Chemotaxonomy, antibacterial and antioxidant activities of selected aromatic plants from Tabuk region-KSA

Abstract

Chemotaxonomy is a valuable tool for obtaining taxonomic insights, which are most effectively employed in combination with other forms of data to establish a system of classification that closely reflects natural connections. The utilization of plant secondary metabolites possessing diverse therapeutic qualities signifies the growing exploitation of natural products in the medical discipline. The objectives of the current study encompassed the identification of phytochemicals in the extracts of nine species of medicinal plants, the examination of their chemotaxonomic properties, and the assessment of the antibacterial and antioxidant capabilities exhibited by the extracts. GC-MS technology was employed for the identification of phytochemical compounds. The study utilized ClassyFire, an automated chemical classification system that incorporates an extensive and computable classification, to categorize chemicals. The chemical classification of plants was examined by the application of principal component analysis (PCA) and cluster analysis (CA). The bactericidal properties of plants were assessed against four harmful bacterial species using the disc diffusion technique. The antioxidant properties of plant extracts were assessed employing the DPPH free radical scavenging methodology, and the half maximal effective concentration (EC50) was determined using dose response models. The calculator being referred to is the Quest Graph™ EC50 Calculator. In the plant extracts, the analysis disclosed the occurrence of 160 phytochemicals, classified into 36 phytochemical classes. The results of CA and PCA demonstrated the proximity and associations among Asteraceae species, while indicating the divergence of the two Lamiaceae species. Achillea fragrantissima and Ducrosia flabellifolia demonstrated the most diversity in phytochemical classes, while Thymus vulgaris displayed the highest level of dominance. Pulicaria undulata and T. vulgaris had the most notable antibacterial activity. D. flabellifolia and P. incisa demonstrated the highest levels of antioxidant activity. Ethanol exhibited superior antibacterial efficacy compared to other solvents. The remarkable biological activities exhibited by these plant extracts can be ascribed to the copious presence of certain chemicals, predominantly sesquiterpenoids, monoterpenoids, benzene and its derivatives, naphthalenes, fatty acyls, and phenols. The susceptibility of Gram-positive bacterial species to plant extracts was shown to be higher in comparison to Gram-negative bacterial species.

Keywords: Antibacterial; Antioxidant activity; Chemotaxonomy; Medicinal plants.

Fig. 1

Stacked chart showing distribution of different phytochemical classes between plant extracts. FUR = furanones; BSD = benzene and substituted derivatives; PHPR = phenyl propanes; PYRCARB = pyridinecarboxamides; USH = unsaturated hydrocarbons; OOC = organooxygen compounds; MT = monoterpenoids; CUM = cumenes; FA = fatty acyls; SESQ = sesquiterpenoids; BENZF = benzofurans; OOx = organic oxides; THF = tetrahydrofurans; NAPHTHP = naphthopyrans; TT = triterpenoids; CAD = carboxylic acids and derivatives; FLAV = flavonoids; THIOPH = thiophenes; QHL = quinone and hydroquinone lipids; COUMD = coumarins and derivatives; HOP = hopanoids; PCH = polycyclic hydrocarbons; BENZ = benzenoids; SESQL = sesquiterpene lactones; PYRD = pyridines and derivatives; DT = diterpenoids; GLYCL = glycerolipids; SULF = sulfonyls; NAPHTH = naphthalenes; L 1,3 = Linear 1,3-diarylpropanoids; PHETH = phenol ethers; THCHR = thiochromenes; QUINL = quinolides and derivatives.

Fig. 2

Euclidian Paired group (UPGMA) classical clustering dendrogram of plant species based on their contents of phytochemical classes. T. v = Thymus vulgaris; L. c = Lavandula coronopifolia; D. f = Ducrosia flabellifolia; P. i = Pulicaria incisa; P. u = Pulicaria undulata; A. j = Artemisia judaica; A. h = Artemisia herba-alba; A. f = Achillea fragrantissima; A. m = Artemisia monosperma.

Fig. 3

Principal component analysis (PCA) Scattered plot (biplot) of plant species and phytochemical classes. T. v = Thymus vulgaris; L. c = Lavandula coronopifolia; D. f = Ducrosia flabellifolia; P. i = Pulicaria incisa; P. u = Pulicaria undulata; A. j = Artemisia judaica; A. h = Artemisia herba-alba; A. f = Achillea fragrantissima; A. m = Artemisia monosperma. FUR = furanones; BSD = benzene and substituted derivatives; PHPR = phenyl propanes; PYRCARB = pyridinecarboxamides; USH = unsaturated hydrocarbons; OOC = organooxygen compounds; MT = monoterpenoids; CUM = cumenes; FA = fatty acyls; SESQ = sesquiterpenoids; BENZF = benzofurans; OOx = organic oxides; THF = tetrahydrofurans; NAPHTHP = naphthopyrans; TT = triterpenoids; CAD = carboxylic acids and derivatives; FLAV = flavonoids; THIOPH = thiophenes; QHL = quinone and hydroquinone lipids; COUMD = coumarins and derivatives; HOP = hopanoids; PCH = polycyclic hydrocarbons; BENZ = benzenoids; SESQL = sesquiterpene lactones; PYRD = pyridines and derivatives; DT = diterpenoids; GLYCL = glycerolipids; SULF = sulfonyls; NAPHTH = naphthalenes; L 1,3 = Linear 1,3-diarylpropanoids; PHETH = phenol ethers; THCHR = thiochromenes; QUINL = quinolides and derivatives.

Fig. 4

Network diagram of plant species based on their contents of phytochemical classes.

Fig. 5

Phytochemical class diversity profile of plant species. T. v = Thymus vulgaris; L. c = Lavandula coronopifolia; D. f = Ducrosia flabellifolia; P. i = Pulicaria incisa; P. u = Pulicaria undulata; A. j = Artemisia judaica; A. h = Artemisia herba-alba; A. f = Achillea fragrantissima; A. m = Artemisia monosperma. a GC-MS Chromatogram of A. fragrantissima ethanolic extract. b GC-MS Chromatogram of A. herba-alba ethanolic extract. c GC-MS Chromatogram of A. judaica ethanolic extract. d GC-MS Chromatogram of A. monosperma ethanolic extract. e GC-MS Chromatogram of D. flabellifolia ethanolic extract. f GC-MS Chromatogram of L. coronopifolia ethanolic extract. g GC-MS Chromatogram of P. incisa ethanolic extract. h GC-MS Chromatogram of P. undulata ethanolic extract. i GC-MS Chromatogram of T. vulgaris ethanolic extract.

Fig. 6

Bar chart showing efficiencies of plant species in bacterial growth inhibition. A.f = Achillea fragrantissima; A.h = Artemisia herba-alba; A.j = Artemisia judaica; A.m = Artemisia monosperma; D.f = Ducrosia flabellifolia; L.c = Lavandula coronopifolia.

Fig. 7

Sensitivity of bacterial species to plant extracts and the antibiotic. P. a = Pseudomonas aeruginosa; S. a = Staphylococcus aureus; B. s = Bacillus subtilis; E. c = Escherichia coli.

Fig. 8

Graph of means (inhibition zones) resulted from application of ethanolic, methanolic and aqueous extracts and the antibiotic on the test bacterial species.

Fig. 9

Radar chart showing antioxidant activity of plant extracts based on EC₅₀ values.