In vitro antiplasmodial and anticancer analyses of endophytic fungal extracts isolated from selected Nigerian medicinal plants.

Ethnomedicinal plants are thought to have better prospects of harboring endophytes that produce natural products with pharmacological activities. This study aimed to investigate the antiplasmodial and anticancer properties of secondary metabolites of endophytic fungi from three medicinal plants. The endophytic fungi included Lasiodiplodia theobromae isolated from Cola acuminata, Curvularia lunata Bv4 isolated from Bambusa vulgaris, and Curvularia lunata Eg7 isolated from Elaeis guineensis. The identification of the fungi was based on the internal transcribed spacer (ITS-rDNA) sequence. The fungi were subjected to solid-state fermentation and the secondary metabolites were extracted with ethyl acetate. In vitro antiplasmodial screening of extracts was performed using the SYBR green I-based fluorescence assay on the chloroquine-resistant Plasmodium falciparum strain DD2. The cytotoxicity of the extracts on human red blood cells and Jurkat (leukemia) cells was assessed using the tetrazolium-based colorimetric MTT assay. Gas chromatography-mass spectrometry (GC-MS) analysis was used to identify the constituents of the fungal extracts. The extract of L. theobromae showed the best antiplasmodial activity against chloroquine-resistant P. falciparum (IC50 = 5.4 µg/mL) and was not harmful to erythrocytes (CC50 > 100 µg/mL). All three fungal extracts showed a weak cytotoxic effect against Jukart cell lines (CC50 > 100 µg/mL). GC-MS analysis of the three endophytic fungal extracts revealed the presence of forty major bioactive compounds, including: oxalic acid, isobutyl nonyl ester, 2,4-di-tert-butylphenol, and hexadecanoic acid, among others. The endophytic fungi from the medicinal plants in this study were promising sources of bioactive compounds that could be further evaluated as novel drugs for the treatment of malaria caused by P. falciparum-resistant strains.

Linking phytochemistry to traditional uses and pharmacology of an underexplored genus - Psydrax: a review.

The genus Psydrax is one of the ethno-medicinally important genera of the Rubiaceae family which has only received a limited scientific attention, despite coming from a pharmacologically and phytochemically important plant family. The genus has found applications in ethnomedical management of diabetes, stomach disorders, inflammations, cardiovascular diseases, epilepsy, wounds, malaria and fever. To unveil knowledge gaps, stimulate research interest and unravel opportunities for drug discovery from the genus Psydrax, we have carried out an extensive review on its traditional applications, phytochemistry and pharmacology for the first time. Literature on these topics was obtained from Google Scholar, Pubmed and ScienceDirect journal articles published from 1788 to September, 2021. Only articles written in English were reviewed. While several species of Pysdrax used in traditional medicine have not been chemically explored for drug discovery, over a hundred secondary metabolites have so far been identified in few species of the genus, and majority of these chemotaxonomic markers are iridoids. Bioactive extracts and some isolated constituents of Psydrax species have shown various in vitro and in vivo pharmacological properties including anti-hyperglycemia, anti-inflammatory, anticonvulsant and antimicrobial, and thus, support some of the ethnomedical uses of the plants. For an evidence-informed application of the genus, Psydrax, in traditional medicine, more ethnobotanical surveys, elaborate in vivo pharmacological assays, in-depth toxicity and holistic phytochemical studies are required to fully exploit more species of the genus prior to future clinical studies. Following documented traditional uses of Psydrax species, the deliberate cultivation of medicinal plants under this genus is recommended for sustainability in medicinal plant utilization.

Newboulasides A and B, two new caffeic acid glycosides from Newbouldia laevis with α-amylase inhibitory activity.

Chemical investigation of the ethanol extract of the leaves of Newbouldia laevis (P. Beauv) led to the isolation of two new caffeic acid glycosides, Newboulasides A (1) and B (2). The structures of these compounds were determined on the basis of extensive spectroscopic methods, including 1D-, 2D-NMR and MS data. The extracts and fractions and the isolated compounds were evaluated for their inhibition of α-amylase enzyme activity. The extract showed inhibition of α-amylase activity with IC50 value of 102.91 µg/mL, while the isolated compounds (1 and 2) exhibited pronounced inhibition with IC50 values of 4.95 and 4.44 µg/mL respectively, comparable to the standard - Acarbose with IC50 value of 4.05 µg/mL. Our findings demonstrated that the inhibition of α-amylase activity may be part of the mechanisms through which N. leavis exhibits antidiabetic effect.

Secondary metabolites of endophytic fungi from Newbouldia laevis and Cassia tora leaves: prospecting for new antimicrobial agents.

AIM: This study tries to prospect for new antimicrobial agents using some Nigerian plants Background: Antimicrobial compounds from fungi endophytes have shown great promise in mitigating the threats of resistant pathogens. OBJECTIVE: The study evaluated the in vitro antimicrobial property of secondary metabolites of endophytic fungi isolated from Newbouldia laevis and Cassia tora leaves. METHODS: Ten endophytic fungi were isolated from the two plants' leaves and later fermented on local rice for 21 days. Thereafter, their secondary metabolites were extracted using ethyl acetate. The antibacterial activity of the extracts on the test organisms were determined using agar diffusion and agar dilution methods, while the bioactive constituents were identified using High performance liquid chromatography coupled to diode array detector. RESULTS: Nine of the crude extracts (NL1, NL3, NL6, NL10, NL12, CT2, CT7, CT9 and CT10) of the fungi isolates inhibited at least one of the microorganisms studied with maximum and minimum Inhibition-Zone-Diameter of 14 mm and 2 mm respectively while CT1 did not inhibit any of the tested microorganisms at tested concentrations. The extracts exhibited good antifungal activity, inhibiting the growth of both C. albicans and Trichophyton tested with an InhibitionZone-Diameter ranging between 4-8 mm and 7-14 mm respectively. The endophytic fungi extracts- CT2 and NL1- exhibited the best antimicrobial activity, inhibiting most of the tested microorganisms. HPLC-DAD analysis of the endophytic fungal extracts identified some classes of compounds such as catechin derivatives, benzoic acid derivatives and apigenin, which were previously reported to have antimicrobial potentials. CONCLUSION: Newbouldia laevis and Cassia tora leaves house endophytic fungi capable of yielding secondary metabolites with potential as anti-infective agents.

Antioxidant, Anti-inflammatory, Analgesic Properties, and Phytochemical Characterization of Stem Bark Extract and Fractions of Anthocleista nobilis.

BACKGROUND: Anthocleista nobilis (Loganiaceae) is used by Mbano people of Imo State, Nigeria, for the treatment of various ailments. OBJECTIVE: The aim of this study is to evaluate the antioxidant, anti-inflammatory, and analgesic properties of the methanol extract, fractions, and subfractions of A. nobilis. MATERIALS AND METHODS: The powdered stem bark was extracted with methanol and sequentially fractionated into n-hexane, ethyl acetate, and butanol fractions. The constituents of the fractions were analyzed using high-pressure liquid chromatography (HPLC), and the components were identified by dereplication. Antioxidant potential of the extracts and fractions was investigated using 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging method. Anti-inflammatory and analgesic activities of the extract and fractions were also investigated using xylene-induced inflammation and acetic acid-induced writhing models, respectively. RESULTS: A total of five compounds isovitexin (Rt = 18.77 min), isovitexin-2''-O-xyl (Rt = 19.68 min), p-Hydroxybenzoic acid (Rt = 11.88 min), Sarasinoside L (Rt = 19.64 min), isovitexin (Rt = 18.77), and apigenin monoglycoside (Rt = 19.64 min) were identified by HPLC analysis and dereplication. The ethyl acetate fraction and subfraction elicited the best anti-inflammatory activity. The ethyl acetate subfraction also inhibited acetic acid-induced pain by 79% and 85.0% at the doses of 100 mg/kg and 200 mg/kg, respectively, which was better than 71.1% and 81.3% observed for diclofenac at similar doses. CONCLUSION: A. nobilis could be a potential source of anti-inflammatory and analgesic lead compounds. SUMMARY: The extract, fractions and subfractions of Anthocleista nobilis were screened or antioxidant, anti-inflammatory and Analgesic properties in vitro and in mice models. Some of the components were identified by dereplication after HPLC analysis. The results demonstrated potent anti-inflammatory and analgesic property of the extracts and fractions. The dereplication analysis also identified vitexin and related compounds. Abbreviation used: HPLC: High performance Liquid Chromatography; VLC: Vacuum Liquid Chromatography; DPPH: 2,2-Diphenyl-1-pycrylhydrazine; SPSS: Statistical Package for the Social Sciences; ROS: Reactive Oxygen Species.

Antiviral activity of Salidroside from the leaves of Nigerian mistletoe (Loranthus micranthus Linn) parasitic on Hevea brasiliensis against respiratory syncytial virus.

Isolated Salidroside from the leaves of Nigerian mistletoe (Loranthus micranthus Linn) parasitic on Hevea brasiliensis was evaluated for its antiviral activity against respiratory syncytial virus. Semi- preparative HPLC separation of the ethyl acetate fraction of the leave extract of Loranthus micranthus Linn parasitic on Hevea brasiliensis led to the isolation of a polyphenol. Using spectroscopic methods (1D and 2D NMR and mass spectroscopic data) as well as by comparison with literature data the structure of the compound was determined as 6-O-galloyl salidroside. The antiviral activity of the isolated compound was evaluated against the respiratory syncytial virus. The isolated Salidroside showed potent inhibition towards a recombinant straining respiratory syncytial virus with Inhibitory Concentration (IC 50) value of 10.3±1.50 µg/mL. The result indicates that Salidroside is an efficient antiviral agent against RSV infection and might be useful for the management of RSV pathogenesis.

In vitro and in vivo antioxidant potentials of Alchornea floribunda leaf extract, fractions and isolated bioactive compounds.

OBJECTIVE: Alchornea floribunda leaves are widely used in ethnomedicine for the management of immuno-inflammatory disorders. We investigated the in vivo and in vitro antioxidant activity of the leaf extract, fractions and isolated compounds of A. floribunda. MATERIALS AND METHODS: The ethyl acetate fraction of the methanol leaf extract was subjected to several chromatographic separations to isolate compounds 1-4. The structures of the isolated compounds were elucidated by a combination of 1D and 2D NMR and mass spectrometry. Oxidative stress was induced with carbon tetrachloride (CCl4). Further analysis on the isolated phenolic compounds were done using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and hydrogen peroxide scavenging activity tests. RESULTS: The ethyl acetate fraction at 200 mg/kg produced significant (p<0.05) elevations of catalase enzyme activity and a significant (p<0.05) reduction in serum malondialdehyde. The chemical investigation of the ethyl acetate fraction led to the isolation of three flavans, (-) cathechin (1), (-) epicathechin (2), (+) epicathechin (3) and a flavanone, 2R, 3R dihydroquercitin (4). In hydrogen peroxide scavenging assay, (-) epicathechin exhibited an EC50 value of 8 µg/ml, similar to the standard ascorbic acid (EC50 = 8 µg/ml). (-) epicathechin showed scavenging of DPPH radical with EC50 value of 19 µg/ml while in the FRAP assay, it had EC50 value of 46 µg/ml which was lower than that of the standard, ascobic acid (EC50 = 66 µg/ml). CONCLUSION: The medicinal uses of A. floribunda may be due to the antioxidant activities of its phenolic compounds.

Mosquito adulticidal activity of the leaf extracts of Spondias mombin L. against Aedes aegypti L. and isolation of active principles.

BACKGROUND & OBJECTIVES: Aedes aegypti is a domestic mosquito and one of the primary vectors for dengue and yellow fever. Since, it is a vector of deadly diseases, its control becomes essential. Medicinal plants may be an alternative to adulticidal agents since they contain rich source of bioactive compounds. This study was designed to determine the adulticidal activity of Spondias mombin leaf methanol crude extract, n-hexane, dichloromethane and ethyl acetate fractions against female adults of Ae. aegypti mosquitoes and isolate active compound(s) responsible for the bioactivity. METHODS: All leaf extract and fractions were evaluated for adulticidal activity against Ae. aegypti mosquitoes. Adult mortality was observed after 24 h of exposure. The dichloromethane fraction was further purified being the most active fraction using silica gel column chromatography and the active compounds were identified with the aid of HPLC and LC-ESI-MS/MS. The LC50 and LC90 were determined by Probit analysis. RESULTS: Dichloromethane fraction was the most effective fraction with LC50 value of 2172.815 µg/ml. Compounds identified were mainly ellagic acid and 1-O-Galloyl-6-O-luteoyl-α-D-glucose. INTERPRETATION & CONCLUSION: The S. mombin leaf extracts and fractions proved to be a strong candidate for a natural, safe and stable adulticide, alternative to synthetic adulticide.

New neolignan glycoside and an unusual benzoyl malic acid derivative from Maytenus senegalensis leaves.

Further investigation of the methanol leaf extract of Maytenus senegalensis led to the isolation of six compounds, including mayselignoside (1) and an unusual benzoyl malic acid derivative, benzoyl R-(+)-malic acid (2). Two known lignan derivatives (+)-lyoniresinol (3) and (-)-isolariciresinol (4), a known neolignan derivative dihydrodehydrodiconiferyl alcohol (5) and the triterpenoid, ß-amyrin (6) were also isolated. The structures of these compounds were elucidated by a combination of 1D and 2D NMR and mass spectroscopy. All compounds were tested for cytotoxicity against mouse lymphoma cell line (L5178Y) and for antimicrobial activity against strains of bacteria and fungi. None of the compounds showed promising cytotoxic and/or antimicrobial activities.

Larvicidal activity of the leaf extracts of Spondias mombin Linn. (Anacardiaceae) from various solvents against malarial, dengue and filarial vector mosquitoes (Diptera: Culicidae).

BACKGROUND & OBJECTIVES: Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus are vector mosquitoes of dengue, malaria, and filariasis, respectively. Since no vaccine is available to treat these diseases, the control of the main mosquito vectors is essential. As conventional insecticides have limited success, plants may be alternative larvicidal agents, since they contain a rich source of bioactive chemicals. The aim of this study was to evaluate the larvicidal activity of methanol crude extract, hexane, dichloromethane, acetone, ethyl acetate and methanol fractions of Spondias mombin leaf against IV instar larvae of dengue, malaria, and lymphatic filariasis vector mosquitoes. METHODS: A total of 25, IV instar larvae of each target mosquito species were exposed to various concentrations (125-1000 ppm) and were assayed in the laboratory by using the protocol of WHO 2005; the LC50 values were determined by Probit analysis. RESULTS: Hexane, dichloromethane and acetone fractions were the most effective against Ae. aegypti with LC50 values of 22.54, 42.13, 45.18 ppm, respectively. Hexane fraction registered the highest activity with LC50 of 92.20 ppm against An. gambiae. It was still hexane fraction that showed better toxicity with LC50 of 326.53 ppm against Cx. quinquefasciatus. CONCLUSION: The Spondias mombin leaf extracts proved to be a strong candidate for a natural, safe and stable mosquito larvicide to be used in population control of Ae. aegypti, An. gambiae and Cx. quinquefasciatus and so may replace the conventional Diclorvos to control malaria, dengue and filariasis in Nigeria.