A new alkaloid paenidigyamycin A (1) was obtained from the novel Ghanaian Paenibacillus sp. isolated from the mangrove rhizosphere soils of the Pterocarpus santalinoides tree growing in the wetlands of the Digya National Park, Ghana. Compound 1 was isolated on HPLC at tR = 37.0 min and its structure determined by MS, 1D, and 2D-NMR data. When tested against L. major, 1 (IC50 0.75 µM) was just as effective as amphotericin B (IC50 0.31 µM). Against L. donovani, 1 (IC50 7.02 µM) was twenty-two times less active than amphotericin B (IC50 0.32 µM), reinforcing the unique effectiveness of 1 against L. major. For T. brucei brucei, 1 (IC50 0.78 µM) was ten times more active than the laboratory standard Coptis japonica (IC50 8.20 µM). The IC50 of 9.08 µM for 1 against P. falciparum 3d7 compared to artesunate (IC50 36 nM) was not strong, but this result suggests the possibility of using the paenidigyamycin scaffold for the development of potent antimalarial drugs. Against cercariae, 1 showed high anticercaricidal activity compared to artesunate. The minimal lethal concentration (MLC) and minimal effective concentration (MEC) of the compound were 25 and 6.25 µM, respectively, while artesunate was needed in higher quantities to produce such results. However, 1 (IC50 > 100 µM) was not active against T. mobilensis.

The plant Zanthoxylum zanthoxyloides (Lam.) Zepern. & Timler is one of the most important medicinal species of the genus Zanthoxylum on the African continent. It is used in the treatment and management of parasitic diseases in sub-Saharan Africa. These properties have inspired scientists to investigate species within the genus for bioactive compounds. However, a study, which details a spectroscopic, spectrometric and bioactivity guided extraction and isolation of antiparasitic compounds from the genus Zanthoxylum is currently non-existent. Tortozanthoxylamide (1), which is a derivative of the known compound armatamide was isolated from Z. zanthoxyloides and the full structure determined using UV, IR, 1D/2D-NMR and high-resolution liquid chromatography tandem mass spectrometry (HRESI-LC-MS) data. When tested against Trypanosoma brucei subsp. brucei, the parasite responsible for animal African trypanosomiasis in sub-Saharan Africa, 1 (IC50 7.78 µM) was just four times less active than the commercially available drug diminazene aceturate (IC50 1.88 µM). Diminazene aceturate is a potent drug for the treatment of animal African trypanosomiasis. Tortozanthoxylamide (1) exhibits a significant antitrypanosomal activity through remarkable alteration of the cell cycle in T. brucei subsp. brucei, but it is selectively non-toxic to mouse macrophages RAW 264.7 cell lines. This suggests that 1 may be considered as a scaffold for the further development of natural antitrypanosomal compounds.

The Ghanaian Paenibacillus sp. DE2SH (GenBank Accession Number: MH091697) is a prolific producer of potent antiparasitic alkaloids. Further detailed study of the culture broth of this strain produced the compound Paenidigyamycin G (1), which is a derivative of the known antiparasitic compound Paenidigyamycin A (2). Compound (1) was isolated on HPLC at tR ≈ 37.5 min and its structure determined by IR, UV, MS, 1D, and 2D-NMR data. Compound 1 produced weak to moderate antileishmanial and antitrypanosomal activity when tested against Leishmania donovani (Laveran and Mesnil) Ross (D10) and Trypanosoma brucei subsp. brucei strain GUTat 3.1 with IC50 = 115.41 and 28.75 μM, respectively. This result is interesting since the parent compound 2 is known to possess consistent and potent antiparasitic activity. However, 1 displayed a promising selectivity profile towards T. brucei subsp. brucei due to its relatively low toxicity against normal mouse macrophages RAW 264.7 cells (SI = 8.70). Given that compound 1 is also the main metabolite found in the hexane fraction of all extracts produced by Paenibacillus sp. DE2SH when it is co-cultured with other bacteria strains, it must possess some unique biological functions which should make it an excellent candidate for further biological activity screening in other bioassays.

Digyaindoleacid A (1) is one of the novel alkaloids produced by the Ghanaian Paenibacillus sp. DE2SH (GenBank Accession Number: MH091697) isolated from the mangrove rhizosphere soils of the Pterocarpus santalinoides tree growing in the wetlands of the Digya National Park, Brong Ahafo Region, Ghana. This compound was isolated on HPLC at tR ≈ 60 min and its structure determined by MS, 1D, and 2D-NMR data. When tested against Trypanosoma brucei subsp. brucei strain GUTat 3.1, 1 produced a half-maximal inhibitory concentration (IC50) 5.21 μM compared to the standard diminazene aceturate (IC50 = 1.86 μM). In the presence of normal mouse macrophages RAW 264.7, 1 displayed a higher selectivity towards T. brucei subsp. brucei (selectivity indices (SI) = 30.2) with low toxicity. This result is interesting given that the drug diminazene aceturate is considerably toxic and 1 is a natural product isolate. The structure of 1 incorporates the backbone of the amino acid tryptophan which is crucial in the metabolism of Trypanosoma brucei subsp. brucei strain GUTat 3.1. It is possible that 1, could interfere with the normal uptake and metabolism of tryptophan in the parasite. However, 1 (IC50 = 135.41 μM) produced weak antileishmanial activity when tested against Leishmania donovani (Laveran and Mesnil) Ross (D10).

Sub-Sahara Africa is burdened with a high incidence of parasitic infections, including schistosomiasis, trypanosomiasis, trichomoniasis, and leishmaniasis. Currently, there is a rapid widespread development of resistance to prescription drugs for these neglected diseases. Microbes provide the largest chemical and biological diversity in drug discovery screening programs; therefore, our project seeks to explore microbes in the sub-region for new drugs. The oxylipin (9Z,11E)-13-oxooctadeca-9,11-dienoic acid (1) was isolated from the Ghanaian endophytic fungus, Penicillium herquei strain BRS2A-AR obtained from the leaves of a Laguncularia racemosa tree growing on the banks of the River Butre in the Western Regional wetlands of Ghana. Compound 1 was isolated on reverse phase HPLC at t R of 34.3 minutes. The structure of compound 1 was confirmed by a combination of mass spectrometry, 1D and 2D-NMR techniques. Compound 1 showed minimal antiparasitic activity when tested against Plasmodium falciparum 3d7 (IC 50 >100µM; aretesunate, IC 50 36nm), Trypanosoma brucei brucei (IC 50 >100µM; Coptis japonica, IC 50 8.20µM), Leishmani donovani (IC 50 >100µM; amphotericin B, IC 50 0.32µM) and Leishmania major (IC 50 >100µM; amphotericin B, IC 50 0.31µM). Compound 1 produced IC 50 of 44.47µM when tested against Trichomonas mobilensis with metronidazole (IC 50 5.20µM) as standard. These results show the potential to further engineer the structure of compound 1 into a potent anti-Trichomonas scaffold.

No abstract

The Mycobacterium sp. BRS2A-AR2 is an endophyte of the mangrove plant Rhizophora racemosa G. Mey., which grows along the banks of the River Butre, in the Western Region of Ghana. Chemical profiling using 1H-NMR and HRESI-LC-MS of fermentation extracts produced by the strain led to the isolation of the new compound, α-d-Glucopyranosyl-(1→2)-[6-O-(l-tryptophanyl)-β-d–fructofuranoside] or simply tortomycoglycoside (1). Compound 1 is an aminoglycoside consisting of a tryptophan moiety esterified to a disaccharide made up of β-d-fructofuranose and α-d-glucopyranose sugars. The full structure of 1 was determined using UV, IR, 1D, 2D-NMR and HRESI-LC-MS data. When tested against Trypanosoma brucei subsp. brucei, the parasite responsible for Human African Trypanosomiasis in sub-Saharan Africa, 1 (IC50 11.25 µM) was just as effective as Coptis japonica (Thunb.) Makino. (IC50 8.20 µM). The extract of Coptis japonica (Thunb.) Makino. is routinely used as laboratory standard due to its powerful antitrypanosomal activity. It is possible that, compound 1 interferes with the normal uptake and metabolism of tryptophan in the T. brucei subsp. brucei parasite.

Microbial pathogens use proteases for their infections, such as digestion of proteins for nutrients and activation of their virulence factors. As an obligate intracellular parasite,Toxoplasma gondiimust invade host cells to establish its intracellular propagation. To facilitate invasion, the parasites secrete invasion effectors from microneme and rhoptry, two unique organelles in apicomplexans. Previous work has shown that some micronemal invasion effectors experience a series of proteolytic cleavages within the parasite's secretion pathway for maturation, such as the aspartyl protease (TgASP3) and the cathepsin L-like protease (TgCPL), localized within the post-Golgi compartment and the endolysosomal system, respectively. Furthermore, it has been shown that the precise maturation of micronemal effectors is critical forToxoplasmainvasion and egress. Here, we show that an endosome-like compartment (ELC)-residing cathepsin C-like protease (TgCPC1) mediates the final trimming of some micronemal effectors, and its loss further results in defects in the steps of invasion, egress, and migration throughout the parasite's lytic cycle. Notably, the deletion of TgCPC1 completely blocks the activation of subtilisin-like protease 1 (TgSUB1) in the parasites, which globally impairs the surface-trimming of many key micronemal invasion and egress effectors. Additionally, we found that TgCPC1 was not efficiently inhibited by the chemical inhibitor targeting its malarial ortholog, suggesting that these cathepsin C-like orthologs are structurally different within the apicomplexan phylum. Taken together, our findings identify a novel function of TgCPC1 in the processing of micronemal proteins within the secretory pathway ofToxoplasmaparasites and expand the understanding of the roles of cathepsin C protease.