The proximate nutrient composition, energy value, mineral concentrations, amino acid composition and chemical score of the larvae of raphia palm beetle (Oryctes rhinoceros) and weevil (Rhyncophorus pheonicis) were evaluated. Values of moisture, ash and crude protein were significantly (p < 0.05) higher in O rhinoceros than in R pheonicis while the reverse was the case for the values of crude fat, total carbohydrate and energy content. The crude protein content of both samples was high, with a value of 42.3 ± 0.84% for the palm beetle and 31.6 ± 0.59% for palm weevil, while crude fat was high (17.3 ± 1.2%) in palm weevil and very low (0.55 ± 0.10%) in palm beetle. The calorific value in kcal 100 g −1 sample was 425 in R pheonicis and was significantly higher (p < 0.05) than the value of 285 in O rhinoceros, due to a relatively higher crude fat and total carbohydrate in the former compared with the latter. The mineral concentrations were high and differed for all the elements, with O rhinoceros having the higher level of many of the mineral elements (calcium, magnesium, potassium, manganese, iron and phosphorus) compared with R pheonicis, consistent with a significantly higher (p < 0.05) ash content of 12.7 ± 0.81% in O rhinoceros against the value of 4.2 ± 0.45% ash in R pheonicis. The amino acid profile showed both samples to be good sources of essential and non-essential amino acids including cysteine and methionine, both of which contain sulfur. Valine, which had the lowest chemical score of 51.2%, was the most limiting amino acid for protein quality in both O rhinoceros and R pheonicis.

Caffeine was administered to male Wistar albino rats for two weeks at three concentrations, namely 0.1, 0.2 and 0.3%, and hepatic cytochrome P450-dependent mixed-function oxidase determined. Caffeine administration gave rise to a marked, dose-dependent increase in the O-deethylation of ethoxyresorufin and, to a lesser extent, in the O-depentylation of pentoxyresorufin. Erythromycin N-demethylase, p-nitrophenol hydroxylase and lauric acid hydroxylase activities, as well as total cytochrome P450 content were unaffected by this treatment. Immunoblot analysis revealed that caffeine gave rise to a dose-dependent increase in the hepatic CYP1A2, and at the highest dose only, CYP2B apoprotein levels. Apoprotein levels of CYP3A and CYP2E1 were not modulated by the treatment with caffeine at all dose levels studied. Caffeine could not displace [3H]TCDD from the rat hepatic cytosolic Ah receptor. Computer analysis showed that caffeine is essentially a planar molecule with an area/depth ratio 4.8, characteristic of CYP1A substrates/inducers. Molecular modelling revealed that the caffeine molecule could orientate itself within the putative CYP1A2 active site so as to facilitate demethylation of the N-1, N-3 and N-7 positions. However, at physiological pH, the N-9 nitrogen atom is likely to be partially protonated, allowing it to participate in an electrostatic interaction with the negatively-charged glutamate 318-residue, favouring N-3 demethylation, the major pathway of metabolism in both humans and animals. In conclusion caffeine, being essentially planar, is an inducer of CYP1A2 in rat liver.

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The effects of the non-steroidal anti-inflammatory drugs fenbufen and ibuprofen on hepatic cytochrome P450 activities and peroxisomal proliferation were investigated in the rat, following intraperitoneal administration at three dose levels. At the two highest doses, 30 and 150 mg/kg, ibuprofen stimulated lauric acid hydroxylase activity but no other dose-dependent effects on cytochrome P450 activities were evident. Fenbufen, at the highest dose of 150 mg/kg, decreased cytochrome P450 content and related activities, and this effect was attributed to the toxicity of the drug at this dose. Immunoblot studies employing solubilized microsomes from ibuprofen-treated rats revealed that ibuprofen increased the apoprotein levels of CYP4A1, at the two higher doses. The same treatment with ibuprofen, at the highest dose only, increased the beta-oxidation of palmitoyl CoA, determined in liver homogenates, and immunoblott analysis showed an increase in the apoprotein levels of the trans-2-enoyl CoA hydratase trifunctional protein. Fenbufen did not influence palmitoyl beta-oxidation. Computer graphic overlays with clofibric acid showed that ibuprofen, when compared with fenbufen, displayed a better overall fit to clofibric acid. Finally, interaction energies between the two drugs and the putative peroxisome proliferator-activated receptor ligand domain revealed that ibuprofen had a higher affinity for the receptor than fenbufen, but the difference was modest. It is concluded that ibuprofen, at doses far exceeding those employed clinically, is a weak inducer of both CYP4A1 activity and peroxisomal proliferation and these effects may be attributed to the presence of an aryl propionic acid moiety.(ABSTRACT TRUNCATED AT 250 WORDS)