Standardization of the Leaves of <i>Ajuga remota</i> Benth

Abstract

Herbal medicines are extensively utilized across the world. In Ethiopia, people use Ajuga remota Benth to treat high blood pressure, hyperlipidaemia, diabetes, malaria, fever, ascariasis, stomach pain, diarrhoea, evil eye, and retained placenta. However, work has not been done on standardizing the herb. Thus, the aim of this study was to standardize the leaves of A. remota. Fresh leaves, powdered leaves, 80% methanol, chloroform, and methanol extracts of leaves of A. remota were evaluated using macroscopic and microscopic characterization, fluorescence analysis, physicochemical characterization, phytochemical analysis and residual analysis. Macroscopically, fresh leaves of A. remota were 17 - 62 mm (length) × 7.5 - 23 mm (width); 1 - 2 mm thick and dark sea green coloured, soft, fibrous, had a very bitter taste and a fruity odour. Microscopic characterization showed turgid guard cells, anisocytic stomata, epidermal cells (stratum spinosum), parenchymatous (aerenchyma) cells, pointed trichomes, spiral tracheids, and xylem fibre in powdered leaves of A. remota. The powder of the plant gave characteristic colours in fluorescence analysis under visible and 366 nm UV light. The powder was also studied for swelling index (2.392), foaming index (100), bitterness value (8400), extractive value (aqueous: 34.33% and methanol: 21.16%), moisture content (6.43%), total ash value (27.10%), water-soluble ash (11.43%), acid-insoluble ash (7.38%), tannin content (0.016%), and powder fineness (moderately fine). TLC, LC-MS, GC-MS, and FT-IR fingerprinting were produced. Ajugarin I, dodecyl acrylate, and hexacosane were identified as analytical marker compounds. In the residual analysis of the leaves of A. remota, soil took the highest percent (0.83%) among foreign matters. Heavy metals (Cd, Co, Pb, Cr, Ni, Cu, Zn, Fe, and Mn) and aerobic bacterial count, mould, yeast, coliform, Escherichia coli, Salmonella and Shigella species were quantified. ²²⁸Ac (7 ± 1.8 Bq kg^-1) and ⁴⁰K (530 ± 34 Bq kg^-1) radionuclides with a low dose were detected. The findings provide the standards for identification and authentication of the plant.