Trichoderma species are free-living fungi that are highly interactive in root, soil and foliar environments and have been used successfully in field trials to control many crop pathogens. Structural and biological studies of the metabolites isolated from Trichoderma species are reviewed. This review, encompassing all the literature in this field up to the present and in which 269 references are cited, also includes a detailed study of the biological activity of the metabolites, especially the role of these metabolites in biological control mechanisms. Some aspects of the biosynthesis of these metabolites and related compounds are likewise discussed.

Secondary metabolites from species of the biocontrol agent Trichoderma

Current knowledge of the biochemistry of Trypanosoma cruzi has led to the development of new drugs and the understanding of their mode of action. Some trypanocidal drugs such as nifurtimox and benznidazole act through free radical generation during their metabolism. T. cruzi is very susceptible to the cell damage induced by these metabolites because enzymes scavenging free radicals are absent or have very low activities in the parasite. Another potential target is the biosynthetic pathway of glutathione and trypanothione, the low molecular weight thiol found exclusively in trypanosomatids. These thiols scavenge free radicals and participate in the conjugation and detoxication of numerous drugs. Inhibition of this key pathway could render the parasite much more susceptible to the toxic action of drugs such as nifurtimox and benznidazole without affecting the host significantly. Other drugs such as allopurinol and purine analogs inhibit purine transport in T. cruzi, which cannot synthesize purines de novo. Nitroimidazole derivatives such as itraconazole inhibit sterol metabolism. The parasite's respiratory chain is another potential therapeutic target because of its many differences with the host enzyme complexes. The pharmacological modulation of the host's immune response against T. cruzi infection as a possible chemotherapeutic target is discussed. A large set of chemicals of plant origin and a few animal metabolites active against T. cruzi are enumerated and their likely modes of action are briefly discussed.

Mode of action of natural and synthetic drugs against Trypanosoma cruzi and their interaction with the mammalian host.

Ecological functions of Trichoderma spp. and their secondary metabolites in the rhizosphere: interactions with plants.

Isoflavonoids of the leguminosae

Metabolite profiling of mycorrhizal roots of Medicago truncatula.

Flavonoids from Tephrosia aequilata

The tea plant, Camellia sinensis (L.) O. Kuntze is an important crop in the agriculturally based economy of Kenya. Many diseases affect the tea plant but the most prevalent is armillaria root rot caused by the fungus Armillaria mellea . Compounds from the fermentation of Trichoderma species in different media were bioassayed against some selected gram-positive and gram-negative bacteria, fungi including Armillaria mellea , a yeast and a Mucor. Compounds obtained from T. harzianum , and T . longibrachiatum when cultured in various media were investigated individually for in-vitro antifungal and antibacterial activities by agar diffusion technique. Some of the compounds produced definite antifungal and antibacterial activities. 2-Phenylethanol ( 1 ) and tyrosol ( 2 ) obtained from T. harzianum are reported for the first time from Trichoderma species. The most active metabolite isolated from these strains was 6-n-pentyl-α-pyrone ( 3 ), which showed the highest antifungal and antibacterial activity and completely inhibited the growth of Armillaria mellea fungus at a concentration of 200 ppm. Compound 4 (sorbicillin) exhibited moderate activity against the fungal test organisms. KEY WORDS: Trichoderma harzianum , Trichoderma longibrachiatum , 2-Phenylethanol, Tyrosol, 6-n-Pentyl-•-pyrone, Armillaria Mellea Bull. Chem. Soc. Ethiop. 2003 , 17(2), 185-190.

https://www.ajol.info/index.php/bcse/article/download/61675/49781

Bioactive metabolites from Trichoderma harzianum and Trichoderma longibrachiatum

Molluscicidal and antimicrobial activity of Solanum aculeastrum

Chromatographic separation of the leaves of Teclea trichocarpa (Engl.) Engl. (Rutaceae) used traditionally by Akamba tribe in Kenya yielded three acridone alkaloids, a furoquinoline alkaloid and two triterpenoids. The total extract (methanol) of the leaves of this plant and the isolated compounds were screened for in vitro for cytotoxicity and against parasitic protozoa, Plasmodium falciparum, Trypanosoma brucei rhodesiense, Trypanosoma cruzi and Leishmania donovani. Among the compounds -amyrin had the best anti-plasmodial activity (IC50 = 0.96 g/ml), normelicopicine and skimmianine had the best anti-trypanosomal activity against T. b. rhodesiense (IC50 = 5.24 g/ml) and T. cruzi (IC50 = 14.50 g/ml), respectively. Normelicopicine also exhibited best anti-leishmanial activity (IC50 = 1.08 g/ml). Arborinine exhibited moderate cytotoxicity (IC50 = 12.2 g/ml) against L-6 cells. The compounds with low anti-protozoal and high cytotoxicity IC50 values are potential source of template drug against parasitic protozoa.

https://www.academicjournals.org/article/article1380553221_Mwangi et al.pdf

Antiprotozoal activity and cytotoxicity of metabolites from leaves of Teclea trichocarpa

Antibacterial and phytochemical screening of methanolic, sequential extracts (hexane, dichloromethane, ethyl acetate and methanol) and alkaloid rich fractions of Tabernaemontana stapfiana Britten was carried out. The phytochemical screening showed the presence of alkaloids, flavonoids, coumarins, tannins and saponins that have been associated with antimicrobial activity. The stem and root bark methanolic extracts showed good activity against the bacterial strains used including the multiple drug resistant Staphylococcus aureus strain with minimum inhibitory concentrations ranging from 15.6 to 500 g/ml and minimum bactericidal concentrations ranging from 31.25 to 500 g/ml. The sequential extracts of the root and stem bark had high antimicrobial activity with minimum inhibitory concentrations (MICs) ranging between 3.9 and 250 g/ml and minimum bactericidal concentrations (MBCs) ranging between 7.8 and 500 g/ml against the tested microorganisms. The dichloromethane extract of the alkaloid rich fractions however exhibited reduced antibacterial activities as compared to methanol and sequential extracts but the dichloromethane:methanol (4:1) mixture showed high activity with MICs ranging between 15.6 and 250 g/ml. These antibacterial efficacy studies suggest that Tabernaemontana stapfiana Britten could be a source of antibacterial agents.

https://www.ajol.info/index.php/ajtcam/article/download/57090/45484

Paul K. Tarus

Papers

Flavonoids from Tephrosia aequilata

Bioactive metabolites from Trichoderma harzianum and Trichoderma longibrachiatum

Molluscicidal and antimicrobial activity of Solanum aculeastrum

Antiprotozoal activity and cytotoxicity of metabolites from leaves of Teclea trichocarpa

Antibacterial Activity of Tabernaemontana Stapfiana Britten (Apocynaceae) Extracts