Regardless of the well-known antioxidant and antimicrobial properties of essential oils, requirement of their large doses is the major bottleneck in using them as food preservatives. In the present study, possible synergistic interactions on antioxidant and antibacterial capacity of essential oils from six selected medicinal plants namely Callistemon lanceolatus (Sm.) Sweet, Ocimum gratissimum L., Cymbopogon winterianus Jowitt ex Bor. (Citronella java), Cymbopogon flexuosus (Nees ex Steud.) W. Watson, Mentha longifolia (L.) L., and Vitex negundo L., in combination as well as with synthetic antioxidant and antibiotics were evaluated. Antibacterial synergistic effect was determined against three Gram positive (Staphylococcus aureus, Micrococcus luteus and Bacillus subtilis) and two Gram negative (Escherichia coli and Klebsiella pneumoniae) bacteria using broth dilution method. Antioxidant combination effect was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method. The types of interactions in different binary combinations were determined by calculating the fractional inhibitory concentration indexes (FICI). Synergistic interactions were observed between essential oil combinations showing enhanced antioxidant and antibacterial activity. Further it was observed that essential oils not only enhanced the antioxidant and antibacterial efficacy of synthetic compounds but also resulted in significant reduction of their active doses due to synergy.

不管香精油众所周知的抗氧化和抗菌特性，将其用作食品防腐剂的主要瓶颈都在于要求大剂量的食用。在本研究中，可能对来自六种精选药用植物的香精油的抗氧化和抗菌能力进行可能的协同相互作用，这些植物为：Callistemon lanceolatus（Sm。）Sweet，Ocimum gratissimum L.，Cymbopogon winterianus Jowitt ex Bor。（香茅JAVA），曲序香茅（内斯前结缕草。）W.沃森，欧薄荷（L.）属和黄荆L.，以及与合成抗氧化剂和抗生素的组合进行了评估。确定了对三种革兰氏阳性（金黄色葡萄球菌，黄微小球菌和枯草芽孢杆菌）和两种革兰氏阴性（大肠杆菌和肺炎克雷伯菌）的抗菌协同作用。）细菌用肉汤稀释法。通过1，1-二苯基-2-甲基苯并肼（DPPH）清除自由基的方法评估抗氧化剂的组合作用。通过计算分数抑制浓度指数（FICI），可以确定不同二元组合中的相互作用类型。在精油组合之间观察到协同相互作用，显示出增强的抗氧化剂和抗菌活性。进一步观察到，精油不仅增强了合成化合物的抗氧化和抗菌功效，而且由于协同作用还导致其有效剂量大大降低。