Pechuel-Loeschea leubnitziae is a predominant medicinal plant in Namibia. It is traditionally utilized in treatment of gastrointestinal issues, sexually transmitted infections and common cold. Despite its therapeutic potential, the phytochemicals profile and compounds compositions are yet to be scientifically validated. This study was conducted to determine the spectrum and total phytochemical constituents present in P. leubnitziae leaves extract using standard qualitative and quantitative methods. Fine powder of P. leubnitziae was extracted by cold maceration using a serial exhaustive approach in a 1:5 dilution in hexane, ethyl acetate, ethanol, methanol and water. A f t e r 7 2 h , obtained filtrate was concentrated using a rotary evaporator or lyophilizer. Crude fraction of each solvent obtained was screened for phytochemicals using qualitative and quantitative methods. The yield of the extracts post-extraction ranged from 5.361 to 23.93 g. The extracts contain alkaloids, phenolics, flavonoids, saponins, terpenoids and tannins. There were significant differences in the total phytochemical contents of each solvent. Total alkaloids contents (TAC) ranged from 29.12 to 106.44 µg, total flavonoids contents (TFC) ranged from 30.41 to 78.84 µg, total phenolic contents (TPC) ranged from 57.14 to 58.70 µg and total tannins contents (TTC) ranged from 13.06 to 30.85 µg. The leaves o f P. leubnitziae contain phytochemicals including alkaloids, flavonoids, phenolic, terpenoids, tannins and saponins that are known to have pharmacological properties and they can be explored for biological potentials.

The complete halt in the synthesis of new effective antimicrobial compounds is a global concern. Pathogenic microorganisms' virulence mechanisms seem to have a significant impact on their pathogenesis. The purpose of this study was to examine the antimicrobial activity of the ethanol and methanol fractions of Pechuel-Loeschea leubnitziae leaf extract, as well as its effect on the expression level of virulence-associated genes.The extract's fractions were evaluated for antimicrobial activity against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae (clinical), Methicillin-resistant Staphylococcus aureus, and Candida albicans ATCC 90029. The test organism's antibiogram pattern was determined. The extracts' attenuation effect on the target genes of the susceptible organisms was investigated employing relative quantification using RT-qPCR. The test organism's antibiogram pattern revealed that it was drug-resistant, intermediate, and sensitive. The extracts tested positive for antimicrobial activity against Methicillin-resistant Staphylococcus aureus and Candida albicans ATCC 90029, with zones of inhibition varying from 20.33 to 29 mm. The lowest recorded MIC value was 4.688 mg/ml, while the highest was 37.5 mg/ml. In contrast to the methanol extract, the ethanol extract had a cidal action at a lower dose. The ethanol extract's Sub-MIC (18.25 mg/ml) merely reduced the expression of the hly gene in MRSA. The MRSA virulence genes were not suppressed by the sub-MIC of methanol extract (18.25 mg/ml). Notably, the expression of als1, pbl1, and sap1 in Candida albicans ATCC 90029 was significantly attenuated when exposed to sub-MICs of ethanol extract (2,344 mg/ml) and methanol extract (9.375 mg/ml). Per the findings of this research, the leaves of P. leubnitziae could be a source of an effective antimicrobial agent in the therapy of MRSA/Candida-related disorders.