal activity of extracts was studied. The findings indicated that A. muricata and U. comperei extracts own antiradical activities and moderate antifungal properties

Investigations of the essential oils of some aframomum species (Zingiberaceae from Cameroon) as potential antioxidant and anti-inflammatory agents

International audienc

Antagonism of Trichoderma asperellum against Phytophthora megakarya and its potential to promote cacao growth and induce biochemical defence

This work aimed to assess the antagonism effects of four different Trichoderma asperellum isolates against Phytophthora megakarya and their ability to enhance cacao growth and biochemical defence. Results showed that In paired culture, all the isolates of T. asperellum used were antagonistic to P. megakarya by means of mycoparasitism. In pot experiments, leaf number, plant height, shoots and root dry matter were significantly increased by T. asperellum. Similarly, chlorophyll rate, P uptake and acid phosphatase activities were also increased. These antagonists reduced significantly the effects of P. megakarya in the leaves of cacao plants. Amino acid and phenolic components content increased in either healthy or infected leaves from cacao plants inoculated with T. asperellum. There was negative correlation between both phenolic compounds and disease severity and amino acids and disease severity. This suggests that these compounds are involved in disease resistance. In fact, the induction of specific amino acids such as alanine, glutamic acid and methionine may play an important role in the adaptation of cacao plant to P. megakarya infection. These findings demonstrated that Trichoderma asperellum (PR10, PR11, PR12 and PR659-7) could be used to improve the development of cacao plants and protect the plant against Phytophthora megakarya