دراسة الصفات المظهرية والكيميائية والفعالية التثبيطية للنوعين Portulaca grandiflora Hook وPortulaca oleracea L. من العائلة Portulacaceae تحت تاثير الاجهاد الحراري والتربة القلوية

Rp-Study of the Morphological, Chemical, and Inhibitory Properties of Two Species, Portulaca grandiflora Hook and Portulaca oleracea L., from the .pdf

The two plant species Portulaca grandiflora Hook and Portulaca oleracea L. were identified and compared based on their chemical and micromorphological characteristics under the influence of heat stress and the characteristics of alkaline soils common in Iraq. Seeds of both species were sown in plastic pots on 5/4/2025. The seeds were obtained from the nurseries of the Abbasid Shrine and from one of the orchards in Karbala. They were collected during the flowering period on 25/7/2024 for P. grandiflora and 25/9/2024 for P. oleracea. Part of these plants were used as crude alcoholic extracts for chemical analysis using gas chromatography-mass spectrometry (GC-MS), and the other part was used to test the inhibitory activity of methanolic and aqueous extracts of the two species against pathogenic isolates of the yeast Candida albicans (C.-P. Robin) Berkhout and the bacterium Proteus mirabilis Hauser.
Part of the plant material was used as crude alcoholic extracts for chemical analysis using gas chromatography-mass spectrometry (GC-MS). The dry floral and vegetative parts and pollen of both species were scanned using scanning electron microscopy (SEM) to detect variations in the qualitative characteristics of the epidermis of the floral and vegetative parts and pollen of the two species. The study revealed differences in the chemical content of active compounds and some fine morphological characteristics of the two species exposed to heat stress and alkaline soil conditions. The results of the study of the fine morphological characteristics of the epidermis of the vegetative and floral parts of both species, using SEM, showed clear qualitative variations of taxonomic importance under heat stress and alkaline soil conditions compared to previous studies that were not exposed to similar environmental conditions. The leaf epidermis of P. oleracea was characterized by irregular cells with prominent wavy walls and a fine granular pattern, while in P. grandiflora it was characterized by irregular cells ranging from polygonal to oblong, with straight to curved walls and a coarse granular pattern. The stem epidermis was considered a distinguishing characteristic; The purpurea exhibited elongated cells with thick, prominent walls and a coarse, granular pattern, while the morning glory was characterized by irregular to elongated cells with thicker, less prominent, and less undulating walls and a smooth to net-like pattern.

The upper petal epidermis of purpurea also displayed a transversely striped net pattern, compared to the morning glory, which had a striped pattern. In the lower petal epidermis, the pattern distinguished the two species, being slightly to coarsely striped in purpurea and transversely to net-like in the morning glory. The lower sepal epidermis of purpurea had a coarse, granular pattern, while it was smooth and striped in the morning glory.
The characteristics of the pollen grains demonstrated a clear difference between the two species; in purpurea, they were characterized by a high density of grains and spines with few pits, while in the morning glory, pits far outweighed grains and spines. The anther epidermis also distinguished the two species taxonomically based on the nature of the indented walls. The vascular structure was wavy in P. oleracea and highly wavy in P. grandiflora.
The surface covering characteristics also distinguished the two species. Both had non-glandular flagellated hairs covering the leaf bases and receptacle, while P. oleracea was characterized by a lower density of papillae on the upper epidermis, whereas the density was higher in the petals of P. grandiflora. Additionally, prismatic crystals were observed on the surfaces of the petals, anthers, and some epidermis.
The results of the chemical analysis using GC-MS further distinguished the two species. Seven active compounds were identified in the ethanolic extract of the vegetative part of Perpene (P. oleracea), four in the ethanolic extract of the vegetative part of Morning Rose (P. grandiflora), and five in the ethanolic extract of its flowering part. The active compounds common to the ethanolic extracts of the vegetative parts of both species were identified as (3) compounds: Cyclohexene, 1-methyl-4-(1-methylethenyl)- (S), Cyclohexanol, 1-methyl-4-(1-methylethenyl)- acetate, and Benzeneacetaldehyde. Most of these compounds are primarily terpenes, aromatic aldehydes, and aromatic cyclic hydrocarbons. The percentage of terpenes in the alcoholic extract of the vegetative parts of P. oleracea reached approximately 74.882%, while the percentage in the alcoholic extract of the flowers of P. grandiflora was lower, at approximately 54.032%. The percentage of terpenes in the vegetative parts of the latter species was similar to that in the flowering parts, reaching 49.281%.
The inhibitory activity of methanolic and aqueous extracts of the vegetative parts of both species and of the flowering part of P. grandiflora was tested against the yeast C. albicans and the bacterium P. mirabilis using six different concentrations (5, 10, 20, 40, 60, and 80 mg/ml). The aqueous extracts of P. oleracea showed twice the inhibitory activity compared to the alcoholic extracts against C. albicans at the higher concentrations, and they were superior in inhibiting P. mirabilis up to a concentration of 40 mg/ml.
The extracts of P. grandiflora showed significant variability; the methanolic extracts of the vegetative parts were more effective against C. albicans, while the aqueous extract was superior against P. mirabilis. The methanolic floral extract of P. grandiflora exhibited inhibitory activity against the yeast C. albicans up to a concentration of 20 mg/ml and against the bacteria P. mirabilis up to a concentration of 10 mg/ml.
The study results demonstrated the effect of heat stress and alkaline soil conditions on chemical and some micromorphological characteristics. Plants grown in full sun exhibited greater resistance to stressful environmental conditions, such as a qualitative increase in secondary metabolites that contribute to resistance to adverse environmental conditions. Furthermore, the plant’s ability to retain water was enhanced by the addition of thickening agents to its cell walls and surfaces.
Based on precise morphological and chemical characteristics and testing of their effect on pathogens as inhibitors, the taxonomic status of the two species P. oleracea and P. grandiflora was confirmed as belonging to the Portulacaceae family.