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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]

• Root extract of Zanthoxylum paracanthum with good antibacterial activities. • Efflux pump inhibitor improved antimicrobial activities of Z. paracanthum extract. • All compounds exhibited activities on at least 2/13 bacteria tested. • Nitrogen-containing compounds showed the best activities against bacteria tested. • The phenolic amide, 1 was bactericidal against the standard and MDR isolates. The antibacterial potency of thirteen compounds reported from two distinct genera, Zanthoxylum (Rutaceae) and Dracaena (Asparagaceae) against a panel of sensitive and multi-drug resistant Gram-positive and Gram-negative bacteria is described. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) determinations on the tested bacteria were established using modified rapid iodonitrotetrazolium chloride (INT) colorimetric assay. The root extract (50% MeOH/CH 2 Cl 2) of Zanthoxylum paracanthum was also combined with an efflux pump inhibitor, phenylalanine arginine β-naphthylamide (PAβN) (at 30 μg/mL), to evaluate the role of efflux pumps in the susceptibility of bacteria. Structure-Activity-Relationship (SAR) of related congeners is also described. The results of the MICs ranged from 4 (against Staphylococcus aureus) to 16 μg/mL (towards Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa) for Z. paracanthum extract and from 16 (against S. aureus MRSA3) to 1024 μg/mL (towards S. aureus ATCC25923 and MRSA3) for the compounds. Addition of phenylalanine arginine β-naphthylamide (PAβN) in the root extract of Z. paracanthum significantly increased the antibacterial potency of the extract against the tested bacteria, with the highest MICs values being observed at 1 μg/mL (against S. aureus and E. coli strains). The root extract of Z. paracanthum and most of the compounds exhibited an MIC/MBC ≤ 4 except for compound 1 , indicating their bactericidal status. Overall, this study provides baseline information on the antibacterial profiles of the studied samples against both Gram-positive and Gram-negative pathogenic bacteria. Structure modification of the moderately active compounds originating from Z. paracanthum and Dracaena usambarensis should be attempted in future studies towards the improvement of their antibacterial potencies. [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]

Introduction: Macaranga species are traditionally used for the treatment and management of coughing, fungal infection, and wounds. In this study, the phytochemical screening and antibacterial activities of nine crude extracts from Macaranga conglomerata, Macaranga kilimandscharica and Macaranga capensis were determined against 13 bacterial strains expressing multi-drug resistance (MDR) phenotypes. Methods: Phytochemical screening of the extracts were carried out according to the standard methods, while the iodonitrotetrazolium chloride (INT) colorimetric assay was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the plants extracts. Results: Flavonoids, terpenoids, saponins and coumarins were the major secondary metabolites found in all the plant extracts. The results of antibacterial studies revealed that all the plant extracts displayed good activities with MIC values ranging from 4 - 128 μg/mL against the tested micro-organisms. Most of the extracts exhibited a bactericidal effect against E. coli, E. aerogenes, K. pneumoniae, P. stuartii, P. aeruginosa, and S. aureus with MBC/MIC ratio ≤ 4. In the presence of efflux pump inhibitor (PaβN), the inhibition potency of all the crude extracts against the tested bacterial strains were substantially enhanced. It is worth noting that the activities of MKL, MCL, and MCR towards P. stuartii (NEA16), E. aerogenes (ATCC13048), and K. pneumoniae (KP55), respectively were improved by more than 8-fold in the presence of PAβN. Conclusion: The findings of this study indicated the possibility of using all the tested plant extracts as a source of therapeutic agents in the fight against multi-drug resistant bacteria. [ABSTRACT FROM AUTHOR]

Introduction: Plants from Kenyan flora are traditionally used to manage a number of ailments including; chronic and infectious disease, to bolster the body immunity and for general health protections. The current investigation was designed to validate the quality with respect to the pharmacological significance of 156 fresh plant materials resulting from 27 ethno-medicinal plants, from Ngong forest, Kenya. Materials and Methods: Pharmacological screening was carried out using the field deployable GIBEX Screens- To-Nature (STN) validated assays. The plant extracts were screened for antifungal; general protozoal lethality; round worm lethality and antioxidant potential. Results: Different plant parts exhibited a range of activities; related to their traditional uses; with eleven out of twenty-seven extracts exhibiting highest activities in only one out of four categories of assays studied. All plant parts of only one plant C. axillaris exhibited high activities in all (4/4) the categories of assays evaluated. The other plants that exhibited high activities in three out of four (3/4) categories of assays studied included; A. oppositifolia, B. huillensis and T. trichocarpa. Conclusion: The current investigation provided additional data in relation to the usefulness of the studied ethno-medicinal plants, mostly of the following plants; C. axillaris, A. oppositifolia, B. huillensis and T. trichocarpa in the management of diseases that are infectious and to bolster the immunity. The reported data will contribute towards authenticating the claimed traditional use of these plants. The extracts that exhibited high activities should be investigated further to determine their effective concentrations. [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]

Currently, researchers have given special attention to the synthesis of heterocyclic compounds with nitrogen and oxygen five in fiveor sixmembered ring systems. This is mainly due to their wide range of biological activities. Hence, in this study, isoxazoline, pyrazole and bypyrimidine derivatives were synthesized from flavonoids, previously isolated from Polygonum senegalense and Psiadia panctulata, and assessed for their antifungal activity. A flavone was reacted with hydrazine hydrate to afford a pyrazole analogue 5-methoxy-2(5-( 2,3,4,5-tetramethoxyphenyl)-1H-pyrazol-3-yl) benzene-1,3-diol (1) Two isoxazoline derivatives namely, 2-(-4-5dihydro-5-phenylisoxazol-3-yl) 5-methoxybenzene-1,3-diol (2) and 2-(-4,5-dihydro-5-phenylisoxazol-3-yl)- 3,5-dimethoxyphenol (3) were successfully synthesized by the reaction of chalcones with hydroxylamine hydrochloride. An oxime derivative (4) was also generated from a similar procedure. A reaction between a chalcone and thiourea gave a bypyrimidine derivative, 4,5-dihydro-6-(-2,4-dihydroxy-3,6-dimethoxyphenyl)-4-phenylpyrimidine-2(1H)-thione (5). The products were then assessed for their antibacterial and antifungal activity. All compounds showed no significant activity except compound 2 that demonstrated activity against standard antibacterial agent, Streptococcus aureus with IC50 value of 7.56 and antifungal Candida neoformans, Candida krusei and Candida glabrata strains with IC50 values 8.01, 8.11 and 13.74 µg/mL respectively. We, therefore, recommend synthetic optimization of compound 2 as a potential antimicrobial agent. [ABSTRACT FROM AUTHOR]

Introduction: Multidrug resistance remains a major obstacle hindering successful antimalarial chemotherapy. In the current study, 50% methanol in dichloromethane extract and six compounds from the stem bark of Zanthoxylum gilletii were explored for their antiplasmodial potential against three strains of Plasmodium falciparum. Materials and Methods: The extract was obtained by cold percolation using 50 % MeOH in CH2Cl2 and the antiplasmodial activities were assayed using a non--radioactive Malaria SYBR Green I assay to determine a concentration that inhibits growth of 50% of parasites in culture (IC50). Results and Discussion: Chromatographic separation of the crude extract yielded six known compounds including: one lignan, sesamin (1), an alkamide, fagaramide (2), three benzo [c] phenanthridine alkaloids, 8--acetonyldihydrochelerythrine (3), dihydrochelerythine (4), norchelerythrine (5) and one pentacyclic triterpenoid, lupeol (6). The extract and sesamin (1) showed promising antiplasmodial activities against the chloroquine resistant (W2), chloroquine sensitive (D6) and 3D7 strains of P. falciparum, with IC50 values of 2.52, 1.48 and 1.43 µg/mL and 5.4, 9.1 and 8.3 µM, respectively. To the best of our knowledge, this is the first report on antiplasmodial activities of the stem bark extract (50% MeOH in CH2Cl2) and compound 1-3 and 6. Furthermore, three of the isolated compounds; 1, 3, 6 are reported from this species for the first time. Conclusion: The good antiplasmodial activities exhibited by the stem bark of Z. gilletii against three different strains of P. falciparum may be attributed to the presence of 1-3 exhibiting good activities against all strains of P. falciparum. [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]

Endophytic fungal isolates Hypocrea lixii F3ST1 and Beauveria bassiana G1LU3 were evaluated for their potential to endophytically colonize and induce active compounds in Phaseolus vulgaris, as a defense mechanism against pea leafminer (Liriomyza huidobrensis) and fall armyworm (Spodoptera frugiperda). Endophytic colonization was achieved through seed inoculation with the volatile emissions from P. vulgaris plants being analyzed using GC-MS. The crude extracts of P. vulgaris obtained using methanol and dichloromethane were assayed against leafminer and fall armyworm larvae using leaf dipping and topical application, respectively. The two isolates successfully colonized the entire host plant (roots, stems, and leaves) with significant variation (p < 0.001) between fungal isolates and the controls. The results showed qualitative differences in the volatile profiles between the control plants, endophytically colonized and insect-damaged plants attributed to fungal inoculation and leafminer damage. The crude methanol extracts significantly reduced the percentage pupation of 2nd instar leafminer larvae (p < 0.001) and adult-flies emergence (p < 0.05). The survival of the 1st instar fall armyworm larvae was also significantly reduced (p < 0.001) compared to the controls. This study demonstrated the high potential of endophytic fungi H. lixii and B. bassiana in inducing mainly specific defense compounds in the common bean P. vulgaris that can be used against pea leafminer and fall armyworm. [ABSTRACT FROM AUTHOR]

Four new steroidal sapogenins, dracaenogenins C F (1 – 4), a new conjugated chalcone-stilbene, 3′′-methoxycochinchinenene H (5) together with eight known compounds namely, (25 S)-spirosta-1,4-dien-3-one (6), trans -resveratrol (7), 4,4′-dihydroxy-3′-methoxychalcone (8), N - trans -coumaroyltyramine (9), N - trans - p -coumaroyloctopamine (10), N - trans -feruloyloctopamine (11), 7-hydroxy-1-(4-hydroxy-3-methoxyphenyl)- N 2 , N 3 - bis (4-hydroxyphenethyl)-6-methoxy-1,2-dihydronaphthalene-2,3-dicarboxamide (12) and grossamide (13) were isolated from the stems of Dracaena usambarensis Engl. from Kenya. It is important to note that compounds 12 and 13 are being reported from this genus for the first time. Structural elucidation of the isolated compounds was done using spectroscopic (NMR, UV, IR, optical rotation) and spectrometric (HRESIMS) techniques. The absolute and relative configurations of the isolated compounds were determined by employing single crystal X-ray crystallography analysis, NOESY correlations and coupling constants. The anti-inflammatory potencies of the isolated compounds were evaluated by measuring the levels of four cytokines (IL-1β, IL-2, GM-CSF and TNF-α) in the supernatant media of human peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide (LPS). At the tested concentration of 100 μM, the new conjugated chalcone-stilbene 5 , the dihydrochalcone, 8 and the lignanamide, 13 were substantially more potent than the standard drug, ibuprofen, inhibiting the release of all the cytokines, IL-1β , IL-2, GM-CSF and TNF-α from 0.06–58.04% compared to LPS control. These compounds should therefore be considered for development into anti-inflammatory drug candidates. Compound 7 significantly decreased the release of GM-CSF (6.11% of LPS control) and TNF-α (18.35% of LPS control). The cytokine TNF-α was sensitive to all the tested compounds 1 - 13. Unlabelled Image • Thirteen secondary metabolites isolated from the stem bark of Dracaena usambarensis. • Four new steroidal sapogenins, 1 - 4 and a new conjugated chalcone-stilbene, 5. • The relative configuration of 1 was confirmed with X-ray analysis. • Inhibitory activity of 5 , 8 and 13 , was higher than ibuprofen against all cytokines. [ABSTRACT FROM AUTHOR]

Two new norhopane derivatives namely 3β,6β,22-trihydroxy-7β,11α-di[(4-hydroxybenzoyl)oxy]-21αH-24-norhopa-4(23)-ene (1) and 3β,6β,22-trihydroxy-7β-[(4-hydroxybenzoyl)oxy]-21αH-24-norhopa-4(23)-ene (2) together with two previously reported compounds, including a norhopane, 3β,6β,11α-trihydroxy-7β-[(4-hydroxybenzoyl)oxy]-24-norhopa-4(23),17(21)-diene (3) and a norneohopane, (21αH)-24-norneohopa-4(23), 22(29)-diene-3β,6β,7β-triol 7-caffeate (4) were isolated from the root bark of Fagaropsis angolensis. Elucidation of their structures was achieved by spectroscopic (NMR, IR and UV) and spectrometric (HRESIMS) data and by comparison of these data with those of related compounds in the literature. Compounds 1–4 were evaluated for their anti-inflammatory activity by measuring the levels of cytokines, IL-1β, IL-2, GM-CSF and TNF-α in lipopolysaccharide (LPS) stimulated peripheral blood mononuclear cells (PBMC). All tested compounds decreased secretion of IL-1β and TNF-α. Compounds 2 and 4 caused significant decrease of the production of IL-2, GM-CSF and TNF-α compared to the reference drug, ibuprofen. These findings showed that the root barks of F. angolensis are rich source of norhopane derivatives and further provide a scientific rationale of using this plant in Kenyan folk medicine to relieve pain. Unlabelled Image [ABSTRACT FROM AUTHOR]

Ethnopharmocological relevance Members of ‘ Mycoplasma mycoides cluster’ are important ruminant pathogens in Africa. Diseases caused by these Mycoplasma negatively affect the agricultural sector especially in developing countries through losses in livestock productivity, mortality and international trade restrictions. There is therefore urgent need to develop antimicrobials from alternative sources such as medicinal plants to curb these diseases. In Kenya, smallholder farmers belonging to the Maasai, Kuria and Luo rely on traditional Kenyan herbals to treat respiratory symptoms in ruminants. In the current study extracts from some of these plants were tested against the growth of members of Mycoplasma mycoides cluster. Aim This study aimed at identifying plants that exhibit antimycoplasmal activities using an ethnobotanical approach. Materials and methods Kenyan farmers of Maasai, Luo and Kuria ethnic groups were interviewed for plant remedies given to livestock with respiratory syndromes. The plant materials were thereafter collected and crude extracts prepared using a mixture of 50% of methanol (MeOH) in dichloromethane (CH 2 Cl 2 ), neat methanol (MeOH), ethanol (EtOH) and water to yield four crude extracts per plant part. The extracts were tested in vitro against five strains of Mycoplasma mycoides subsp. capri , five strains of Mycoplasma mycoides subsp. mycoides and one strain of Mycoplasma capricolum subsp capricolum using broth micro-dilution assays with an initial concentration of 1 mg/ml. Minimum inhibitory concentration (MIC) of the most active extracts were determined by serial dilution. Results Extracts from five plants namely: Solanum aculeastrum , Albizia coriaria , Ekebergia capensis , Piliostigma thonningii and Euclea divinorum exhibited the highest activities against the Mycoplasma strains tested. Mycoplasma mycoides subsp. mycoides were more susceptible to these extracts than Mycoplasma mycoides subsp. capri and Mycoplasma capricolum susp. capricolum. The activities of the crude extracts varied with the solvent used for extraction. The MICs mean values of the active extracts varied from 0.02 to 0.6 mg/ml. Conclusions The results suggested that these plants could potentially contain antimicrobial compounds that might be useful for the treatment of respiratory diseases in ruminants. Future work should focus on the isolation and identification of the active compounds from the plant extracts that showed interesting activities and evaluation of their antimicrobial and cytotoxic potential. [ABSTRACT FROM AUTHOR]