Isolation and antibacterial activity of anomanol B and other secondary metabolites from the stem bark of Anonidium mannii (Annonaceae).

A new Lanosta-7,9(11),22-trien-3,15,20-triol named Anomanol B 1, together with five known compounds: manniindole 2, arborinine 3, polycarpol 4, 8,9-dimethoxyphenanthridin-6(5H)-one 5 and 3-O-ß-D-glucopyranosyl-ß-sitosterol 6 were isolated from the stem bark extract of Anonidium mannii by routine chromatography techniques. 8,9-dimethoxyphenanthridin-6(5H)-one 5, was reported from natural origin for the first time. The structures of the compounds were established by comprehensive elucidation of spectroscopic data and by comparison with literature data. Evaluation of the isolates on Gram-negative bacteria such as Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Providencia stuartii, and Pseudomonas aeruginosa showed that, compound 1 had weak antibacterial activity with minimal inhibitory concentrations (MIC) varying from 128 to 256 µg/mL. Compounds 3, 5, and 6 exhibited moderate to weak activity with MIC of 32 to 128 µg/mL and 64 to 256 µg/mL compared to the reference drug chloramphenicol which inhibited the growth of all studied bacteria with MIC values of 16 to 64 µg/mL.

The Effects of Tormentic Acid and Extracts from Callistemon citrinus on Candida albicans and Candida tropicalis Growth and Inhibition of Ergosterol Biosynthesis in Candida albicans.

Candida albicans and Candida tropicalis are the leading causes of human fungal infections worldwide. There is an increase in resistance of Candida pathogens to existing antifungal drugs leading to a need to find new sources of antifungal agents. Tormentic acid has been isolated from different plants including Callistemon citrinus and has been found to possess antimicrobial properties, including antifungal activity. The study aimed to determine the effects of tormentic and extracts from C. citrinus on C. albicans and C. tropicalis and a possible mode of action. The extracts and tormentic acid were screened for antifungal activity using the broth microdilution method. The growth of both species was inhibited by the extracts, and C. albicans was more susceptible to the extract compared to C. tropicalis. The growth of C. albicans was inhibited by 80% at 100 µg/ml of both the DCM: methanol extract and the ethanol: water extract. Tormentic acid reduced the growth of C. albicans by 72% at 100 µg/ml. The effects of the extracts and tormentic acid on ergosterol content in C. albicans were determined using a UV/Vis scanning spectrophotometer. At concentrations of tormentic acid of 25 µg/ml, 50 µg/ml, 100 µg/ml, and 200 µg/ml, the content of ergosterol was decreased by 22%, 36%, 48%, and 78%, respectively. Similarly, the DCM: methanol extract at 100 µg/ml and 200 µg/ml decreased the content by 78% and 88%, respectively. A dose-dependent decrease in ergosterol content was observed in cells exposed to miconazole with a 25 µg/ml concentration causing a 100% decrease in ergosterol content. Therefore, tormentic acid inhibits the synthesis of ergosterol in C. albicans. Modifications of the structure of tormentic acid to increase its antifungal potency may be explored in further studies.

Antibiofilm Activity of Extract and a Compound Isolated from Triumfetta welwitschii against Pseudomonas aeruginosa.

Triumfetta welwitschii has been used as a traditional medicine in Africa. It is documented as a rich source of phytochemicals with antibacterial activities. To further explore the antibacterial potential of these phytochemical components, the phytochemical profile of the dichloromethane: methanol leaf extract from T. welwitschii was investigated using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Compounds were isolated from the extract using column chromatography and thin-layer chromatography. Compound B1 was isolated from the fraction eluted by 90 hexane:10 ethyl acetate using column chromatography. The antibacterial activity of B1 against Pseudomonas aeruginosa was evaluated in vitro using the broth microdilution method and the iodonitrotetrazolium (INT) colorimetric assay. The antibiofilm activities of the extract and B1 against P. aeruginosa were determined by quantifying the biofilms using crystal violet. The effect of the extract and B1 on capsular polysaccharide and extracellular DNA content of biofilm formed by P. aeruginosa was determined using phenol-sulphuric acid and propidium iodide, respectively. A total of 28 peaks were detected and identified using UPLC-MS/MS. The three most abundant phytochemicals identified were catechin, umbelliferone, and a luteolin derivative. B1 showed antibacterial activity against P. aeruginosa with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) value of 25 µg/ml. Only 38% and 6% of the biofilms were formed in the presence of the extract and B1, respectively. The extract and B1 reduced the capsular polysaccharide content in biofilms formed in P. aeruginosa by 40% and 65%, respectively. The extract and B1 significantly reduced the extracellular DNA content of biofilms by 29% and 72%, respectively. The results of this study provide evidence of the antibacterial and antibiofilm activities of B1 and leaf extracts from T. welwitschii. Future work should identify the chemical structure of B1 using nuclear magnetic resonance and mass spectrometry.

Isolation and Antimicrobial Activities of Phytochemicals from Parinari curatellifolia (Chrysobalanaceae).

The widespread use of antimicrobial agents to treat infectious diseases has led to the emergence of antibiotic resistant pathogens. Plants have played a central role in combating many ailments in humans, and Parinari curatellifolia has been used for medicinal purposes. Seven extracts from P. curatellifolia leaves were prepared using serial exhaustive extraction of nonpolar to polar solvents. The microbroth dilution method was used to evaluate antimicrobial bioactivities of extracts. Five of the extracts were significantly active against at least one test microbe. Mycobacterium smegmatis was the most susceptible to most extracts. The methanol and ethanol extracts were the most active against M. smegmatis with an MIC of 25 µg/mL. The hexane extract was the most active against Candida krusei with an MIC of 25 µg/mL. None of the extracts significantly inhibited growth of Klebsiella pneumoniae and Staphylococcus aureus. Active extracts were selected for fractionation and isolation of pure compounds using gradient elution column chromatography. TLC analyses was carried out for pooling fractions of similar profiles. A total of 43 pools were obtained from 428 fractions. Pools 7 and 10 were selected for further isolation of single compounds. Four compounds, Pc4963r, Pc4962w, Pc6978p, and Pc6978o, were isolated. Evaluation of antimicrobial activities of Pc4963r, Pc4962w, and Pc6978p showed that the compounds were most active against C. krusei with MFC values ranging from 50 to 100 µg/mL. Only Pc6978p was shown to be pure. Using spectroscopic analyses, the structure of Pc6978p was determined to be ß-sitosterol. The antifungal effects of ß-sitosterol were evaluated against C. krusei in vitro and on fabrics. Results showed that ß-sitosterol reduced the growth of C. krusei attached to Mendy fabric by 83%. Therefore, P. curatellifolia can be a source of lead compounds for prospective development of novel antimicrobial agents. Further work needs to be done to improve the antifungal activity of the isolated compound using quantitative structure-activity relationships.

The Effects of Combining Cancer Drugs with Compounds Isolated from Combretum zeyheri Sond. and Combretum platypetalum Welw. ex M.A. Lawson (Combretaceae) on the Viability of Jurkat T Cells and HL-60 Cells.

Combretum zeyheri and Combretum platypetalum have been shown to have anticancer, antibacterial, antituberculosis, and antifungal effects in both in vivo and in vitro studies. This study sought to evaluate the antiproliferative effects of compounds isolated from C. zeyheri and C. platypetalum on Jurkat T and HL-60 cancer cell lines in combination with doxorubicin and/or chlorambucil. At their GI50 concentrations, the isolated compounds were combined with the corresponding GI50 of chlorambucil and doxorubicin. The cytotoxic effects of the combined compounds were determined on BALB/c mouse peritoneal cells. All the 4 isolated compounds had significant cytotoxic effects on Jurkat T cells. Compounds CP 404 (1), CP 409 (2), CZ 453 (3), and CZ 455 (4) had GI50s on Jurkat T cells of 3.98, 19.33, 6.82, and 20.28 µg/ml, respectively. CP 404 (1), CP 409 (2), CZ 453 (3), and CZ 455 (4) showed GI50s of 14.18, 28.69, 29.87, and 16.46 µg/ml on HL-60 cancer cell lines, respectively. The most potent combination against Jurkat T cells was found to be CP 404 (1) and chlorambucil. This combination showed no cytotoxic effects when tested on BALB/c mouse peritoneal cells. It was concluded that the compounds extracted from C. zeyheri and C. platypetalum inhibit the growth of Jurkat T cells in vitro. The combination of the compounds with anticancer drugs enhanced their anticancer effects. The combination of CP 404 (1) and chlorambucil was found not to be toxic to normal mammalian cells. Therefore, CP 404 (1), 3-O-ß-L-rrhamnopyranosyl-5,7,3'4',5'-pentahydroxyflavone, has the potential to be a source of lead compounds that can be developed for anticancer therapy. Further structure-activity relationship studies on this compound are warranted.

A phenanthridin-6(5H)-one derivative and a lanostane-type triterpene with antibacterial properties from Anonidium mannii (Oliv). Engl. & Diels (Annonaceae).

The chemical investigation of Anonidium mannii root extract by column chromatography techniques led to the isolation of eight compounds among which two previously unreported compounds; a lanostane-type triterpene, lanosta-7,9(11),23-triene-3ß,15α-diol 1 and an alkaloid, 9-hydroxy-8-methoxyphenanthridin-6(5H)-one 2 along with six known compounds: lanosta-7,9(11),24-triene-3ß,21-diol 3, oxoanolobine 4, 3, 4-dihydroxybenzoic acid 5, stigmasterol 6, ß-sitosterol 7 and 3-O-ß-D-glucopyranosyl-ß-stigmasterol 8. Their structures were established from spectral data, mainly HR-ESIMS, 1 D and 2 D NMR and by comparison with literature data. The crude root and stem bark extracts (AMR and AMB) and the isolated compounds (1-8) were tested against nine Gram-negative bacteria using rapid p-iodonitrotetrazolium chloride ≥97% (INT) microdilution technique. It was found that AMR, AMB and compound 5 were active against the nine tested bacteria with MIC values ranging from 64 to 1024 µg/mL. Compounds 1-4 had selective antibacterial activities whilst 6-8 were not active.

Ethnomedicinal uses, phytochemistry, and pharmacology of the genus Vepris (Rutaceae): A review.

ETHNOPHARMACOLOGICAL RELEVANCE: Species of the genus Vepris are used in traditional African pharmacopeia for the treatment of various conditions, including chronic diseases and other parasitic. Further uses are against whooping cough and colic in children and as an antidote against snakebite. Data presented will enable the interested scientists to work on this genus applying the so-called "ethnopharmacologic approach", which may lead towards the discovery of the effective, safe plant medicinal products. AIM OF THE REVIEW: This review article aims to collate and analyse the available information on the traditional uses, phytochemistry, pharmacology, and toxicological aspects of Vepris species in order to explore the trends and perspectives for further studies. METHODOLOGY: The present review paper collected the literature published prior to August 2020 on the ethnomedicinal uses, phytochemistry, and pharmacology of the genus Vepris. The available information about the genus Vepris was collected via Google Books, Google Scholar, PubMed, ScienceDirect, SciFinder, Web of Science, and other internet sources. The Global Biodiversity Information Facility (www.gbif.org), Plants of the world online (www.plantsoftheworldonline.org), and The Plant List (www.theplantlist.org) databases were used to verify the scientific names and provide distribution information of Vepris species. RESULTS: Comprehensive analysis of the literature provided information on ethnopharmacological uses of 30 species out of 83 members in the genus. A total of 213 compounds - predominantly alkaloids - were reported together with results from antioxidant, cytotoxic, antimicrobial, antiplasmodial, antitrypanosomal, antileishmanial, antidiabetic, antipyretic, analgesic, insect antifeedant, and toxicity assays. Arborinine (49) and skimmianine (4) isolated from the leaves of V. trichocarpa were tested toxic in rat skeletal myoblast cell line L6, a stable skeletal muscle progenitor cell line, while the leaves of V. heterophylla, the stem bark of V. louisii, and the roots of V. uguenensis were shown to be toxic against model organisms T. castaneum (Tenebrionidae), H. bakeri (Trychostrongylidae), and M. domestica (Muscidae), respectively. In addition, 6,7-methylenedioxy-5-hydroxy-8-methoxy-dictamnine (40) isolated from the leaves of a combined sample of V. renieri + V. suaveolens displayed an extremely low IC50 of 0.67 µM against the normal fibroblastic lung cell line MRC-5 indicating high toxicity. Thus, medical use of these plant parts, as well of the stem bark of V. verdoorniana used locally in poison fishing, should be avoided if alternative treatments exist. Furthermore, a good number of significantly in vitro bioactive compounds have been reported from the genus Vepris: against malaria and against microbial infections. CONCLUSIONS: Various Vepris species were found to be used in traditional African pharmacopeia. However, few of these species were studied for their bioactive chemical constituents with even fewer bioassay-guided isolation studies being reported. Moreover, detailed pharmacological studies in animal models to explore their mode of action were not reported. Therefore, future studies should focus on these aspects. In addition, we would like to recommend further research on some significantly bioactive crude extracts that were identified in this review: V. leandriana; V. lanceolata; V. nobilis; and V. trichocarpa, as well as those plants reported to be used against chronic diseases.

Steroidal saponins from Raphia vinifera and their cytotoxic activity.

Phytochemical analysis of the fruits of Raphia vinifera led to the isolation of four new steroidal saponins (1-4), along with six known secondary metabolites (6-10). The structures of the isolated compounds were determined based on the analyses of NMR and mass spectrometric data, and chemical degradation reactions. Among the compounds tested, 1 and 4 showed the most promising cytotoxic activity against the drug-sensitive CCRF-CEM leukemia cell lines, with IC50 values of 3.55 µM and 7.14 µM, respectively.

A new isoflavonol and other constituents from Cameroonian propolis and evaluation of their anti-inflammatory, antifungal and antioxidant potential.

Propolis is rich in diverse bioactive compounds. Propolis samples were collected from three localities of Cameroon and used in the study. Column chromatography separation of propolis MeOH:DCM (50:50) extracts yielded a new isoflavonol, 2-hydroxy-8-prenylbiochanin A (1) alongside 2',3'-dihydroxypropyltetraeicosanoate (2) and triacontyl p-coumarate (3) isolated from propolis for first time together with seven compounds: ß-amyrine (4), oleanolic acid (5), ß-amyrine acetate (6), lupeol (7), betulinic acid (8), lupeol acetate (9) and lupenone (10). These compounds were tested for their inhibitory effect on oxidative burst where intracellular reactive oxygen species (ROS) were produced from zymosan stimulated human whole blood phagocytes and on production of nitric oxide (NO) from lipopolysaccharide (LPS) stimulated J774.2 mouse macrophages. The cytotoxicity of these compounds was evaluated on NIH-3 T3 normal mouse fibroblast cells, antiradical potential on 2,2-diphenyl-1-picrylhydrazylhydrazyl (DPPH·) as well as their anti-yeast potential on four selected candida species. Compound 1 showed higher NO inhibition (IC50 = 23.3 ± 0.3 µg/mL) than standard compound L-NMMA (IC50 = 24.2 ± 0.8 µg/mL). Higher ROS inhibition was shown by compounds 6 (IC50 = 4.3 ± 0.3 µg/mL) and 9 (IC50 = 1.1 ± 0.1 µg/mL) than Ibuprofen (IC50 = 11.2 ± 1.9 µg/mL). Furthermore, compound 1 displayed moderate level of cytotoxicity on NIH-3 T3 cells, with IC50 = 5.8 ± 0.3 µg/mL compared to the cyclohexamide IC50 = 0.13 ± 0.02 µg/mL. Compound 3 showed lower antifungal activity on Candida krusei and Candida glabrata, MIC of 125 µg/mL on each strain compared to 50 µg/mL for fuconazole. The extracts showed low antifungal activities ranging from 250 to 500 µg/mL on C. albicans, C. krusei and C. glabrata and the values of MIC on Candida parapsilosis were 500 µg/mL and above. DPPH* scavenging activity was exhibited by compounds 1 (IC50 = 15.653 ± 0.335 µg/mL) and 3 (IC50 = 89.077 ± 24.875 µg/mL) compared to Vitamin C (IC50 = 3.343 ± 0.271 µg/mL) while extracts showed moderate antiradical activities with IC50 values ranging from 309.31 ± 2.465 to 635.52 ± 11.05 µg/mL. These results indicate that compounds 1, 6 and 9 are potent anti-inflammatory drug candidates while 1 and 3 could be potent antioxidant drugs.