Content uploaded by Sylvia Awino Opiyo
Author content
All content in this area was uploaded by Sylvia Awino Opiyo on Jul 18, 2015
Content may be subject to copyright.
A preview of the PDF is not available
Antimicrobial Compounds from Terminalia brownii against Sweet Potato Pathogens
Abstract
Phytochemical evaluation of Terminalia brownii extracts led to the isolation of five compounds namely-sitosterol, stigmasterol, monogynol A, betulinic acid and arjungenin. Their structures were established by spectroscopic and physical methods as well as by comparison with literature data. The in vitro antimicrobial activities of the extracts and isolates were investigated against fungi and bacteria which infect sweet potato. Ethyl acetate extract exhibited the highest (p 0.05) antifungal and antibacterial activities compared to n-hexane and methanol ones. Streptomyces ipomoeae was more susceptible to ethyl acetate extract (inhibition zone, 18.6 mm) than streptocycline used as a positive control. The minimum inhibitory concentration (MIC) for the isolates ranged between 50 and 200 g/ml with the lowest MIC value of 50 g/ml being observed with betulinic acid against Aspergillus niger and S. ipomoea.
... Numerous positive effects of flavonoids have been shown in an increasing number of research associated to their cardioprotective, anticoagulant antiplatelet, antiviral, antimicrobial, anti-inflammatory, antitumor, anti-allergic, neuroprotective and weight management activity 76,77 . Flavonoids including apigenin (1), hispidulin (2), luteolin (3), conyflavone (4), Gardenin C (5), takakin 8-O-glucuronide (6), kampferol (7) (20), myricetin (21), epicatechin (22) and conyzoflavone (23) have been reported from Conyza species (Table 1). Compounds 1, 3 and 6 were isolated from C. bonariensis and C. canadensis 78,79 . ...
A large proportion of the African population's primary healthcare requirements are still mostly met by traditional medicine. Previous studies have demonstrated the potential of plant extracts disease management. Conyza species are traditionally used for a variety of pharmacological applications including treatment of malaria, smallpox, chickenpox, sore throat, ringworm and other skin related infections, toothache and wounds. The aim of this study was to provide a review of the chemical compounds from Conyza species and their bioactivities. Extracts from Conyza species have a wide range of bioactivities including antioxidant, anti-inflammatory, antimicrobial, antitumor, analgesic, antiplasmodial, wound healing, insecticidal, allopathic, antidiabetic, antiviral, anticonvulsant and anti-amnesic effects. These bioactivities are attributed to the bioactive secondary metabolite including terpenoids, phenolic acids, flavonoids and tannins, saponins and steroids which are biosynthesized by the plants. Previous phytochemical test have shown that Conyza species are rich in alkaloids. However, the information about the alkaloids previously isolated from Conyza species is scanty in literature. Further studies should be done isolate and characterize the alkaloids from the plants.
... Use of herbal medicine is favoured as they are more affordable, easily accessible and chanced of development of resistance by microorganisms is limited 26,27 . Important bioactive compounds including terpenoids, alkaloids, steroids, flavonoids, and quinones have been identified as a result of such investigations [28][29][30][31][32] . The aim of this paper was to review the biological activities and chemical composition of essential oils from Conyza species. ...
The genus Conyza (Asteraceae) comprises about 50 species and found in the tropical and warm regions. Extracts from Conyza species have numerous pharmacological applications. The aim of this study was review the chemical composition and biological activity of Conyza species. Extracts from the plants have antimicrobial, antioxidant, cytotoxic, anti-inflammatory, antiplasmodial, analgesic, antiviral, allelopathic and insecticidal activities. The constituents of essential oils from Conyza species include limonene and β
... Plants have been identified as a source of important metabolites that are used in defense against different pests and pathogenic microorganism [8][9][10][11][12][13][14][15][16][17][18][19][20] ...
... In recent years, many researchers have focused on authenticating the efficacy of medicinal plant extracts through in-vivo and in-vitro experiments (Opiyo 2011(Opiyo , 2019Opiyo et al. 2015Opiyo et al. , 2017Ochieng et al. 2017;Kuria and Opiyo 2020). Such studies have resulted in to the identification of important biologically active terpenoids, alkaloids, steroids, flavonoids and quinones Opiyo et al. 2011aOpiyo et al. , 2011b. The bioactive compounds derived from natural origin represent an important source of drugs in the process of developing new pharmacologically active compounds. ...
Traditional medicine still plays an important role in managing infections especially in Africa. Extracts of Conyza floribunda Kunth are used to treat sore throat, ringworm and other skin related infections, toothache and to stop bleeding from injuries. Extracts from the plant have been reported to exhibit antibacterial and antifungal activities. Previous phytochemical studies on the plant yielded terpenoid, sterols and flavonoids. The aim of the present study was to determine the analgesic activity Conyza floribunda extracts. Methanol, DCM and n-hexane extracts of the plant were subjects to toxicity, hot plate latency and acetic acid induced-writhing tests using Swiss Albino Mice. The plant extract showed analgesic activity in both hot plate latency and acetic acid induced-writhing tests. The extracts significantly increased the response time in the animals compared to the negative control. In the hot plate latency test, the analgesic activity of the extracts and that of morphine rose over time to peak at 90 minutes and then decreased afterwards. In the acetic acid-induces writhing test, administration of the plant extracts significantly reduced the number of abdominal contractions compared to the negative control. The percentage inhibitions of abdominal contractions were 67.2, 46.5 and 39.4 for methanol, DCM and n-hexane extracts respectively. The findings from this study have confirmed the folkloric information that extracts from C. floribunda have analgesic properties. We therefore recommend the extracts from the plant for use in pain management. Further studies should be carried out to isolate and characterize the analgesic principles from the plant.
... This underscores the need for affordable alternatives that are convenient to use and are environmentally friendly. Plant extracts contain secondary metabolites some of which inhibit the growth of pests and pathogenic microorganism [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The use of botanical for pests and disease control is preferred because they are safe and non-toxic to humans [19][20][21][22][23][24]. ...
Sitophilus zeamais and Prostephanus truncatus, the destructive pests of maize in Africa, cause extensive tunneling in maize grain leading to conversion of maize grain into flour within a very short time. Small-scale farmers are often forced to sell maize shortly after harvest to minimize losses during storage, thereby attract low prices and compromising food security. Most available pesticides have adverse effects on environment and humans. The aim of this study was to evaluate efficacy of extracts and compounds of Warburgia ugandensis in controlling of S. zeamais and P. truncatus. Chromatographic fractionation of extracts from W. ugandensis afforded 7α-acetylugandensolide (1), ugandensolide (2), polygodial (3), warbuganal (4), ugandensidial (5), mukaadial (6) and muzigadial (7). The structures of the compounds were determined using spectroscopic and physical methods. n-Hexane extract was the most repellent among the extracts while polygodial (3) was the most repellent compound against the two pests. n-Hexane and ethyl acetate extracts caused 76.3-78.3% and 71.1-75.0% deaths of the insects respectively. Polygodial (3) and warbuganal (4) caused 64.3-70.0 and 61.7-65.0% deaths respectively. n-Hexane and ethyl acetate extracts, polygodial (3) and ugandensolide (2) significantly inhibited the emergence of the insects. The findings from this study show that extracts from W. ugandensis are effective in controlling maize insect pests.
... In most developing countries, traditional medicine plays an important role in meeting the primary healthcare needs of the population 1-2 . Plants produce chemical compounds that are toxic to pathogenic microorganism as well as pests [3][4][5][6][7][8][9][10][11][12][13][14][15] . Despite the availability of modern synthetic drugs, continued search for novel bioactive compounds is unavoidable as most of the synthetic drugs have limitations in terms of side effects and drug resistance [16][17][18][19] . ...
Traditional medicine plays an important role in disease especially in developing countries. The essential oils of Ocimum species showed anti-oxidant, anti-inflammatory, anti-cancer and insecticidal activities. Essential oils from O. kilimandscharicum are widely used in modern perfumery and the pharmaceutical industry. However information about the chemical composition remains scanty. This study reviewed the chemical composition of essential oils the plant. Peer-reviewed articles were retrieved from Scopus, Science Direct, SciFinder and Google Scholar. Fifteen articles reporting on chemical composition of essential oils extracted from O. kilimandscharicum were accessed. The major compounds in the essential oils were identified to be camphor, linalool, limonene, methyl eugenol, 1,8-cineole, camphene, β-caryophyllene and α-terpineol. Camphor was reported to be in the range of 0.1-70.4%, linalool 0.2-58.9 %, limonene 1.2-13.6%, methyl eugenol 0.1-53.9%, β-Caryophyllene 0.2-31.5%, 1,8-cineole 0.6-20.1% and camphene 0.4-13.6%. Results from this study have confirmed that Ocimum kilimandscharicum essential oils contain a wide range of chemical compounds. The type of compounds and the percentage composition of compounds present in the essential oils were differed. Further studies to determine medicinal activities of the compound present in the essential oils both in pure and blended forms are necessary.
... There is an urgent need to develop safe alternatives that are of readily available, convenient to use and environmentally friendly. Previous studies have shown that plants synthesis important compounds that are toxic to pests and pathogenic microorganism [9][10][11][12][13][14][15][16][17][18][19] . Bioassay guided fractionation of plants extracts has led to identification of bioactive secondary metabolites including alkaloids, terpenoids, flavonoids, steroids and quinones [20][21][22][23][24][25][26][27] . ...
Post-harvest pests cause serious losses to agricultural products in Africa. The pests consist mostly of beetles or moths and infest the grains at the crop stage or during the storage. Larger grain borer, Prostephanus truncatus (Horn), causes maize-grain losses during storage ranging from 30% to greater 40% of total production in 6 months. It reduces germination potential of maize grain and increases the grain's moisture content thus accelerating contamination by fungi and bacteria. The aim of this study was to determine the insecticidal extracts and compounds from Ocimum suave. Percentage mortality of the insects were recorded 1, 2, 14 and 21 days after treatment while adult emergence inhibition and weight loss prevention activities were recorded 42 days after treatment. The essential oil of the plant gave 75.4, 77.1 and 78.5% mortality after 7, 14 and 21 days respectively, while leaf powder gave 50.3, 63.7 and 66.6% mortality after 7, 14 and 21 days respectively. Betulinic acid gave 56.9 and 58.1% mortality 14 and 21 days after treatment respectively. The essential oil completely prevented the emergence of the insects and also completely prevented weight loss of maize grains. The findings from this study have provided scientific data to support the use of Ocimum suave to control insect pests. Further studies aimed at identification on plant materials which can be used in pest management are highly recommended.
... Plants have been identified as a source of important metabolites that are used in defense against different pests and pathogenic microorganism [8][9][10][11][12][13][14][15][16][17][18][19][20] ...
Avocado is one of the world's most economically significant tropical fruit crops. In recent years, there has been a lot of interest in avocado as a natural functional food in due to its excellent nutritional value and several health advantages. Avocados are rich in unsaturated fatty acids, fat-soluble vitamins like vitamin E and vitamin B6, alpha-carotene, sterols, fiber, protein, magnesium and potassium. Fatty acids play crucial structural and functional roles in biological systems and are a significant source of energy. The essential polyunsaturated fatty acids such as linoleic acid and the α-linolenic acid cannot be synthesize by human body hence must be obtained from food. This study reviewed the fatty acid composition of avocado. Peer-reviewed articles were retrieved from and 0.07-10.95% respectively. Hass, Quintal, Fortuna and Margarida avocado cultivars were found to contain docosahexaenoic acid, an omega-3 amino acid which is mainly obtained from fish. The type of fatty acids and their percentage composition in the avocados differed depending on the cultivar, plant part, ripening stage, geographical location and sample processing method. Results from this study have confirmed that avocado is a rich source of essential fatty acid. Further research on methods of enhancing fatty acid content is necessary. It is also necessary to determine the bioactivities of the fatty acids present in avocado.
Allamanda leaf extract and separated compounds were studied to determine their inhibitory efficiency against Phomopsis vexans, Fusarium sp, Rhizoctina solani, Sclerotiurn rolfsii and Phytophthora capsici. Four concentrations of the extract namely 1:1, 1:2, 1:3 and 1:4 were used. Extract at 1:3 concentration completely inhibited mycelial growth of P. vexans while other three concentrations were also near completely inhibitory. No concentration showed good performance to inhibit mycelial growth of Fusarium sp. But all concentrations completely inhibited the growth of mycelia of R. solani. Higher concentration (1:1, 1:2) completely inhibited S. rolfsii whereas lower concentration (1:3, 1:4) arrested its growth to some extent. Incase of P. capsici, though 1:3 concentration completely inhibited mycelial growth but other three were also promising. For separated compounds, compound 1 and 3 completely inhibited the growth of P. vexans, the other one was not so much promising. In case of Fusarium sp and R. solani, compound 3 showed partial inhibition, but the same compound completely inhibited the growth of S. rolfsii and P. capsici. Water extract showed better performance compared to separated compounds which indicated that some of the essential compounds for the inhibitory action might have been removed during preparation of extracts in other solvents.
Two 1,3-diarylpropanes, 1-(4'-hydroxy-2'-methoxyphenyl)-3-(3"-methoxy-4" -hydroxyphenyl)-propane and 1-(2'-hydroxy-4',6'-dimethoxyphenyl)-3-(3"-methoxy-4" -hydroxyphenyl)-propane, seven flavanones, naringenin, naringenin-4',7-dimethyl-ether, sakuranetin, isosakuranetin, liquiritigenin-4',7-dimethyl-ether, liquiritigenin-7-methyl-ether and liquiritigenin-4'-methyl-ether, two chalcones, isoliquiritigenin-4-methyl-ether and isoliquiritigenin-4'-methyl-ether, one flavan, 7,4'-dihydroxy-3'-methoxyflavan, nine triterpenes, arjunic acid, arjunetin, arjungenin, arjunglucoside I, arjunolic acid, arjunglucoside II, 23-galloylarjunglucoside II (isolated as its mono-, di- and tri-O-methyl derivatives after methylation with diazomethane), betulinic acid and ursolic acid acetate, along with gallic acid and sitosterol were isolated from the heartwood and trunk bark of of Terminalia fagifolia. The flavanones and chalcones obtained in the present work are new in the Combretaceae and this is the first report of the occurrence of 1,3-diarylpropanes in this family. The isolated compounds were evaluated for their in vitro cytotoxic activity against two human cancer cell lines (Hep2 larynx carcinoma and H292 lung mucoepidermoid carcinoma) and antioxidant properties. Isoliquiritigenin-4-methyl-ether, isoliquiritigenin-4'-methyl-ether, 1-(2'-hydroxy-4',6'-dimethoxyphenyl)-3-(3"-methoxy -4"-hydroxyphenyl)-propane and the di- and tri-O-methyl derivatives of 23-galloylarjunglucoside II were the most active in the cytotoxic assay.
Two inoculation methods were developed and compared to evaluate cured sweetpotato (Ipomoea batatas) storage roots for resistance to Rhizopus soft rot caused by Rhizopus stolonifer and R. arrhizus. Roots that had been cured and stored for at least 3 wk were first washed in a commercial washer. In the impact/dip method, roots were wounded by allowing them to drop approximately I m from the end of the washer into crates, after which they were dipped in a suspension of sporangiospores. In the puncture inoculation method, deep-threaded wood screws were dipped in a spore suspension and then hammered about 5-10 mm deep into the median of the root. Most genotypes were more susceptible to R. stolonifer than to R. arrhizus; thus, subsequent evaluations were made using only R. stolonifer. Ranking of genotypes was similar with both methods, and there was an overall correlation in soft rot incidence (R2 = 0.22) between the methods. However, overall incidence of soft rot and differences among genotypes were greater by the puncture method. Genotypes with white-fleshed storage roots were uniformly susceptible, while those with orange flesh varied. Linear relationships were observed between inoculum concentrations and soft rot incidence on four different genotypes by the puncture method. By the impact/dip method, differences in soft rot incidence were not influenced as strongly by inoculum concentration. Of the commercial cultivars evaluated, Beauregard was the most resistant, Jewel and Hernandez varied from intermediate to susceptible, and the white-fleshed cultivars Hi Dry and Sumor were among the most susceptible.
The effect of the matric component of soil water potential (Ψm) on infection of fibrous roots of sweetpotato (Ipomoeae batatas) cv. Jewel by Streptomyces ipomoeae and the influence of infection on water extraction by fibrous roots were examined. The severity of disease on fibrous roots was low in plants grown at constant Ψm of 0, −1.0 or −2.5J kg−1 in non-fumigated or fumigated soils infested with S. ipomoeae. Disease severity increased with decreasing Ψm and was greatest at Ψm of −7.5 to −20J kg−1. Growth of S. ipomoeae in water-filled pores and subsequent infection may have been limited at Ψm of 0, −1.0 and −2.5J kg−1. Root and shoot dry weights of sweetpotato were significantly lower in plants grown in infested soil than in non-infested soils at Ψm between −5 and −20J kg−1, but were not affected by disease at Ψm of 0, −1.0 or −2.5 J kg−1. The severity of disease on fibrous roots was low in plants drip-irrigated on a daily schedule, whereas the severity of disease on fibrous roots was significantly greater in plants irrigated on either a 4- or 6-day schedule. Total dry weights of roots were lower in plants grown for 4 weeks in infested than non-infested soil. However, total dry weights of roots were not affected by disease as compared to non-inoculated controls in plants grown for 8 weeks, thus suggesting that roots of cv. Jewel may be able to compensate for disease by production of additional root biomass in soil. Although root dry weight was not affected by disease in plants grown for 8 weeks, diseased plants extracted significantly less water from soil than healthy plants. Therefore, the effect of disease on water extraction from soil was not due solely to a reduction in root biomass. Limited growth of roots to inoculum in saturated soil, limited growth of the pathogen in saturated soil, or altered susceptibility of the host may explain the reduction of disease at high Ψm.
Arjun (Terminalia arjuna) is a source of many potent, biologically active com- pounds, planned all over Bangladesh. The chemical examinations of its fruits were taken up to isolate and identify active principles. For this purpose fresh fruits of Terminalia arjuna were extracted with rectified spirit. The extract was then triturated with petroleum ether (40-60 O C), which was then subjected to column chromatograph- ic separation followed by PTLC. Such separation led to the isolation of some new pure compounds, TA-1 to TA-5. The structures of compounds were characterized through spectroscopic studies (IR, 1 H-NMR and 13 C-NMR).
Crude ethanolic extract of the stem bark of Terminalia arjuna (Combretaceae) and its three compounds namely arjunic acid, arjungenin and arjunetin were evaluated for antifeedant, growth inhibitory and oviposition-deterrent activities against a lepidopterous insect Spilarctia obliqua. The compound arjunetin showed highest growth inhibitory and feeding-deterrent properties with a growth inhibition (GI(50)) and feeding-inhibition (FD(50)) of 188.5 and 287.1 micro g/g diet respectively. Oviposition bioassays indicated no oviposition-deterrence in any of the compounds tested. The structure-activity relationship study indicated the importance of a glycosidation linkage in arjunetin.
Symptomless sweet potato (Ipomoea batatas) plants obtained from farmers' fields in each of the main sweet potato growing regions of Uganda were tested by nitro-cellulose membrane enzyme-linked immunosorbent assays (NCM-ELISA) for sweet potato feathery mottle virus (SPFMV), sweet potato mild mottle virus (SPMMV), sweet potato chlorotic fleck virus (SPCFV), sweet potato latent virus (SPLV), C-6 virus (C-6) and sweet potato caulimo-like virus (SPCa-LV). Most of the plants tested gave negative reactions in all NCM-ELISA, only c. 5% giving positive reactions to SPFMV and c 1% to SPMMV or SPCFV. Graft inoculations of cuttings from symptomless sweet potato plants, obtained either at Namulonge Agricultural and Animal Production Research Institute (NAARI) or from farmers' fields, onto seedlings of the near-universal indicator plant for sweet potato viruses, Zpomoea setosa, caused symptoms in c. 15% of indicator plants; in all such cases, SPFMV alone was identified by NCM-ELISA. Supplementary tests, involving further grafting of sweet potato to I. setosa seedlings or grafting sweet potato plants themselves with sweet potato sunken vein virus (SPSVV), which in the presence of SPFMV causes sweet potato virus disease (SPVD), confirmed the absence of infection in sweet potato cuttings which had not caused symptoms on I. setosa in the initial graft test. Possible mechanisms explaining the prevalence of virus-free sweet potato plants in farmers' fields are discussed.