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Title: Chemical and biological studies of some plants of the Labiatae family growing in the United Arab Emirates
Author: Al Yousuf, Maryam.
Awarding Body: University of Portsmouth
Current Institution: University of Portsmouth
Date of Award: 2002
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Abstract:
Traditional medicine is very popular in the United Arab Emirates. The present study is part of an active programme directed towards phytochemical, pharmacological and toxicological studies on herbs used in folkloric medicine. Leucas inflata Benth, Salvia aegyptiaca L. and Teucrium stocksianum Boiss belonging to the family Labiatae were selected for this study. The coarsly powdered plant materials were extracted and the dried extracts were fractionated using different chromatographic procedures. The structures of the isolated compounds were elucidated using spectroscopic and spectrometric techniques. The acetone extract of L. inflata afforded stigmasterol, the 3ß-glucoside of sitosterola nd a chromone( leucasone[ 2,8-dimethyl-(2,2-dimethylethenyl)-5,6-benzo-4 pyrone]). Also a number of coumarins were obtained: coumarsabin [4,7 dimethoxy-3,5 dimethylcoumarin], 8-methoxycoumarsabin[4 ,7,8 trimethoxy-3,5-dimethylcoumarin], siderin [4,7-dimethoxy-5-methyl coumarin] and coumarleucasin [5-formyl-4,7,8- trimethoxy-3-methylc oumarin].L eucasonea ndc oumarleucasina re novel compounds. The acetone extract of S. aegyptiaca afforded oleanolic acid (3ß-hydroxy-olean- 12-en-28-oic acid), 3ß-hydroxy-oleana-11,13(18)-dien-28-oic acid, the 3ß-glucoside of sitosterol, ß-sitosterol and stigmasterol. Three novel diterpenoids were isolated (6- methyl-cryptoacetalide; epi-6-methyl-cryptoacetalide and 6-methylcryptotanshinone (14,16-epoxy-6-methyl-5(10), 6,8,13-abietatetraene-11,12-dione). In addition, the flavonoids 5-hydroxy-7,3', 4'-trimethoxyflavone and 5,6-dihydroxy-7,3', 4'-trimethoxyflavone were isolated. A number of compounds were isolated from the n -hexane extract of T. stocksianum: 5-hydroxy-7,4'-dimethoxyflavone, salvigenin (5- hydroxy-6,7,4'- trimethoxyflavone), oleanolic acid (3, ß-hydroxy-olean-12-en-28-oic acid) and two diastereoisomeric sesquiterpenoids shiromool 1,10-epoxide (1ß, 10a; 4 ß, 5a-diepoxy-7a- H-germacran-6ß -ol) and shiromool 1,10-epoxide (1 a, 10 ß; 4 ß, 5 a -diepoxy-7a -Hgermacran- 6ß-ol). This is the first report of the two diastereoisomers as natural products, although the latter was previously produced as a synthetic product. The essential oils obtained by steam distillation of the aerial parts of T. stocksianum and S. aegyptiaca were analysed by GC and GC/MS. Forty-one components were identified in the oil samples of T. stocksianum. The major compounds were alpha-cadinol and delta-cadinene. S. aegyptiaca oil afforded twenty-six components and the most predominant constituents were beta-caryophyllene and gammamuurolene. The pharmacological studies of the methanol and acetone extracts of L. inflata on mice showed that they significantly and dose - dependently, reduced formalininduced pain, acetic acid -induced abdominal constrictions and increased the reaction time in the hot-plate test. Both extracts caused significant and dose-related impairment in the sensorimotor control of treated mice. Both extracts exhibited anti-inflammatory action by reducing paw edema of treated mice. The extracts did not significantly affect the rectal temperature of normothermic mice. However, they were effective in preventing Brewers yeast -induced pyrexia. It is concluded that the crude methanol and acetone extract of L. inflata has CNS depressant properties, manifested as antinociception and sedation. Both extracts have anti-inflammatory and antipyretic actions. The crude acetone and methanol extracts of S. aegyptiaca caused dose-related inhibition of acetic acid-induced abdominal constriction, and significantly reduced formalin-induced pain. Treatment with the extracts significantly increased the reaction time in the hot-plate test. In treated mice both extracts caused significant and doserelated impairment of the sensorimotor control. Treatment with both extracts did not significantly affect the rectal temperature of normothermic mice. The methanol extract (0.5 and 1.0 g/ Kg) did not affect the rectal temperature of hyperthermic mice, but the acetone extract was effective in significantly reducing the rectal temperature of hyperthermic mice. It is concluded that the crude methanol and acetone extract of S. aegyptiaca has CNS depressant properties, manifested as antinociception and sedation. Both extracts have some anti-inflammatory and antipyretic actions. Generally the acetone extract appeared to be slightly more effective than the methanol extract in this regard.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.271447  DOI: Not available
Keywords: Medicinal plants Pharmacology Botany
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