Phytochemical and Biological Study of Melissa officinalis (Family Lamiaceae) Cultivated in Egypt

Phytochemical investigation of 70% aqueous methanol extract of leaves of lemon balm (Melissa officinalisL., Lamiaceae) was subjected to different chromatographic separation techniques. The structures of isolated compounds were determined on the basis of spectral data (UV, 1H-NMR, 13CNMR and mass spectrometry).Also, evaluation of the antioxidant, anticonvulsant, anti-inflammatory and antimicrobial activity were determined using different techniques.Result:three isoflavones;4'- methoxy genistein Biochanin A] (1),6, 8 dimethoxy- biochanin A -7 - O- α - L- rhamnopyranosyl (1'''-6'') - O -  - D- glucopyranoside (2), isoflavone 6, 8dimethoxy 7-O- - D rutinoside, 4'-O- α- L-rhamnopyranoside (3).Besides sixknown flavonoids; quercetin -3- O- β -D-galactopyranoside(hyperin)(4), luteolin 7-O- rhamnoside(5), scutellarein – 4',7 dimethyl ether(6), nepetin - 7- methyl ether(7),luteolin(8),and apigenin(9),in addition to caffeic acid(10), chlorogenic acid (11) isolated for the first time from Melissa officinalis. The investigated extract showed significant anticonvulsant activity, effective in inhibition of both acute & chronic inflammation. Scutellarein – 4',7-dimethyl ether sample(6) showed remarkable inhibition against fungi, and exhibited the highest antibacterial effect against both gram +ve and gram -ve bacteria. The above evidences suggest that Melissa officinalis leaves is a potential source of natural isoflavones and can be used to prevent convulsion, inflammation, can be used as antioxidant and antimicrobial drug.