Uses and Pharmacology: Anti-inflammatory Rosmarinic acid was found to inhibit the C3 and C5 convertase steps in the complement cascade. This action may play a role in the anti-inflammatory action of Melissa extract, because the action was observed in vitro and in vivo in rats with oral administration of the compound. Antimicrobial
Animal data: Lemon balm has antiviral activity against a variety of viruses, including herpes simplex virus (HSV) and HIV-1. The activity has been attributed to caffeic acid and its di- and trimeric derivatives, as well as to tannins. A concentration-dependent inhibition of HSV-2 proliferation by lemon balm essential oil has been demonstrated, possibly due to the citral or citronellal components. Activity against bacteria and fungi has been evaluated with varying results. Activity against culex mosquito larvae has also been demonstrated.
Clinical data: Placebo-controlled trials have shown symptomatic improvement for herpes virus lesions after application of a standardized lemon balm cream applied 2 to 4 times daily for 5 to 10 days.
Antioxidant: In vitro antioxidant activity has been described for lemon balm essential oil and its extracts. Cancer Activity against human and mouse cancer cell lines has been demonstrated in vitro.
Cholesterol: In hyperlipidemic rats and mice, lemon balm extracts improved the lipid profile as well as liver enzyme markers (AST, ALT, alkaline phosphatase) and increased glutathione levels in the tissue. A double-blind, randomized, placebo controlled trial (n=58) in borderline hyperlipidemic adults documented a significant improvement in low-density lipoprotein (LDL) cholesterol levels (P=0.022) as well as AST (P=0.009) with administration of M. officinalis leaf powder (500 mg 3 times daily for 2 months) compared to placebo. Baseline mean LDL dropped by 13.96 mg/dL with the intervention compared to a 1.17 mg/dL increase with placebo. Similarly, mean AST decreased 1.35 units/L with treatment and increased 2.23 units/L with placebo. No significant differences were found between groups in total cholesterol (TC), high-density lipoprotein (HDL), LDL:HDL, TC:HDL, fasting blood sugar, triglycerides, ALT, creatinine, body mass index, or physical activity. No serious adverse events were reported. CNS effects
Animal data: The lyophilized hydroalcoholic extract, which does not contain the volatile oil components, exhibited sedative activity in several mouse models when given intraperitoneally. This extract was also active in an acetic acid writhing analgesia assay but not in a hot plate test. The volatile oil of the plant had much weaker activity or was inactive in the same assays.
Clinical data: In a series of trials investigating the effects of lemon balm extract on laboratory-induced stress, a dose-dependent effect was demonstrated for single doses of Melissa officinalis. Cholinergic receptor-binding properties have also been demonstrated. With 600 mg of extract, increased calmness and decreased alertness were demonstrated compared with placebo. With 300 mg, no modulation of stress was found, but speed and accuracy of mathematical processing increased. At the highest dosage of 1,600 mg, a paradoxically negative effect on mood resulted, with reduced alertness. Lemon balm 80 mg combined with valerian 160 mg taken for 1 month significantly improved sleep quality compared with baseline (P = 0.001) and placebo (P = 0.0001) in women experiencing sleep disruption/disorders subsequent to natural menopause. The placebo group in this randomized trial (n = 100) also experienced a significant improvement in sleep scores compared with baseline (P = 0.0001). No adverse events were reported. In patients with mild to moderate Alzheimer disease, 60 drops of lemon balm extract (citral 500 mcg/mL) increased cognitive function and decreased agitation over placebo. Essential oil of lemon balm applied to the faces of patients with dementia decreased agitation compared with placebo.
Gastrointestinal: The contractility of rat ileum was reduced with essential oil of lemon balm and its citral extract. Babies with colic given a combination preparation containing lemon balm extract as well as 2 other extracts showed improved symptoms.