Characteristics and chemical compositions of propolis from Ethiopia
© Rushdi et al.; licensee Springer. 2014
Received: 17 February 2014
Accepted: 8 May 2014
Published: 20 May 2014
Propolis is a sticky material mixed by honeybees to utilize it in protecting their hives from infection by bacteria and fungi. The therapeutic properties of propolis are due to its chemical composition with bio-active compounds; therefore, researchers are interested in studying its chemical constituents and biological properties. The main objective of this study is to determine the chemical compositions, characteristics and relative concentrations of organic compounds in the extractable organic matter of propolis samples collected from four different areas in Ethiopia.
The propolis samples were extracted with a mixture of dichloromethane and methanol and analyzed by gas chromatography–mass spectrometry (GC-MS).
The results showed that the total extract yields ranged from 27.2% to 64.2% (46.7 ± 19.1%). The major compounds were triterpenoids (85.5 ± 15.0% of the total extracts, mainly α-, β-amyrins and amyryl acetates), n-alkanes (5.8 ± 7.5%), n-alkenes (6.2 ± 7.0%,), methyl n-alkanoates (0.4 ± 0.2%), and long chain wax esters (0.3 to 2.1%).
The chemical compositions of these propolis samples indicate that they are potential sources of natural bio-active compounds for biological and pharmacological applications.
Honeybees collect resinous/waxy substances from exudates of plants to make a sticky material known as propolis (Ghisalberti 1979; Parolia et al. 2010). They utilize propolis to seal cracks in hives, encapsulate invader carcasses and protect their hives from infection by bacteria and fungi (Banskota et al. 2001; Simone-Finstrom & Spivak 2010). In ancient times, Egyptians, Greeks and Romans all used propolis as a remedy against some diseases (Sforcin & Bankova 2011). The therapeutic properties of propolis are due to its chemical composition with bio-active compounds; therefore, researchers are interested in studying its chemical constituents and biological properties (Sforcin & Bankova 2011; Bankova 2005; Castaldo & Capasso 2002; Sforcin 2007). The diverse chemical compositions and biological activities of propolis are attributed to geographical settings, plant sources and collecting season (Sforcin & Bankova 2011). Flavonoids, aromatic acids, diterpenoid acids, triterpenoids, and phenolic compounds are the major components of propolis (Bankova et al. 2000; Chen et al. 2008; Cursta-Rubio et al. 2007; Daugsch et al. 2008; Kumazawa et al. 2008; Markham et al. 1996; Popova et al. 2010). Some of these compounds are responsible for its biological activities (Bankova et al. 2000; Barros et al. 2007; Bassani-Silva et al. 2007; Bufalo et al. 2009; Cvek et al. 2007; Orsatti et al. 2010a; Orsatti et al. 2010b; Orsi et al. 2005; Zamami et al. 2007). There are three possible sources for the organic compounds of propolis: plants, secreted substances from honeybee metabolism, and materials that are introduced during propolis formation (Marcucci 1995). Propolis is typically composed of 50% resin and vegetable balsam, 30% wax, 10% essential and aromatic oils, 5% pollen and 5% other substances (Cirasino et al. 1987; Monti et al. 1983). Most of the studies on propolis composition and pharmacological effects have been performed on samples from Europe and Latin America (e.g. (Bankova et al. 2000; Daugsch et al. 2008; Barros et al. 2007; Monti et al. 1983)), whereas few have reported on propolis from north Africa (El-Hady & Hegazi 2002; Hegazi & El-Hady 2002) with none from Ethiopia. Ethiopia is located in north-eastern Africa with varied climatic and physiographic conditions that endowed the country with more than 7,000 species of flowering plants (Edwards 1976). They are considered as a potential for producing huge volume of propolis with high probabilities for various biologically active substances. However, many beekeepers in the country focus only on honey production.
Therefore, the main objective of this study is to determine the chemical compositions, characteristics and relative concentrations of organic compounds in the extractable organic matter of propolis samples collected from four different areas in Ethiopia.
The relative concentrations (%), and organic parameters of the various lipid compound groups of propolis samples from different regions of Ethiopia
CPI(o/e as esters) c
The chemical compositions of propolis samples obviously vary between different samples (Popova et al. 2010; El-Hady & Hegazi 2002; Hegazi & El-Hady 2002; Edwards 1976; Popova et al. 2011; Trusheva et al. 2003). Recent studies have shown that diterpenoids were the major compounds in propolis samples from Greece and Sicily (Popova et al. 2010; Trusheva et al. 2003; Popova et al. 2009). The major components of Greek propolis consist of communic, cupressic, isocupressic acids and totarol (Popova et al. 2010), indicating a potential origin from conifer (e.g. cedar) resin (Cox et al. 2007). Triterpenoids including β-amyrin, β-amyrone, lupeol, and lupenone, and polyprenyl benzophenones such as 7-epi-nemorosone, 7-epi-clusianone, xanthochymol, and gambogenone have been detected in propolis samples from the Brazilian Amazon (de Castro Ishida et al. 2011). Propolis samples from Egypt contained caffeate esters, triterpenoids with major diterpenoids, but no aromatic acids and flavonoids (El-Hady & Hegazi 2002; Hegazi & El-Hady 2002). The results show that these propolis extracts include primarily lipid compounds from terrestrial plant sources as reported before (Bankova et al. 2000; Cursta-Rubio et al. 2007; Ugur et al. 2011; Campo Fernandez et al. 2008; Lotti et al. 2010; Melliou & Chinou 2004; Salatino et al. 2005). Phenols (e.g. flavonoids) or other antioxidants were not detected.
Triterpenoids have been reported to occur in diverse plant species as resin or gum constituents (Cursta-Rubio et al. 2007; de Castro Ishida et al. 2011). They are rarely found in fungi and animals (Lutta et al. 2008). Therefore, the major source of triterpenoids is terrestrial vegetation (Hernández-Vázquez et al. 2010; Manguro et al. 2009; Moreau et al. 2009; Ramadan et al. 2009). They are found in plant leaves (Ramadan et al. 2009; van Maarseveen & Jetter 2009; Silva et al. 2009), bark (Hernández-Vázquez et al. 2010; Rosas-Acevedo et al. 2011; Feng et al. 2010; Vouffo et al. 2010), resins (Hernández-Vázquez et al. 2010; Manguro et al. 2009; Wang et al. 2011), and oils (Moreau et al. 2009; Akihisa et al. 2010; Bakowska-Barczak et al. 2009; Wesolowska et al. 2011). Their concentrations vary and depend on the plant species. For example, α- and β-amyrin are found in Protium sp. Byrosonima fagifolia and Byrosonima crassifolia (Hernández-Vázquez et al. 2010) and only α-amyrin is present in Cassia obtusifolia (Sob et al. 2010).
The main compounds in these propolis samples were triterpenoids. The relative concentrations of these substances ranged from 64.0% to 97.6% with a mean value of 85.5 ± 15.0%. They were mainly α- and β-amyrones, amyrins, and amyryl acetates, lupeol, and α- and β-lupeyl acetates. The highest triterpenoid concentrations were observed in the propolis from the Bako (97.6%) and Gedo (93.7%) areas, where the major vegetation is dominated by Acacia species, as well as Euphorbiaceae species (Croton macrostachys) and Boraginaceae species (Cordia africana). β-Amyrin was the major triterpenoid in the samples from the Enemor and Holleta with relative concentrations of 83.8% and 63.1%, respectively. Whereas, α-amyryl acetate was the major compound in the samples from the Bako with a relative concentration of 46.7%, followed by β-amyryl acetate at 44.9%. In the propolis from the Gedo the major compounds were also β-amyryl acetate (53.8%) followed by α-amyryl acetate (29.7%). Lupeol and α- and β- lupeyl acetates were also present in significant amounts (Table 1). This percentage variation in the contents is likely due to different plant species of the same family. As previously mentioned, these triterpenoid compounds were also detected in propolis samples from Brazil and Egypt (El-Hady & Hegazi 2002; Hegazi & El-Hady 2002; de Castro Ishida et al. 2011) as well as from Cuba (Márquez Hernández et al. 2010). This indicates that triterpenoid compounds are likely dominant components of propolis samples from tropical and semi-tropical regions.
The presence of triterpenoids (mainly amyrins and amyryl acetates) can act as antibacterial and antitumor agents (Sforcin & Bankova 2011; de Castro Ishida et al. 2011). Obviously, the main source of triterpenoids in propolis is the surrounding vegetation. Therefore, the determination of the chemical compositions of the regional vegetation should be considered, because it will be useful for investigating the pharmacologically active components of local plants as well as of propolis.
n-Alkanes and n-alkenes
The relative concentrations of n-alkanes in these samples ranged from 0.87% to 16.9% of the total extracts with a mean of 5.82 ± 7.48% (Table 1). The lowest relative concentration (0.87%) was measured in the propolis from Bako, while the highest concentration (16.9%) was in the sample from the Holleta area. The dominant n-alkanes were in the range of C21 to C31, with a carbon number maximum concentration (Cmax) at 27 (e.g. Figure 2a, (Mazurek & Simoneit 1984)). The carbon preference index (CPI, (Mazurek & Simoneit 1984)) varied from 10.95 to 13.56 with an average of 12.75 ± 1.46 (Table 1). Plant wax n-alkanes generally have a Cmax in the range of C25–C31, which varies depending on the plant species as well as the season and locality (e.g. (Eglinton & Hamilton 1967)). Thus, the odd carbon number preference of the C21-C31 n-alkanes and the Cmax at 27 indicate the major sources of these n-alkanes are likely from the beeswax (Tulloch 1970).
The relative concentrations of the n-alkenes ( Δ 1 or Δ 9 ) ranged from 0.85% to 15.92% with a mean of 6.23 ± 6.96%. The highest relative concentration (15.92%) was found in the propolis sample from the Holleta area and the minimum (0.85%) in the samples from Bako. The n-alkenes ranged from C25 to C36 with a Cmax at 33. The odd carbon numbered n-alkenes were dominant with a CPI of 2.49 to 7.24 (mean 5.30 ± 2.02). The distribution of n-alkenes with major concentrations of the odd numbered homologues and Cmax at 33 supports an origin from insect wax (Jackson 1972; Jackson & Baker 1970), possibly from alteration of long chain n-alkanols.
The concentrations of methyl n-alkanoates were relatively low at 0.19% to 1.14% with a mean of 0.64 ± 0.40% (Table 1). They ranged from C13 to C29 with a Cmax at 17 and 25 (as acids Cmax = 16 and 24) (Figure 2c). Methyl n-alkanoates may be natural or form by transesterification of n-alkanoic acids during extraction as indicated by their low relative concentrations. The highest concentration (1.14%) was found for the propolis sample from Gedo and the lowest (0.19%) from Bako. The methyl n-alkanoates of these samples have a strong even carbon number predominance as the alkanoic acids (CPI > 17, except for Gedo, Table 1), indicating that they are originally from natural biota (Harwood & Russell 1984).
Long chain wax esters
Long chain wax esters were also detected in these samples with relative concentrations of 0.29% to 2.08%, and consisting mainly of docosanyl-, tetracosanyl-, hexacosanyl- and octacosanyl hexadecanoates. The major compound of the wax esters was tetracosanyl hexadecanoate in all samples (Table 1, Figure 2f). They are likely derived from lipid components of terrestrial plants (Baker 1982; Kolattukudy 1976; Hamilton 1995) of the region or from waxes secreted by the bees (Tulloch 1971). Subsequent reports have shown that the components of waxes in some younger plants are generally alcohols (40%) and they are mainly wax esters (42%) in older plants (Avato et al. 1990; Bianchi et al. 1989). The vegetation wax ester composition depends not only on plant species, but also on the geographical location (Sforcin & Bankova 2011). Waxes secreted by bees contain more than 15% of wax esters (Katzav-Gozansky et al. 1997). Bee wax esters generally include tetradecyl-dodecanoate, tetradecanoate and hexadecanoate, as well as hexadecyl-tetradecanoate and hexadecanoate (Katzav-Gozansky et al. 1997).
It has been reported that propolis components, which are complex, have biological properties including antimicrobial, antioxidant and anticancer activities (Lustosa et al. 2008; Naito et al. 2007; Diaz-Carballo et al. 2008). Propolis was also reported to have effects against cariogenic bacteria (de Castro Ishida et al. 2011). Triterpenoids are major and to date unique components of these propolis samples from different regions in Ethiopia, indicating a high potential as sources of biologically active substances. Further studies are needed to investigate the biological activities of these propolis samples, and the correlations between their chemical compositions and botanical origins.
The solvent-extractable organic matter (DCM:MeOH) of propolis samples from four regions in Ethiopia have been characterized using GC–MS techniques. The mixed solvent was used to extract both polar and non-polar compounds of proplis samples. The major compounds were in order: triterpenoids > > n-alkanes ~ n-alkenes > long chain wax esters > methyl n-alkanoates. The predominant triterpenoids were α- and β-amyrins, α- and β-amyryl acetates, followed by lupeol, and α- and β-lupeyl acetates. n-Alkanes and n-alkenes ranged from C21 to C31 and C25 to C35 with Cmax at 27 and 33, respectively. Long chain wax esters and methyl n-alkanoates were minor components in these samples. The sources of the major triterpenoids are from the regional Acacia waxes and gums. Phenols (e.g. flavonoids) or other antioxidants were not detectable in these samples.
The variation in the identities of propolis components among various reports is likely due to diverse environmental source vegetation, and different extraction methods and solvents used. Therefore, a standardized analytical method should be adopted in order to be able to compare results obtained by different investigators.
Materials and methods
About 20 g of each sample was broken up and extracted three times using ultrasonic agitation for a 15 min period each with a mixture of dichloromethane (DCM) and methanol (MeOH, 40 mL, 3:1 v:v) mixture to make certain that both polar and non-polar compounds were extracted. The extraction was carried out in a precleaned beaker. The extract was then filtered using a filtration unit containing an annealed glass fiber filter for the removal of undissolved particles. The filtrate was first concentrated on a rotary evaporator and then reduced using a stream of dry nitrogen gas to a volume of approximately 2 mL. The volume was then adjusted to exactly 2 mL by addition of DCM:MeOH (3:1, v:v). A 50-μL aliquot of each total extract was derivatized with silylating reagent [N,O-bis(trimethylsilyl)trifluoroacetamide, BSTFA, Pierce Chemical Co.] by the standard procedure (Knapp 1979), before analysis by gas chromatography–mass spectrometry (GC–MS). This derivatizing agent replaces the H in hydroxyl groups with a trimethylsilyl [(CH3)3Si, i.e. TMS] group for better GC resolution of polar compounds.
Instrumental analysis by GC–MS was carried out with an Agilent 6890 gas chromatograph coupled to a 5973 Mass Selective Detector, using a DB-5MS (Agilent) fused silica capillary column (30 m × 0.25 mm i.d., 0.25 μm film thickness) and helium as carrier gas. The GC was temperature programmed from 65°C (2 min initial time) to 310°C at 6°C min−1 (isothermal for 55 min final time) and the MS was operated in the electron impact mode at 70 eV ion source energy. Mass spectrometric data were acquired and processed using the GC–MS ChemStation data system.
Identification and quantification
The identification of n-alkanes was based on the GC–MS data. Retention times were compared with those of external standards. The identities of triterpenoids, n-alkanes, n-alkenes, n-alkanoic acids, methyl n-alkanoates, and long chain wax esters are based primarily on their mass spectra (i.e. key ions at m/z 191/189, 85, 83, 117, 87, and 257, respectively), comparison with those of standards or in the literature, and gas chromatographic retention times. Average response factors were calculated for each compound. All quantifications were based on the compound peak areas derived from the ion fragmentograms correlated with the total ion current (TIC) trace.
This study was supported by the NPST (National Plan for Sciences and Technology) at King Saud University (NPST Grants No. 09-ENV658-02 and No. 11-AGR1748-02).
- Akihisa T, Kojima N, Katoh N, Ichimura Y, Suzuki H, Fukatsu M, Maranz S, Masters E: Triterpene alcohol and fatty composition of sea nuts from seven African countries. J Oleo Sci 2010, 59: 351-360. 10.5650/jos.59.351View ArticleGoogle Scholar
- Avato P, Bianchi G, Pogna N: Chemosystematics of surface lipids from maize and some related species. Phytochemistry 1990, 29: 1571-1576. 10.1016/0031-9422(90)80124-YView ArticleGoogle Scholar
- Baker EA: Chemistry and morphology of plant epicuticular waxes. In The Plant Cuticle. Edited by: Cutler DF, Alvin KL, Price CE. London: Academic Press; 1982.Google Scholar
- Bakowska-Barczak AM, Schieber A, Kalodziejczyk P: Characterization of Saskatoon berry (Amelanchier alnifolia Nutt.) seed oil. J Agric Food Chem 2009, 57: 5401-5406. 10.1021/jf9006278View ArticleGoogle Scholar
- Bankova V: Chemical diversity of propolis and the problem of standardization. J Ethnopharmacol 2005, 100: 114-117. 10.1016/j.jep.2005.05.004View ArticleGoogle Scholar
- Bankova V, De Castro S, Marcucci M: Propolis: Recent advances in chemistry and plant origin. Apidologie 2000, 31: 3-15. 10.1051/apido:2000102View ArticleGoogle Scholar
- Banskota AH, Tezuka Y, Kadota S: Recent progress in pharmacological research of propolis. Phytother Res 2001, 15: 561-571. 10.1002/ptr.1029View ArticleGoogle Scholar
- Barros MP, Sousa JP, Bastos JK, Andrade SF: Effect of Brazilian green propolis on experimental gastric ulcers in rats. J Ethnopharmacol 2007, 110: 567-571. 10.1016/j.jep.2006.10.022View ArticleGoogle Scholar
- Bassani-Silva S, Sforcin JM, Amaral AS, Gaspar LFJ, Rocha NS: Propolis effect in vitro on canine transmissible venereal tumor cells. Revista Portuguesa de Ciencias Veterinarias 2007, 102: 261-265.Google Scholar
- Bianchi G, Avato P, Scarpa O, Murelli C, Audisio G, Rossini A: Composition and structure of maize epicuticular wax esters. Phytochemistry 1989, 28: 165-171. 10.1016/0031-9422(89)85031-9View ArticleGoogle Scholar
- Bufalo MC, Figueiredo AS, Sousa JPB, Candeias JMG, Bastos JK, Sforcin JM: Anti-poliovirus activity of Baccharis dracunculifolia and propolis by cell viability determination and real-time PCR. Appl Microbiol 2009, 107: 1669-1680. 10.1111/j.1365-2672.2009.04354.xView ArticleGoogle Scholar
- Campo Fernandez M, Cuesta-Rubio O, Rosado Perez A, Montes de Oca Porto R, Marquez Hernandez I, Piccinelli AL, Rastrelli L: GC–MS determination of isoflavonoids in seven red Cuban propolis samples. J Agr Food Chem 2008, 56: 9927-9932. 10.1021/jf801870fView ArticleGoogle Scholar
- Castaldo S, Capasso F: Propolis, an old remedy used in modern medicine. Fitoterapia 2002, 73: S1-6.View ArticleGoogle Scholar
- Chen YW, Wu SW, Ho KK, Lin SB, Huang CY, Chen CN: Characterization of Taiwanese propolis collected from different locations and seasons. J Sci Food Agric 2008, 88: 412-419. 10.1002/jsfa.3101View ArticleGoogle Scholar
- Cirasino L, Pisati A, Fasani F: Contact dermatitis from propolis. Contact Dermatitis 1987, 16: 110-111. 10.1111/j.1600-0536.1987.tb01394.xView ArticleGoogle Scholar
- Cox RE, Yamamoto S, Otto A, Simoneit BRT: Oxygenated di- and tricyclic diterpenoids of southern hemisphere conifers. Biochem Syst Ecol 2007, 35: 342-362. 10.1016/j.bse.2006.09.013View ArticleGoogle Scholar
- Cursta-Rubio O, Piccineli AL, Campo Fernandez M, Hernandez IM, Rosado A, Rastrelli L: Chemical characterization of Cuban propolis by HPLC-PDA, HPLC-MS, and NMR: the brown, red, and yellow Cuban varieties of propolis. J Agric Food Chem 2007, 55: 7502-7509. 10.1021/jf071296wView ArticleGoogle Scholar
- Cvek J, Medić-Šarí M, Jasprica I, Zubči S, Vitali D, Mornar A, Vedrina- Dragojevi I, Tomi S: Optimization of an extraction procedure and chemical characterization of Croatian propolis tinctures. Phytochem Anal 2007, 18: 451-459. 10.1002/pca.1001View ArticleGoogle Scholar
- Daugsch A, Moraes CS, Fort P, Park YK: Brazilian red propolis – chemical composition and botanical origin. Evid Based Complement Alternat Med 2008, 5: 435-441. 10.1093/ecam/nem057View ArticleGoogle Scholar
- de Castro Ishida VF, Negri G, Salatino A, Bandeira MFCL: A new type of Brazilian propolis: Prenylated benzophenones in propolis from Amazon and effects against cariogenic bacteria. Food Chemistry 2011, 125: 966-972. 10.1016/j.foodchem.2010.09.089View ArticleGoogle Scholar
- Diaz-Carballo D, Malak S, Bardenheuer W, Freistuehler M, Reusch HP: The contribution of plukenetione A to the anti-tumoral activity of Cuban propolis. Bioorg Med Chem 2008, 16: 9635-9643. 10.1016/j.bmc.2008.10.019View ArticleGoogle Scholar
- Edwards S: Some Wild Flowering Plants of Ethiopia. Addis Ababa, Ethiopia: Addis Ababa University Press; 1976.Google Scholar
- Eglinton G, Hamilton RJ: Leaf epicuticular waxes. Science 1967, 156: 1322-1335. 10.1126/science.156.3780.1322View ArticleGoogle Scholar
- El-Hady FK, Hegazi AG: Egyptian propolis: 2. Chemical composition, antiviral and antimicrobial activities of East Nile Delta propolis. Z Naturforsch C 2002, 57c: 386-394.Google Scholar
- Feng T, Wang R, Cai X, Zheng T, Luo X: Anti-human immunodeficiency virus-1 constituents of the bark of Poncirus trifoliate . Chem Pharm Bull 2010, 58: 971-975. 10.1248/cpb.58.971View ArticleGoogle Scholar
- Ghisalberti EL: Propolis: A review. Bee World 1979, 60: 59-84.View ArticleGoogle Scholar
- Hamilton RJ (Ed): Waxes: Chemistry, Molecular Biology and Functions. Dundee, WA: The Oily Press; 1995.Google Scholar
- Harwood JL, Russell NJ: Lipids in Plants and Microbes. London: George Allen and Unwin; 1984.View ArticleGoogle Scholar
- Hegazi AG, El-Hady FK: Egyptian propolis: 3. Antioxidant, antimicrobial activities and chemical composition of propolis from reclaimed lands. Z Naturforsch C 2002, 57c: 395-402.Google Scholar
- Hernández-Vázquez L, Mangas S, Palazón J, Navarro-Ocana A: Valuable medicinal plants and resins: Commercial phytochemicals with bioactive properties. Ind Crop Prod 2010, 31: 476-480. 10.1016/j.indcrop.2010.01.009View ArticleGoogle Scholar
- Jackson LL: Cuticular lipids of insects—IV. Hydrocarbons of the cockroaches Periplaneta japonica and Periplaneta americana compared to other cockroach hydrocarbons. Comp Biochem Physiol A Mol Integr Physiol 1972, 41: 331-336.View ArticleGoogle Scholar
- Jackson LL, Baker GL: Cuticular lipids of insects. Lipids 1970, 5: 239-246. 10.1007/BF02532475View ArticleGoogle Scholar
- Katzav-Gozansky T, Soroker V, Hefetz A: Plasticity of caste-specific Dufour’s gland secretion in the honey bee (Apis mellifera L.). Naturwissenschaften 1997, 84: 238-241. 10.1007/s001140050386View ArticleGoogle Scholar
- Knapp DR: Handbook of Analytical Derivatization Reactions. New York: John Wiley and Sons; 1979.Google Scholar
- Kolattukudy PE (Ed): Chemistry and Biochemistry of Natural Waxes. Amsterdam: Elsevier; 1976.Google Scholar
- Kumazawa S, Nakamura J, Murase M, Miyagawa M, MR A, Fukumoto S: Plant origin of Okinawan propolis: honeybee behavior observation and phytochemical analysis. Naturwissenschaften 2008, 95: 781-786. 10.1007/s00114-008-0383-yView ArticleGoogle Scholar
- Lotti C, Campo Fernandez M, Piccinelli AL, Cuesta-Rubio O, Marquez Hernandez I, Rastrelli L: Chemical constituents of red Mexican propolis. J Agr Food Chem 2010, 58: 2209-2213. 10.1021/jf100070wView ArticleGoogle Scholar
- Lustosa SR, Galindo AB, Nunes LCC, Randau KP, Rolin Neto PJ: Propolis: Updates on chemistry and pharmacology. Brazilian J Pharm 2008, 18: 447-454.Google Scholar
- Lutta KP, Bill C, Akenga AT, Cornelius WW: Antimacrobial marine natural products from sponges Axnella infundibuliformis. Nat Prod Rep 2008, 25: 110-127.Google Scholar
- Manguro LOA, Opiyo SA, Herdtweck E, Lemmen P: Triterpenes of Commiphora holtziana oleo-gum resin. Can J Chem 2009, 87: 1173-1179. 10.1139/V09-078View ArticleGoogle Scholar
- Marcucci MC: Propolis: chemical composition, biological properties and therapeutic activity. Apidologie 1995, 26: 83-99. 10.1051/apido:19950202View ArticleGoogle Scholar
- Markham KR, Mitchell KA, Wilkins AL, Daldy JA, Lu Y: HPLC and GC–MS identification of the major organic constituents in New Zealand propolis. Phytochemistry 1996, 42: 205-211. 10.1016/0031-9422(96)83286-9View ArticleGoogle Scholar
- Márquez Hernández I, Cuesta-Rubio O, Fernández MC, Pérez AR, Porto RMO, Piccinelli AL, Rastrelli L: Studies on the constituents of yellow Cuban propolis: GC-MS determination of triterpenoids and flavonoids. J Agric Food Chem 2010, 58: 4725-4730. 10.1021/jf904527nView ArticleGoogle Scholar
- Mazurek MA, Simoneit BRT: Characterization of biogenic and petroleum-derived organic matter in aerosols over remote, rural, and urban areas. In Identification and analysis of organic pollutants in air. Edited by: Keith LH. Woburn: Ann Arbor Science; 1984:353-370.Google Scholar
- Melliou E, Chinou I: Chemical analysis and antimicrobial activity of Greek propolis. Planta Medica 2004, 70: 515-519. 10.1055/s-2004-827150View ArticleGoogle Scholar
- Monti M, Berti E, Carminati G, Cusini M: Occupational and cosmetic dermatitis from propolis. Contact Dermatitis 1983, 9: 163.View ArticleGoogle Scholar
- Moreau RA, Lampi AM, Hicks KB: Fatty acid, phytosterol and polyamine conjugates profiles of edible oils extracted from corn germ, corn fiber, and corn kernels. J Am Oil Chem Soc 2009, 86: 1209-1214. 10.1007/s11746-009-1456-6View ArticleGoogle Scholar
- Naito Y, Yasumuro M, Kondou K, Ohara N: Antiinflammatory effect of topically applied propolis extract in carrageenan-induced rat hind paw edema. Phytother Res 2007, 21: 452-456. 10.1002/ptr.2093View ArticleGoogle Scholar
- Orsatti CL, Missima F, Pagliarone AC, Bachiega TF, Bufalo MC, Araujo JP Jr, Sforcin JM: Propolis immunomodulatory action in vivo on Toll-like receptors 2 and 4 expression and on pro-inflammatory cytokines production in mice. Phytother Res 2010, 24: 1141-1146.Google Scholar
- Orsatti CL, Missima F, Pagliarone AC, Sforcin JM: Th1/Th2 cytokines’ expression and production by propolis-treated mice. J Ethnopharmacol 2010, 129: 314-318. 10.1016/j.jep.2010.03.030View ArticleGoogle Scholar
- Orsi RO, Sforcin JM, Rall VLM, Funari SRC, Barbosa L, Fernandes A Jr: Susceptibility profile of Salmonella against the antibacterial activity of propolis produced in two regions of Brazil. J Venom Anim Toxins 2005, 11: 109-116.Google Scholar
- Parolia A, Tomas M, Kundabala M, Mohan M: Propolis and its potential uses in oral health. Int J Med Medical Sci 2010, 2: 210-215.Google Scholar
- Popova M, Chinou I, Marekov I, Bankova V: Terpenes with antimicrobial activity from Cretan propolis. Phytochemistry 2009, 70: 1262-1271. 10.1016/j.phytochem.2009.07.025View ArticleGoogle Scholar
- Popova M, Chen CN, Chen PY, Huang CY, Bankova V: A validated spectrophotometric method for quantification of prenylated flavanones in Pacific propolis from Taiwan. Phytochem Anal 2010, 21: 186-191.Google Scholar
- Popova M, Trusheva B, Antonova D, Cutajar S, Mifsud D, Farrugia C, Tsvetkova I, Najdenski H, Bankova V: The specific chemical profile of Mediterranean propolis from Malta. Food Chemistry 2011, 126: 1431-1435. 10.1016/j.foodchem.2010.11.130View ArticleGoogle Scholar
- Ramadan M, Ahmad AS, Nafady AM, Mansour AI: Chemical composition of the stem bark and leaves of Ficus pandurata Hance. Nat Prod Res 2009, 23: 1218-1230. 10.1080/14786410902757899View ArticleGoogle Scholar
- Rosas-Acevedo H, Terrazas T, González-Trujano ME, Guzmán Y, Soto-Hernández M: Anti-ulcer activity of Cyrtocarpa procera analogous to that of Amphipterygium adstringens , both assayed on the experimental gastric injury in rats. J Ethnopharmacol 2011, 134: 67-73. 10.1016/j.jep.2010.11.057View ArticleGoogle Scholar
- Salatino A, Teixeira EW, Negri G, Message D: Origin and chemical variation of Brazilian propolis. Evid base Compl Alternative Med 2005, 2: 33-38. 10.1093/ecam/neh060View ArticleGoogle Scholar
- Sforcin JM: Propolis and the immune system: a review. J Ethnopharmacol 2007, 113: 1-14. 10.1016/j.jep.2007.05.012View ArticleGoogle Scholar
- Sforcin JM, Bankova V: Propolis: Is there a potential for the development of drugs? J Ethnopharmacol 2011, 133: 253-260. 10.1016/j.jep.2010.10.032View ArticleGoogle Scholar
- Silva AM, Simeoni LA, Silveira D: Genus Pouteria: Chemistry and biological activity. Brazilian J Pharm 2009, 19: 501-509.Google Scholar
- Simone-Finstrom M, Spivak M: Propolis and bee health: the natural history and significance of resin use by honey bees. Apidologie 2010, 41: 295-311. 10.1051/apido/2010016View ArticleGoogle Scholar
- Sob SVT, Wabo HK, Tchinda AT, Tane P, Ngadjui BT, Ye Y: Anthraquinones, sterols, triterpenoids and xanthones from Cassia obtusifolia . Biochem Syst Ecol 2010, 38: 342-345. 10.1016/j.bse.2010.02.002View ArticleGoogle Scholar
- Trusheva B, Popova M, Bankova V, Tsvetkova I, Naydensky C, Sabatini AG: A new type of European propolis, containing bioactive labdanes. Rivista Italiana E.P.P.O.S 2003, 36: 3-7.Google Scholar
- Tulloch AP: The composition of beeswax and other waxes secreted by insects. Lipids 1970, 5: 247-258. 10.1007/BF02532476View ArticleGoogle Scholar
- Tulloch AP: Beeswax: Structure of the esters and their component acids and diols. Chem Phys Lipids 1971, 6: 235-265. 10.1016/0009-3084(71)90063-6View ArticleGoogle Scholar
- Ugur A, Sarac N, Duru ME: Chemical composition of antimicrobial activity of endemic Onopordum caricum . Middle East J Sci Res 2011, 8: 594-598.Google Scholar
- van Maarseveen C, Jetter R: Composition of the epicuticular and intracuticular wax layers on Kalanchoe daigremontiana (Hamet et Perr. de la Bathie) leaves. Phytochemistry 2009, 70: 899-906. 10.1016/j.phytochem.2009.04.011View ArticleGoogle Scholar
- Vouffo B, Dongo E, Facey P, Thorn A, Sheldrick G, Maier A, Fiebig H, Laatsch H: Antiarol cinnamate and africanoside, a cinnamoyl triterpene and a hydroperoxy-cardenolide from the stem bark of Antiaris africana . Planta Medica 2010, 76: 1717-1723. 10.1055/s-0030-1249958View ArticleGoogle Scholar
- Wang F, Li Z, Cui H, Hua H, Jing Y, Liang M: Two new triterpenoids from the resin of Boswellia carterii . J Asian Nat Prod Res 2011, 13: 193-197. 10.1080/10286020.2010.548808View ArticleGoogle Scholar
- Wesolowska A, Jadczak D, Grzeszczuk M: GC-MS analysis of lemon catnip ( Nepeta cataria L. var. citriodora Balbis) essential oil. Acta Chromatographica 2011, 23: 169-180. 10.1556/AChrom.23.2011.1.12View ArticleGoogle Scholar
- Zamami Y, Takatori S, Koyama T, Goda M, Iwatani Y, Doi S, Kawasaki H: Effect of propolis on insulin resistance in fructose-drinking rats. Yakugaku Zasshi 2007, 127: 2065-2073. 10.1248/yakushi.127.2065View ArticleGoogle Scholar
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