Chemical constituents of the roots of Kniphofia schimperi and evaluation of their antimicrobial activity.

Kniphofia schimperi is one of the endemic plants of Ethiopia and is widely used for the treatment of microbial infections. However, the biological and phytochemical information pertaining to this plant has not been reported so far. Anticipated by these claims, the chromatographic isolation of the CHCl3/CH3OH (1:1 v/v) extract of the roots of K. schimperi afforded five compounds, viz., knipholone (1), asphodeline (2), ß-sitosterol (3), 9-pentacosenoic acid (4), and nonacosanoic acid (5). The structures of the isolated compounds were identified based on their NMR (1D and 2D) spectral data analysis and comparison with reported literature data. The crude extract and isolated compounds were evaluated for their in vitro antimicrobial activity against four bacterial strains (Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Bacillus cereus) and a fungal strain (Candida albicans) using the agar disk diffusion method. The test samples showed moderate antimicrobial activity, with the highest activity observed for compound 3 (with a zone of growth inhibition of 15.5 ± 0.71 mm) against S. typhimurium.

MnOx-Coffea arabica Husk and Catha edulis Leftover Biochar Nanocomposites for Removal of Methylene Blue from Wastewater.

In this study, we investigated the use of manganese oxide-biochar nanocomposites (MnOx-BNC), synthesized from coffee husk (CH) and khat leftover (KL) for the removal of methylene blue (MB) from wastewater. Pristine biochars of each biomass (CH and KL) as well as their corresponding biochar-based nanocomposites were synthesized by pyrolyzing at 300°C for 1 h. The biochar-based nanocomposites were synthesized by pretreating 25 g of each biomass with 12.5 mmol of KMnO4. To assess the MB removal efficiency, we conducted preliminary tests using 0.2 g of each adsorbent, 20 mL of 20 mg·L-1 MB, pH 7.5, and shaking the mixture at 200 rpm and for 2 h at 25°C. The results showed that the pristine biochar of CH and KL removed 39.08% and 75.26% of MB from aqueous solutions, respectively. However, the MnOx-BNCs removed 99.27% with manganese oxide-coffee husk biochar nanocomposite (MnOx-CHBNC) and 98.20% with manganese oxide-khat leftover biochar nanocomposite (MnOx-KLBNC) of the MB, which are significantly higher than their corresponding pristine biochars. The adsorption process followed the Langmuir isotherm and a pseudo-second-order model, indicating favorable monolayer adsorption. The MnOx-CHBNC and MnOx-KLBNC demonstrated satisfactory removal efficiencies even after three and six cycles of reuse, respectively, indicating their potential effectiveness for alternative use in removing MB from wastewater.

In vitro antimicrobial and antioxidant activities, essential oil composition, and in silico molecular modeling analysis of secondary metabolites from roots of Verbascum sinaiticum.

Verbascum sinaiticum is locally used to treat wound, stomachache, viral infection, cancer, sunstroke fever, abdominal colic, diarrhea, hemorrhage, anthrax, and hepatitis. The objective of this study was to identify the compounds and to evaluate the antimicrobial and antioxidant activity of the extracts and isolated compounds from V. sinaiticum. The 1H-NMR, 13C-NMR, and DEPT-135 were used to elucidate the structures of isolated compounds. Essential oils were extracted by hydrodistillation method and their chemical analyses were performed by GC-MS. The broth microdilution method was used to evaluate the antimicrobial activity. The radical scavenging activity of the extracts and isolated compounds were evaluated using DPPH method. Silica gel column chromatographic separation of root extracts afforded seven known compounds: 3'-(4''-methoxy phenyl)-3'-oxo-propionyl hexadecanoate (1), harpagoside (2), pulverulentoside I (3), scrophuloside B4 (4), scropolioside A (5), scropolioside-D2 (6), and harpagide 6-O-ß-glucoside (7), which are all reported from this species for the first time. The EO extracts from leaves and roots were the most susceptible to Streptococcus agalactiae, with a 2 mg/mL MIC. The EO from roots was effective against Candida albicans and Trichophyton mentagrophytes, with a MIC of 8 mg/mL. The MeOH and CH2Cl2/CH3OH (1:1) root extracts showed the maximum activity against S. epidermidis with MIC values of 0.25 mg/mL. The strongest antibacterial effects were demonstrated against Staphylococcus epidermidis, which exhibited a 0.0625 mg/mL MIC for compound 1. The strongest radical scavenging activity was exhibited by the methanol extract (IC50 = 3.4 µg/mL), and compounds 4, 6, 5, 3, 7, and 2 with IC50 values of 3.2, 3.38, 3.6, 3.8, 4.2, and 4.7 µg/mL, respectively, in comparison with ascorbic acid (IC50 = 1.3 µg/mL). The results of the molecular docking analysis of compounds revealed minimal binding energies range from -38.5 to -43.1 kJ/mol, -33.1 to -42.7 kJ/mol, -34.7 to -39.3.7 kJ/mol, -25.5 to -37.6 kJ/mol against human myeloperoxidase (PDB ID: 1DNU), murA enzyme (PDB ID: 1UAE), human topoisomerase IIß (PDB ID: 4fm9), S. epidermidis FtsZ (PDB number: 4M8I) proteins, respectively. The docking results and the in vitro antibacterial activity are in good agreement. These findings show that the isolated compounds 2-7 can act as potential antioxidants and strong antibacterials against Staphylococcus aureus and S. epidermidis. As a result, V. sinaiticum root extracts have the potential to be effective in treating diseases caused by bacteria and free radicals, as long as further investigation has been suggested for the ultimate decision of this plant's potential candidate.

Phytochemical Screening and Antimicrobial Activity Evaluation of Selected Medicinal Plants in Ethiopia.

Background: The emergence and spread of resistant microbes continue to be a major public health concern. Effective treatment alternatives, particularly from traditionally used medicinal plants, are needed. Objective: The main objective of this study was to conduct phytochemical screening and antimicrobial activity evaluation of selected traditionally used medicinal plants in Ethiopia. Methods: The ethnomedicinal use value frequency index (FI) was used to select twelve medicinal plants. Phytochemical classes of compounds were screened using different standard methods. Anti-microbial activities of plant extracts were evaluated against Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Candida albicans. Minimum inhibitory concentrations were measured using the broth micro-dilution method. The data were analyzed using Statistical Package for the Social Sciences (SPSS) version 21.0 and the findings were presented descriptively and using non parametric one-way ANOVA analysis (Kruskal-Wallis/Ddunn's test). Results: The phytochemical constituents identified were flavonoids, alkaloids, glycosides, phenols, saponins, steroids, and terpenoids, with flavonoids, alkaloids, and phenols being the most abundant. The crude extracts and chloroform fractions of the extracts showed an activity against the tested strains. The crude extract of Thalictrum rhynchocarpum Quart.-Dill. and A.Rich root demonstrated superior activity against all the tested strains with the lowest minimum inhibitory concentrations of 0.48 µg/mL against Staphylococcus aureus and Escherichia coli; 0.98 µg/mL against Klebsiella pneumoniae, Pseudomonas aeruginosa; and 3.90 µg/mL against Candida albicans, which are even better than the reference drug, gentamicin and clotrimazole. Conclusion: The majority of evaluated medicinal plants demonstrated remarkable activity against tested microbial strains, which can be attributed to the presence of secondary metabolites of different classes of compounds. The finding provided scientific evidence for the use of these traditionally used medicinal plants.

Furoquinoline and bisindole alkaloids from the roots of Teclea nobilis and their in-silico molecular docking analysis.

Teclea nobilis is a medicinal plant widely used to treat oral pathogens, gonorrhea, fever, analgesics, asthma, joint pains, pneumonia, and intestinal worms in Ethiopia. Anticipated by these claims, column chromatographic separation of the roots extract of T. nobilis led to the isolation of eight alkaloids (1-8). The structures of the isolated compounds were identified based on their NMR (1D and 2D) spectral data analysis and comparison with reported literature data. In-silico molecular docking analysis of the isolated compounds were performed against Staphylococcus aureus DNA Gyrase (PDB ID: 2XCT) and human topoisomerase IIß DNA (PDB ID: 3QX3) by using AutoDock Vina. ADMET analysis were performed by SwissADME, PreADMET, and OSIRIS Property predictions. The study revealed that the isolated compounds exhibited promising binding affinity to DNA gyrase, especially with compound 5 forms a stable drug-protein complex. Whereas the ADME and drug-likeness analysis revealed that compound 5 is less absorbed from the gastrointestinal tract, crossblood brain barrier and a P-glycoprotein substrate. This indicated that compound 5 could be a good candidate as anticancer agent provided that in vivo analysis done for more confirmation.

Determination of total phenolic content and antioxidant activity of Commiphora mollis (Oliv.) Engl. resin.

In this study, total phenolic contents (TPC) and antioxidant activity of Commiphora mollis (Oliv.) Engl. (Burseraceae) resin were investigated. The resin was extracted using petroleum ether, chloroform, and methanol to give 27.46 ± 0.48, 46.56 ± 0.42, and 53.00 ± 1.39% extractable solids, respectively. The Folin-Ciocalteu (F-C) redox assay was optimized considering relevant parameters such as reaction time, maximum wavelength, and sample dilution effect before the determination of TPC. The concentration of antioxidants necessary to decrease by 50% the initial concentration of DPPH (EC50) was determined at 60 min. The reaction kinetics was analyzed using the pseudo-first-order kinetics model. For the F-C assay, the optimum conditions for the maximum absorbance and analysis time were 760 nm and 30 min, respectively. Under these conditions, the method exhibited good sensitivity and linear instrumental responses over wide ranges of concentrations. The highest TPC;168.27 ± 3.44, 137.43 ± 1.32, and 136.16 ± 0.42 mgGAE/g were recorded in the diluted samples (500 µg/mL) of methanol, chloroform, and petroleum ether extracts, respectively. By using different concentrations of the test sample, exhaustive reduction of phenolics and/or antioxidant substrates was achieved. Regarding the DPPH radical scavenging capacity, the EC50 values for methanol, chloroform, and petroleum ether extracts were 295.03 ± 3.55, 342.75 ± 9.72, and 353.69 ± 7.30 µg/mL, respectively. The standard (L-ascorbic acid), however, exhibited much lower EC50 value (44.72 ± 0.48 µg/mL). The methanol extracts showed kinetic behavior (k2 values,115.08 to 53.28 M-1 s-1; steady-state time, < 29 min) closer to that of L-ascorbic acid (k2 values, 190 to 109 M-1 s-1; steady-state time, < 16 min), than other two extracts (k2 values,14 to 28 M-1 s-1; steady-state time, 63 to 130 min). For all tested samples, the rate of the DPPH radical scavenging increases with concentration from 50 to 250 µg/mL. The current study demonstrated that the polar solvent (methanol) extract has a better F-C reducing capacity and DPPH radical scavenging activity than the nonpolar solvents extracts. This could be due to phenolics and other oxidation substrates extracted by methanol from the C. mollis resin. For a better understanding of the antioxidant constituents of the resin, a further study including isolation of its compounds is recommended.

Chemical Constituents of Root Barks of Gnidia involucrata and Evaluation for Antibacterial and Antioxidant Activities.

The genus Gnidia, with species close to 152, is traditionally used to treat wide ranges of ailments in humans and animals. Gnidia involucrata is one of the species found in Ethiopia and traditionally used as a laxative, antirheumatic agent, insecticide, antibacterial agent, and antimalarial agent. In view of its traditional use, the root bark was sequentially extracted with n-hexane, EtOAc, and MeOH to afford 0.78%, 4%, and 6% crude extracts, respectively. The chromatographic separation of the EtOAc extract using silica gel column chromatography yielded three pure compounds: tetratriacontanyl caffeate (1), 12-O-dodeca-2,4-dienoylphorbol-13-acetate (2), and naringenin (3). This is the first report of the isolation of 1 and its kind from the genus and most probably from the Thymelaeaceae family. The structures of these compounds were characterized and identified by NMR and mass spectrometric analyses and comparison with literature data. The EtOAc extract and isolated compounds were assessed for their in vitro antibacterial and antioxidant activities. The EtOAc extract (1.5 mg/mL) showed significant inhibitory activity against S. aureus, E. coli, P. mirabilis, and K. pneumonia bacterial strains with the highest inhibition zone observed against S. aureus (23 mm), which is even greater than that of the reference drug ciprofloxacin (22 mm). However, the inhibition displayed on these bacterial strains for the three pure compounds was marginal with variable degrees of potency between the compounds. The better activity of the crude extract could be due to the synergistic interactions of several phytochemicals present in the extract, which cannot be the case when pure compounds are evaluated alone. The antioxidant activities of the extracts and isolated compounds were evaluated using DPPH and ferric thiocyanate methods. The EtOAc and MeOH extracts and compounds 1 and 2 were found to inhibit the DPPH radical by 70.7, 66.9, 85.8, and 52.8%, respectively. The EtOAc extract and compound 1 inhibited peroxidation of lipids by 84 and 86%, respectively. The radical scavenging displayed by compound 1 was significant compared with that displayed by ascorbic acid, indicating the strong antilipid peroxidation potential of the extract of root barks of G. involucrata. Therefore, the extracts of the root bark of G. involucrata can be used as a remedy in combating diseases caused by bacteria and free radicals provided that further comprehensive evaluation could be recommended for the conclusive decision on potential candidacy of this plant.

Secondary metabolites from Penicillium sp. 8PKH isolated from deteriorated rice straws.

In the search for bioactive secondary metabolites from terrestrial fungi, four compounds, namely, 3-methyl-3H-quinazolin-4-one (1), aurantiomide C (2), 3-O-methylviridicatin (3), and dehydrocyclopeptine (4), were isolated from Penicillium sp. 8PKH, fungal strain, isolated from deteriorated rice straws. The structures of the isolated compounds were identified by extensive NMR and mass analyses and comparison with literature data. This is the first report of the structure of 3-methyl-3H-quinazolin-4-one (1) with full NMR spectral data having been previously identified by GC-MS from Piper beetle. Analysis of the non-polar fractions of the strain extract by GC-MS revealed the presence of additional eight compounds: methyl-hexadecanoate, methyl linoleate, methyl-9 (Z)-octadecenoate, methyl-octadecanoate, cis-9-oxabicyclo (6.1.0) nonane, 9,12-octadecadienal (9E,12E), ethyl-(E)-9-octadecenoate, and 3-buten-2-ol. The isolated compounds were evaluated for their antimicrobial and cytotoxic activities and exhibited little or no inhibitory activities against the test strains. The taxonomical characterisation and fermentation of the fungal strain were reported as well.

Bioactive secondary metabolites from new endophytic fungus Curvularia. sp isolated from Rauwolfia macrophylla.

Over the last decades, endophytic fungi represent a new source of pharmacologically active secondary metabolites based on the underlying assumption that they live symbiotically within their plant host. In the present study, a new endophytic fungus was isolated from Rauwolfia macrophylla, a medicinal plant from Cameroon. The fungus showed a highest homology to Curvularia sp. based on complete nucleotide sequence data generated from the internal transcribed spacer (ITS) of ribosomal DNA region. Large scale fermentation, working-up and separation of the strain extract using different chromatographic techniques afforded three bioactive compounds: 2'-deoxyribolactone (1), hexylitaconic acid (2) and ergosterol (3). The chemical structures of compounds 1-3 were confirmed by 1 and 2D NMR spectroscopy and mass spectrometry, and comparison with corresponding literature data. Biologically, the antimicrobial, antioxidant activities and the acetylcholinesterase inhibitory of the isolated compounds were studied.

Antimicrobial Abietane-Type Diterpenoids from Plectranthus punctatus.

Four new para-benzoquinone containing abietane-type diterpenoids (1-4) along with thirteen known diterpenoids (5-17) were isolated from the roots of Plectranthus punctatus. The structures of the compounds were established by detailed spectroscopic analyses and comparison with literature data. The compounds were tested for their antibacterial and cytotoxic activity and showed significant inhibitory activity against all bacterial strains used, with compounds 6, 8, 10, and 11 showing an inhibition zone for Staphylococcus warneri even greater than the reference drug, gentamycin.

Cytotoxic Compounds from Aloe megalacantha.

Phytochemical investigation of the ethyl acetate extract of the roots of Aloe megalacantha led to the isolation of four new natural products-1,8-dimethoxynepodinol (1), aloesaponarin III (2), 10-O-methylchrysalodin (3) and methyl-26-O-feruloyl-oxyhexacosanate (4)-along with ten known compounds. All purified metabolites were characterized by NMR, mass spectrometric analyses and comparison with literature data. The isolates were evaluated for their cytotoxic activity against a human cervix carcinoma cell line KB-3-1 and some of them exhibited good activity, with aloesaponarin II (IC50 = 0.98 µM) being the most active compound.

Phytochemical investigation of Aloe pulcherrima roots and evaluation for its antibacterial and antiplasmodial activities.

Medicinal plants with documented traditional uses remain an important source for the treatment of a wide range of ailments. Evidence shows that majority of the Ethiopian population are still dependent on traditional medicine. Aloe pulcherrima Gilbert & Sebsebe is one of the endemic Aloe species traditionally used for the treatment of malaria and wound healing in central, Southern and Northern part of Ethiopia. The aim of the current study was, therefore, to isolate active compounds from roots of A. pulcherrima and evaluate for their antibacterial and antiplasmodial activities using standard test strains. Bioassay-guided sequential extraction and column chrom-atographic separation were employed for the isolation of bioactive pure compounds. The structures of the compounds were determined by 1D and 2D NMR spectro-scopic techniques. Disk diffusion method was employed to evaluate the antibacterial activities of the isolated compounds against four bacterial strains specifically (Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Pseudomonas aeruginosa ATCC 27853). The malaria SYBR Green I-based in vitro assay technique was used for in vitro antiplasmodial activity evaluation of the compounds against chloroquine resistant (D6) and -sensitive (W2) strains of P. falciparum. Three compounds, chrysophanol, aloesaponarin I and aloesaponarin II were isolated from the acetone extracts of roots of A. pulcherrima. Evaluation of antibacterial activities revealed that aloesaponarin I and aloesaponarin II had significant activities against all the bacterial strains with inhibition zone diameters ranging from 18-27 mm as compared to the reference drug (gentamicin), which displayed inhibition zone diameter ranging between 20 mm (B. subtilis) and 25 mm (P. aeruginosa). The isolated compounds showed moderate in vitro antiplasmodial activity against both chloroquine resistant (W2) -sensitive (D6) strains. Isolation of chrysophanol, aloesaponarin I and aloesaponarin II from roots of A. pulcherrima is the first report of its kind. The finding could be used for further comprehensive evaluation of the isolated compounds for their antibacterial and antimalarial activities besides consideration of the same for potent drug development.

Naphthalene Derivatives from the Roots of Pentas parvifolia and Pentas bussei.

The phytochemical investigation of the CH2Cl2/MeOH (1:1) extract of the roots of Pentas parvifolia led to the isolation of three new naphthalenes, parvinaphthols A (1), B (2), and C (3), two known anthraquinones, and five known naphthalene derivatives. Similar investigation of the roots of Pentas bussei afforded a new polycyclic naphthalene, busseihydroquinone E (4), a new 2,2'-binaphthralenyl-1,1'-dione, busseihydroquinone F (5), and five known naphthalenes. All purified metabolites were characterized by NMR and MS data analyses, whereas the absolute configurations of 3 and 4 were determined by single-crystal X-ray diffraction studies. The E-geometry of compound 5 was supported by DFT-based chemical shift calculations. Compounds 2-4 showed marginal cytotoxicity against the MDA-MB-231 human triple-negative breast cancer cell line with IC50 values ranging from 62.3 to 129.6 µM.

Cytotoxic quinones from the roots of Aloe dawei.

Seven naphthoquinones and nine anthraquinones were isolated from the roots of Aloe dawei by chromatographic separation. The purified metabolites were identified by NMR and MS analyses. Out of the sixteen quinones, 6-hydroxy-3,5-dimethoxy-2-methyl-1,4-naphthoquinone is a new compound. Two of the isolates, 5,8-dihydroxy-3-methoxy-2-methylnaphthalene-1,4-dione and 1-hydroxy-8-methoxy-3-methylanthraquinone showed high cytotoxic activity (IC50 1.15 and 4.85 µM) on MCF-7 breast cancer cells, whereas the others showed moderate to low cytotoxic activity against MDA-MB-231 (ER Negative) and MCF-7 (ER Positive) cancer cells.

Antiplasmodial quinones from the rhizomes of Kniphofia foliosa.

Extracts of the rhizomes of Kniphofia foliosa exhibited antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 3-5 microg/mL. A phenyloxanthrone, named 10-acetonylknipholone cyclooxanthrone (1) and an anthraquinone-anthrone dimer, chryslandicin 10-methyl ether (2), were isolated from the rhizomes, along with known quinones, including the rare phenylanthraquinone dimers, joziknipholones A and B. The structures of these compounds were determined based on spectroscopic data. This is the second report on the occurrence of the dimeric phenylanthraquinones in nature. In an in vitro antiplasmodial assay of the isolated compounds, activity was observed for phenylanthraquinones, anthraquinone-anthrone dimers and dimeric phenylanthraquinones, with joziknipholone A being the most active. The new compound, 10-acetonylknipholone cyclooxanthrone, also showed anti-plasmodial activity. In an in vivo assay, knipholone anthrone displayed marginal antimalarial activity.