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The present chapter highlights the antibacterial potential of nine highly active compounds isolated from the African medicinal plants: 8,8-bis-(dihydroconiferyl)-diferulate, buesgenine, candidone, diospyrone, ferruginin A, isobavachalcone, neobavaisoflavone, neocyclomorusin, and plumbagin. Their botanical source as well as their hypothetical biosynthetic pathways have also been discussed. Regarding their inhibitory potential towards the Gram-negative and Gram-positive bacteria, and mycobacteria, the above phytochemicals constitute potential pharmaceuticals that deserve clinical studies to develop antibacterial drugs to combat bacterial infections involving both drug-sensitive and drug-resistant phenotypes. [ABSTRACT FROM AUTHOR]

To overcome the negative impacts of invasive fall armyworm (FAW), this study assessed the laboratory and field efficacy of aqueous and oil-based formulations of Metarhizium anisopliae ICIPE 41 as an alternative source for FAW management. Three oil formulations, including canola, corn, olive and an aqueous formulation of ICIPE 41, were assessed against the second-instar larvae of FAW in the laboratory. Field experiments were also conducted at Mbita and Migori, Kenya, using the best formulation, with four treatments: (a) A corn oil formulation of ICIPE 41; (b) Mazao Achieve® biopesticide, with the M. anisopliae ICIPE 78 strain as the active ingredient; (c) spinetoram-based synthetic pesticide; (d) a control (water + corn oil), where the FAW incidence, infestation, larval mortality and the effects on parasitoids and yield were evaluated. The laboratory results showed no significant differences in the efficacies among the oil-based formulations, with mortality rates of >70% and an LT50 of ~2 days compared to 15.15% in the controls with an LT50 of 8.11 days. Under the field conditions, no significant differences in the FAW infestation were observed between ICIPE 41 and Mazao Achieve®, compared to the control treatments in both agro-ecological zones. From the field-collected samples, both fugal-based biopesticides exhibited high mortality and mycosis rates, with no negative impacts on Cotesia icipe compared to the spinetoram pesticide. There were significant differences in the total grain yields among the treatments in Mbita and Migori. ICIPE41 could, therefore, be formulated in corn oil to promote sustainable FAW management in maize cropping systems. [ABSTRACT FROM AUTHOR]

Purification of the aerial parts of Vernonia auriculifera Hiern afforded steroids (1–2), flavonoids (3–5), and polyalcohol (6). Their structures were determined using spectral evidences as well as by comparison with reported data. Iodonitrotetrazolium chloride (INT) colorimetric assay was used to assess the antibacterial activity of the extract and isolates against 13 pathogenic strains. The crude extract showed strong antibacterial activity (MIC < 100 µg/mL) against the tested bacterial strains. When combined with an efflux pump inhibitor phenylalanine beta naphthylamide (PAβN), the inhibition potency of the extract was substantially enhanced with the lowest MIC value at 4 µg/mL. Compounds 5 and 6 showed moderate activity (MIC < 100 µg/mL) against 12/13 (92.3%), and 8/13 (61.5%) bacterial strains, respectively. A minimal bactericidal concentration (MBC)/minimal inhibitory concentration (MIC) ratio ≤ 4 indicated their bactericidal effect against Escherichia coli, Enterbacter aerogenes, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa, and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Chemical investigation of the root of Zanthoxylum paracanthum afforded 1 new alkamide derivative, (2E,4E)-6-oxo-N-isobutyldeca-2,4-dienamide (1) together with 10 known congeners including one phenolic amide (2), four benzophenanthridines (3 − 6), three indolonaphthyridines (7 − 9) and two lignans (10 and 11). Their structures were elucidated by a combination of spectroscopic and spectrometric data. Using resazurin reduction assay, the crude extract (10 µg/mL) and isolates (10 µM) were screened for their cytotoxic activities against the drug-sensitive (CCRF-CEM) leukemia cell line and its multidrug-resistant counterpart (CEM/ADR5000). Compounds 3, 4 and 6 showed cytotoxicity against CCRF-CEM with IC50 values of 2.00 ± 0.33, 2.31 ± 0.20 and 0.11 ± 0.04 µM, respectively. Only compound 6 exhibited strong cytotoxic activity against CEM/ADR5000 with an IC50 value of 2.34 ± 0.34 µM in comparison with the standard drug doxorubicin which showed IC50 values of 0.01 ± 0.14 (CCRF-CEM) and 26.78 ± 3.30 µM (CEM/ADR5000). [ABSTRACT FROM AUTHOR]

In our continuous search for cytotoxic compounds from the genus Zanthoxylum, chromatographic separation of the MeOH/CH2Cl2 (1:1) extract of Z. chalybeum yielded one new alkamide; 4-(isoprenyloxy)-3-methoxy-3,4-deoxymethylenedioxyfagaramide (1) and a known one; fagaramide (2). Similarly, from the MeOH/CH2Cl2 (1:1) extract of the stem bark of Z. parachanthum four known compounds; canthin-6-one (3), dihydrochelerythrine (4), lupeol (5) and sesamin (6) were isolated. Characterization of the structures of these compounds was achieved using spectroscopic techniques (NMR and MS). Using resazurin reduction assay 1, 3 and 6 displayed moderate cytotoxicity with IC50 values below 50 μM against the drug sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cell lines. It is interesting to note that 3 was more active than the standard drug, doxorubicin against CEM/ADR5000 leukemia cells. Compounds 3 and 6 showed good selectivity on leukemia cells than normal cells. In future studies 3 should be tested against a panel of drug resistant human cells. [ABSTRACT FROM AUTHOR]

This paper describes the semi-synthesis and anti-microbial activity of novel pyrazoline derivatives of Polygonum senegalense chalcones. The study was carried out on the understanding that heterocycles with pyrazoline ring systems are known to possess a broad spectrum of biological activities. The derivatives were afforded by refluxing mixtures of chalcones and phenylhydrazine, hydrazine hydrate, and / or acetic acid in DMSO or ethanol at low temperatures between 40-60°C in an oil-bath. The products were characterized in by 1H-NMR (200 or 400 MHz), 13C-NMR spectroscopy and ESI-HRMS. NMR data was described in detail for each derivative. The compounds 6-15 have been screened for their in vitro anti-bacterial activity against one gram positive bacteria (S. aureus) and anti-fungal activity against five strains C. krusei, C. neoformans, and C. glabrata. They all showed insignificant antimicrobial activities with lower IC50 as compared to positive control, except compound 7 that demonstrated moderate antifungal activity with ICIC50 values ranging between 8.01 - 13.74 µg/mL against C. krusei, C. neoformans and C. glabrata. The compound also showed antibacterial activity of IC50 value 7.56µg/mL against S. aureus. Based on these findings, we recommend that compound 7 should undergo further structural modification in order to optimize its anti-microbial activity. [ABSTRACT FROM AUTHOR]

Multidrug resistance is a prevailing phenomenon leading to chemotherapy treatment failure in cancer patients. In the current study two known cytotoxic pseudoguaianolide sesquiterpene lactones; neoambrosin (1) and damsin (2) that circumvent MDR were identified. The two cytotoxic compounds were isolated using column chromatography, characterized using 1D and 2D NMR, MS, and compared with literature values. The isolated compounds were investigated for their cytotoxic potential using resazurin assays and thereafter confirmed with immunoblotting and in silico studies. MDR cells overexpressing ABC transporters (P-glycoprotein, BCRP, ABCB5) did not confer crossresistance toward (1) and (2), indicating that these compounds are not appropriate substrates for any of the three ABC transporters analyzed. Resistance mechanisms investigated also included; the loss of the functions of the TP53 and the mutated EGFR. The HCT116 p53-/- cells were sensitive to 1 but resistant to 2. It was interesting to note that resistant cells transfected with oncogenic EGFR exhibited hypersensitivity CS toward (1) and (2) (degrees of resistances were 0.18 and 0.15 for (1) and (2), respectively). Immunoblotting and in silico analyses revealed that 1 and 2 silenced c-Src kinase activity. It was hypothesized that inhibition of c-Src kinase activity may explain CS in EGFR-transfected cells. In conclusion, the significant cytotoxicity of 1 and 2 against different drug-resistant tumor cell lines indicate that they may be promising candidates to treat refractory tumors. [ABSTRACT FROM AUTHOR]

Species of the genus Garcinia (Clusiaceae) have been used for centuries in different folk medicine for the treatment of several ailments, as well as food supplements. Evidence from previous studies has demonstrated a rich depository of structurally diverse secondary metabolites with a wide array of biological activities. The present chapter summarizes the information on the ethnobotany, phytochemistry, and antibacterial potential of the Garcinia genus against drug-sensitive and multi-drug resistant (MDR) phenotypes. A literature survey of the published information was collected from databases such as Google Scholar, PubMed, SciFinder, Scopus, Web of Science, conference proceedings, books, M.Sc., and Ph.D. dissertations. Phytochemical studies showed that xanthones, benzophenones, and flavonoids as the main secondary metabolites. Pharmacological investigations with crude extracts and isolated compounds from G. kola, G. lucida, G. nobilis as well as other Garcinia species revealed a broad range of antibacterial activity against several drug-sensitive and MDR phenotypes. Among the isolated compounds, a-mangostin, a prenylated xanthone from G. mangostana was found to display the most potent antibacterial effects against both Gram-positive and Gram-negative bacteria while (-)-hydroxycitric acid from some Garcinia fruits is utilized in the pharmaceutical industry as an anti-obesity agent. Thus, this review demonstrated that there are convincing in vitro studies confirming the traditional use of Garcinia species to treat bacterial infections. Furthermore, the reviewed data herein would be a valuable reference tool for future researchers seeking to explore the application potentials of Garcinia species for the development of antibacterial agents. [ABSTRACT FROM AUTHOR]