Pharmacological effects of Safranal: An updated review

**Background:** Safranal (2,6,6-trimethyl 1,3-cyclohexadien 1-carboxaldehyde) is a monoterpene aldehyde that constitutes 30-70% of volatile compounds in saffron (Crocus sativus L.) and is responsible for its characteristic odor. It is present in saffron dry matter at 0.001-0.006% and in Iranian saffron at 0.06–0.29 mg/g. Previous research has indicated various pharmacological activities, including anti-inflammatory, antioxidant, anticonvulsant, and antidepressant effects. This updated review aims to comprehensively summarize the pharmacological and medical effects of safranal reported from 2010 to June 2022, and to present related patents.

**Methods:** Electronic databases (Web of Sciences, Scopus, PubMed) were searched for pharmacological effects of safranal, and US Patent, Patentscope, and Google Patent were searched for patents, using the keyword "safranal" in title, abstract, and keywords. The search covered publications from 2010 to June 2022. References of retrieved articles were manually checked.

**Key Results:** The review covers multiple pharmacological domains:

- **Antioxidant and Anti-inflammatory:** Intraperitoneal safranal (0.5 mg/kg/day for one month) in old rats suppressed age-induced oxidative damage. Oral safranal (50 and 100 mg/kg for 14 days) improved liver antioxidant systems and decreased IL-6 and TNF-α. Safranal (100 mg/kg/day) reduced oxidative stress from thinner inhalation in rats. In vitro, safranal inhibited NO, iNOS, COX-2, IL-6, and TNF-α in RAW264.7 cells.

- **Cardiovascular:** In DOCA salt-induced hypertensive rats, safranal (1, 2, 4 mg/kg/day) reduced systolic blood pressure, with the highest dose comparable to spironolactone. In isolated rat aorta, safranal induced >100% maximal relaxation via L-type calcium channel blockade. In H9C2 myoblasts under hypoxia/reoxygenation, safranal increased viability, reduced ROS, and modulated apoptotic proteins (cleaved caspase-3, Bax, Bcl-2) via PI3K/GSK3β/AKT signaling. In isoprenaline-induced myocardial infarction in rats, safranal reduced CK, LDH, MDA, and increased SOD activity.

- **Renal:** In diabetic rats, four-week safranal administration improved renal dysfunction (decreased BUN and creatinine) and reduced TNF-α, IL-1β, IFN-γ. In cisplatin-induced nephrotoxicity, safranal (200 mg/kg orally for one month) ameliorated biochemical indices.

- **Respiratory:** In LPS-induced acute lung injury in mice, safranal (150 mg/kg) decreased TNF-α, IgE, IL-33; 300 mg/kg reduced lung wet:dry weight ratio. In asthmatic mice, safranal (0.5 ± 0.067 mg/g) reduced oxidative stress. In OVA-induced asthma, safranal (200 and 500 mg/kg) reduced IgE, NF-κB, and mast cells, and normalized Th1/Th2 balance. In guinea pigs, safranal (4, 8, 16 μg/mL) reduced endothelin-1 and total protein.

- **Metabolic:** Safranal reduced fasting blood glucose and HbA1c, improved insulin levels. In diabetic rats, safranal (0.25, 0.50, 0.75 mg/kg/day) lowered MDA, NO, glucose, cholesterol, triglycerides, and increased GSH, CAT, SOD. Safranal (1 mg/kg with insulin) improved diabetic neuropathy. In type 2 diabetic rats, four-week safranal reduced TNF-α and IL-1β.

- **Gastrointestinal:** In cyclophosphamide-induced liver injury, safranal (50, 100 mg/kg/day) improved liver function, decreased MDA, increased GSH and Nrf2. In liver ischemia-reperfusion, safranal (100 mg/kg) decreased ALT and AST. In indomethacin-induced gastric ulcer, safranal (0.063, 0.25, 1 mg/kg) controlled gastric volume and pH, reduced ulcer area. In DSS-induced colitis, safranal (200, 500 mg/kg) suppressed MAPK and NF-κB, reduced IL-6 and TNF-α.

- **Dermatologic:** Safranal showed sun-protective effects with SPF 6.6 at 0.01% concentration. Solid lipid nanoparticle formulations of safranal (4%) demonstrated higher SPF than 8% homosalate. Anti-elastase, anti-collagenase, and anti-hyaluronidase IC50 values were 43.6, 9.4, and 70 µg/ml, respectively.

- **Central Nervous System:** - Anti-anxiety: Crocin-safranal mixture (CSM) at 4.08 mg/kg increased time in open arm of elevated plus-maze. - Anticonvulsant: Nanostructured lipid vehicles carrying safranal (100 mg/kg for pilocarpine, 300 mg/kg for MES) showed effects greater than sodium valproate. - Neuroprotection: In spinal cord injury, safranal (100 mg/kg) inhibited p38 MAPK, Bax, IL-1β, TNF-α, and aquaporin-4. In Huntington's model, safranal (0.75, 1.5, 3 mg/kg) prevented increases in nitrite and MDA, and restored GSH, CAT, SOD. In Alzheimer's model, safranal (0.025, 0.1, 0.2 ml/kg for 7 days) improved cognition and reduced oxidative and inflammatory markers. In Parkinson's models, safranal induced Nrf2 signaling, increased tyrosine hydroxylase and dopamine transporter, and inhibited α-synuclein fibrillation. - Anti-ischemia: Safranal (145 mg/kg) reduced infarct volume and hippocampal cell loss after MCAO. - Anti-tremor: Safranal (0.1, 0.3 ml/kg) decreased tremor duration and intensity in harmaline-induced tremor.

- **Cytotoxic:** Safranal inhibited proliferation of colo-205 cancer cells (G2/M arrest, suppressed PI3K/AKT/mTOR), repressed invasion in oral squamous cell carcinoma, inhibited Bcr-Abl gene expression in K562 cells, and reduced viability of HeLa cells.

- **Antinociceptive:** Safranal (0.5 mg/kg) suppressed both phases of carrageenan-induced edema and formalin-induced pain. Sub-analgesic doses enhanced effects of morphine and diclofenac. Safranal (0.1 mg/kg) attenuated pain sensitivity and inhibited glial activation markers.

- **Ocular:** In choroidal neovascularization, safranal inhibited IRS-PI3K-PDK1/2-AKT-BAD signaling and reduced fluorescein leakage. In cataract model, safranal increased Nrf2 and GSH, decreased MDA.

- **Toxicity:** LD50 values for intraperitoneal safranal: 1.5 ml/kg (male rats), 1.48 ml/kg (male mice), 1.88 ml/kg (female mice). Oral LD50: 5.53 ml/kg (male rats), 21.42 ml/kg (male mice), 11.42 ml/kg (female mice). Sub-acute oral safranal (0.1, 0.25, 0.5 mL/kg/day for 21 days) reduced triglycerides, cholesterol, hematocrit, platelets, RBC, hemoglobin; increased LDH and BUN; caused pathological changes in kidneys and lungs. Safranal induced fetal malformations in pregnant mice. No immunotoxicity was observed.

**Clinical Implications:** Safranal demonstrates broad pharmacological potential, particularly for CNS disorders, cardiovascular protection, and metabolic diseases. Its antioxidant and anti-inflammatory mechanisms underpin many effects. However, all evidence comes from preclinical studies; no human clinical trials are reported. The toxicity profile shows low acute toxicity but sub-acute changes, and fetal toxicity in animals. Safranal-based patents exist for liver cancer, depression, obesity, sleep disorders, and cognitive function. Further clinical studies are essential to translate these findings into human therapeutics.