Antagonistic fungi, trichoderma spp.: panoply of biological control

Woody Plants of Ghana and Their Uses@@@Woody Plants of Ghana, with Special Reference to Their Uses

Aqueous extract of fifty-two plants from different families were tested for their antifungal potential against eight important species of Aspergillus such as A. candidus, A. columnaris, A. flavipes, A. flavus, A. fumigatus, A. niger, A. ochraceus, and A. tamarii which isolated from
sorghum, maize and paddy seed samples. The test fungi were mainly associated with seed biodeterioration during storage. Among fifty-two plants tested, aqueous extract of Acacia nilotica, Achras zapota, Datura stramonium, Emblica officinalis, Eucalyptus globules, Lawsonia inermis, Mimusops elengi, Peltophorum pterocarpum, Polyalthia longifolia, Prosopis juliflora, Punica granatum and Sygigium cumini have recorded significant antifungal
activity against one or the other Aspergillus species tested. A. flavus recorded high susceptibility and hence solvent extracts viz., petroleum ether, benzene, chloroform, methanol and ethanol extracts of all the twelve plants were tested for their antifungal activity against it.
Among the solvent extracts tested, methanol gave more effective than ethanol, chloroform,benzene and petroleum ether, except for Polyalthia longifolia, where petroleum ether extract recorded highly significant antifungal activity than other solvent extracts.

Antifungal activity of some plant extracts against important seed borne pathogens of aspergillus sp

Phyllanthus amarus: Ethnomedicinal uses, phytochemistry and pharmacology: A review

Medicinal plants have been the mainstay of traditional herbal medicine amongst rural dwellers worldwide since antiquity to date. The therapeutic use of plants certainly goes back to the Sumerian and the Akkadian civilizations in about the third millenium BC. Hippocrates (ca. 460–377 BC), one of the ancient authors who described medicinal natural products of plant and animal origins, listed approximately 400 different plant species for medicinal purposes. Natural products have been an integral part of the ancient traditional medicine systems, e.g. Chinese, Ayurvedic and Egyptian (Sarker & Nahar, 2007). Over the years they have assumed a very central stage in modern civilization as natural source of chemotherapy as well as amongst scientist in search for alternative sources of drugs. About 3.4 billion people in the developing world depend on plant-based traditional medicines. This represents about 88 per cent of the world’s inhabitants, who rely mainly on traditional medicine for their primary health care. According to the World Health Organization, a medicinal plant is any plant which, in one or more of its organs, contains substances that can be used for therapeutic purposes, or which are precursors for chemo-pharmaceutical semi synthesis. Such a plant will have its parts including leaves, roots, rhizomes, stems, barks, flowers, fruits, grains or seeds, employed in the control or treatment of a disease condition and therefore contains chemical components that are medically active. These non-nutrient plant chemical compounds or bioactive components are often referred to as phytochemicals (‘phyto-‘ from Greek phyto meaning ‘plant’) or phytoconstituents and are responsible for protecting the plant against microbial infections or infestations by pests (Abo et al., 1991; Liu, 2004; Nweze et al., 2004; Doughari et al., 2009). The study of natural products on the other hand is called phytochemistry. Phytochemicals have been isolated and characterized from fruits such as grapes and apples, vegetables such as broccoli and onion, spices such as turmeric, beverages such as green tea and red wine, as well as many other sources (Doughari & Obidah, 2008; Doughari et al., 2009).

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Phytochemicals: Extraction Methods, Basic Structures and Mode of Action as Potential Chemotherapeutic Agents

Medicinal and aromatic plants are reservoirs of curative elements used by a large population of Africans in the treatment of various diseases such as malaria, diabetes, mental disorders, cancer, hypertension and human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). These medicinal and aromatic plants are used based on ethnobotanical evidence as being safer, acceptable, affordable, culturally compatible and suitable for chronic treatment. Phytochemical screening of these plants revealed that they contain bioactive chemical substances such as alkaloids, tannins, saponin, and others with therapeutic potentials. The screening of plants for various bioactive substances has led to the discovery of anti HIV drugs from plant such as Ancistrocladus korupensis containing the alkaloid,michellamine A and B. The active ingredients of medicinal and aromatic plants can be found either in the roots, leaves, stems, flowers or bark and can be extracted using an appropriate extraction method. Plant selection for drug discovery can be achieved through phytochemical screening, conducting bioassays on experimental models, ethnobotanical evidence and biologic activity report on the plant. Despite the benefits derived from plants, some of them have some unpleasant side effects which may be related to over doses or other factors. This may lead to acute toxicity and death but when these problems are carefully addressed, will help to harness the therapeutic potentials of medicinal and aromatic plants for further drug development in the future.

	 

	Key words: African, treatment, bioactive, alkaloid, health care.

https://africaneditors.org/journal/JMPR/full-text-pdf/97181-129798

Advances in selected medicinal and aromatic plants indigenous to Africa.

Effects of leaf extracts of Ocimum gratissimum and Aframomum melegueta on spore germination and mycelial reduction of the most occurring fungal pathogen causing soft rot of yam tuber were investigated. Fungi isolated from rotted yams were Aspergillus niger, A. flavus, Fusarium oxsporium Rhizopus stolonifer, Botryodiplodia theobromae and Penicillium chrysogenum. The leaf extracts with ethanol extraction were most effective followed by cold-water and hot water extraction. The fungicidal activity with Ocimum gratissimum leaf extracts was more effective. In vitro inoculation of fresh yam with A. niger, A. flavus and F. oxsporum at room temperature for 3 months showed typical rot symptoms characteristic of the disease. The significance of these findings is discussed in relation to plant chemical or non-chemical means of disease control on yams in Africa.

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Antifungal effects of two tropical plant leaf extracts (Ocimum gratissimum and Aframomum melegueta) on postharvest yam (Dioscorea spp.) rot

Investigation was carried out to test the potency of some plant extracts for the control of yam tuber rot caused by Fusarium oxysporum, Aspergillus niger and Aspergillus flavus. Hot water extracts were obtained from leaf and seed of uda (Xylopia aethiopica) and Ginger (Zinigiber officinale), and were found to be fungitoxic against the fungi. The extracts of suppressed the growth of these fungi in culture and reduced rot development in yam tubers.

/pdf/control-of-yam-tuber-rot-with-leaf-extracts-of-xylopia-1l9egyhxtf.pdf

Control of yam tuber rot with leaf extracts of Xylopia aethiopica and Zingiber officinale

From in vitro and in vivo screening tests for antagonism by isolates of Trichoderma against postharvest pathogens of yams (Dioscorea spp.), an isolate of Trichoderma viride Pers. ex S.F. Gray was selected as the most promising candidate for the biocontrol of postharvest rot of yams. Inoculation of white yam (Dioscorea rotundata Poir.) with conidiaspores of T. viride and subsequent storage of the tubers under the ambient environment conditions of a traditional yam barn, resulted in a drastic reduction in the frequency of occurrence of the normal tuber surface mycoflora over a 4-month (December-April) storage period. Trichoderma viride on the other hand, maintained a high frequency of occurrence during the same period. Furthermore, whereas up to 52.0%) rot was found among groups of tubers that were artificially inoculated with the postharvest pathogens of yams, Aspergillus niger Van Tiegh., Botryodiplodia theobromae Pat. or Penicillium oxalicum Currie and Thom, and also the group that was not inoculated with any organism (control), among groups of tubers that were inoculated with T. viride the rot was either totally suppressed or only a low percentage of rot occurred. The significance of the findings is discussed in relation to yam storage especially by farmers with limited resources.


Zusammenfassung

Trichoderma-Isolate wurden in vitro und in vivo hinsichtlich ihrer antagonistischen Wirkung auf Nacherntepathogene von Yamswurzeln (Dioscorea spp.) getestet. Dabei wurde ein Isolat von Trichoderma viride Pers. ex S.F. Gray als vielversprechendster Kandidat fur die biologische Bekampfung der Lagerfaule von Yamswurzeln ausgewahlt. Nach Inokulation von weisem Yam (Dioscorea rotundata Poir.) mit Konidiosporen von T. viride und anschliesender Lagerung der Knollen unter Umweltverhaltnissen, die denjenigen in den traditionell zur Lagerung verwendeten Schuppen entsprechen, kam es wahrend einer viermonatigen Lagerung (Dezember bis April) zu einem starken Ruckgang bei der Haufigkeit des Auftretens der normalen Mykoflora der Knollenoberflache. Trichoderma viride kam wahrend dieses Zeitraums jedoch weiterhin haufig vor. Bei Knollen, die mit den Nacherntepathogenen Aspergillus niger Tiegh., Botryodiplodia theobromae Pat. oder Penicillium oxalicum Curie und Thom kunstlich inokuliert worden waren, betrug der Faulnisanteil am Ende der Lagerzeit ebenso wie bei den nicht inokulierten Knollen der Kontrollvariante bis zu 52,0%. Bei den mit T. viride inokulierten Knollen war die Faulnis dagegen vollkommen unterdruckt, oder nur ein kleiner Prozentanteil der Knollen faulte. Die Bedeutung dieser Ergebnisse wird besonders im Hinblick auf die Lagerung von Yamswurzeln durch Bauern diskutiert, denen nur begrenzte Mittel zur Verfugung stehen.

Studies on biological control of postharvest rot in yams (Dioscorea spp.) using Trichoderma viride.

Many human pathogens require serious attention in developing countries like Nigeria. Six pathogens were used for the study of the antimicrobial effect of Cajanus cajan leaf extract on some pathogens. Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Salmonella typhi, and Klebsiella pneumoniae were the bacteria isolates and Candida albicans was the only yeast (fungi) isolate used. Solvents used for the extraction of active ingredients of the plant leaf were water (as the aqueous solvent), petroleum ether, ethanol, and chloroform/methanol mixture (as organic solvents). The antibacterial effect of the plant extract showed that the organic solvent extracts were inhibitory to E. coli, S. aureus, and S. typhi; the aqueous extract was inhibitory to E. coli and S. aureus; while K. pneumoniae and P. mirabilis showed resistance to all the extracts. The minimum inhibitory concentration value of the extracts on the organisms ranged between 0.125 and 0.25 mg/ml for E. coli, 0.125 mg/ml for S. aureus...

R. N. Okigbo

Papers

Advances in selected medicinal and aromatic plants indigenous to Africa.

Antifungal effects of two tropical plant leaf extracts (Ocimum gratissimum and Aframomum melegueta) on postharvest yam (Dioscorea spp.) rot

Control of yam tuber rot with leaf extracts of Xylopia aethiopica and Zingiber officinale

Studies on biological control of postharvest rot in yams (Dioscorea spp.) using Trichoderma viride.

Antimicrobial Effect of Leaf Extracts of Pigeon Pea (Cajanus cajan (L.) Millsp.) on Some Human Pathogens