Quinazolines are nitrogen-containing heterocycles that consist of a benzene ring fused with a pyrimidine ring. Quinazolinones, oxidized quinazolines, are promising compounds with a wide range of biological activities. In the pharmaceutical field, quinazolinones are the building blocks of more than 150 naturally occurring alkaloids isolated from different plants, microorganisms, and animals. Scientists give a continuous interest in this moiety due to their stability and relatively easy methods for preparation. Their lipophilicity is another reason for this interest as it helps quinazolinones in penetration through the blood–brain barrier which makes them suitable for targeting different central nervous system diseases. Various modifications to the substitutions around the quinazolinone system changed their biological activity significantly due to changes in their physicochemical properties. Structure–activity relationship (SAR) studies of quinazolinone revealed that positions 2, 6, and 8 of the ring systems are significant for different pharmacological activities. In addition, it has been suggested that the addition of different heterocyclic moieties at position 3 could increase activity. In this review, we will highlight the chemical properties of quinazolinones, including their chemical reactions and different methods for their preparation. Moreover, we will try to modify some of the old SAR studies according to their updated biological activities in the last twelve years.

The aqueous extracts of Hibiscus calyphyllus (HcA), Hibiscus micranthus (HmA), and Hibiscus deflersii (HdA) growing in Saudi Arabia did not receive enough attention in phytochemical and biological studies. This inspired the authors to investigate the phytochemicals of these extracts for the first time using UPLC-ESI-MS/MS in negative and positive ionization modes. The analysis afforded the tentative identification of 103 compounds including phenolic compounds, flavonoids, and anthocyanins. Moreover, in vitro evaluations of their cytotoxic, antioxidant, antidiabetic, and antiobesity activities were carried out. The results showed that aqueous extract of Hibiscus calyphyllus had the highest activity as an antioxidant agent (SC₅₀ = 111 ± 1.5 μg/mL) compared with ascorbic acid (SC₅₀ = 14.2 ± 0.5 μg/mL). MTT assay was used to evaluate cytotoxic activity compared to cisplatin. Hibiscus deflersii showed the most potent cytotoxic effect against A-549 (human lung carcinoma) with IC₅₀ = 50 ± 5.1 μg/mL, and Hibiscus micranthus showed a close effect with IC₅₀ = 60.4 ± 1.7 μg/mL. Hibiscus micranthus showed the most potent effect on HCT-116 (human colon carcinoma) with IC₅₀ = 56 ± 1.9 μg/mL compared with cisplatin (IC₅₀ = 7.53 ± 3.8 μg/mL). HcA and HdA extracts showed weak cytotoxic activity against A-549 and HCT-116 cell lines compared to the other extracts. Eventually, Hibiscus deflersii showed astonishing antidiabetic (IC₅₀ = 56 ± 1.9 μg/mL) and antiobesity (IC₅₀ = 95.45 ± 1.9 μg/mL) activities using in vitro α-amylase inhibitory assay (compared with acarbose (IC₅₀ = 34.71 ± 0.7 μg/mL)) and pancreatic lipase inhibitory assay (compared with orlistat (IC₅₀ = 23.8 ± 0.7 μg/mL)), respectively. In conclusion, these findings are regarded as the first vision of the phytochemical constituents and biological activities of different Hibiscus aqueous extracts. Hibiscus deflersii aqueous extract might be a hopeful origin of functional constituents with anticancer (on A-549 cell line), antidiabetic, and antiobesity activities. It might be a natural alternative remedy and nutritional policy for diabetes and obesity treatment without negative side effects. Isolation of the bioactive phytochemicals from the aqueous extracts of aerial parts of Hibiscus calyphyllus, Hibiscus micranthus, and Hibiscus deflersii and estimation of their biological effects are recommended in further studies.

The resistance and pathogenesis of bacteria could be related to their ability to sense and respond to population density, termed quorum sensing (QS). Inhibition of the QS system is considered as a novel strategy for the development of antipathogenic agents, especially for combating drug-resistant bacterial infections. In the present study, the anti-QS activity of Onion peel ethylacetate fraction (ONE) was tested against Chromobacterium violaceum CV12472 and Pseudomonas aeruginosa PAO1. ONE inhibit the QS-mediated virulence factors production such as violacein in C. violaceum and elastase, pyocyanin in P. aeruginosa. Further, the treatment with sub-MICs of ONE significantly inhibited the QS-mediated biofilm formation, EPS (Extracellular polymeric substances) production and swarming motility. Further, quercetin 4′-O-β-D glucopyranoside (QGP) was isolated from ONE and its anti-QS potential was confirmed after observing significant inhibition of QS-controlled virulence factors such as violacein, elastase, pyocyanin and biofilm formation in test pathogens. Molecular docking analysis predicted that QGP should be able to bind at the active sites of Vfr and LasR, and if so blocks the entry of active sites in Vfr and LasR.

The objective of this study was to evaluate the antioxidant, anti-inflammatory, and anticancer properties of thymol, carvacrol, and their equimolar mixture. Antioxidant activities were assessed using the DPPH, ABTS, and ORAC methods. The thymol/carvacrol mixture exhibited significant synergism, surpassing the individual compounds and ascorbic acid in DPPH (IC₅₀ = 43.82 ± 2.41 µg/mL) and ABTS (IC₅₀ = 23.29 ± 0.71 µg/mL) assays. Anti-inflammatory activity was evaluated by inhibiting the 5-LOX, COX-1, and COX-2 enzymes. The equimolar mixture showed the strongest inhibition of 5-LOX (IC₅₀ = 8.46 ± 0.92 µg/mL) and substantial inhibition of COX-1 (IC₅₀ = 15.23 ± 2.34 µg/mL) and COX-2 (IC50 = 14.53 ± 2.42 µg/mL), indicating a synergistic effect. Anticancer activity was tested on MCF-7, MDA-MB-231, and MDA-MB-436 breast cancer cell lines using the MTT assay. The thymol/carvacrol mixture demonstrated superior cytotoxicity (IC₅₀ = 0.92–1.70 µg/mL) and increased selectivity compared to cisplatin, with high selectivity indices (144.88–267.71). These results underscore the promising therapeutic potential of the thymol/carvacrol combination, particularly for its synergistic antioxidant, anti-inflammatory, and anticancer properties against breast cancer. This study paves the way for developing natural therapies against breast cancer and other conditions associated with oxidative stress and inflammation, leveraging the synergistic effects of natural compounds like thymol and carvacrol.

Bee pollens are rich source of essential amino acids and are often considered as complete food for human beings. Herein, we exploited the potential reducing abilities of Bee pollens extract for the eco-friendly preparation of silver nanoparticles (AgNPs-G). The resulting NPs were characterized using a combination of microscopic and spectroscopic techniques. The analyses confirm the formation of spherical Ag NPs. AgNPs-G obtained from the aqueous extract of bee pollens was used to study their antibacterial properties against Gram-positive and Gram-negative microbes using the Minimum Inhibitory Concentration 50 (MIC₅₀) method. The antibacterial properties of AgNPs-G were compared to the properties of chemically synthesized Ag NPs (AgNPs-C) using sodium borohydride as a reducing agent. The green synthesized nanoparticles (AgNPs-G) exhibited a better antibacterial activity against most of the studied strains when compared to the chemically synthesized Ag NPs (AgNPs-C). In addition, the anti-cancer activity of Ag NPs was also studied against human liver and breast carcinoma cell lines by applying MTT-assay. The Ag NPs demonstrated considerable anticancer activity against the studied cell lines and exhibited high IC₅₀ values in both MCF-7 and HepG2 cell lines.

Parkinsonia aculeata L. growing in Saudi Arabia was investigated for its phytochemical profile, antioxidant, and cytotoxic properties. UPLC-ESI-MS/MS was employed as a powerful technique for the characterization of secondary metabolites from a hydroalcoholic extract, dichloromethane, and ethyl acetate fractions of P. aculeata L. aerial parts. Sixty-nine compounds (flavonoids, anthocyanins, phenolics and fatty acids) were detected and characterized; flavonoids were the abundant components in the analyzed samples. The dichloromethane fraction was rich in phenolics as vanillic acid hexoside, flavonols as 3,7-dimthylquercetin, and flavones as 3′-hydroxymelanettin. However, the ethyl acetate fraction was rich in flavonoid-C-glycosides as luteolin-8-C-β-D-glucoside (orientin) and apigenin-8-C-glucoside (vitexin), flavonoid- O, C-diglycosides such as luteolin 7-O-[6′'-dihydrogalloyl]-glucosyl-8-C-pentosyl-(1 → 2)-glucoside and 2′'-O-rhamnosyl isoorientin. These compounds were identified for the first time in dichloromethane and ethyl acetate fractions of Saudi P. aculeata L.