Atchade, AT

Fekam Boyom, F

Henoumont, Céline

Kamdem Simo, M

Keumoe, R

Lambert Sameza, M

Laurent, Sophie

Mbafor Tanyi, J.

Menkem Zeukoo, E

Muller, Robert

Ngenge, TA

Roch, Alain

Taboula Kayo, M

Tagatsing Fotsing, M

Talla, E.

Vander Elst, Luce

Yankep, E

ORBi UMONS

Full Terms & Conditions of access and use can be found athttps://www.tandfonline.com/action/journalInformation?journalCode=gnpl20Natural Product ResearchFormerly Natural Product LettersISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/gnpl20Antifungal potential of extracts, fractions andcompounds from Uvaria comperei (Annonaceae)and Oxyanthus unilocularis (Rubiaceae)Maurice Taboula Kayo , Marguerite Kamdem Simo , Maurice TagatsingFotsing , Emmanuel Talla , Sophie Laurent , Luce Vander Elst , CélineHenoumont , Emmanuel Yankep , Tamfu Alfred Ngenge , Rodrigue Keumoe ,Alex de Theodore Atchade , Elisabeth Menkem Zeukóo , Modeste LambertSameza , Alain Roch , Robert Muller , Fabrice Fekam Boyom & Joseph TanyiMbaforTo cite this article: Maurice Taboula Kayo , Marguerite Kamdem Simo , Maurice TagatsingFotsing , Emmanuel Talla , Sophie Laurent , Luce Vander Elst , Céline Henoumont , EmmanuelYankep , Tamfu Alfred Ngenge , Rodrigue Keumoe , Alex de Theodore Atchade , ElisabethMenkem Zeukóo , Modeste Lambert Sameza , Alain Roch , Robert Muller , Fabrice FekamBoyom & Joseph Tanyi Mbafor (2020): Antifungal potential of extracts, fractions and compoundsfrom Uvaria￿comperei (Annonaceae) and Oxyanthus￿unilocularis (Rubiaceae), Natural ProductResearch, DOI: 10.1080/14786419.2020.1828409To link to this article:  https://doi.org/10.1080/14786419.2020.1828409View supplementary material Published online: 27 Nov 2020.Submit your article to this journal Article views: 8View related articles View Crossmark dataSHORT COMMUNICATIONAntifungal potential of extracts, fractions and compoundsfrom Uvaria comperei (Annonaceae) and Oxyanthusunilocularis (Rubiaceae)Maurice Taboula Kayoa,b, Marguerite Kamdem Simoc,d, Maurice TagatsingFotsinga, Emmanuel Tallae, Sophie Laurentf, Luce Vander Elstf, CelineHenoumontf, Emmanuel Yankepa, Tamfu Alfred Ngengee , Rodrigue Keumoec,Alex de Theodore Atchadea, Elisabeth Menkem Zeukooc, Modeste LambertSamezag, Alain Rochf, Robert Mullerf, Fabrice Fekam Boyomc andJoseph Tanyi MbaforaaLaboratory No. 3 of Organic Chemistry, Department of Organic Chemistry, Faculty of Science,University of Yaounde I, Yaounde, Cameroon; bDepartment of Chemistry, Higher Teacher TrainingCollege, University of Bamenda, Bambili, Cameroon; cLaboratory for Phytobiochemistry andMedicinal Plants Studies, Department of Biochemistry, Faculty of Science, University of Yaounde I,Yaounde, Cameroon; dDepartment of Biological Sciences, Faculty of Science, University of Maroua,Maroua, Cameroon; eDepartment of Materials Engineering/Chemical Engineering, School of ChemicalEngineering and Mineral Industries, University of Ngaoundere, Ngaoundere, Cameroon; fNMR andMolecular Imaging Laboratory, Department of General, Organic and Biomedical Chemistry, Faculty ofMedicine and Pharmacy, University of Mons, Mons, Belgium; gDepartment of Biochemistry, Facultyof Science, University of Douala, Douala, CameroonABSTRACTPhytochemical study of Uvaria comperei afforded an alkaloid, 8,9-dimethoxy-5H-phenanthridin-6-one (1), isolated and characterised(assignment of 1H and 13C NMR) for the first time from a naturalsource along with two flavonoids, (2S)-5-hydroxy-7,8-dimethoxy-flavanone (2) and (2S)-7-hydroxy-5-methoxy-6,8-dimethylflavone(3). Clethric acid (4), oleanoic acid (5), b-sitosterol 3-O-b-D-gluco-pyranoside (9), b-sitosterol palmitate (6) and a mixture of stigmas-terol (7) and b-sitosterol (8) were isolated from Oxyanthusunilocularis. The structures of these compounds were elucidatedusing modern spectroscopic techniques including1D and 2DNuclear Magnetic Resonance (NMR) Spectroscopy (1H, 13C, 1H-1HCOSY, HSQC, HMBC) and Mass Spectrometry. Some fractions andcompounds from Uvaria comperei exhibited good antifungal activ-ity against clinical isolates and standard strains of yeast species ofCandida and Cryptococcus genera while extracts from Oxyanthusunilocularis displayed weak antifungal activity. The resultsobtained show that Uvaria comperei could be a potential sourceof antifungal drugs.ARTICLE HISTORYReceived 20 July 2020Accepted 12 September 2020KEYWORDSUvaria comperei; Oxyanthusunilocularis; 8,9-dimethoxy-5H-phenanthridin-6-one;antifungal activityCONTACT Kayo Taboula Maurice kayotaboula@gmail.com 2020 Informa UK Limited, trading as Taylor & Francis GroupNATURAL PRODUCT RESEARCHhttps://doi.org/10.1080/14786419.2020.18284091. IntroductionMicrobial infections pose a health problem throughout the world, due to the resist-ance of bacteria against manufactured drugs, and plants can be used as possible sour-ces of antimicrobial agents (Adenisa et al. 2000). Medicinal plants contain activeprinciples which can be used as an alternative to cheap and effective herbal drugsagainst common bacterial, fungal and viral infections (Adesina et al. 2000; Kareru et al.2008). Oxyanthus unilocularis and Uvaria comperei are two medicinal plants used tomanage infectious diseases in Cameroon. Oxyanthus is a genus of plants belonging toRubiaceae family best known in West Africa, plant of this genus occupy a prominentposition in African traditional medicine (Tigoufack et al. 2012). It comprises 53 species,subspecies, varieties, forms and cultivars (Sonke and Cheek 1999). The leaves, bark orroots of Oxyanthus unilocularis are used for the treatment of fever, arthritis, swelling,pain, mild to moderate depression as well as for cutaneous and subcutaneous parasiticinfestations (Nkeoua and Boundzana 1999; Nkeh-Chungag et al. 2010). The analgesicand anti-inflammatory properties of methanol extracts of the leaves and the bark of O.unilocularis have been reported (Nkeh-Chungag et al. 2010). The genus Uvaria belongsto the Annonaceae family, one of the biggest plant family comprising about 130 gen-era and species belonging to this genus are used in traditional medicine for the treat-ment of dysentery, wound, abdominal ache, malaria (Gina et al. 2014). The free-radicalscavenging and antifungal activity of U. comperei extracts were reported (Simo et al.2018). However, fractions and compounds responsible for the antifungal activity ofthis plant were not known.This involves the evaluation of antifungal activity of fractions and compounds fromU. comperei as well as chemical constituents from O. unilocularis and antifungal poten-tial of its crude extracts.2. Results and discussionThe synthesis of 8,9-dimethoxy-5H-phenanthridin-6-one was reported (Rigby andLaurent 1998; Chen et al. 2014) but without proper spectral assignments. The isolationand spectral characterisation of 8,9-dimethoxy-5H-phenanthridin-6-one (1) from a2 M. T. KAYO ET AL.natural source is reported here for the first time alongside (2S)-5-hydroxy-7,8-dime-thoxyflavanone (2) and (2S)-7-hydroxy-5-methoxy-6,8-dimethylflavone (3) from thestem bark of Uvaria comperei. From the stem bark of Oxyanthus unilocularis, clethricacid (4), oleanoic acid (5), b-sitosterol 3-O-b-D-glucopyranoside (9), b-sitosterol palmi-tate (6) with a mixture of stigmasterol (7) and b-sitosterol (8) were isolated andcharacterised.Compound 1, was obtained as a yellow solid and melted between 295–297 C. Itgave a positive Dragendorff test suggesting that it is an alkaloid. The TOF-ESI-MSþ showed pseudo-molecular ion pic and dimer ion pic at m/z 256.3 and 511.3attributable to [MþH]þ and [2MþH]þ, respectively which is in accordance with themolecular formula C15H13O3N, with 10 degrees of unsaturation. In the1H NMR spec-trum of compound 1 (see Table S1) in DMSO-d6, 6 aromatic proton signals wereobserved and could be assigned to a 1,2,4,5-tetrasubstituted benzene and a 1,2-disubstituted benzene rings on the basis of 1H-1H COSY spectrum and coupling pat-terns. The 1H NMR spectrum displayed two signals at dH 7.16 (1H, s, H-10) and 7.86(1H, s, H-7) characteristic of a 1,2,4,5-tetrasubstituted benzene nucleus. It also exhib-ited a coupling pattern of 4 aromatic protons at dH 7.57 (1H, td, J¼ 7.63, 1.36, H-2),7.61(1H, td, J¼ 7.63, 1.36, H-3), 7.86 (1H, s, H-7), 7.99 (1H, dd, J¼ 7.63, 1.36, H-1) and9.15 (1H, dd, J¼ 7.63, 1.36, H-4), confirming the presence of an O-disubstituted ben-zene ring. The remaining signals in the 1H NMR spectrum were protons of twomethoxy groups at higher field [dH 4.04 (3H, s, H-OMe-9) and 4.06 (3H, s, H-OMe-8)]and a singlet at dH 10.86 showing no correlation with any carbons in HSQC spectrumthat could be ascribed to an D2O exchangeable proton of an NH group. The13CNMR spectrum (BB and DEPT) showed 13 carbon signals among which 2 methyls, 6methines, and 7 quaternary carbons. At the low-field region of the 13C NMR spec-trum the presence of the quaternary carbon signal at dC 168.4 (C-6) was assigned tothe carbonyl of an amide. The signals at dC 104.6 (CH, C-10), 109.6 (CH, C-7), 121.6(C, C-10a), 123.3 (C, C-6a), 125.5 (CH, C-2), 125.9 (C, C-1a), 126.8 (CH, C-4), 127.5 (CH,C-3), 129.0 (CH, C-1), 135.1 (C, C-4a), 150.4 (C, C-9) and 154.2 (C, C-8) were attributedto aromatic carbons. At the up-filed region the two deshielded methyl signalsobserved at dC 56.8 and 60.0 are characteristic of two methoxy groups. In the HMBCspectrum, the H-1 at dH 7.99 revealed a2J correlation with C-2 (dC 125.5). The H-4 atdH 9.15 showed a2J correlation with C-4a (dC 135.1). The amide proton (NH, dH10.86) showed 2J correlations with C-4a (dC 135.1) and C-6 (dC 168.4); and a3J correl-ation with C-6a (dC 123.3). The H-7 at dH 7.86 showed2J correlations with C-6a (dC123.3) and C-8 (dC 154.2); and3J correlations with C-6 (dC 168.4) and C-9 (dC 150.4).The H-10 at dH 7.16 showed a3J correlation with C-1a (dC 125.9) and a4J correlationwith C-1 (dC 129.0). The methoxy proton H-OMe-8 at dH 4.06 showed a3J correlationwith C-8 (dC 154.2). The methoxy proton H-OMe-9 at dH 4.04 showed a3J correlationwith C-9 (dC 150.4). On the basis of these data, the structure of compound 1 wasestablished as 8.9-dimethoxy-5H-phenantridin-6-one. The 1H–1H COSY spectrum ofcompound 1 showed the presence of a spin system due to a 1,4-disubstituted ben-zene ring. In fact, this spectrum exhibited correlations between H-1 and H-2, H-2and H-3; and H-3 and H-2. Furthermore, 1H–1H COSY spectrum of compound 1showed the presence of a spin system due to a long-range correlation between theNATURAL PRODUCT RESEARCH 3proton H-10 at dH 7.16 and the proton H-1 at dH 7.99. Details of the spectradescribed here are summarised on Table S1.2.1. Antifungal activity of extracts, fractions and compounds isolatedThe results of the antifungal activity of fractions and compounds from Uvaria comperei,8,9-dimethoxy-5H-phenanthridin-6-one (1), (2S)-5-hydroxy-7,8-dimethoxyflavanone (2)and (2S)-7-Hydroxy-5-methoxy-6,8-dimethylflavone (3) as well as the crude extractsfrom O. unilocularis are shown in Table S2. That table presents the MIC of fractions onyeasts. It indicated that the activity of fractions changes in function of yeast strain.The most active fractions with low MIC values were fraction 10–11, 12, 13–14, 8, 7, 19,25–34 and 35 this in function of lower values of MIC, whereas, in function of spectrumof activity the most active fraction was fraction 7 followed by fractions 8, 19, 25–34,10–11, 12, 13–14 and 35. Fractions 8, 10–11, 12, 19, 25–34, 7, 13–14 and 35 have thesame statistically activity whereas it is significantly different from fractions 15–18 and36–39 (p 0.05). Non-polar fractions showed higher activity than polar fractions. Theantifungal activity of fractions is higher than that of pure compounds. However, frac-tions 19, 25–34 and 35 afforded compounds 1, 2 and 3 respectively. Interesting, eachcompound had same activity with the corresponding fraction from which it results.The ethyl acetate extract of Oxyanthus unilocularis showed better activity than otherextracts from the plant.After 48 h, MFC were determined and values were indicated in Table S3. Fraction 7to fraction 35 were fungicidal on almost all yeast with MFC of 1.04 to 4.17mg/mL.Fractions 56–62, 75–85, 155–163 were fungistatic (Table S4).3. ConclusionFungal infections constitute a global health problem and many plants have been usedin traditional medicine to manage this situation. Uvaria comperei and Oxyanthus unilo-cularis are two plants that are usually employed in traditional medicine to fight fungaland microbial infections. The chemical compounds contained in these two plants havebeen isolated and characterized in this study. Some of the compounds and fractionsfrom Uvaria comperei as well as the extracts Oxyanthus unilocularis were tested onvarious fungal clinical isolates and standard strains and the results showed appreciableactivity especially for fractions and compounds from Uvaria comperei. This study sup-ports the ethnopharmacology application of Uvaria comperei as remedy for fun-gal diseases.AcknowledgementsThe authors are grateful to the Commission Universitaire pour le Developpement (CUD) for provid-ing a grant to Kayo Taboula Maurice to work at the Free University of Brussels, Belgium andUniversity of Mons, Belgium in 2009, 2010 and 2011. We also thank Prof Pierre DUEZ and theLaboratory of Pharmacognosy, Bromatology and Human Nutrition of the Faculty of Pharmacy ofthe Free University of Brussels for hosting Kayo Taboula Maurice during his internshipsin Belgium.4 M. T. KAYO ET AL.Disclosure statementNo potential conflict of interest was reported by the authors.ORCIDTamfu Alfred Ngenge http://orcid.org/0000-0001-6683-3337ReferencesAdesina SK, Idowu O, Ogundaini AO, Oladimeji H, Olugbade TA, Onawunmi GO, Pais M. 2000.Antimicrobial constituents of the leaves of Acalypha hispida. Phytother Res. 14(5):371–374.Chen YF, Wu YS, Jhan YH, Hsieh JC. 2014. An efficient synthesis of (NH)-phenanthridinones vialigand-free copper-catalyzed annulation. Supplementary information. ElectronicSupplementary Material (ESI). Org Chem Front. 1:253–257.Gina F, Renata B, Souza L, Ari-de-Freitas H, Maas P, Pohlit A. 2014. Plants of the annonaceaetraditionally used as antimalarials: a review. Rev Bras Frutic. 36(spe1):315–336.Kareru PG, Gachanja AN, Keriko JM, Kenji GM. 2008. Antimicrobial activity of some medicinalplants used by herbalists in Eastern Province of Kenya. Afr J Trad Comp Altern Med. 5:51–55.Nkeh-Chungag NB, Bekwa PCM, Ndebia JE, Kayo M, Mbafor TJ, Iputo EJ. 2010. Analgesic andanti-inflammatory properties of Oxyanthus unilocularis. J Med Plants Res. 4(10):932–939.Nkeoua G, Boundzana GC. 1999. Donnees sur les produits forestieres non ligneux en Republiquedu Projet GCP/INT/679/EC Programme de partenariat. EC - FAO; pp. 95–96.Rigby JH, Laurent S. 1998. Addition of alkyl and aryl isocyanides to benzyne. J Org Chem.63(19):6742–6744.Simo KM, Dongmo NMD, Sameza ML, Toghueo RK, Fekam FB, Froldi G. 2018. Cameroonianmedicinal plants belonging to Annonaceae family: radical scavenging and antifungal activities.Nat Prod Res. 32(17):2092–2095.Sonke B, Cheek M. 1999. A new species of Oxyanthus (Rubiaceae-Gardeniinae) from WesternCameroon. Kew Bull. 55(4):889–893.Tigoufack BI, Ngnokam D, Tapondjou LA, Harakat D, Voutquenne L. 2012. Isolation and caracter-isation of sodium monocarboxylate ixoside salt from the stem bark of Oxyanthus pallidus. IntJ Biol Chem Sci. 6(6):7007–7012.NATURAL PRODUCT RESEARCH 5

Antifungal potential of extracts, fractions and compounds from Uvaria comperei (Annonaceae) and Oxyanthus unilocularis (Rubiaceae)

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Antifungal potential of extracts, fractions and compounds from Uvaria comperei (Annonaceae) and Oxyanthus unilocularis (Rubiaceae)

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