PHARMACOGNOSTIC STANDARDIZATION AND MOLECULAR AUTHENTICATION OF Parquetina nigrescens (AFZEL.) BULLOCK ROOTS
SILAS ACHOR AKAH1*, UMAR FARUK SHEHU1, KABIRU YUSUF MUSA1
1. Department of Pharmacognosy and Drug Development, Faculty of Pharmaceutical Sciences, Ahmadu Bello University, Zaria, Nigeria.
Afr. J Pharm Res Dev; Volume 18(2): 726-737; 2026
ABSTRACT
Quality assurance of herbal medicines remains a critical challenge, particularly for plant materials sold in powdered form where traditional identification methods become ineffective. Parquetina nigrescens (Afzel.) Bullock (Apocynaceae) features prominently in African traditional healthcare systems, yet its root material lacks established quality control parameters. This investigation aimed to develop pharmacognostic and molecular markers for authenticating and standardizing powdered P. nigrescens roots. Authentication procedures encompassed powder microscopic examination, histochemical staining, physicochemical profiling, and phytochemical characterization. Chemical fingerprinting was accomplished through thin-layer chromatography (TLC), while molecular identification employed rbcL gene amplification and sequencing. Microscopic assessment revealed diagnostically valuable features including lignified fibres, parenchymatous cells, cork cells, and starch grains. Histochemical analysis confirmed the presence of cellulose, lignin, suberin, calcium oxalate crystals, mucilage, tannins, starch, aleurone grains, and inulin. Physicochemical constants (moisture: 4.53%; total ash: 32.20%; acid-insoluble ash: 2.50%) fell within acceptable ranges, though total ash showed notable variability. Phytochemical screening detected carbohydrate, flavonoids, tannins, saponins and steroids/triterpenes, with phenolic compounds being the most abundant (1.10 ± 0.02 mg GAE/g). TLC analysis produced reproducible characteristic bands (Rf 0.3-0.95). The rbcL amplicon yielded a 540 bp sequence (GenBank PV611177) demonstrating 98-100% homology with Apocynaceae members. These findings establish integrated quality control benchmarks for P. nigrescens roots, facilitating their safe utilization and reducing adulteration risks. The deposited rbcL sequence contributes to expanding DNA reference libraries for African medicinal flora.
Keywords: DNA barcoding, medicinal plants, pharmacognostic standardization, Parquetina nigrescens, rbcL gene, quality control.
Email of correspondence: [email protected]
https://doi.org/10.59493/ajopred/2026.2.3 ISSN: 0794-800X (print); 1596-2431 (online)