Background: The genus Syzygium (Myrtaceae) comprises several essential oil-rich species that are utilized traditionally for treating tooth infections and toothache. The current study aimed to extract essential oils (EOs) from the leaves of Syzygium samarangense and Syzygium malaccense cultivated in Egypt for the first time and screen their antimicrobial potential against oral-related pathogens. Methods: The intended EOs were extracted using hydrodistillation (HD) by boiling fresh leaves with distilled water; supercritical fluid (SF) by extracting the dried leaves using supercritical CO₂ at 40 °C and 150 bar; and the headspace (HS) in which the fresh leaves were heated in a glass vial and the vaporized aroma were analyzed. The volatile constituents were analyzed using GC/MS and identified by comparing the experimental Kovats' retention indices with the literature. The antimicrobial activity was assessed against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Candida albicans using agar diffusion, microwell dilution, and biofilm formation assays. Statistical significance (p < 0.05) was determined by applying one-way ANOVA and Duncan's post hoc test. Results: The yield of the extracted EOs differs between the applied methods, and the SF approach harvested the maximum (0.52–0.46%). The GC–MS analysis of SF EOs revealed a discrepancy between the two species. Since S. malaccense showed an abundance of hydrocarbons represented mainly by squalene (60.60%), S. samarangense was deemed to have oxygenated sesquiterpenes exemplified in globulol (52.09%). On the other side, the HD and HS EOs were sequentially comparable, while differed in the percentage of their majors. γ-terpinene (33.06%) pioneered the HS-derived aroma of S. malaccense, while S. samarangense was abundant with α-pinene (30.18%). Concurrently, the HD EOs of S. malaccense and S. samarangense were commonly denoted by caryophyllene oxide (8.19%-18.48%), p-cymene (16.02%- 19.50%), and γ-terpinene (12.20%-17.84). Ultimately, both species EOs exhibited broad-spectrum antimicrobial potential, although the HD EO was more potent than the SF EO. The HD EOs of both species potently inhibited the growth of E. coli (MIC 3.75 µL/mL) and suppressed C. albicans biofilm formation by 83.43 and 87.27%, respectively. The SF-EOs efficiently suppressed the biofilm formation of Gram-positive bacteria by 76.45%-82.95%. Conclusion: EOs extracted from both species by different methods possessed a unique blend of volatile components with broad-spectrum antimicrobial activity. They were promoted as bioactive hits for controlling oral infections, however further investigations concerning their safety in clinical settings are needed.

Background/Objectives: Colorectal cancer (CRC) is the third most common cancer in the US and the second leading cancer-associated mortality cause. Available CRC therapies achieve modest outcomes and fail to prevent its recurrence. Epidemiological studies indicated that the Mediterranean diet rich in olive oil reduced CRC incidence. This study aimed at the identification and assessment of active anti-CRC olive phenolics. Methods: The MTT, wound-healing and colony formation assays were used to discover and assess the in vitro anti-CRC activity of olive phenolics. A nude mouse xenografting model was used to assess the in vivo CRC progression and recurrence suppressive activity of OC in pure and crude forms. OC was isolated from olive oil using liquid–liquid extractions. Results: Screening of olive phenolics for in vitro antiproliferative activity against a diverse panel of CRC cell lines identified the extra-virgin olive oil (EVOO) S-(-)-oleocanthal (OC) as the most active hit. OC showed IC₅₀ values of 4.2, 9.8, 14.5, and 4.9 μM against HCT-116, COLO-320DM, WiDr, and SW48 CRC cells, respectively. The lysine methyltransferases SMYD2 and EZH2, along with the receptor tyrosine kinase c-MET proved aberrantly dysregulated in invasive and metastatic CRC. SMYD2 and c-MET were validated as OC molecular targets in multiple malignancies. Daily oral 10 mg/kg OC treatments over 15 days suppressed 72.5% of the KRAS mutant HCT-116-Luc cells tumors weight in male nude mice. Continued OC daily oral use after primary tumor surgical excision over an additional 40 days significantly suppressed the HCT-116-Luc locoregional tumor recurrence and totally prevented the distant tumor recurrence. The SMYD2-EZH2 expressions and c-MET activation were notably suppressed by OC treatments in vitro and in collected animal primary tumors. Conclusions: OC and olive phenolics are potential nutraceutical interventions useful for CRC control and the prevention of its relapse.

Endophytes are prolific producers of privileged secondary metabolites with diverse therapeutic potential, although their anticancer and antimicrobial potential still have a room for further investigation. Herein, seven known secondary metabolites namely, arugosin C (1), ergosterol (2), iso-emericellin (3), sterigmatocystin (4), dihydrosterigmatocystin (5), versicolorin B (6), and diorcinol (7) were isolated from the rice culture of Aspergillus sp. retrieved from Tecoma stans (L.) Juss. ex Kunth leaves. Their anticancer and antimicrobial activities were evaluated in MTT and agar well diffusion assays, respectively. The cytotoxicity results showed that metabolite 3 displayed the best viability inhibition on the MCF-7 breast cancer cells with IC₅₀ = 225.21 µM, while 5 on the HepG2 hepatocellular carcinoma cells with IC₅₀ = 161.81 µM. 5 demonstrated a 60% apoptotic mode of cell death which is virtually correlated to its high docking affinity to Hsp90 ATP binding cleft (binding score −8.4 Kcal/mol). On the other side, metabolites 4 and 5 displayed promising antimicrobial activity especially on Pseudomonas aeruginosa with MIC = 125 μg/ml. The observed effect may be likely related to their excellent in silico inhibition of the bacterial DNA-gyrase kinase domain (binding score −10.28 Kcal/mol). To the best of our knowledge, this study is the first to report the promising cytotoxic and antibacterial activities of metabolites 3, 4, and 5 which needs further investigation and renovation to therapeutic leads.