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1.
Nat Prod Res ; : 1-6, 2024 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-38684042

RESUMEN

The methanol stem bark extract of A. boonei and methanol seed extract of P. nitida, were subjected to purification using chromatographic techniques. A. boonei yielded loganic acid (1), sweroside (2) and secoxyloganin (3), while P. nitida afforded (1), akuammidine (4), akuammicine (5) and alstonine (6). The structures of the compounds were elucidated based on their nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS) profiles and comparison with literature data. The antibacterial activities of the compounds were evaluated using the disc diffusion assay with chloramphenicol as the positive control. Alstonine (6) demonstrated weak activity against Pseudomonas aeruginosa and Streptococcus agalactiae with zones of inhibition of 9.3 ± 0.6 and 10.0 ± 0.0 mm, respectively. This is the first report of sweroside (2) and secoxyloganin (3) in A. boonei.

2.
Front Pharmacol ; 15: 1338333, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38482058

RESUMEN

Diabetes remains an important disease worldwide with about 500 million patients globally. In tropical Africa, Morus mesozygia is traditionally used in the treatment of diabetes. Biological and phytochemical investigation of the root bark extracts of the plant led to the isolation of a new prenylated arylbenzofuran named 7-(3-hydroxy-3-methylbutyl)moracin M (1) and two congeners, moracins P (2) and M (3). When compared to acarbose (IC50 = 486 µM), all the isolated compounds are better inhibitors of α-glucosidase with in vitro IC50 values of 16.9, 16.6, and 40.9 µM, respectively. However, they were not active against α-amylase. The compounds also demonstrated moderate inhibition of dipeptidyl peptidase-4 (DPP4). Based on in silico docking studies, all isolates (1, 2, and 3) exhibit binding affinities of -8.7, -9.5, and -8.5 kcal/mol, respectively against α-glucosidase enzyme (PDB: 3AJ7). They are stabilized within the α-glucosidase active site through hydrogen bonds, pi interactions, and hydrophobic interactions. This study provides scientific support for the traditional use of Morus mesozygia in the treatment of diabetes as well as adding to the repository of α-glucosidase inhibitory agents.

3.
Fitoterapia ; 175: 105904, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38508498

RESUMEN

Three novel derivatives of microporenic acid, microporenic acids H-J, were identified from submerged cultures of a Lentinus species obtained from a basidiome collected during a field trip in the tropical rainforest in Western Kenya. Their structures were elucidated via HR-ESIMS spectra and 1D/2D NMR spectroscopic analyses, as well as by comparison with known derivatives. Applying biofilm assays based on crystal violet staining and confocal microscopy, two of these compounds, microporenic acids H and I, demonstrated the ability to inhibit biofilm formation of the opportunistic pathogen Staphylococcus aureus. Thereby, they were effective in a concentration range that did not affect planktonic growth. Additionally, microporenic acid I enhanced the anti-biofilm activity of the antibiotics vancomycin and gentamicin when used in combination. This opens up possibilities for the use of these compounds in combination therapy to prevent the formation of S. aureus biofilms.


Asunto(s)
Antibacterianos , Biopelículas , Lentinula , Staphylococcus aureus , Biopelículas/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Antibacterianos/farmacología , Antibacterianos/aislamiento & purificación , Estructura Molecular , Lentinula/química , Kenia , Pruebas de Sensibilidad Microbiana , Vancomicina/farmacología , Gentamicinas/farmacología
4.
J Nat Prod ; 86(11): 2457-2467, 2023 11 24.
Artículo en Inglés | MEDLINE | ID: mdl-37910033

RESUMEN

Abundisporin A (1), together with seven previously undescribed drimane sesquiterpenes named abundisporins B-H (2-8), were isolated from a polypore, Abundisporus violaceus MUCL 56355 (Polyporaceae), collected in Kenya. Chemical structures of the isolated compounds were elucidated based on exhaustive 1D and 2D NMR spectroscopic measurements and supported by HRESIMS data. The absolute configurations of the isolated compounds were determined by using Mosher's method for 1-4 and TDDFT-ECD calculations for 4 and 5-8. None of the isolated compounds exhibited significant activities in either antimicrobial or cytotoxicity assays. Notably, all of the tested compounds demonstrated neurotrophic effects, with 1 and 6 significantly increasing outgrowth of neurites when treated with 5 ng/mL NGF.


Asunto(s)
Polyporaceae , Sesquiterpenos , Estructura Molecular , Sesquiterpenos/química , Polyporaceae/química , Proyección Neuronal
5.
Fitoterapia ; 171: 105698, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37802229

RESUMEN

From the leaves and stem bark of the Kenyan medicinal plant Calpurnia aurea subsp. aurea, four previously undescribed quinolizidine alkaloids namely, 2ß-methoxy-13α-O-(2'-pyrrolylcarbonyl) virgiline, 2α-methoxy-13ß-O-(2'-pyrrolylcarbonyl) virgiline, 3α-O-angelate-2ß-hydroxy-13α-O-(2'-pyrrolylcarbonyl) virgiline, 2,3-dehydro-virgiline were isolated together with four known ones. Structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy and mass spectrometry. Their relative configurations were determined by NOESY correlations and literature. The quinolizidine alkaloids were tested against Trichophyton rubrum, Trichophyton interdigitale, Trichophyton benhamiae, Microsporum canis and Nannizzia gypsea, common causative agents of most of the tinea infections in human. All the isolated quinolizidine alkaloids exhibited antidermatophytic activity with MIC ranging from 37.5 µg/ml to 300 µg/ml.


Asunto(s)
Arthrodermataceae , Fabaceae , Plantas Medicinales , Humanos , Alcaloides de Quinolizidina , Kenia , Estructura Molecular , Fabaceae/química
6.
Beilstein J Org Chem ; 19: 1161-1169, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37560136

RESUMEN

Chemical exploration of solid-state cultures of the polypore Fomitopsis carnea afforded two new C31 lanostane-type triterpenoid glycosides, forpiniosides B (1) and C (2) together with two known derivatives, namely 3-epipachymic acid (3) and (3α,25S)-3-O-malonyl-23-oxolanost-8,24(31)-dien-26-oic acid (4). The structures of the isolated compounds were established based on HRESIMS and extensive 1D and 2D NMR experiments. All the isolated compounds were assessed for their antimicrobial and cytotoxic activities. Among the tested compounds, forpinioside B (1) exhibited significant antimicrobial activity against Staphylococcus aureus and Bacillus subtilis at MIC values comparable to gentamycin and oxytetracycline (positive controls), respectively.

7.
J Agric Food Chem ; 71(29): 11094-11103, 2023 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-37440475

RESUMEN

Neurodegenerative diseases are currently posing huge social, economic, and healthcare burdens among the aged populations worldwide with few and only palliative treatment alternatives available. Natural products continue to be a source of a vast array of potent neurotrophic molecules that could be considered as drug design starting points. The present study reports eight new isoindolinone and benzofuranone derivatives, for which we propose the trivial names, hericioic acids A-G (1-7) and hericiofuranoic acid (8), which were isolated from a solid culture (using rice as substrate) of the rare European edible mushroom Hericium flagellum. The chemical structures of these compounds were determined based on extensive 1D and 2D NMR spectroscopy along with HRESIMS analyses. The isolated compounds were assessed for their neurotrophic activity in rat pheochromocytoma cells (PC-12) to promote neurite outgrowth on 5 ng NGF supplementation; all the compounds increased neurite outgrowths, with compounds 3, 4, and 8 exhibiting the strongest effects.


Asunto(s)
Agaricales , Basidiomycota , Ratas , Animales , Agaricales/química , Basidiomycota/química , Hericium , Células PC12 , Neuritas
8.
Antibiotics (Basel) ; 11(8)2022 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-36009941

RESUMEN

In our continued search for biologically active metabolites from cultures of rare Basidiomycota species, we found eight previously undescribed cyathane-xylosides from submerged cultures of Dentipellis fragilis, which were named dentifragilins A-H. In addition, the known cyathane derivatives striatal D and laxitextine A were isolated. All compounds were characterized by high-resolution electrospray ionization mass spectrometry (HR-ESIMS) as well as by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. Several of the compounds exhibited significant activities in standardized cell-based assays for the determination of antimicrobial and cytotoxic effects. The discovery of cyathanes in the genus Dentipellis has chemotaxonomic implications, as this class of diterpenoids has already been shown to be characteristic for mycelial cultures of the related genera Hericium and Laxitextum, which are classified as Dentipellis in the family Hericiaceae.

9.
Phytochemistry ; 198: 113153, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35240134

RESUMEN

From the leaves of Kenyan medicinal plant Bersama abyssinica Subspecies abyssinica, four previously undescribed compounds namely, three bufadienolides, 10ß-formylpaulliniogenin B, 10ß-formylpaulliniogenin A and 1ß-acetoxy-3ß,5ß-dihydroxy-15-methoxy-16,19-dioxobufa-14(15),20,22-trienolide, and a phenolic compound 2,6,4'-trihydroxybenzophenone-4-O-(6‴-cinnamoyl)-ß-D-glucoside were isolated together with four known compounds. The structural elucidation of the compounds was based on 1D and 2D NMR spectroscopy and HRMS data analyses. The relative configurations were defined by NOESY correlations. Cytotoxic activities on L929 and KB3.1 cell lines of the isolated compounds were investigated using MTT assay. The 1ß-acetoxy-3ß,5ß-dihydroxy-15-methoxy-16,19-dioxobufa-14(15),20,22-trienolide showed significant cytotoxic activity against KB3.1 cell lines with IC50 of 3.9 ± 0.99 µM.


Asunto(s)
Antineoplásicos , Bufanólidos , Magnoliopsida , Plantas Medicinales , Bufanólidos/análisis , Bufanólidos/química , Línea Celular Tumoral , Kenia , Magnoliopsida/química , Hojas de la Planta/química
10.
J Agric Food Chem ; 67(31): 8468-8475, 2019 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-31310114

RESUMEN

Fermentation of the fungal strain Skeletocutis sp. originating from Mount Elgon Natural Reserve in Kenya, followed by bioassay guided fractionation led to the isolation of 12 previously undescribed metabolites named skeletocutins A-L (1-5 and 7-13) together with the known tyromycin A (6). Their structures were assigned by NMR spectroscopy complemented by HR-ESIMS. Compounds 1-6 and 11-13 exhibited selective activities against Gram-positive bacteria, while compound 10 weakly inhibited the formation of biofilm of Staphylococcus aureus. The isolated metabolites were also evaluated for inhibition of L-leucine aminopeptidase, since tyromycin A had previously been reported to possess such activities but only showed weak effects. Furthermore, all compounds were tested for antiviral activity against Hepatitis C virus (HCV), and compound 6 moderately inhibited HCV infectivity with an IC50 of 6.6 µM.


Asunto(s)
Antibacterianos/farmacología , Polyporales/química , Madera/microbiología , Antibacterianos/química , Antibacterianos/metabolismo , Antivirales/química , Antivirales/metabolismo , Antivirales/farmacología , Hepacivirus/efectos de los fármacos , Kenia , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Polyporales/crecimiento & desarrollo , Polyporales/aislamiento & purificación , Polyporales/metabolismo
11.
J Nat Prod ; 82(5): 1283-1291, 2019 05 24.
Artículo en Inglés | MEDLINE | ID: mdl-31001977

RESUMEN

During the course of searching for new anti-infective and other biologically active secondary metabolites from Kenyan basidiomycetes, 13 previously undescribed metabolites, (6 R,7 S,10 R)-7,10-epoxy-7,11-dimethyldodec-1-ene-6,11-diol (1) and 12 sesquiterpenes named elgonenes A-L (2-13), and the known compound P-coumaric acid (14) were isolated from a basidiomycete collected in Mount Elgon Natural Reserve. The producing organism represents a new species of the genus Sanghuangporus, which is one of the segregates of the important traditional Asian medicinal mushrooms that were formerly known as the " Inonotus linteus" complex. The structure elucidation of compounds 1-13, based on 2D NMR spectroscopy, high-resolution mass spectrometry, and other spectral methods, and their antibacterial, antifungal, and cytotoxic activities are reported.


Asunto(s)
Agaricales/química , Antiinfecciosos/química , Antiinfecciosos/farmacología , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/farmacología , Basidiomycota/química , Sesquiterpenos/química , Sesquiterpenos/farmacología , África Oriental , Bacterias/efectos de los fármacos , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Fermentación , Hongos/efectos de los fármacos , Humanos , Kenia , Espectroscopía de Resonancia Magnética , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Espectrometría de Masas en Tándem
12.
Phytochemistry ; 132: 95-101, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27745908

RESUMEN

Eight previously undescribed compounds were isolated and characterised from the supernatant and mycelium of a culture of the basidiomycete Favolaschia calocera originating from Kakamega equatorial rainforest in Kenya. These were: 9- oxostrobilurins A, G, K and I and the four monochlorinated calocerins A, B, C and D. The calocerins extend our knowledge of halogenated compounds obtained from natural sources. Four further known compounds were also identified: strobilurin G, favolon, pterulinic acid and 2,3 -dihydro-1-benzoxepin derivative. The four oxostrobilurins exhibited prominent antifungal and cytotoxic activities while the four calocerins only showed cytotoxic activity.


Asunto(s)
Antifúngicos/aislamiento & purificación , Basidiomycota/química , Ácidos Grasos Insaturados/aislamiento & purificación , Hidrocarburos Clorados/aislamiento & purificación , Metacrilatos/aislamiento & purificación , Antifúngicos/química , Antifúngicos/farmacología , Benzofuranos/química , Ensayos de Selección de Medicamentos Antitumorales , Ácidos Grasos Insaturados/química , Ácidos Grasos Insaturados/farmacología , Humanos , Hidrocarburos Clorados/química , Hidrocarburos Clorados/farmacología , Kenia , Metacrilatos/química , Metacrilatos/farmacología , Pruebas de Sensibilidad Microbiana , Oxepinas/química , Estrobilurinas , Triterpenos/química
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