Browsing by Author "Mosa, Rebamang Anthony"
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- ItemIn vitro anti-platelet aggregation activity of the extracts of protorhus longifolia(2011) Mosa, Rebamang Anthony; Opoku, A.R.; Oyedeji, A.O.Platelet aggregation beyond purpose of haemostasis is the underlying cause of blood-clotting related diseases. Concoctions of P. longifolia are used by Zulu traditional healers to manage such diseases. This work aimed at investigating the anti-platelet aggregation activity of the extracts of this plant and to identify and characterise the active components present and responsible for the anti-platelet aggregation activity. Phytochemical screening of the plant material revealed the presence of various secondary metabolites (tannins, flavonoids, alkaloids and terpenoids). Crude extracts (obtained by sequential extraction of plant material with hexane, chloroform, ethyl acetate, methanol and water) and two triterpenes (3-oxo- 5á-lanosta-8,24-dien-21-oic acid, and 3â-hydroxylanosta-9,24-dien-24-oic acid) isolated and characterized (using various chromatographic and spectrometric techniques-IR, MS, 1H-NMR, and 13C-NMR) from the crude chloroform extract were screened for antioxidant, anti-platelet aggregation, anti-inflammatory activities, and cytotoxicity. The antioxidant activity of the plant components was determined on DPPH and ABTS+ radicals. Their reduction potential and chelating activity on Fe2+ were also determined. Except the methanol extract (IC50 of 0.07 and 0.16 mg/ml), the crude extracts and the isolated compounds showed poor (< 50%) antioxidant activities as they weakly scavenged DPPH and ABTS+ radicals, exhibited low reduction potentials and poor Fe2+ chelating activities. The anti-platelet aggregation activity of both the crude extracts and isolated compounds was separately investigated on thrombin, ADP and epinephrine induced rat platelet aggregation. The extracts and the isolated triterpenes exhibited a concentration dependent anti-platelet aggregation activity induced by the three agonists. The highest activity by the hexane extract (IC50 of 0.59 mg/ml) was observed on the thrombin-induced platelet aggregation. In addition, the isolated compound also exhibited in vitro anticoagulant activity on the whole rats blood. The acute anti-inflammatory activity of the isolated triterpene was determined using the carrageenan- induced rat paw oedema model. The compound (500 mg/kg body weight) significantly (p<0.05) inhibited the acute inflammation of rat paw. The hexane and chloroform extracts showed weak cytotoxic effects on brine shrimps with LC50 39.6 and 54.7mg/ml respectively. Also the pure compound- 3â-hydroxylanosta-9,24-dien-24-oic acid exhibited weak cytotoxic effects on HEK293 and HEPG2 cell lines (IC50 8520 and 7960 ìg/ml respectively). These results support the use of P. longifolia in folk medicine in the management of blood-clotting related diseases.
- ItemSome bioactivity of triterpenes from stem bark of protorhus longifolia and their derivatives(University of Zululand, 2014) Mosa, Rebamang Anthony; Opoku, A.R.Despite availability of the current clinical drugs, metabolic disorders and microbial infections continue to be serious threats to human health. The diverse significant pharmacological effects possessed by plant-derived triterpenes have made these compounds new targets for drug development against an array of diseases resistant to conventional medicines. This work investigated some bioactivity of two lanostane triterpenes and their derivatives. Two lanostane triterpenes (ã..-hydroxylanosta-9,24-dien-21-oic acid, RA5 and methyl-ã..-hydroxylanosta-9,24-dien-21-oate, RA3) were isolated from stem bark of Protorhus longifolia (Benrh) Engl and their acetyl (ã..-acetyloxylanosta-9,24-dien-21- oic acid, R51, methyl-ã..-acetyloxylanosta-9,24-dien-21-oate, R31) and oxo (ã..- oxolanosta-9,24-dien-21-oic acid, R52, methyl-ã..-oxylanosta-9,24-dien-21-oate, R32) derivatives were prepared. Structures of the compounds were established based on spectroscopic (IR, NMR, HRMS) data analysis. The in vitro anti-hyperlipidemic activity of the compounds was evaluated on selected lipid and carbohydrate digestive enzymes. The effect of the compounds on glucose uptake in C2C12 muscle cells and 3T3-L1 adipocytes, and triglyceride accumulation in 3T3-L1 adipocytes was also investigated. The anticoagulant and anti-inflammatory activity was investigated using tail bleeding time assay and cotton pellet-induced granuloma model in Sprague-Dawley rats, respectively. The effect of the triterpenes on the expression of heat shock protein 70 (Hsp70) and their anti-protein aggregation activity using malate dehydrogenase (MDH) aggregation suppression assay were studied. The broth micro dilution assay was also used to determine the antimicrobial and antiplasmodial activity of the isolated compounds. The triterpenes effectively inhibited the activities of lipid digestive enzymes (pancreatic lipase, cholesterol esterase) and HSL with IC50 values ranging from 60.1 to 677.8 ìM; except for the weak activity of R52 on C2C12 cells, the other compounds (50 ìg/ml) effectively stimulated glucose uptake in both 3T3-L1 and C2C12 cells. A significant reduction (34.8%) of intracellular lipid accumulation was also observed following a 48 h exposure of the 3T3-L1 adipocytes to RA5 (â5 ìM). The compounds did not show any cytotoxic effects on the 3T3-L1 and C2C12 cells. The triterpenes exhibited anti-inflammatory activity and a reduction of granuloma formation by up to 40.3% after treatment with RA5 (250 mg/kg) was observed. Both triterpenes significantly (p < 0.05) increased bleeding time with up to 7.3 min recorded post treatment with RA3 (250 mg/kg). The triterpenes improved the activity of Hsp70 on MDH aggregation suppression. They also effectively stimulated expression of Hsp70 in E. coli cells and in the plasma of inflamed rats. While both compounds exhibited strong antibacterial activity against the tested bacteria with MIC and MBC values ranging from 0.16 to 5.00 mg/ml and 0.63 to 5.00 mg/ml, respectively, the compounds did not show any antifungal and antiplasmodial activity. The various bioactivity exhibited by the compounds suggest potential new approaches towards development of pharmacologically active agents with beneficial multiple effects.