Tax Audits and Tax Compliance in Rivers State Internal Revenue Service, Nigeria

This study examined the relationship between tax audits with the empirical referents of desk audit, field audit and tax compliance with its measures of  taxpayers registration, filing of tax return and penalties in Rivers State Internal Revenue Service. Tax audits as emerging concepts has suffered from scarcity of empirical evidence in Rivers State. Research hypotheses were formulated to test the relationship between tax audits and tax compliance. Copies of Questionnaire were distributed. The data that was obtained via survey instruments were analyzed using the descriptive statistical method to test for the mean, Rho analysis. Reliability test was conducted using Cronbach Alpha reliability with the scores of the variables of 0.7. The hypotheses were tested using Pearson’s Product Moment Correlation (PPMC) and regression analysis. From the analysis, the result shows that there is a significant relationship between empirical referent of tax audits and the measures of tax compliance. The study also found that there is a significant association between desk audits and filing of tax returns. Also desk audit is significantly correlated to penalties. Other results show that there is significant association between field audits and filing of tax returns, field audit and penalties also have a significant association. It was also found that adequate manpower does have mediating influence in the association between tax audits and tax compliance. Consequently, the study concludes thus, organizations prefers desk audits to field audits because field audits reveals more detailed work and encourages the provision of more documents by the taxpayer. The desk audit is more convenient for both the revenue authority and the taxpayer because field audit entails elaborate job to be performed by the Revenue authority. The study recommends that tax audits should be carried out on regular intervals, by this compliance rate will increase if tax audit is administered and the revenue realized is judiciously used. Tax audits should include desk audit and field audit. Adequate personnel should be engaged to carry out tax audits. Desk audit for the sake of convenience should be  preferred to field audit and finally, companies that fall within the tax net should comply to avoid penalties. Keywords: Tax, Tax audits, Tax Compliance, Internal revenue Service DOI: 10.7176/RJFA/11-16-13 Publication date:August 31st 202

Synthesis and evaluation of thymoquinone analogues as anti-ovarian cancer agents

Conference abstract, presented at the 2nd Molecules Medicinal Chemistry Symposium (MMCS): Facing Novel Challenges in Drug Discovery, Barcelona, Spain, 15–17 May 2019

Clerodane Diterpenoids from an Edible Plant Justicia insularis: Discovery, Cytotoxicity, and Apoptosis Induction in Human Ovarian Cancer Cells

Objectives: The toxicity of chemotherapeutic anticancer drugs is a serious issue in clinics. Drug discovery from edible and medicinal plants represents a promising approach towards finding safer anticancer therapeutics. Justicia insularis T. Anderson (Acanthaceae) is an edible and medicinal plant in Nigeria. This study aims to discover cytotoxic compounds from this rarely explored J. insularis and investigate their underlying mechanism of action. Methods: The cytotoxicity of the plant extract was evaluated in human ovarian cancer cell lines and normal human ovarian surface epithelia (HOE) cells using a sulforhodamine B assay. Bioassay-guided isolation was carried out using column chromatography including HPLC, and the isolated natural products were characterized using GC-MS, LC-HRMS, and 1D/2D NMR techniques. Induction of apoptosis was evaluated using Caspase 3/7, 8, and 9, and Annexin V and PI based flow cytometry assays. SwissADME and SwissTargetPrediction web tools were used to predict the molecular properties and possible protein targets of identified active compounds. Key finding: The two cytotoxic compounds were identified as clerodane diterpenoids: 16(alpha/beta)-hydroxy-cleroda-3,13(14)Z-dien-15,16-olide (1) and 16-oxo-cleroda-3,13(14)E-dien-15-oic acid (2) from the Acanthaceous plant for the first time. Compound 1 was a very abundant compound (0.7% per dry weight of plant material) and was shown to be more potent than compound 2 with IC50 values in the micromolar range against OVCAR-4 and OVCAR-8 cancer cells. Compounds 1 and 2 were less cytotoxic to HOE cell line. Both compounds induced apoptosis by increasing caspase 3/7 activities in a concentration dependent manner. Compound 1 further increased caspase 8 and 9 activities and apoptosis cell populations. Compounds 1 and 2 are both drug like, and compound 1 may target various proteins including a kinase. Conclusions: Clerodane diterpenoids (1 and 2) in J. insularis were identified as cytotoxic to ovarian cancer cells via the induction of apoptosis, providing an abundant and valuable source of hit compounds for the treatment of ovarian cancer

A characterization of the antimalarial activity of the bark of Cylicodiscus gabunensis Harms

ETHNOPHARMACOLOGICAL RELEVANCE AND AIM: A decoction of the bark of Cylicodiscus gabunensis Harms is used as a traditional medicine in the treatment of malaria in Nigeria. This study aims to validate the antimalarial potency of this decoction in vitro against Plasmodium falciparum and define potential bioactive constituents within the C. gabunensis bark. MATERIALS AND METHODS: A bioassay-guided separation and fractionation protocol was applied to C. gabunensis extracts, exploiting the use of a Malaria Sybr Green I Fluorescence assay method to monitor antiproliferative effects on parasites as well as define 50% inhibition concentrations. Spectroscopic techniques, including GC-MS, TOF LC-MS and (1)H NMR were used to identify phytochemicals present in bioactive fractions. Analogues of gallic acid were synthesized de novo to support the demonstration of the antimalarial action of phenolic acids identified in C. gabunensis bark. In vitro cytotoxicity of plant extracts, fractions and gallate analogues was evaluated against the HepG2 cell line. RESULTS: The antimalarial activity of ethanolic extracts of C. gabunensis bark was confirmed in vitro, with evidence for phenolic acids, primarily gallic acid and close analogues such as ethyl gallate, likely providing this effect. Further fraction produced the most potent fraction with a 50% inhibitory concentration of 4.7µg/ml. Spectroscopic analysis, including (1)H NMR, LC-MS and GC-MS analysis of this fraction and its acid hydrolyzed products, indicated the presence of conjugates of gallic acid with oligosaccharides. The extracts/fractions and synthetic alkyl gallate showed moderate selectivity against P. falciparum. CONCLUSIONS: These results support the use of the bark of C. gabunensis as a traditional medicine in the treatment of human malaria, with phenolic acid oligosaccharide complexes evident in the most bioactive fractions

A Review of the Bio-Activity Relationship of Mistletoes and the Leaves of their Host Trees

An investigation into the bioactivity relationship of mistletoes and the leaves of their host trees have been carried out. The following six host trees and their mistletoes were investigated: Azadirachta indica (neem), Psidium guajava (guava), Pentaclethra macrophylla (oil-bean), Kola acuminata (cola nut), Persea americana (avocado), and Baphia nitida (cam wood). The work showed that of the six host trees and their mistletoes studied, four host trees, namely: neem, guava, cola nut and avocado had lots of significant bioactivity, while the other two host trees: oil bean and cam wood had few significant bioactivities. The study revealed that the mistletoes parasitic on the host trees with significant bioactivity possessed some of the reported activities of their host trees. While the mistletoes parasitic on the host trees with few significant bioactivities also showed less significant bioactivities. Also, it was observed from the study that some of the bioactive host trees studied possessed significant insecticidal properties. It could be inferred, that their mistletoes may also possess insecticidal properties. In conclusion, the study has established that there is a relationship between the bioactivity of host trees and the bioactivity of the mistletoes parasitic on them.Keywords: bioactivity, Mistletoes, host tree, leavesNigerian Journal of Pharmaceutical Research, Vol. 8 No 1 pp. 145 - 150 (September 2010

An investigation of the role of carbon-chain length of precipitating solvent in the precipitation/dissolution of heavy organics

An investigation of the role of carbon-chain length of precipitating solvent in the precipitation/dissolution of heavy organics (HO) has been carried out. The heavy organics-rich residue was generated from a medium crude called Qua Iboe blend having an API gravity < 40. The precipitates were obtained from the n-pentane (n-C5), n-hexane (n-C6) and n-heptane (n-C7) solvents using a modified ASTM  D6560 method. Precipitation of heavy organics, Dissolution of heavy organics  precipitates of lower molecular weight n-alkane solvents by higher molecular weight n-alkane solvents and Stirring in of precipitates of the higher molecular weight n-alkane solvents in lower molecular weight n-alkane solvents (i.e. reprecipitation) were the experimental determinations carried out using the named solvents. The following results were obtained from these experiments: Precipitated heavy organics from n-pentane, n-hexane and n-heptane were 8.68%, 7.46% and 6.25%  respectively. The dissolution showed that 95% of n-C5 ppt. and 96% of n-C6 ppt. dissolved in n-C6 and n-C7 solvents respectively. The re-precipitation results demonstrated that 93% of n-C6 ppt. and 96% of n-C7 ppt. were insoluble in n-C5 and n-C6 solvents respectively. These findings further reiterate the observation that heavy organics precipitation increases with decrease in carbon-chain-length of the precipitating solvent. It is also shown that HO precipitation from solutions does occur. This same trend is also observed in the precipitation and dissolution

Advances of Plant-Derived Natural Products in Ovarian Cancer Therapy

Ovarian cancer is the leading cause of death in the gynaecologic cancers within the UK and US. Presently the standard treatment for ovarian cancer entails the use of chemotherapy drugs paclitaxel and carboplatin after aggressive surgical reduction in order to prolong the patient’s life for multiple years. However, prolonged use of platinum-based chemotherapy often leads to drug resistance, which causes the ovarian cancer patient to relapse and potential death. Therefore there is an urgent medical need for breakthrough drugs with an effective therapeutic impact on ovarian cancer. Phytochemicals (plant-derived natural products) have been used for thousands of years as treatment for various diseases, because of their huge chemical diversity and wide range of biological activities. In this review, the role of phytochemicals as chemo-preventive compounds, potential sources of new drugs for ovarian cancer and the benefits of their adoption as monotherapeutic agents or as chemosensitizers when used in-conjunction with the conventional anti-cancer drugs is highlighted. We will describe the phytochemicals: 1) clinically approved drugs such as paclitaxel and camptothecin including its semi-synthetic derivatives topotecan and irinotecan; 2) currently in clinical trials such as epipodophyllotoxin derivatives etoposide and teniposide, ventfolide, phenoxodiol, and combretastatins; 3) in preclinical trials such as quercetin, baicalein, baicalin,thymoquinone, betulinic acid and tetrandrine; and recently discovered compounds which have high potency (IC50 less than 10 µM) and have been discovered recently (last 15 years). In particular, several new compounds including bufatrienolides, ipomoeassin D,2'-(R)-O-acetylglaucarubinone, and molvizarin have IC50s lower than 100 nM in ovarian cancer cells and might have different mechanisms of action from those of platinum derivatives/paclitaxel, therefore providing potential ways to attack multidrug resistance in ovarian cancer without jeopardising the patient’s treatment