International Journal of Biochemistry Research & Review

Metformin is the widely prescribed first line oral antidiabetic drug used in diabetes mellatus, type 2 . The global sales turnover of metformin runs into millions of dollars. The Increased risk of  metformin (Met) users for developing  Alzheimer disease (AD)is reported first in a study conducted in 2011.  Since then, the subject has attracted the attention   of the researchers as well as the pharmaceutical industry, resulting in a number of studies, both clinical as well as experiments on animals. Confusing results poured in , ranging from confirmation of the risk of AD to protection  against developing AD , making the scenario, all the more intriguing . Added to the confusion, is the diversity of various studies as well as the parameters interpreting their results. Of the many clinical trials, some are retrospective cohort studies (Tseng Chin-Hsiao 2019) , case control  studies (Imfeld P, et al.) Randomised studies (Hsu CC, et al.),  double blind , cross over pilot studies. (Aaron Koenig et al.)  and some longitudinal studies (Ng TP, et al.) , besides studies doing  meta analysis . Of these studies most of the trials estimate the risk of development of dementia with metformin alone (Tseng Chin-Hsiao 2019) or in comparison with other OHAs (Hsu et al, Cheng et al.) .The other studies studied the effect of metformin on the cognition. (Moore EM, et al.). These trials have different out come measures, (like Hazard ratio, (HR) Odds(OR) ratio, relative risk (RR) etc.) which don’t mean one and the same. So the multiplicity of the types of studies and different out- comes with different conclusions will be surely baffling to an average reader who tries to take cognisance of the involved issues. The article attempts to take stock of the overall developments in this regard. The author adopted a reader friendly approach which is discussed in the article, at the outset. Finally, it is  reiterated that future prospective studies only can resolve the conflict of opinion on the nexus between metformin and Alzheimer’s disease.

Aim: To analyze the most complex multi-subunit (MSU) DNA dependent RNA polymerases (RNAPs) of eukaryotic organisms and find out conserved motifs, metal binding sites and catalytic regions and propose a plausible mechanism of action for these complex eukaryotic MSU RNAPs, using yeast (Saccharomyces cerevisiae) RNAP II, as a model enzyme.

Study Design: Bioinformatics, Biochemical, Site-directed mutagenesis and X-ray crystallographic data were analyzed.

Place and Duration of Study: School of Biotechnology, Madurai Kamaraj University, Madurai, India, between 2007- 2013.

Methodology: Bioinformatics, Biochemical, Site-directed mutagenesis (SDM) and X-ray crystallographic data of the enzyme were analyzed. The advanced version of Clustal Omega was used for protein sequence analysis of the MSU DNA dependent RNAPs from various eukaryotic sources. Along with the conserved motifs identified by the bioinformatics analysis, the data already available by biochemical and SDM experiments and X-ray crystallographic analysis of these enzymes were used to confirm the possible amino acids involved in the active sites and catalysis.

Results: Multiple sequence alignment (MSA) of RNAPs from different eukaryotic organisms showed a large number of highly conserved motifs among them.  Possible catalytic regions in the catalytic subunits of the yeast Rpb2 (= β in eubacteria) and Rpb1 (= β’ in eubacteria) consist of an absolutely conserved amino acid R, in contrast to a K that was reported for DNA polymerases and single subunit (SSU) RNAPs. However, the invariant ‘gatekeeper/DNA template binding’ YG pair that was reported in all SSU RNAPs, prokaryotic MSU RNAPs and DNA polymerases is also highly conserved in eukaryotic Rpb2 initiation subunits, but unusually a KG pair is found in higher eukaryotes including the human RNAPs. Like the eubacterial initiation subunits of MSU RNAPs, the eukaryotic initiation subunits, viz. Rpb2, exhibit very similar active site and catalytic regions but slightly different distance conservations between the template binding YG/KG pair and the catalytic R. In the eukaryotic initiation subunits, the proposed catalytic R is placed at the -9^th position from the YG/KG pair and an invariant R is placed at -5 which are implicated to play a role in nucleoside triphosphate (NTP) selection as reported for SSU RNAPs (viral family) and DNA polymerases.

Similarly, the eukaryotic elongation subunits (Rpb1) are also found to be very much homologous to the elongation subunits (β’) of prokaryotes. Interestingly, the catalytic regions are highly conserved, and the metal binding sites are absolutely conserved as in prokaryotic MSU RNAPs. In eukaryotes, the template binding YG pair is replaced with an FG pair. Another interesting observation is, similar to the prokaryotic β’ subunits, in the eukaryotic Rpb1 elongation subunits also, the proposed catalytic R is placed double the distance, i.e., -18 amino acids downstream from the FG pair unlike in the SSU RNAPs and DNA polymerases where the distance is only -8 amino acids downstream from the YG pair. Thus, the completely conserved FG pair, catalytic R with an invariant R, at -6^th position are proposed to play a crucial role in template binding, NTP selection and polymerization reactions in the elongation subunits of eukaryotic MSU RNAPs. Moreover, the Zn binding motif with the three completely conserved Cs is also highly conserved in the eukaryotic elongation subunits. Another important difference is that the catalytic region is placed very close to the N-terminal region in eukaryotes.

Conclusions: Unlike reported for the DNA polymerases and SSU RNA polymerases, the of eukaryotic MSU RNAPs use an R as the catalytic amino acid and exhibit a different distance conservation in the initiation and elongation subunits. An invariant Zn²⁺ binding motif found in the Rpb1 elongation subunits is proposed to participate in proof-reading function. Differences in the active sites of bacterial and human RNA polymerases may pave the way for the design of new and effective drugs for many bacterial infections, including the multidrug resistant strains which are a global crisis at present.

Background and Objectives: The developments of fourier transform infrared (FT-IR) spectroscopic instrumentation, and application, over the years has made it a powerful analytical tool in the study of oils and fats. This work has explored fourier transform Infra-Red for characterization of plant oils from selected cultivars grown in Nigeria. The selection of these plants oils that flourishes in Nigeria aside their used primarily for nutritional applications, is dependent on the fatty acid (FA) composition of triacylglycerol (TAG which make them potential for bioenergy and biofiuel production considering the explosion of energy demand through alternative energy sources. They are also needed for the preparations of chemical feedstocks, biopolymer and composites, skin care products. Oils from these plants can provide renewable sources of high-value fatty acids for both the chemical and health-related industries. We report here several areas where these plant oils can have a significant impact on the emerging bioeconomy.

Materials and Methods: The samples were each placed in contact with KBr disc and FT-IR spectra were collected in frequency 4500-400 cm-1 by coadding 32 scans and at resolution of 4 cm-1. All spectra were rationed against a background spectrum. In each scan, a new reference background spectrum was detected.

Results: The spectra of oils of the present investigation revealed the following bands 1522, 1449.55, 1364.68, 1444.73, 1364.68, 1445.09, 1369.50, 1447.62, 1362.75, 1449.55, 1371.43, 1447.62, 1366.54, 1447.62, 1450.5, 1360.82, 1370.47, 1446.66, 1246.06, 1364.47, 1448.59 for Adansonia digitata, Ricinus communis, Sesamum indicum, Jatropha curcas, Allium cepa, Cucumis melo, Lannea microcarpa, Lagenaria vulgaris and Sesamun indicum seed oil respectively. 1450 cm-1- 1444 is related to bending vibration of CH₂, and CH₃; (cis =C–H bending) and at 1360 - 1370 cm-1 is concerned with the bending vibrations CH₂ groups which showed total unsaturation. The results obtained shows that all the oils are unsaturated because there is no band around 3005- 3009 which is the band that normally determine the index of degree of unsaturation.

Conclusion: The FT- IR spectroscopy proved to be an important technique for identification, analysis, determination of degree of saturation of fatty acids in oils suitable for industrial applications.

Cancer a leading cause of human mortality worldwide is characterised by the unseemly growth of cellular mass and signalled through the enlargement of stress.  Management of cancer treatment is still buried and has been recently alerting the need to discover a drug molecule with lesser side effects. The objective of the present study is to explore the anticancer activity and docking studies of 1-(5-substituted phenyl) isoxazol-3-yl)-5-phenyl-1H-tetrazole derivatives. The compounds were evaluated for in-vitro anticancer activity under the drug discovery program of National Cancer Institute (NCI), USA. Only seven compounds were selected and screened for anticancer activity at a single high dose (10^-5 M) using NCI 60 cancer cell lines. Among all the selected compounds, 4b and 4i exhibited significant anticancer activity against Leukemia cell lines. Molecular docking studies for the 5-phenyl-1-(5-substituted phenylisoxazol-3-yl)-1H-tetrazole analogues was done by Schrodinger software. Docking results stated that the compounds 4b and 4i has good dock score among the other derivatives which shows good binding efficiency towards receptor.

Aims: The present study was aimed at evaluating the physicochemical and functional properties of flours and oil from the Shea Caterpillar Cirina butyrospermi Vuillet, one of the most widely eaten insects in the Northern Côte d’Ivoire as alternative protein source.

Methodology: Fresh C. butyrospermi larvae were collected from Vitellaria paradoxa trees in the different regions producing shearbutter in northern Côte d’Ivoire. The larvae were oven dried and ground to obtain crude flour. Flours and Oil extracted from this insect was analysed for physicochemical properties and fatty acid constituents using standard methods.

Results: The chemical composition revealed that it contains crude protein about 60.09%, crude fat 22.23%, ash 3.71% and total carbohydrate 6.69%. These results suggest that C. butyrospermi larvae can be used in human diet to prevent undernourishment due to protein. Albumin and glutelin constitute the main part of protein fractions. The defatted flour showed good functional properties such as water and oil absorption capacity (77.96 and 150.00% respectively), dispersibility (70.90%), wettability (5 min) and foam stability (50.05%). As regards oil, it exhibited good physicochemical properties as saponification and stability. Fatty acids profile reveals that the unsaturated fatty acids accounted for 49.33% of the total fatty acids, whereas the saturated fatty acids constituted 49.83% of the fatty acids.

Conclusion: C. butyrospermi larvae could be considered as valuable source of protein and oil accounting for more than 80% of nutrients. Its flour exhibits some good functional properties making it suitable for many food product formulations. Compared with oils which have been reported of high quality, C. butyrospermi oil has potentials that could be exploited for nutritional and pharmaceutical purposes.