Abstract
Current sickle cell disease (SCD) therapies are limited and inefficient. The ethnomedicinal values of Annona muricata in the treatment of SCD, leading to this present research. Leaves and fruits of Annona muricata were processed using solvent extraction and partitioning; aqueous, chloroform and ethyl acetate fractions. In vitro (anti-oxidant and anti-sickling), in silico, quantitative (amino acids) and kinetic simulation experiments were done. 15-acetyl guanacone, was used, in silico against 2,3-bisphosphoglycerate (2, 3-BPG) mutase and deoxyhaemoglobin. The ethyl acetate and chloroform fractions better NO● scavengers, iron-chelators and ferric reducing. In vitro unsickling (UT50) had ethyl acetate = 5 h and methanol = 7 h. Chloroform fraction had EC50 1.00 mg/mL (EC50 = 546 mg/mL) to 10.00 mg/mL (EC50 = 99 mg/mL). EC50 and IC50 of ethyl acetate fraction had steady-decrease. At higher concentration, chloroform fraction had higher Bmax (1.48 × 1021 U/mL) and higher Kd (3.66 × 1019 mg/mL), whereas, at a lower concentration, the ethyl acetate fraction demonstrated higher Bmax (7.23 × 1012 U/mL) and lower Kd (2.12 × 1011 mg/mL); The relative affinity (BP) of chloroform fraction increased progressively with concentration. The amino acid profile revealed rich concentrations glycine, valine, leucine, lysine, phenylalanine, histidine, arginine, and tryptophan. From the in silico experiments, 15-acetyl guanacone specifically targeted the A and B chains, with greater affinity for the beta subunit. This suggested that 15-acetyl guanacone might be able to prevent the polymerisation of deoxyHbSS, induce an allosteric conformational change that increases the oxygen affinity, and decrease the cellular 2, 3-BPG concentration.
Communicated by Ramaswamy H. Sarma
Acknowledgements
We hereby wish to acknowledge the immense supports of Mrs. Anne Oghenerukevwe Obayiuwana (for assisting with ) and Dr. Kennedy Modugu for assisting with the grammatical revision. Mr. Christopher Ugbodaga, Mr. Reuben Ofeimun and Ms. Ngozi Rose-Mary Agageme are also appreciated for assisting to obtain and process the plant materials used for this research.
Authors’ contribution
KCA and PNO designed the project design, protocols, as well as, supervision of the research; CU and RO assisted with the processing of the plant material; KCA, MA, RI, MCT, JJO, SKO and ORE carried out the in vitro anti-sickling experiments; KCA carried out the enzyme kinetic simulation experiments; JO and AK carried out the amino acid analysis; KCA, LNE and OA carried out the in vitro anti-oxidant experiments; KCA and NRA did the statistical analysis of the research; KCA and OE carried out the in silico experiments; KCA, MA, RI, and LNE wrote the manuscript.