In vitro antiplasmodial activity-directed investigation and UPLC–MS fingerprint of promising extracts and fractions from Terminalia ivorensis A. Chev. and Terminalia brownii Fresen.

Please read abstract in the article.The Grand Challenges Africa programme is supported by the African Academy of Sciences (AAS), Bill & Melinda Gates Foundation (BMGF), Medicines for Malaria Venture (MMV), and Drug Discovery and Development Centre of University of Cape Town (H3D).https://www.elsevier.com/locate/jethpharm2023-07-09hj2023Chemistr

Crude metabolites from endophytic fungi inhabiting Cameroonian Annona muricata inhibit the causative agents of urinary tract infections.

Urinary tract infections (UTIs) are common bacterial infections. The global emergence of multidrug-resistant uropathogens in the last decade underlines the need to search for new antibiotics with novel mechanisms of action. In this regard, exploring endophytic fungi inhabiting medicinal plants used locally against urinary tract infections could be a promising strategy for novel drug discovery. This study investigates crude metabolites from endophytic fungi isolated from Annona muricata as potential sources of antibiotic drugs to fight against uropathogens and reduce related oxidative stress. Crude ethyl acetate extracts from 41 different endophytic fungi were screened against three bacterial strains using the broth microdilution method, and fungi producing active crude extracts were identified using ITS1-5.8S rRNA-ITS2 nucleotide sequences. The antibacterial modes of action of the five most active extracts were evaluated using Staphylococcus aureus ATCC 43300 and Klebsiella oxytoca strains. The DPPH and FRAP assays were used to investigate their antioxidant activity, and their cytotoxicity against the Vero cell line was evaluated using the MTT assay. Out of the 41 crude extracts tested, 17 were active with minimum inhibitory concentrations (MICs) ranging from 3.125 μg/mL to 100 μg/mL and were not cytotoxic against Vero cell lines with a cytotoxic concentration 50 (CC50) >100 μg/mL. The more potent extracts (from Fusarium waltergamsii AMtw3, Aspergillus sp. AMtf15, Penicillium citrinum AMf6, Curvularia sp. AMf4, and Talaromyces annesophieae AMsb23) significantly inhibited bacterial catalase activity, lysed bacterial cells, increased outer membrane permeability, and inhibited biofilm formation, and the time-kill kinetic assay revealed concentration-dependent bactericidal activity. All seventeen extracts showed weak ferric iron-reducing power (1.06 to 12.37 μg equivalent NH2OH/g of extract). In comparison, seven extracts exhibited DPPH free radical scavenging activity, with RSA50 ranging from 146.05 to 799.75 μg/mL. The molecular identification of the seventeen active fungi revealed that they belong to six distinct genera, including Aspergillus, Curvularia, Fusarium, Meyerozyma, Penicillium, and Talaromyces. This investigation demonstrated that fungal endophytes from Cameroonian Annona muricata, a medicinal plant used locally to treat bacterial infections, might contain potent antibacterial metabolites with multiple modes of action. The antibacterial-guided fractionation of these active extracts is currently ongoing to purify and characterise potential antibacterial active ingredients

Antibacterial and Mode of Action of Extracts from Endophytic Fungi Derived from Terminalia mantaly, Terminalia catappa, and Cananga odorata

Mbekou MIK, Dize D, Yimgang VL, et al. Antibacterial and Mode of Action of Extracts from Endophytic Fungi Derived from Terminalia mantaly, Terminalia catappa, and Cananga odorata. BioMed research international. 2021;2021: 6697973.Emerging drug-resistant bacteria creates an urgent need to search for antibiotics drugs with novel mechanisms of action. Endophytes have established a reputation as a source of structurally novel secondary metabolites with a wide range of biological activities. In the present study, we explore the antibacterial potential of endophytic fungi isolated from different tissues of Terminalia mantaly, Terminalia catappa, and Cananga odorata. The crude ethyl acetate extracts of 56 different endophytic fungi were screened against seven bacterial strains using the broth microdilution method. The antibacterial modes of action of the most active extracts (04) were evaluated using E. coli ATCC 25922 and H. influenzae ATCC 49247 strains. Both the DPPH and FRAP assays were used to investigate their antioxidant activity, and their cytotoxicity against the Vero cell line was evaluated using the MTT assay. Out of the 56 crude extracts tested, about 13% were considered very active, 66% partially active, and 21% nonactive against all tested bacterial strains with MIC values ranging from 0.32mug/mL to 25mug/mL. The four more potent extracts (MIC 100mug/mL). Results from this investigation demonstrated that endophytes from Cameroonian medicinal plants might content potent antibacterial metabolites. The bioguided fractionation of these potent extracts is ongoing to isolate and characterise potential active ingredients. Copyright © 2021 Michele Ines Kanko Mbekou et al

Identification of 3,3'-O-dimethylellagic acid and apigenin as the main antiplasmodial constituents of Endodesmia calophylloides Benth and Hymenostegia afzelii (Oliver.) Harms

Keumoe R, Koffi JG, Dize D, et al. Identification of 3,3'-O-dimethylellagic acid and apigenin as the main antiplasmodial constituents of Endodesmia calophylloides Benth and Hymenostegia afzelii (Oliver.) Harms. BMC complementary medicine and therapies. 2021;21(1): 180.BACKGROUND: Endodesmia calophylloides and Hymenostegia afzelii belong to the Guttiferae and Caesalpiniaceae plant families with known uses in African ethno-medicine to treat malaria and several other diseases. This study aimed at identifying antiplasmodial natural products from selected crude extracts from H. afzelii and E. calophylloides and to assess their cytotoxicity.; METHODS: The extracts from H. afzelii and E. calophylloides were subjected to bioassay-guided fractionation to identify antiplasmodial compounds. The hydroethanol and methanol stem bark crude extracts, fractions and isolated compounds were assessed for antiplasmodial activity against the chloroquine-sensitive 3D7 and multi-drug resistant Dd2 strains of Plasmodium falciparum using the SYBR green I fluorescence-based microdilution assay. Cytotoxicity of active extracts, fractions and compounds was determined on African green monkey normal kidney Vero and murine macrophage Raw 264.7 cell lines using the Resazurin-based viability assay.; RESULTS: The hydroethanolic extract of H. afzelii stem bark (HasbHE) and the methanolic extract of E. calophylloides stem bark (EcsbM) exhibited the highest potency against both Pf3D7 (EC50 values of 3.32±0.15mug/mL and 7.40±0.19mug/mL, respectively) and PfDd2 (EC50 of 3.08±0.21mug/mL and 7.48±0.07mug/mL, respectively) strains. Both extracts showed high selectivity toward Plasmodium parasites (SI>13). The biological activity-guided fractionation led to the identification of five compounds (Compounds 1-5) from HasbHE and one compound (Compound 6) from EcsbM. Of these, Compound 1 corresponding to apigenin (EC50 Pf3D7, of 19.01±0.72muM and EC50 PfDd2 of 16.39±0.52muM), and Compound 6 corresponding to 3,3'-O-dimethylellagic acid (EC50 Pf3D7 of 4.27±0.05muM and EC50 PfDd2 of 1.36±0.47muM) displayed the highest antiplasmodial activities. Interestingly, both compounds exhibited negligible cytotoxicity against both Vero and Raw 264.7 cell lines with selectivity indices greater than 9.; CONCLUSIONS: This study led to the identification of two potent antiplasmodial natural compounds, 3,3'-O-dimethylellagic acid and apigenin that could serve as starting points for further antimalarial drug discovery

Anti-inflammatory, Antinociceptive, and Toxicological Properties of Uvaria comperei Stem Crude Extract and Fractions

The present study was carried out to investigate the anti-inflammatory activity of a methanolic extract and fractions of Uvaria comperei stems. The crude extract was obtained by maceration of the powder in methanol and fractions by vacuum chromatography from the methanolic extract. To study the anti-inflammatory activity in vitro, red blood cell lysis inhibition assay and albumin denaturation inhibition were performed, while in vivo measurements of carrageenan-induced paw oedema and formalin-induced pain in albino mice were performed. Acute toxicity and cytotoxicity studies of the fraction F2 were performed, as well as its HPLC, and some biochemical parameters were quantified. Uvaria comperei crude extract (UCCE) at 250 and 500 μg/mL completely inhibited albumin denaturation, while decreasing 75.5% of heat blood cell lysis at 500 μg/mL. The fractions 128-136 (F3), 10-11 (F1), and 56-62 (F2) at 500 μg/mL displayed a significant anti-inflammatory activity with percentages of inhibition of 60.5, 67.4, and 100%, respectively. Administration of fraction F2 (25, 50, and 100 mg/kg, p.o.) produced a dose-dependent inhibition of formalin-induced pain of 60.2% at 50 mg/kg in the neurogenic phase (p < 0:05) and 70.2% at 25 mg/kg in the inflammatory phase (p < 0:05). Similarly, the time-dependent increase in carrageenan-induced paw circumference induced by carrageenan was inhibited by pretreatment with F2: 50% of inhibition at 25 mg/kg after 30 min (p < 0:05) and 96.5% inhibition at 25 mg/kg after 6 h (p < 0:05). In this research, the fraction F2 presented its maximum analgesic property at 50 mg/kg, while it presented the highest anti-inflammatory property at 25 mg/kg. The oral lethal median dose (LD50) of F2 was determined to be greater than 2000 mg/kg; further low cytotoxicity in RAW cells was also observed. Overall, this work shows that the methanolic crude extract and fractions, mainly F2, of Uvaria comperei stem have interesting anti-inflammatory properties

Bioguided antiplasmodial isolation of six new labdane-type diterpenoids from the stem bark of Croton sylvaticus Hochst. Ex. Krauss

Gouni CD, Fongang YSF, Dize D, et al. Bioguided antiplasmodial isolation of six new labdane-type diterpenoids from the stem bark of Croton sylvaticus Hochst. Ex. Krauss. Phytochemistry Letters. 2024;59:92-100.The CH2Cl2-MeOH (1:1, v/v) extract of Croton sylvaticus stem bark selectively exhibited good antiplasmodial activity during preliminary screening against the multidrug-resistant (Dd2) and chloroquine sensitive (3D7) strains of Plasmodium falciparum with IC50 values of 10.57 and 18.47 μg/mL, respectively. After fractionation, the fractions exhibited moderate to good activity with IC50 values ranging from 4.31 to 25.49 μg/mL. The purification of these fractions led to the isolation of six new labdane-type diterpenoids named sylvacrotonins Asingle bondF (1single bond6), alongside seven known compounds (7single bond13). Their structures were determined based on the analysis of their NMR and MS data. The isolated compounds were assessed in vitro for their antiplasmodial activity against Pf3D7 and PfDd2. The new labdane-type diterpenoids showed moderate antiplasmodial activity against the two P. falciparum strains, with compound 6 being the most active, with IC50 values of 11.26 and 21.80 μg/mL against PfDd2 and Pf3D7, respectively. Cytotoxic assays were performed on African green monkey kidney Vero cells to ensure that the obtained activity was specific to the parasites. Interestingly, all the tested extracts, fractions, and isolated compounds showed acceptable selectivity (SI > 10) against both Plasmodium strains, except fractions CSB-E (SI = 3.93) and CSB-C (SI = 9.22) against Pf3D7. Globally, with resistance indexes (RIs) lower than 1, all the tested samples were found to be more active against multidrug-resistant (PfDd2) than sensitive (Pf3D7) strains. Furthermore, all the isolated compounds exhibited cell cytotoxicity in the normal Vero cell line. The results from this study confirm the use of C. sylvaticus in malaria-endemic countries for its management and suggest that further lead-optimization studies on hit compounds could drive to the identification of potential lead molecules for antimalarial control and eradication

New lignan glycosides from Justicia secunda Vahl (Acanthaceae) with antimicrobial and antiparasitic properties

Three new lignan glucosides, namely, justisecundosides A (1), B (2a), and C (2b), were isolated from the whole plant of Justicia secunda together with seven known compounds (3−9). Their structures were established based on a comprehensive analysis of HR-ESI-MS, IR, UV, and CD, in conjunction with their 1D and 2D-NMR data. A putative biogenetic pathway of compounds 1−2a,b from coniferyl alcohol was proposed. In addition, the antimicrobialactivities of the extract, fractions, and some isolated compounds were assessed against multiresistant bacterial and fungal strains. Furthermore, the antiplasmodial, antileishmanial, and antitrypanosomal activities were assessed against the sensitive (3D7) and multidrug-resistant (Dd2) strains of P. falciparum, promastigote and bloodstream forms of L. donovani, and Trypanosoma brucei, respectively. Compound 4 exhibited moderate antibacterial activity against Staphylococcus aureus SA RN 46003 with a MIC value of 62.5 μg/mL. Besides, compound 6 demonstrated a very good activity against sensitive (IC50 Pf3D7: 0.81 μg/mL) and multidrug-resistant (IC50 PfDd2: 14.61 μg/mL) strains of P. falciparum while compound 4 displayed good antitrypanosomal activity (IC50: 1.19 μg/mL). Also, compound 1 was the most active on the promastigote form of L. donovani with an IC50 of 13.02 μg/mL

Constituents of Peperomia vulcanica Baker & C. H. Wright (Piperaceae) with antiparasitic activity

Chouna HSD, Bankeu JJK, Fongang YSF, et al. Constituents of Peperomia vulcanica Baker &amp; C. H. Wright (Piperaceae) with antiparasitic activity. PHYTOCHEMISTRY LETTERS. 2021;41:14-20.The investigation of the CH2Cl2-MeOH (1:1) extract of Peperomia vulcanica which showed antileishmanial activity during preliminary screening led to the isolation of two previously unknown compounds named peperolignan (1) and peperotannin (2) along with 13 known compounds. Their structures were determined on the basis of their spectroscopic data. The isolated compounds were assessed in vitro for their antileishmanial and antiplasmodial activities against Leishmania donovani 1S (MHOM/SD/62/1S) promastigotes and the Plasmodium falciparum chloroquine-sensitive 3D7 strain (Pf3D7), respectively. They were also assessed for their cytotoxicity on Raw 264.7 macrophage cells. The mixture of 4-hydroxy-2[(3,4-methylenedioxyphenyl)nonanoyl)cyclo-hexan-1,3-dione and 4-hydroxy-2[(3,4-methylenedioxyphenyl) undecanoyl] cyclo-hexane-1,3-dione (10a and 10b) exhibited potent antiplasmodial activity (IC50 = 0.35 mu g/mL) with selectivity index higher than 10-fold (SI = 63.4) and moderate leishmanicidal activity (IC50 = 12.17 mu g/mL) with very low selectivity index (SI = 1.82). The obtained results could provide an extent of validation to the traditional uses of Peperomia vulcanica for the treatment of malaria in endemic areas

Preliminary Structure&ndash;Activity Relationship Study of the MMV Pathogen Box Compound MMV675968 (2,4-Diaminoquinazoline) Unveils Novel Inhibitors of Trypanosoma brucei brucei

New drugs are urgently needed for the treatment of human African trypanosomiasis (HAT). In line with our quest for novel inhibitors of trypanosomes, a small library of analogs of the antitrypanosomal hit (MMV675968) available at MMV as solid materials was screened for antitrypanosomal activity. In silico exploration of two potent antitrypanosomal structural analogs (7-MMV1578647 and 10-MMV1578445) as inhibitors of dihydrofolate reductase (DHFR) was achieved, together with elucidation of other antitrypanosomal modes of action. In addition, they were assessed in vitro for tentative inhibition of DHFR in a crude trypanosome extract. Their ADMET properties were also predicted using dedicated software. Overall, the two diaminoquinazoline analogs displayed approximately 40-fold and 60-fold more potency and selectivity in vitro than the parent hit, respectively (MMV1578445 (10): IC50 = 0.045 &micro;M, SI = 1737; MMV1578467 (7): IC50 = 0.06 &micro;M; SI = 412). Analogs 7 and 10 were also strong binders of the DHFR enzyme in silico, in all their accessible protonation states, and interacted with key DHFR ligand recognition residues Val32, Asp54, and Ile160. They also exhibited significant activity against trypanosome protein isolate. MMV1578445 (10) portrayed fast and irreversible trypanosome growth arrest between 4&ndash;72 h at IC99. Analogs 7 and 10 induced in vitro ferric iron reduction and DNA fragmentation or apoptosis induction, respectively. The two potent analogs endowed with predicted suitable physicochemical and ADMET properties are good candidates for further deciphering their potential as starting points for new drug development for HAT

Bio-guided isolation of anti-leishmanial natural products from Diospyros gracilescens L. (Ebenaceae)

Njanpa CAN, Wouamba SCN, Yamthe LRT, et al. Bio-guided isolation of anti-leishmanial natural products from Diospyros gracilescens L. (Ebenaceae). BMC Complementary Medicine and Therapies. 2021;21(1): 106.Background Plants represent an intricate and innovative source for the discovery of novel therapeutic remedies for the management of infectious diseases. The current study aimed at discovering new inhibitors of Leishmania spp., using anti-leishmanial activity-guided investigation approach of extracts from Diospyros gracilescens Gurke (1911) (Ebenaceae), targeting the extracellular (promastigotes) and intracellular (amastigotes) forms of Leishmania donovani. Methods The plant extracts were prepared by maceration using H(2)0: EtOH (30:70, v/v) and further fractionated using a bio-guided approach. Different concentrations of D. gracilescens extracts, fractions and isolated compounds were tested in triplicate against L. donovani promastigotes and amastigotes in vitro. The antileishmanial potency and cytotoxicity on RAW 264.7 cells were determined using the resazurin colorimetric assay. The time kill kinetic profile of the most active sample was also investigated. The structures of all compounds were elucidated on the basis of extensive spectroscopic analyses, including 1D and 2D NMR, and HR-ESI-MS and by comparison of their data with those reported in the literature. Results The hydroethanolic crude extract of D. gracilescens trunk showed the most potent antileishmanial activity (IC50 = 5.84 mu g/mL). Further fractionation of this extract led to four (4) fractions of which, the hexane fraction showed the most potent activity (IC50 = 0.79 mu g/mL), and seven (07) compounds that exhibited moderate potency (IC50 = 13.69-241.71 mu M) against L. donovani. Compound 1-deoxyinositol (7) inhibited the promastigote and amastigote forms of L. donovani with IC50 values of 241.71 mu M and 120 mu M respectively and also showed the highest selectivity against L. donovani promastigotes (SI > 5.04). To the best of our knowledge, the antileishmanial activity of this compound is being reported here for the first time. The promising hexane fraction showed significant inhibition of parasites growth at different concentrations, but with no evidence of cidal effect over an exposure period of 120 h. Conclusions The results obtained indicated that the hydroethanolic extract from the D. gracilescens trunk and the derived hexane fraction have very potent inhibitory effect on cultivated promastigotes and amastigotes of L. donovani parasite. The isolated compounds showed a lesser extent of potency and selectivity. However, further structure-activity-relationship studies of 1-deoxyinositol could lead to more potent and selective hit derivatives of interest for detailed drug discovery program against visceral leishmaniasis