Antioxidant potential of African medicinal plants

Cellular damage or oxidative injury arising from free radicals or reactive oxygen species (ROS) now appears the fundamental mechanism underlying a number of human neurodegenerative disorders, diabetes, inflammation, viral infections, autoimmune pathologies and digestive system disorders. Free radical are generated through normal metabolism of drugs, environmental chemicals and other xenobiotics as well as endogenous chemicals, especially stress hormones (adrenalin and noradrenalin). Accumulated evidence suggests that ROS can be scavenged through chemoprevention utilizing natural antioxidant compounds present in foods and medicinal plants. Africa is blessed with enormous biodiversity resources, but plagued with several diseases, including those with ROS as the etiological factor. In this review, research on the antioxidant potential of medicinal plants of African origin between 1965 and September, 2004 is considered.African Journal of Biotechnology Vol. 4 (2), pp. 128-133, 200

Bacterial reduction of N-oxides of tobacco- specific nitrosamines (TSNA)

1 Contrary to established metabolic pattern, a recent investigation of NNK metabolism produced in rat urine higher levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone (NNK) and 4-(methylnitrosamino)-1-(3-pyri dyl)-1-butanol (NNAL) than their N-oxides, suggesting that reconversion of N-oxides could occur after urine formation. 2 To verify the possible role of bacteria in the reduction of NNK-N-oxide and NNAL-N-oxide to their respective parent compounds, NNK and NNAL, in smokers with urinary tract infection (UTI), the N-oxides were isolated from the urine of rats treated with 5-3HNNK and individually incubated at 37°C with ten bacterial species in sterile human urine under different pH regimens. After incubation with the bacteria, aliquots of culture media were analyzed by high pressure liquid chromatography (HPLC) with radiochemical detection. 3 Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae and Proteus mirabilis possessed varying capacity to regenerate NNK and NNAL from their N- oxides while others showed no detectable reductive capability within 24 h. 4 This result constitutes the first experimental evidence that in tobacco users with concomitant UTI, bacterial regeneration of the procarcinogenic NNK and NNAL from their N-oxides could occur in the bladder leading to increased carcinogen burden in these individuals

Pharmacokinetics of biliary excretion of N-nitrosodiphenylamine (NDPA) in animals of different species

Pharmacokinetic investigations into the biliary excretion of N-nitrosodiphenylarnine given as an i.p. dose of 50 mg/kg were conducted and results compared in three animal species; rat, guinea pig and rabbit following bile duct (Simulation and collection of bile in vitro. The guinea pig excreted NDPA into bile fastest while the rabbit, which excreted it slowest, eliminated it fastest Both appearance and disappearance of the nitrosamine were comparatively slow in the rat NDPA elimination half-life values in the animal species were 510, 240 and 95 min respectively, while cumulative excretions amounted to 12, 3 and 0.3 percent. The toxicological implications of these species differences are highlighte

Potential of endogenous formation of volatile nitrosamines from Nigerian vegetables and spices

Nitrosatability of dried Nigerian vegetables and spices was investigated under simulated gastric conditions. N-Nitroso-dimethylamine (NDMA) was the only volatile nitrosamine found above the preformed level except in ugwu where N-nitroso-piperidine (2.3 ppb) was also detected. The lowest NDMA value of 0.4 ppb was found in bitterleaf while onions had the highest level (14.7 ppb) of nitrosation. The results suggest that, under endogenous conditions, nitrosation of these foodstuffs could be an important contributory factor in cancer aetiolog

Preformed volatile nitrosamines in some Nigerian foodstuffs

Some common Nigerian foodstuffs were assessed for their content of preformed volatile nitrosamine by chemiluminescence detection following gas chromatographic separation. Nitrosodimethylamine levels of between 0.4 and 4.6 ppb were detected in 75% of the samples analysed. The highest value was found in Brassica oleraceae, while Vernonia amygdalina contained the lowest detectable level. These data suggest that Nigerians may be exposed to chronic but very low levels of carcinogenic nitrosamines in their food

HYPOGLYCAEMIC ACTIVITY OF NAUCLEA LATIFOLIA SM. (RUBIACEAE) IN EXPERIMENTAL ANIMALS.

Aqueous, ethanolic and hexane extracts of the leaves of Nauclea latifolia (Rubiaceae) were assessed for their fasting blood glucose lowering effect in normoglycaemic and streptozotocin – diabetic rats. Wistar strain albino rats were given different doses of the extracts after 18 hrs fast and their blood glucose measured at 0,1,2,4 and 6 hours after treatment. The aqueous and ethanolic extracts significantly lowered the fasting blood glucose levels of the STZ–diabetic rats in a dose–dependent manner. The highest dose administered (400mg/kg) lowered the fasting blood glucose of the diabetic rats by 31.7% (aqueous) and 36.1% (ethanolic) extracts. The aqueous extract did not significantly lower the glucose levels of normoglycaemic rats (maximum 6.6%), nor was any significant decrease seen in the rats administered with the hexane (maximum of 4.0% for normoglycaemic and 2.4% for diabetics) extract. The hypoglycaemic and antihyperglycaemic potentials of the aqueous and ethanolic extracts were comparable to that of glibenclamide (1mg/kg).These results further support the traditional use of the plant in the treatment of diabetes mellitus

Trypanocidal and leishmanicidal activity of six limonoids

Six limonoids [kotschyienone A and B (1, 2), 7-deacetylgedunin (3), 7-deacetyl-7-oxogedunin (4), andirobin (5) and methyl angolensate (6)] were investigated for their trypanocidal and leishmanicidal activities using bloodstream forms of Trypanosoma brucei and promastigotes of Leishmania major. Whereas all compounds showed anti-trypanosomal activity, only compounds 1–4 displayed anti-leishmanial activity. The 50% growth inhibition (GI 50) values for the trypanocidal and leishmanicidal activity of the compounds ranged between 2.5 and 14.9 μM. Kotschyienone A (1) was found to be the most active compound with a minimal inhibition concentration (MIC) value of 10 μM and GI 50 values between 2.5 and 2.9 μM. Only compounds 1 and 3 showed moderate cytotoxicity against HL-60 cells with MIC and GI 50 values of 100 μM and 31.5–46.2 μM, respectively. Compound 1 was also found to show activity against intracellular amastigotes of L. major with a GI 50 value of 1.5 μM. The results suggest that limonoids have potential as drug candidates for the development of new treatments against trypanosomiasis and leishmaniasis

Review - Antioxidant potential of African medicinal plants

Cellular damage or oxidative injury arising from free radicals or reactive oxygen species (ROS) now appears the fundamental mechanism underlying a number of human neurodegenerative disorders, diabetes, inflammation, viral infections, autoimmune pathologies and digestive system disorders. Free radical are generated through normal metabolism of drugs, environmental chemicals and other xenobiotics as well as endogenous chemicals, especially stress hormones (adrenalin and noradrenalin). Accumulated evidence suggests that ROS can be scavenged through chemoprevention utilizing natural antioxidant compounds present in foods and medicinal plants. Africa is blessed with enormous biodiversity resources, but plagued with several diseases, including those with ROS as the etiological factor. In this review, research on the antioxidant potential of medicinal plants of African origin between 1965 and September, 2004 is considered

Polymerase chain reaction: Theory, practice and application: A review

Polymerase Chain Reaction (PCR) is a rapid procedure for in vitro enzymatic amplification of specific DNA sequences using two oligonucleotide primers that hybridize to opposite strands and flank the region of interest in the target DNA. Repetitive cycles involving template denaturation, primer annealing and the extension of the annealed primers by DNA polymerase, result in the exponential accumulation of a specific fragment whose termini are defined by 5′ end of the primers. The primer extension products synthesized in one cycle can serve as a template in the next. Hence the number of target DNA copies approximately doubles at every cycle. Since its inception, PCR has had an enormous impact in both basic and diagnostic aspects of molecular biology. Like the PCR itself, the number of applications has been accumulating exponentially. It is therefore recommended that relevant scientists and laboratories in developing countries like Nigeria should acquire this simple and relatively inexpensive, but rather robust technology