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Piper capense Linn is a plant used in Cameroon to treat cancer and several other diseases such as urinary tract disorder, fever, stomach-ache and to improve appetite. The methanol extract of Piper capense has been reported for its antiproliferative activity towards several human cancer cell lines. The aim of this work was to evaluate the acute and subchronic oral toxicities of a methanol extract from P. capense fruits on rats. The acute oral toxicity assay was carried out by administration of a single dose of 5000 mg/kg body weight of methanol extract of the Piper capense to five female rats, after which the behavior of the animals and the number of deaths were noted after 48 h. The animals were then kept for observation for 14 days. On the 15th day, the rats were sacrificed and macroscopic observation of the organs was made. Concerning the subchronic toxicity study, the rats composed of males and females received three doses (250, 500 and 1000 mg/kg body weight/day) for a period of 28 days by oral gavage. General animal behavior, food intake, weight gain, organ weights, haematological parameters, serum, and urinary biochemical parameters, and histological sections of liver and kidneys, were evaluated. Methanol extract from the Piper capense fruits did not cause any death in rats that were administered a single dose of 5000 mg/kg body weight of extract and therefore, the letal dose 50 (LD50) of the extract is greater than 5000 mg/kg body weight. Subchronic administration of the methanol extract of Piper capense fruits showed significant variations (P > 0.05) after analysis of certain biochemical parameters: serum urea, urinary urea, alanine aminotransferase (ALAT), aspartate aminotransferase, (ASAT), serum protein; in both male and female rats that received the dose of 1000 mg/kg body weight/day. No major signs of toxicity were observed in the liver and kidneys of animals after analysis of the histological sections performed. Beside, some signs of toxicity were observed, including cell lysis and inflammation on the liver and kidney organs at a dose of 1000 mg/kg body weight/day. Finally, the methanol extract of Piper capense fruits is safe at lower doses, but could cause some damages at doses as high as 1000 mg/kg body weight/day. Consequently, it should be taken with caution when used in therapy.

Natural products have been a major source of drugs for centuries. The fruit of Piper capense is used traditionally as spice and for the treatment of infectious diseases in different parts of Ethiopia. The main objective of this work is to carry out phytochemical study of the EtOAc crude extract of the fruit of P. capense. Phytochemical screening on this crude extract revealed the presence of phenols, alkaloids, steroids, terpenes, saponins and flavonoids. After silica gel column chromatography the crude extract led to the isolation of compound PC1 identified as 5-Hydroxy-7, 4’-dimethoxyflavone. Characterization of this compound was achieved via spectroscopic methods (NMR, UV and IR). The structure of compound PC2 was elucidated, the spectral data showed the presence of more than one compound one of which is partially characterized and proposed to be rotenone.

For valorization and diversification of medicinal plants used in Comoros, we are interested in three species growth in this archipelago. Four essential oils were extracted from these plants and used in this study. Essential oils were obtained by hydrodistillation and analyzed by gas chromatography (GC) and GC–mass spectrometry (GC–MS). Sesquiterpene compounds are predominant in Piper borbonense and Vetiveria zizanoides essential oils but for Piper capense essential oil, monoterpenes are predominant. Essential oils were investigated for their fungicidal activities against four fungi decay wood: Gloeophyllum trabeum (Persoon ex Fries) Murril (ATCC 11539), Poria placenta (Fries) Cooke sensu J. Eriksson (ATCC 9891), Coniophora puteana (Schumacher ex Fries) Karsten (ATCC 9351) and Coriolus versicolor (Linnaeus) Quelet (ATCC 12679). These essential oils showed an in important activity against all strains tested. However, the highest activity was observed in Vetiveria and P. borbonense essential oils.

Together with apigenine dimethylether and piperchabamide A, a new amide alkaloid, Kaousine and the Z form of antiepilepsirine were isolated from the aerial part of Piper capense L.f (Piperaceae). Their structures were elucidated by spectrometric methods and their in vitro antiparasitic activities were evaluated on Plasmodium falciparum.

The fruits of P. capense from Ethiopia were hydro-distilled with Clevenger apparatus to furnish 2.6-2.8% yellowish oil which was analyzed with GC–MS. Results of the GC-MS analysis revealed the presence of twenty one components with the major ones are β-caryophyllene (5%), g-muurolene (7.22%), germacrene D (9.30%), dihydroxy-isocalamendiol (11.6%), and cis-muurola-3,5-diene (15.6%). The fruits were also successively extracted with n -hexane and EtOAc to give 1.3% and 2.3% yield on dry weight basis, respectively. The EtOAc extract was screened for the presence of secondary metabolites which showed the presence of alkaloids, phenols, steroids, flavonoids, saponins and terpenoids while tannin was not detected. The EtOAc extract after silica gel column chromatography resulted in the isolation of 5-hydroxy-7,4’-dimethoxyflavone. The DPPH radical scavenging activity of the EtOAc extract, essential oil and 5-hydroxy-7,4’-dimethoxyflavone were evaluated and found to inhibit DPPH radical by 78%, 70% and 84% at 100 µg mL -1 , respectively. Likewise, the EtOAc extract, essential oil and 5-hydroxy-7,4’-dimethoxyflavone inhibited peroxidation of lipid by 74, 64 and 80%, respectively. The results are significant compared to ascorbic acid used as positive control suggesting the use of the fruit of P. capense as a natural antioxidant. KEY WORDS : Piper capense , DPPH, Ferric thiocyanate, 5-hydroxy-7,4’-dimethoxyflavone Bull. Chem. Soc. Ethiop. 2018 , 32(1), 167-174 DOI: https://dx.doi.org/10.4314/bcse.v32i1.16

Piper capense L.f. (Piperaceae) is used traditionally in South Africa as a sleep inducing remedy. Bioassay-guided fractionation of the roots of P. capense led to the isolation of piperine (1) and 4,5-dihydropiperine (2), which showed moderate affinity for the benzodiazepine site on the GABA(A) receptor (IC(50) values of 1.2 mM and 1.0 mM, respectively). The present study suggests that strict structural properties of the amides are essential for affinity. Taken together, these observations suggest that the carbon chain must contain not less than four carbons, and that a conjugated double bond, adjacent to the amide group, is necessary for binding to the receptor and that the amine part should be bulky.

Further studies on extracts of Piper capense root have resulted in the isolation and characterization of the novel sesquiterpene capentin. This compound contains a highly oxidized farnesane skeleton and an unusual eleven-membered ether ring.

Three new lignans have been isolated from the roots of the African shrub Piper capense , and characterized by means of spectroscopic studies and, in one case, a single crystal X-ray analysis. These compounds include a new 8.O.3′-neolignan, further distinguished by an uncommon 1,3,5-trisubstituted ring system, and two dihydrobenzofuranoid neolignans.

Further studies of a chloroform extract ofPiper capense roots have resulted in the isolation and characterization of four new neolignans. Three of these compounds are unusual 2′-oxo-8.1′-neolignans, while the fourth is of the more common 6′-oxo-8.3′-neolignan variety.

The essential oils from Piper capense, P. nigrum, P. guineense and P. umbellatum from S. Tomé e Príncipe were investigated for the first time. They were analysed by GC, GC-mass spectrometry and 13C NMR. Monoterpene hydrocarbons were the main group of constituents in three of the samples (P. capense, P. nigrum and P. umbellatum), whereas for the other species (P. guineense) phenylpropanoid derivatives were the most important ones. [beta]-Pinene (32.5%) and [beta]-caryophyllene (12.6%) were the major compounds in the volatile oil of P. capense. Dillapiole (44.8%), followed by myristicin (9.8%), were the main constituents of P. guineense. The most important constituents in the essential oil of P. nigrum were limonene (18.8%), [beta]-caryophyllene (15.4%), sabinene (16.5%) and [beta]-pinene (10.7%). The essential oil of P. umbellatum was characterised by its high [beta]-pinene (26.8%), [alpha]-pinene (17.6%) and (E)-nerolidol (12.4%) content. http://www.sciencedirect.com/science/article/B6TH7-40M54TJ-10/1/a5c8bec3d552f4aa2b7ee01483ad1e55