Biokemistri <p><em>Biokemistri</em> is a journal devoted to the dissemination of knowledge relating to all aspects of biochemistry. These include theoretical biochemistry, Biophysical chemistry, animal and plant biochemistry, microbial biochemistry, clinical and forensic biochemistry, enzymology, Protein chemistry, Analytical biochemistry, nutritional biochemistry, toxicology and xenobiochemistry, molecular biology, genomics and bioinformatics. Manuscripts will be rejected if the contents do not sufficiently conform to modern day biochemistry. <em></em></p><p>Other websites related to this journal: <a title="" href="" target="_blank"></a></p> Klobex Academic Publishers for Bioscience Study Group en-US Biokemistri 0795-8080 ©Nigerian Society for Experimental Biology In-situ generation of peroxynitrite from 3-morpholinosydnonimine decay in pulmonary cell culture medium Background: Peroxynitrite (ONOO-) is a strong oxidising and nitrating agent generally implicated in oxidative stress. Its cellular action is linked with pulmonary artery cell hyper-proliferation and vascular remodelling seen in pulmonary hypertensive diseases. It is thus vital to elucidate the biological actions of peroxynitrite; however, working with the anion is challenging. Whether supplied commercially or prepared extemporaneously, ONOO- is stabilised and stored under strongly alkaline conditions and the exposure of cells to this form of ONOO- will in tandem increase culture media pH. Accordingly, increasing number of studies are seeking alternative means of generating peroxynitrite and have utilised 3-morpholinosydnonimine (SIN-1) the active metabolite of the vasodilatory drug molisdomine to generate peroxynitrite in-situ. Even so, it is not clear how much authentic ONOO- is generated under these conditions and for how long. Aim: To establish the formation of peroxynitrite and to determine its decay kinetics following SIN-1 decomposition in a medium formulated for the culture of primary human and bovine pulmonary artery cells. Results: The half-life of authentic peroxynitrite was determined to be 1.38s in pulmonary artery cell culture medium. Formation of peroxynitrite during 3-morpholinosydnonimine (SIN-1) decomposition was continuously monitored from the loss in fluorescence associated with the ONOO- oxidation of nicotinamide adenine dinucleotide (NADH) to NAD+. SIN-1 decayed by 1st order kinetics and 20μM SIN-1 generated ONOO- at the rate of 0.11 μM min-1. SIN-1 decomposition in cell culture medium was associated with the formation of a stable intermediate product SIN-1C with absorbance (λ<sub>max</sub>) at 279±2nm. The SIN-1 ➝ SIN-1C transformation was oxygen dependent and the result of -OH catalyzed hydrolytic decomposition. Stopped-flow spectroscopic evidence revealed that SIN-1 can be deprotonated in a pH dependent manner during the phase of the reaction leading up to SIN-1A formation. Conclusion: The formation of ONOO- was demonstrated by the qualitative and quantitative determination of its insitu generation from the decay of 3-morpholinosydnonimine (SIN-1). This will enable relevant correlations of the life of peroxynitrite in culture conditions to its actions in pulmonary cells.<br /><br /><strong>Keywords</strong>: Peroxynitrite, from SIN-1, culture medium<br /><br /><em>Biokemistri</em> 28(1): 1–15 Ejaife Ono Agbani Copyright (c) 2020-02-03 2020-02-03 28 1 1 1 10.4314/biokem.v28i1. Larvicidal activity of essential oil from citrus sinensis and <i>Citrus paradisi</i> against <i>Anopheles gambiae</i> Malaria is a major health challenge in the developing world causing millions of death annually. Synthetic pesticides used in the vectors control are not environmentally safe and are expensive. We screened the essential oils of <em>Citrus sinensis</em> and <em>Citrus paradisi</em> peels at concentrations ranging between 40 and 400 ppm against late 3rd instar of <em>Anopheles gambiae</em> larvae. The effects of ethanol and methanol on the larvicidal activity of these oils were examined. The effects of combined oils formulations on larvicidal activity were also determined. The larvicidal concentration (LC<sub>50</sub>) of the orange and grape oil was 73ppm and 76 ppm, respectively in methanol, and 121 ppm and 82 ppm in ethanol solution. The LC<sub>50</sub> of the combined oil formulations ranged between 54 and 99ppm. The different oil combinations showed synergism except when combined at equal proportion in ethanol. Conclusively, orange and grape oils could be used as biopesticides against <em>A. gambiae</em> larvae.<br /><br /><strong>Keywords</strong>: <em>Anopheles gambiae; Citrus paradisi; Citrus sinensis</em>; essential oils; Mosquito larvae<br /><br /><em>Biokemistri</em> 28(1): 16–23 Wahab O. Okunowo Lukman O. Afolabi Abiola O. Oyedejia Eniola Matanmi Olufunsho Awodele Copyright (c) 2020-02-03 2020-02-03 28 1 16 16 10.4314/biokem.v28i1. GC-MS analysis and antimicrobial properties of methanolic extracts of the Marine Algae <i>Skeletonema costatum</i> and <i>Chaetoceros</i> spp. In this report, we describe the antimicrobial potential and phytochemical constituents of two Nigerian marine algae; <em>Skeletonema costatum</em> and <em>Chaetoceros</em> spp. The minimum inhibitory concentration (MIC) of the methanolic extract of the algae spp. was determined against 7 clinical isolates (<em>Enterococcus faecalis, Staphylococcus aureus</em> ATCC 25923, <em>Bacillus species, Klebsiella pneumonia, Salmonella typhi, Escherichia coli</em> ATCC 25922 and <em>Candida albicans</em>) using broth dilution method. The volatile constituents of the extracts were analyzed using the Gas Chromatography- Mass Spectrometry technique. The results showed that S. costatum inhibited all isolates except<em> Salmonella typhi</em> and ATCC <em>E.coli</em> while <em>Chaetoceros</em> spp. had no inhibitory effect on <em>Candida albicans</em>. The MIC values of the two algae extract was least; &lt; 2.0 mg/ml and highest; 10 mg/ml for the test isolates. A total of 42 and 25 volatile compounds which includes 9- Octadecenamide, (Z) - as the major constituent were obtained in<em> S. costatum</em> and <em>Chaetoceros</em> spp. respectively. Other compounds identified were known antimicrobial compounds; 1-Hexacosanol, Eugenol, Benzenesulfonamide, 4-methyl-N-phenyl- and Thiazole, 4-(4-aminophenyl)-2-methylamino- as well as some phytochemicals such as flavonoids, tannins, terpenoids, steroids and phenols. These may account for the antibiotic property of the algae extracts. This study showed that <em>S. costatum</em> and <em>Chaetoceros</em> spp. possess antimicrobial compounds which may be explored for therapeutic purposes.<br /><br /><strong>Keywords</strong>: Antimicrobial, Marine algae, Clinical isolates, GC-MS, Phytochemicals.<br /><br /><em>Biokemistri</em> 28(1): 24–33 Wahab O. Okunowo Lukman O. Afolabi Ifeoma E. Umunnakwe Abiola O. Oyedeji Josiah A. Ilesanmi Copyright (c) 2020-02-03 2020-02-03 28 1 24 24 10.4314/biokem.v28i1. Central nervous system depressant effect of the fruits of <i>Piper guineense</i> The central nervous system depressant effect of the butanol extract of the fruits of <em>Piper guineense</em> was pharmacologically screened by measuring the prolongation of barbiturate sleeping time. Nine rats (n=9) were used and assigned into three groups, with each group comprising of three rats (n=3). Group A served as the Control, while Groups B and C served as tests. Thiopentone sodium (40 mg/kg body weight) was administered subcutaneously to the rats in Group A, 2 mg/kg of the butanolic extract of the fruits of Piper guineense was administered subcutaneously to the rats in Test Group B, 30 minutes before administering same dose of thiopentone sodium, while rats in Group C received 4 mg/kg of the butanolic extract 30 minutes before administering same dose of thiopentone sodium. The sleeping time was recorded. Student-t-test at 5% significance level was used to analyze the results obtained. The mean barbiturate sleeping time prolongation of 53.67 minutes was produced by 2 mg/kg of the extract while a dose of 4 mg/kg produced mean barbiturate sleeping time prolongation of 103.67 minutes. This study suggests that the fruits of Piper guineense have central nervous system depressant effect.<br /><br /><strong>Keywords</strong>: <em>Piper guineense</em>, fruits, glycosidic constituents, central nervous system, depressant<br /><br /><em>Biokemistri</em> 28(1): 34–37 Felicia E. Williams Olusegun S. Adedeji Julius O. Aiyedun Hope Obianwu Copyright (c) 2020-02-03 2020-02-03 28 1 34 34 10.4314/biokem.v28i1.