The phytochemicals present in Datura species are well-known for their anti-inflammatory and analgesic properties due to their ability to suppress the production of chemical mediators responsible for the stimulation of nociceptors and induction of pain or inflammation [35,36]. The ethanolic extract of roots of D. fastuosa was found to exhibit anti-inflammatory activity when studied for paw edema induced by carrageenan in rats, with Indomethacin as a standard drug [37,38]. The progress of edema can be explained in different phases; release of histamine and serotonin in the initial phase, edema maintained by substances like kinin in the plateau phase, and prostaglandin release in the edema accelerating phase [37,38]. The root extracts showed considerable activity against inflammation at 200 mg/kg compared to Indomethacin (at 10 mg/kg). Moreover, the aqueous extracts of seeds and leaves possessed significant analgesic effects at 800 and 400 mg/kg dosage, respectively, when experimented on mice using a writhing test (induced by acetic acid) and hot plate reaction [8]. However, the analgesic activity induced by leaves could be potentially decreased by naloxone, while that of seed extract remained unaffected. The aqueous leaf extracts of D. innoxia have been evaluated for their anti-inflammatory activity to develop an active herbal pain-relieving drug [39]. The basic mechanism involved in anti-inflammatory and analgesic action is believed to be the cyclooxygenase (COX1 and COX2) inhibition, followed by suppression of prostaglandin-synthesis or probably the narcotic effects of Datura species [36,39].

The antioxidant activity of Datura extracts can also be attributed to the presence of phytochemical compounds, which act as potent free radical scavengers and help prevent cellular damage [40]. Analysis of Datura plant extracts for antioxidant characteristics revealed its ability to cure various health disorders, including cancers, since antioxidants are known to inhibit cell damage, the general pathway for cancers, aging, and several other diseases [41]. The antioxidant capacity of leaf extracts in different solvents, estimated by various in vitro methods, including hydroxyl radical scavenging activity, DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, superoxide radical scavenging activity, β-carotene bleaching activity, and reducing power assay, revealed that chloroform extract of leaves possessed maximum concentration-dependent antioxidant activity [42,43]. The IC₅₀ value of methanolic and hydroalcoholic seed extracts of D. metel recorded using the DPPH model showed that hydroalcoholic extract possesses slightly higher antioxidant activities (IC₅₀ of 25.78 µg/mL) than methanolic seed extract (IC₅₀ of 28.34 µg/mL) [7,42].

In the estimation of DPPH free radicals scavenging activities, a positive correlation was observed between the flavonoid and phenolic content of the D. metel extracts [8,42]. Maximum DPPH scavenging activity of methanolic seed extracts of D. stramonium was found to be 59.50% at a concentration of 60 μg/mL with IC₅₀ value of 94.87 μg/mL; similarly, the maximum superoxide radical scavenging activity was 53.17% at a concentration of 60 μg/mL, while maximum scavenging activity of hydroxyl radical was 57.88% at concentration of 30 μg/mL with IC₅₀ value of 39.59 μg/mL [41]. Moreover, the hydromethanolic root extract of D. stramonium exhibited a significant amount of correlation with DPPH free radical scavenging activity.

The antimicrobial activity against pathogenic microbes was evaluated using aqueous and ethanolic extracts of different plant parts of D. stramonium, and the results revealed that the ethanolic extracts showed better antimicrobial activity than the aqueous extracts [44,45]. Moreover, the leaf extracts were found to be more effective than stem and root. The branches and leaves of Datura stramonium extracted with different organic solvents such as benzene, chloroform, and ethanol exhibited significant antibacterial and antifungal activity when studied against Enterobacter sp., Micrococcus luteus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Klebsiella pneumonia [8,46]. It was observed from the MBC (minimum bactericidal concentration) values that benzene extracts with the concentration of 3.12 mg/mL inhibited P. aeruginosa while the chloroform extracted with the same concentration was effective against S. aureus, P. aeruginosa, and M. luteus. Further, all the D. stramonium extracts were effective against various fungal strains such as Aspergillus fumigatus, Aspergillus niger, and Saccharomyces cerevisiae also, with maximum activity against S. cerevisiae and minimum antifungal activity against A. niger [8]. The methanolic and hydroalcoholic seed extracts of D. fastuosa also possessed considerable antimicrobial properties against bacterial (Bacillus subtilis, Escherichia coli, Staphylococcus aureus) and fungal (Aspergillus niger and Candida albicans) strains [8,20]. The methanolic extract acted against E. coli effectively with MBC of 25 µg/mL, while the hydroalcoholic extract was more effective against B. subtilis with both MBC and MIC (minimum inhibitory concentration) of 25 µg/mL. Methanolic plant extracts of D. inoxia also showed antifungal activity, and Fusarium solani was found more sensitive than other fungal species. The inhibition against different fungal species varied from 18.29 to 85.36%, where F. solani were affected more while A. niger showed more resistance [47]. D. metel seed oil had antibacterial activity against at least seven bacterial strains with the highest inhibition zone and lowest MIC against Lactobacillus delbrueckii lactis (19 mm) and Pseudomonas aeruginosa (18 mm), signifying susceptibility of bacterial strains to D. metel seed oil. The antibacterial activity exhibited a concentration-dependent response, and the inhibition zone increased with an increase in seed oil concentration [48].

Alkaloids found in D. stramonium, such as atropine and scopolamine, which possess significant anticholinergic and bronchodilating activities, block the muscarinic receptors (which are important for airways regulation), subsequently dilating bronchial smooth muscles [49,50]. Acetylcholine (the neurotransmitter synthesized and released by cholinergic neurons) leads to the contraction of smooth muscle after interaction with cholinergic muscarinic Acetylcholine (Ach) receptors [51]. The muscarinic receptors associated with the airway and lung tissues are M1, M2, and M3, of which M1 and M3, fully active in asthmatics, are responsible for bronchoconstriction while M2 which suppresses the release of acetylcholine, are less functional in asthmatics [52]. Datura administration inhibits M2 function, ultimately leading to the continued release of neurotransmitters. The anticholinergic activity of D. stramonium involves blocking the functions of muscarinic receptors on airway smooth muscles and submucosal gland cells [14]. The anti-asthmatic D. stramonium cigarette acts as a potential bronchodilator in asthmatic patients with the mild airway. A substantial decrease in the specific airway resistance (sRaw) was observed after inhaling smoke from the cigarette [8,53]. However, when exposed to the fetus during its use by the mother for asthma, D. stramonium releases acetylcholine. It desensitizes nicotinic receptors, resulting in slow or no response to repetitive agonist modulatory effects on the brain’s functioning, consequently damaging the fetus [3,13].