Chemistry

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Analyses of the Essential Oils of Artemisl Rehan and Cymbopogon Citratus
(Addis Ababa Universty, 1980-06) G.Yohannes Paulos; Abegaz Berhanu (PhD)
Artemisia rehan Chiov and Cyifopogon citratus (DC) Stapf are widely grown in thelighlands of Ethiopia. These plants occupy a significant|sition in Ethiopian I plantlore. | The oil of Artemisia rehan, anendemic plant to Ethiopia , has been analysed for the first time.' Eighteen components of the oil have Wen identified using GLC and/or MS. Two compounds, chamaiulene and dsvanone were isolated from the oil and characterized using ir , nmr and ms• Davanone (44/) and Camphor (27/) were found to be the major constituents of the oil. Cymbopogon citratus which is also widely grown in the tropics , is used as a. crop plant in many countries of the Western Hemisphere.' The oil of the Ethiopian variety was analysed for the first time. Fifteen - components of the oil have been identified using GLC and/or MS. The major component identified was geraniol (39D * The second major component (12/), not identified , is presumed to be an aromatic compound
Anthraquinones and Fla Vonolds from the Pods of S. Didymobotrya
(Addis Ababa Universty, 1995-06) Hailu Ayele; Abegaz Berhanu (PhD)
Two hitherto unknown dimeric anthraquinones, lO-(Physcion-Tyl)-lO-hydroxy chrysophanol anthrone (122) and 9-(Physcion-T -yI)5, lO-dihdroxy-2-methyl-l,4- anthraquinone (124) along with chrysophanol (120), physcion (121), emodin (125) and knipholone (126) were isolated from the chloroform extract of the pods of Senna didymobotrya. Knipholone (126) is isolated from the genus Senna for the first time. The methanol extract of the pods yielded three flavonoids, kaempferoI4'-methyl ether (127), acacetin (129) and 3,5,6,7,8,3' ,4'-heptahydroxy flavone (130). Their presence in the genus Senna is reported for the first time. Structural elucidations were carried by chemical and spectroscopic methods.
The Bitter Constituent of Gesho ( Rhamnus Prinoides ) Leaves
(Addis Ababa Universty, 1994-06) Kebede Teshome; Abegaz Berhanu (PhD)
Gesho, Rhamnus prinoides L’Herit (Rhamnaceae) is a shrub or tree which can be up to 6 m tall. It is cultivated in Ethiopia for use as an ingredient in the making of the home brewed drinks-Telia and Tej. Phytochemical investigations of the leaves of this plant resulted in the isolation and characterization of the bitter prinicple- a naphthaenic lactone glucoside named geshoidin, in addition to three anthraquinones, a pre-anthraquinone and a flavonol. These compounds are chrysophanol (1), physcion (2), musizin (19), emodin (3), rhamnocitrin (40) and /3- sorigenin-8-0-/3-D-glucoside (68). Acetylated and methylated derivatives as well as hydrolysis products of the glucoside and the permethylated compound are also characterized. These include|6-sorigenin-8-0-/3-D-glucoside-peracetate(69), /3-sorigenin-8- 0-/3-D-glucoside-permethylate (70) , /3-sorigenin (22) and /3-sorigenin-l -methylether (71), respectively. Compounds 2 and 3 have been isolated previously from the fruits of R. prinoides. 19 and 40 have not been reported from this plant while 68 is a novel natural product , Based on spectroscopic data, two possible explanations are offered for the upfield chemical shift of the peri hydroxyl proton in 68. A sensory panel concluded that compound 68 is a bitter principle in the leaves of Gesho. At least 1% of the dry leaves of Gesho contain this bitter component
The Chemical Composition and Antimicrobial Activlty of Impatiens Tinctffii a Rich
(Addis Ababa Universty, 1981-07) Fassil Yohannes; Abegaz Berhanu (PhD)
The plant Impatiens tinctoria A-Rich grows widely in Ethiopia. its tubers are traditionall;y used to dye the palms of nails of women and to treat infections of the hands and feet. The methanol extract of I. tinctoria gave dark red solution which was chromatographically separated to give trace cnnount of a comp01md which readily dissolves in benzene ethanol and carbon tetrC\chloride but vms insoluble in Ivater. Thts compound was characterized by comparing with stalndard naphthoquinones and the TLC, UV, MS, LC corresponds with 2-methoxy-l, 4•-naphthoquinono. is presence of anthocyaniclin and tri terpene ~'IRS also observed. .,(evie", of the liberature r8v0a1s that 2- lilethoxy-•l, 4,-naphthoquinone is present in flowers of I.Balsamina .• Hence, this study adds one more species of the genus Impatiens to plants that are knolm to contan 2-methoxy-1, 4--naphthoquinone and anthocyanidin. The methanol extract of I. tinctoria was found to have an antifungal and antibiotic activity • this extract inhibited the growth of staph qureus E.coli and candida albjcans at concentration levels of 1:448,1:280 respectively
Chemical Composition of Croton Macrostachys
(Addis Ababa Universty, 1981-06) Henberu Dirshaye; Abegaz Berhanu (PhD)
The root~·bark powder of Croton macrostachys Hochstex. A. Rich. (Euphorbeaceae) (ብሳና), used in Ethiopia for curing spreading wounds, was extracted with diethyl ether. The crude extract, on fractionation by column chromatography (Silica gel) yielded a major solid compound A (mp 210'-212o) crystallizable from acetone~methanol (9:1) into beautiful needle aggregates, the structure of -Ihich was identifted, using IR, PMR and MS data, to be that of lupeol, a known antitumor agent. The tumor inhibitory compound Crot-poxide which was previously isolated from the fruits could not be detected in the root~ bark extract. Preliminary investigation also showed the presence of trace solids Band C having the same Rf on TLC. B was water isoluble \.,hi te solid while C was water soluble and sho~led strong blue fluorescence under UV-lamp. The presence of quaternary alkaloid was also confirmed in the root-bark.
Chemical Composition of Croton Macrostacrys
(Addis Ababa, 1981) emberu, Dirshaye; Abegaz Berhanu (PhD)
The root- bark powder of Croton macrostachys Hochstex. A. Rich . (Euphorheaceae) ( n nCj') , used in Ethiopia for curing spreading wounds, was extraced with diethyl ether . The crude extract, on fractionation by column chromatography (Silica gel) yielded a major solid compound A (mp 210- 212o ) crystallizable from acetone- methanol (9 ; l) into be autiful needle aggregates, the structure of which was identified , using I R, PHR and MS data , to be that of lupeol , aknown antitumor agent. The tumor inhibitor y compound Crotepoxide which was previously isolated from the fruits could not be detecte in t he rootbark extract. Preliminary investigation also showed the presence of trace solids B and C having the same Rf on TLC. B was water isoluble white solid while C was water soluble and showed strong blue fluorescence unde r UV- I amp. The presence of quaternary alkaloid was also confirmed in the root- bark .
Chemical Composition of Rumex abyssinicus
(Addis Ababa Universty, 1982-06) Bezabih Alemu; Abegaz Berhanu (PhD)
Rumex abyssinicus, family polygonaceae is a plant used traditionally for colouring textiles and food. It has several medicinal application such as purgative, antidiabetic, and taencide. l'he powdered root of R0abyssinicus was packed on a column and extracted using acetone. The sticky brownish mass(A-l)which was produced on evaporation was further separated by column chromatography and showed to consist of anthraquinone derivatives A-4, A-6 and A-7 which were latter identified as emodin (1,3,8 trihydroxy-6-methylanthraquinone), chrysopyanvl (1,8 dihydroxyT3-methylanthraquinone, and physicone (1,8 dihydroxy-3-methoxy-6-raethylanth-raquinone)respectively. The structural ilucidation of emodin, chryso~phanol and physicone are based on their ultraviolet,visible, infrared, nuclear magnetic resonance and massspectras.
Chemical Investigation on the Essential Oils of Endemic Wild and Cultivated Lippia Adoensis:a Comparative Study
(1992-06) Asfaw Nigist; Abegaz Berhanu (PhD)
study on the essential oil of endemic L. adoensis Hochst. ex. Walp. was undertaken. The 'search work was conducted on samples from four areas where the ethnic groups claim a lfference in the flavour of the wild and cultivated L. adoensis. The chemical investigation Idicated that the essential oils obtained from the wild and cultivated L. adoensis are markedly ifferent in their physical characteristics and chemical composition. The eSsential oils froM~ese NO types were differentiated from each other by the Presence of l-linaloo las a major component 1 the cultivated and its absence in the wild; and by the presence of d-limonene, peri1laldehyde, .iperitenone, and citral a in the wild and their absence in the cultivated L. adoensis. The oils listilled from cultivated L. adoensis show a laevo rotation while those from the wild are dextro otatory. Morphological differences of the leaves were also observed. There are no published eports on the morphological or chemical differences between the wild and cultivated L. adoensis erior to this work.ourteen components comprising 88.1 - 94.8% of the oil from the cultivated, and 16 components ;onstituting 68.4 - 86.5 % of the oil from the wild were identified. These include ipsdienone, 1- inalool, germacrene D, d-limonene, d-perillaldehyde, piperitenone, citral a and b, ocimene, Ci; opaene, Ci- and Jl-caryophyllene, Ci-farnesene, Ci- and Jl-cadinene. To the best of our knowledge, this is the first time that ipsdienone is reported from a natural source. All the other compounds are known. However, piperitenone, perillaldehyde, germacrene D, citral a and b, have not been reported before in L. adoensis. The elucidations of the structures are based on spectroscopic techniques and by comparison of these data with those reported in the literature.
Photochemical Remote Oxidation of Oleyl Bster of P_Benzoylbenzoic Acid
(Addis Ababa, Ethiopia, 1981) Gerba, Sendaba; Abegaz Berhanu (PhD)
Photochemical Remote Oxination of Oleyl Ester of P-Benl:Joylbenzoic Acid
(Addis Ababa Universty, 1981-07) Gerba Semlaba; Abegaz Berhanu (PhD)
Oleyl ester of p-benzoylbenzoic acid (I) was irradiated in carbontetrachloride. The triplet state of benzophenone served to abstract hydrogen; intramolecular to, but structurally remote from the excited carbonyl
Photochemical Studies on 2-Hydroxy - and 2-Methoxy-1.4- Naphthoquinone
(Addis Ababa Universty, 1989-06) Libsu Solomon; Abegaz Berhanu (PhD)
Photolysis of a dilute chloroform solution of 2-hydroxy 1.4 naphthoquinone with diffuse day light yielded 2-chloro-3- hydroxy-1,4-naphthoquinone (SB) and an unidentified compound (SA). Compound 58 was characterized by spectroscopic methods. Its photoformation from the materials used in the present study is unprecedented. The photochemical reaction of 2-hydroxy-1.4-naphthoquinone is carbon tetrachloride failed to yield to compound SB. On the other hand. the room temperature reaction of thionyl chloride or phosgene with the hydroxy quinone afforded a compound Y/hich. by comparative TLC. was identified as compound SO. The significance of these results is discussed, Photolysis of a dilute chloroform solution of 2-methoxy-1.4-naphthoquinone also gave a major reaction oroduct (SC) which has not been fully elucidated
Phytochemical Investigation on the Pods of S. septemtnonalis
(Addis Ababa Universty, 1996) Woldeyesus Bekuretsion; Abegaz Berhanu (PhD)
The chloroform extract of the pods of S.septemtriona /is afforded anthraquinones: physcion, chrysophanol, emodin, floribundone - 1, torosanin-9',10' - quinone, torosachrysone as well as 5,7 '-pnyscion- fal!acinol. The isolation of the dimeric anthracene derivative 5,7'-physcion- fallacino! is reported here for the first time Quercetin, luteolin, a glycoside of quercetin and a number of unidentified pigments were isolated from the methanol extract The elucidations of the structures are based on spectroscopic techniques and by ,comparison of the spectral data with those reported in the literature

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