Adebola O. Oyedeji

Chemical composition and antibacterial activity of the essential oils of Callistemon citrinus and Callistemon viminalis from South Africa.

The chemical composition and the antibacterial activity of the essential oils obtained by hydrodistillation from the leaves of Callistemon citrinus and Callistemon viminalis were analyzed by GC and GC/MS. Twenty-four and twelve components were identified for C. citrinus and C. viminalis, representing 92.0% and 98.3% of the total oils. The major components of C. citrinus and C. viminalis were 1,8-cineole (61.2% and 83.2%) and α-pinene (13.4% and 6.4%), respectively. The in vitro antibacterial activity of the essential oils was studied against 12 bacteria strains using disc diffusion and broth microdilution methods. The oils exhibited strong zone of inhibitions against some bacteria such as S. faecalis (20.3-24.0 mm), both strains of S. aureus (23.0-26.3 mm), B. cereus (17.3-19.0 mm) and S. macrcesens (11.3-23.7 mm) when compared to standard antibiotics gentamycin and tetracycline used as controls. Expect for P. aeruginosa and S. macrcescens, the MIC values of both essential oils ranged from 0.31-2.50 mg/mL.

Chemical Composition of the Essential Oils of Cyperus rotundus L. from South Africa

The essential oils from the rhizomes of Cyperus rotundus L. collected from two different locations (Empangeni-A and KwaDlangezwa-B; both in the Kwa-Zulu Natal Province of South Africa) were obtained by hydrodistillation and analyzed by capillary GC and GC/MS. Forty-one and 43 components were identified, representing 89.9% and 92.0% of sample A and sample B, respectively. α-Cyperone (11.0%), myrtenol (7.9%), caryophyllene oxide (5.4%) and β-pinene (5.3%) were major compounds in the oil of sample A. The main constituents of the oil of sample B were β-pinene (11.3%), α-pinene (10.8%), α- cyperone (7.9%), myrtenol (7.1%) and α-selinene (6.6%).

Psychoneuropharmacological activities and chemical composition of essential oil of fresh fruits of Piper guineense (Piperaceae) in mice

ETHNOPHARMACOLOGICAL RELEVANCE Piper guineense Schum & Thonn (Piperaceae) is a medicinal plant used in the Southern States of Nigeria to treat fever, mental disorders and febrile convulsions. AIMS OF THE STUDY This study aims at determining the chemical composition and the central nervous system (CNS) activities of the essential oil obtained from the plant׳s fresh fruits in order to rationalize its folkloric use. MATERIALS AND METHODS Essential oil of P. guineense (EOPG) obtained by hydrodistillation was analysed by GC/MS. EOPG (50-200mg/kg, i.p.) was evaluated for behavioural, hypothermic, sedative, muscle relaxant, anti-psychotic and anticonvulsant activities using standard procedures. RESULTS AND DISCUSSION Analysis of the oil reveals 44 compounds of which 30 compounds constituting 84.7% were identified. The oil was characterized by sesquiterpenoids (64.4%) while only four monoterpeneoids (21.3%) were found present in the oil. Major compounds identified were β-sesquiphellandrene (20.9%), linalool (6.1%), limonene (5.8%), Z-β-bisabolene (5.4%) and α-pinene (5.3%). The EOPG (50-200mg/kg, i.p.) caused significant (p<0.01) inhibition on rearing {F(4,20)=43}, locomotor {F(4,20)=22} activity and decreased head dips in hole board {F(4,20)=7} indicating CNS depressant effect; decreased rectal temperature {F(4,20)=7-16}, signifying hypothermic activity; decreased ketamine-induced sleep latency {F(4,20)=7.8} and prolonged total sleeping time {F(4,20)=8.8}, indicating sedative effect; reduced muscular tone on the hind-limb grip test {F(4,20)=22}, inclined board {F(4,20)=4-49} and rota rod {F(4,20)=13-106}, implying muscle relaxant activity; induced catalepsy {F(4,20)=47-136}, inhibited apomorphine-induced climbing behaviour {F(4,20)=9} and inhibited apomorphine-induced locomotor {F(4,20)=16}, suggesting anti-psychotic effect; and protected mice against pentylenetetrazole-induced convulsions, indicating anticonvulsant potential. CONCLUSION The most abundant component of the fresh fruits essential oil of P. guineense was β-sesquiphellandrene (20.9%); and the oil possesses CNS depressant, hypothermic, sedative, muscle relaxant, antipsychotic and anticonvulsant activities, thus providing scientific basis for its ethnomedicinal applications.

Chemical composition and anti-inflammatory activities of the essential oils from Acacia mearnsii de Wild

The volatile oils of the leaves and the stem bark of Acacia mearnsii de Wild obtained by hydro-distillation were analysed by gas chromatography–mass spectrometry. A total of 20, 38, 29 and 38 components accounted for 93.8%, 92.1%, 78.5% and 90.9% of the total oils of the fresh, dry leaves and fresh, dry stem bark, respectively. The major components of the oil were octadecyl alcohol (25.5%) and phytol (10.5%); cis-verbenol (29.5%); phytol (10.1%) and phytol (23.4%) for the fresh leaves, dried leaves, fresh stem, dry stem bark, respectively. Oral administration of essential oils at a dose of 2% showed significant (p < 0.05) anti-inflammatory properties in the albumin-induced test model in rats. Oils from the fresh leaves and dry stems inhibited inflammation beyond 4 h post treatment. The potent anti-inflammatory activity of essential oils of A. mearnsii hereby confirmed its traditional use in treating various inflammatory diseases.

Anti-Inflammatory and Membrane-Stabilizing Properties of Two Semisynthetic Derivatives of Oleanolic Acid

Acetylation and methylation semisynthesis of oleanolic acid (OA) isolated from Syzygium aromaticum L. yielded two compounds: 3-acetoxyoleanolic acid (3-AOA) and 3-acetoxy, 28-methylester oleanolic acid (3-A,28-MOA). Anti-inflammatory properties of these compounds were assessed using the serotonin and fresh egg albumin-induced inflammatory test models in male Wistar rats weighing 250–300 g. Furthermore, erythrocyte membrane-stabilizing property of these compounds was evaluated in the heat- and hypotonicity-induced in vitro hemolysis test models. The two semisynthetic compounds significantly (p < 0.05) inhibited albumin-induced inflammation better than OA and indomethacin from 1–5 h post administration. Both compounds were membrane stabilizing in heat-induced hemolysis test while only 3-AOA showed membrane-stabilizing effects in a hypotonic milieu. Semisynthesis of OA yielded two compounds which had better in vivo anti-inflammatory and in vitro membrane-stabilizing properties.

Chemical Composition and Larvicidal Activity of the Essential Oil of Tarchonanthus camphoratus Against Anopheles arabiensis Mosquito Larvae

Abstract The chemical composition of the essential oil of Tarchonanthus camphoratus was analysed using GC and GC-MS instruments. The major monoterpene was 1,8-cineole (5.4 %), while α-copaene (3.8 %) and γ-cadinene (3.1 %) were major sesquiterpenes. Major oxygenated monoterpenes and sesquiterpenes identified in the oil were 1,6-octadien-3-ol (4.5 %) and (-)-globulol (3.3 %) respectively. Hexadecanoic acid (3.5 %) was the major fatty acid present. The larvicidal assay of the essential oil against larvae of Anopheles arabiensis mosquito revealed that at a concentration of 300 ppm, the oil caused 100 % mortality after 24 hr exposure with an LC50 value of 78.7 %.

Compositional Variations and Antibacterial Activities of the Essential Oils of three Melaleuca Species from South Africa

Abstract The leaf oils of three Melaleuca species, M. bracteata var. revolution gold, M. bracteata var. revolution green and M. trichostachya var. compacta from South Africa have been studied for their volatile constituents and bacterial activities. Isolation of the oils were performed through hydrodistillation using a Clevenger apparatus for 4h. Redistillation after 7 h was carried out on the extracted plant material via hydrodistillation method for another 3 h. The compositions of the first distillates were at variance with the second distillates especially with M. trichostachya var. compacta oils. A schematic postulate has been proposed for the rearrangement transformation of some compounds. The chemical profile of oils of M. trichostachya var. compacta has been reported for the first time. The results of zone of inhibition (ZI) and minimum inhibition concentration (MIC) activities of the 6 oils against an array of 12 bacteria pathogens are also reported.

Semisynthesis of Derivatives of Oleanolic Acid from Syzygium aromaticum and Their Antinociceptive and Anti-Inflammatory Properties

Oleanolic acid is a pentacyclic triterpenoid compound widely found in plants and well known for its medicinal properties. Oleanolic acid (OA) was isolated from the ethyl acetate extract of Syzygium aromaticum flower buds. Semisynthesis afforded both acetate and ester derivatives. The derived compounds were monitored with thin layer chromatography and confirmed with nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS), Fourier infrared (FT-IR) spectroscopy, and melting point (Mp). All these compounds were evaluated for their analgesic and anti-inflammatory properties at a dose of 40 mg/kg. Significant analgesic and anti-inflammatory effects were noted for all OA-derived compounds. In the formalin-induced pain test, the derivatives showed better analgesic effects compared to their precursor, whereas, in the tale flick test, oleanolic acid proved to be superior in analgesic effects compared to all its derivatives with the exception of the acetyl derivative. Acute inflammatory tests showed that acetyl derivatives possessed better anti-inflammatory activity compared to the other compounds. In conclusion, semisynthesis of oleanolic acid yielded several derivatives with improved solubility and enhanced analgesic and anti-inflammatory properties.

Synthesis, Characterization, and Antibacterial Studies of Some Metal Complexes of Dialkyl Thiourea: The X-Ray Single Crystal Structure of [CoCl2(detu)2]

Co(II), Cu(II), and Zn(II) complexes of diethylthiourea and dimethylthiourea have been synthesized and characterized by elemental analysis, conductivity, magnetic susceptibility measurements, and FTIR UV-vis spectroscopy. The single-crystal X-ray structure of the Co(II) complex of diethylthiourea, [CoCl2(detu)2], is reported. The metal(II) complexes are four coordinated with two molecules of the alkyl thiourea and two molecules of either chloride or acetate ions. The compounds are nonelectrolytes in solution and the spectroscopic analysis is consistent with the proposed structures. The complexes were screened against six bacteria isolates to determine their antibacterial potentials.

Volatile Constituents of the Leaf Oils of Callistemon salignus from Two Provinces in South Africa

Abstract Essential oil was isolated from the leaves of Callistemon salignus ‘Rubra’ collected from two Provinces using hydrodistillation method. Analyses of the compound were done using GC and GC/MS. Between 16–22 compounds were identified, accounting for 90.1–98.5% of the oil samples. The characterized oil samples show a high percentage of oxygen-containing monoterpenes in all the localities. 1,8-Cineole was found to be the main component in all the samples being present in the range of 44.4–85.4%. Others prominent compounds of the oils were α-pinene (6.2–27.8%), α-terpineol (tr-6.8%) and E-(β)-ocimene (tr-6.7%).