Methiin — SMCSO (Brassica Cysteine Sulfoxide · Cholesterol Lowering · Hepatoprotective)
| Compound | Methiin (S-Methyl-L-cysteine sulfoxide; SMCSO) |
| Chemical class | Organosulfur — Cysteine Sulfoxide (S-Methyl-L-cysteine sulfoxide) |
| CAS | 3108-60-9 |
| Primary source | Brassica oleracea (cabbage, broccoli, Brussels sprouts), Allium spp. |
| Key applications | Antioxidant, hepatoprotective, lipid metabolism, cholesterol modulation |
| Claim strength | Moderate |
| Typical form | Brassica vegetable extract (methiin co-constituent); dried cabbage/broccoli powder |
| Buy from Herbuno | Cabbage Liquid Extract (Water Soluble) - Brassica oleracea → |
Name origin: From the methyl (—CH3) group attached to the sulfur — the simplest S-alkyl cysteine sulfoxide. Methiin (S-methyl-L-cysteine sulfoxide, SMCSO) is the most structurally simple of the cysteine sulfoxides — a methyl group on the sulfur rather than allyl (garlic) or propenyl (onion). It is the primary organosulfur compound in cabbage and Brussels sprouts, and occurs in broccoli, kale, and other Brassica vegetables alongside glucosinolates. Traditional use: Cabbage (Patta gobhi in Hindi) has centuries of traditional use for gastric ulcer healing — Garnett Cheney’s 1950s work with fresh cabbage juice for peptic ulcers established cabbage as a therapeutic food. Methiin alongside glutamine (also abundant in cabbage) contributes to this mucosal protective activity. Research trajectory: Methiin has documented cholesterol-lowering activity (reducing LDL-C and total cholesterol in animal models), hepatoprotective effects (reducing liver lipid peroxidation), and antioxidant mechanisms. It is also a methyl donor participating in one-carbon metabolism. The primary research interest is methiin’s contribution to the overall bioactivity of Brassica vegetable consumption for lipid management and liver health. Commercial source: Broccoli extract and Cabbage Liquid Extract from Herbuno provide methiin as a co-constituent of Brassica organosulfur profile. See sourcing options below.
Evidence for Methiin Applications
Cholesterol lowering: Multiple animal studies demonstrate that methiin (SMCSO) at dietary concentrations reduces total serum cholesterol, LDL-C, and triglycerides in hypercholesterolaemic models. The mechanism involves inhibition of hepatic cholesterol synthesis and promotion of hepatic LDL receptor expression. Effect sizes in animal models are comparable to some pharmaceutical hypolipidaemic agents. Human clinical data are limited. Claim strength: Moderate (animal data; limited human).
Hepatoprotective and antioxidant: Methiin reduces hepatic lipid peroxidation, increases hepatic glutathione (GSH), and protects against CCl4-induced liver injury in animal models. These mechanisms parallel the hepatoprotective activity of other organosulfur compounds (SAC, allicin) and are consistent with Brassica vegetable consumption’s association with liver health. Claim strength: Moderate.
One-carbon metabolism: Methiin serves as a methyl donor in methylation reactions — a role parallel to betaine and choline. As a component of Brassica vegetable metabolism, methiin contributes to dietary methyl group availability, relevant for DNA methylation, homocysteine metabolism, and epigenetic regulation. Claim strength: Moderate (metabolic role established; supplement-specific implications limited).
Antimicrobial (minor): S-methylmethane thiosulfinate (methylsulfinyl methanesulfinate) — the hydrolysis product of methiin via Brassica myrosinase-equivalent enzymes — has mild antimicrobial activity. Contributes to Brassica’s overall antimicrobial profile alongside glucosinolate-derived isothiocyanates. Claim strength: Emerging.
Cabbage Liquid Extract (Water Soluble) - Brassica oleracea →
Browse Standardised Extract Powders →
Dosage & Formulator Specification
No established human supplement dose for isolated methiin. Dietary intake from Brassica vegetable consumption: fresh cabbage provides approximately 200–600 mg methiin per 100 g fresh weight — making it one of the most abundant single organosulfur compounds in the Western diet. Cholesterol-lowering animal studies extrapolate to approximately 500–1,500 mg/day methiin equivalent in humans. For supplement formulations, Brassica extract standardised to total organosulfur content (specifying methiin alongside glucosinolates) provides the most comprehensive quality characterisation. Request HPLC analysis for methiin alongside glucoraphanin and glucobrassicin on CoA for Brassica extracts.
Frequently Asked Questions — Methiin
What is the difference between methiin and glucosinolates in Brassica vegetables?
Methiin (a cysteine sulfoxide) and glucosinolates (glucosinolate class) are completely different organosulfur compound classes that co-occur in Brassica vegetables. Glucosinolates are S-glucosides with a thioglucose unit generating isothiocyanates via myrosinase. Methiin is a free amino acid derivative (cysteine sulfoxide) generating methylsulfinyl compounds via different enzyme pathways. They have complementary but non-overlapping pharmacological profiles and can be measured separately by HPLC for comprehensive Brassica extract characterisation.
Is methiin related to N-acetyl cysteine (NAC)?
Related in that both are cysteine derivatives that can donate sulfhydryl groups to biological systems, but they are structurally different. N-acetyl cysteine (NAC) is acetylated cysteine, a glutathione precursor widely used as a mucolytic and hepatoprotective supplement. Methiin is S-methylated cysteine sulfoxide, more analogous to alliin structurally. NAC has a well-established human clinical evidence base for hepatoprotection (acetaminophen overdose), mucolysis (COPD), and antioxidant applications. Methiin has a primarily animal-model evidence base for cholesterol lowering and hepatoprotection.
Does cooking Brassica vegetables destroy methiin?
Methiin, as a water-soluble compound, is leached into cooking water during boiling (up to 60% loss in boiling water). Steaming retains approximately 80–90% of methiin. Methiin is more heat-stable than glucosinolates and does not require an enzyme for its primary activity (unlike glucosinolates needing myrosinase). For supplement applications, cold extraction or mild temperature extraction of Brassica plant material preserves methiin content better than hot water extraction.
Can methiin be combined with glucoraphanin/sulforaphane for a comprehensive Brassica supplement?
Yes — methiin and sulforaphane address different but complementary aspects of Brassica health effects: sulforaphane targets Nrf2 activation and Phase-II detoxification; methiin targets lipid metabolism and hepatoprotection via one-carbon metabolism and direct antioxidant mechanisms. A comprehensive Brassica supplement characterised for both glucoraphanin (sulforaphane precursor) and methiin (SMCSO) content addresses the full organosulfur bioactivity spectrum of cruciferous vegetable consumption.
Related compounds: Isoalliin, Alliin, Glucoraphanin, Sulforaphane
Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.
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