Bioactive Compounds of Verbascum sinuatum L.: Health Benefits and Potential as New Ingredients for Industrial Applications

**Background:** Verbascum sinuatum L. (mullein) is a biennial herbaceous plant of the Scrophulariaceae family, predominantly found in the Mediterranean region and the Turkey–Iraq–Iran area. Its aerial parts have been used in traditional medicine for respiratory problems, urinary tract infections, and various inflammatory conditions. The plant contains bioactive compounds—primarily polyphenols and iridoids—that may justify its traditional uses. This narrative review aims to evaluate current findings on the bioactive compounds of V. sinuatum, extraction methods, and biological properties to discuss potential applications in food, pharmaceutical, and cosmetic industries.

**Methods:** This is a narrative review of the literature on V. sinuatum. The authors compiled data from published studies on the plant's phytochemical composition (phenolic compounds and iridoids), conventional and green extraction techniques (maceration, Soxhlet, hydro-distillation, supercritical fluid extraction, pulsed electric field, microwave-assisted extraction, and ultrasound-assisted extraction), and biological activities (antioxidant, antimicrobial, anticancer, neuroprotective, cardiovascular, and antidiabetic). The review also discusses encapsulation strategies and potential industrial applications.

**Key Results:** The total phenolic content (TPC) of V. sinuatum flower extracts ranges from 29.03 to 54.77 mg GAE/g DW, and total flavonoid content (TFC) ranges from 13.72 to 19.91 mg RE/g DW (ethanolic maceration). Methanolic flower extracts showed TPC of 51.94 mg GAE/g DW and TFC of 22.57 mg QE/g DW. Major phenolic compounds identified include rutin (21.00 mg/g DW), p-coumaric acid (10.22 mg/g DW), apigenin (5.85–13.82 µg/mg DW), luteolin (3.18–16.98 µg/mg DW), naringin (7.10–12.32 µg/mg DW), and caffeic acid (4.98–7.78 µg/mg DW). Iridoids identified include harpagoside (0.01 mg/g DW), verbascoside (12.4–13.1 µg/mL), and isoverbascoside (2.3–2.5 µg/mL). For antioxidant activity, DPPH IC50 values ranged from 0.11 mg/mL (methanolic extract) to 263.52 µg/mL (ethanolic extract), and TBARS IC50 values were 4.2 µg/mL (ethanolic) and 17.4 µg/mL (infusion). Antimicrobial activity showed MIC values as low as 4 µg/mL against Enterococcus faecalis and 8 µg/mL against Candida albicans (ethanolic extract). Anticancer activity: infusion extracts showed GI50 values of 74.8 µg/mL (MCF-7), 92.1 µg/mL (NCI-H640), 59.1 µg/mL (HeLa), and 65.4 µg/mL (HepG2). The alkaloid fraction showed a mitotic index of 33.00 and aberration index of 21.49. Verbascoside demonstrated ACE inhibitory activity with IC50 of 2.22 mM and α-amylase inhibition with IC50 of 125.21 mg/mL.

**Clinical Implications:** The review suggests that V. sinuatum extracts and their bioactive compounds—particularly verbascoside—have potential as natural ingredients for pharmaceutical applications (antimicrobial, anticancer, neuroprotective for Alzheimer's disease, antihypertensive, antidiabetic), food industry applications (natural preservatives, functional food ingredients), and cosmetic products. However, the authors emphasize that most evidence comes from in vitro studies, and only one study reported in vitro cytotoxicity against non-cancer cells (PLP2) with GI50 of 223.1 µg/mL for infusion extract. The review identifies knowledge gaps including the need for in vivo studies, clinical trials, toxicity assessments, and herb–drug interaction studies before industrial application. Encapsulation techniques (microencapsulation and nanoencapsulation) are proposed to preserve bioactive compound stability and bioavailability.