Natural bioactive compounds have shown various antibacterial, antifungal, and anti-inflammatory properties. They are gaining considerably attention as eco-friendly alternative to synthetic antibacterial active compound or agents. With this boom, it urge us to determine the synergistic antioxidant and antimicrobial activity of defatted seeds of medicinal plant such as Azadirachta indica, Ocimum sanctum and Momordica charantia to reveal their therapeutic activities against microbial and neurological disorders. This book provides the pattern of isolation of polyphenolic flavonoids from defatted seed by using various solvents and chromatography techniques. It also describe the method to determine antimicrobial activity by agar well diffusion and broth dilution method against two gram negative and gram positive bacteria. In vitro antioxidant activity was determined by enzymatic activity and nonenzyme content in neuronal cells (Rat PC-12 Cells) treated with synergistic extract against neurotoxic shock. This also signifies levels of antioxidant activity present in synergistic extract, which can be utilized as a good source of herbal drug for various diseases.