Thyme (Thymus vulgaris) and cinnamon (Cinnamomum cassia ) extracts were investigated for their phenolic
compounds , antioxidant and antimicrobial activity. Moreover, the gross chemical composition for both herbs was determined.
Polyphenols were found to be 21.22 and 16.13 mg gallic acid/g for thyme and cinnamon ,respectively. Data
of HPLC revealed thirteen peaks of phenolic compounds in thyme extract, while cinnamon extract exhibited ten peaks
only. Gallic, p-coumaric , vanillic, caffeic, ferulic acids were detected in both extracts, in addition to rosmarinic acid
and thymol in thyme, also catechin was found in cinnamon. Both thyme and cinnamon extracts have high antioxidant
activity, being 83.70 % and 73.60%, respectively as measured by DMPD, Radical Scavenging Activity. Boiling of
extracts for 20 min resulted in a significant decline of phenolic compounds content and antioxidant activities of thyme
and cinnamon extracts .Moreover, sunflower oil contained 400 ppm of thyme extract exhibited the least peroxide
value (PV) when stored at 60ºC for 7 days. Sunflower oil contained 400 ppm of cinnamon extract or BHT had lower
PV than that of the control. Thyme and cinnamon extracts explored considerable antimicrobial inhibition of each of
Bacillus subtilis, Escherichia coli , Saccharomyces cerevisiae and Aspergillus niger . In this respect, cinnamon extract
was more effective than thyme extract.