Essential oil composition, antioxidant, antimicrobial and larvicidal activities of Piper betle leaf

The present study reports antioxidant, larvicidal and antimicrobial activities of betel (Piper betle) leaves essential oil (EOs). The GC-MS analysis of EOs revealed the presence of total 33 chemical constituents with safrole (50.46%) in highest amount followed by eugenol (19.28%) and a-selinene (3.58%). The remaining constituents were present in minor amounts (0.13 to 3.15%). The EOs depicted good larvicidal activity against larvae of Aedes aegypti with concentration ranging from 0.001–100 μg/ml and minimum inhibition at 0.1 μg/ml. The antimicrobial activity was assessed against both Gram-positive bacteria (Bacillus subtilis (NCIM 2920), Staphylococcus aureus (NCIM- 5345), and Gram-negative bacteria (E.coli (NCIM 5346), Enterobacter aerogenes (NCIM 5267, Pseudomonas fluorescens (NCIM 5226); and fungi (Fusarium oxysporum (NCIM 1008), Aspergillus flavus (NCIM 1316), Penicillium citrinum (NCIM 1435), Rhizopus stolonifera (NCIM 1139) and Candida albicans (NCIM 3628) by agar cup-plate method. The highest antimicrobial activity was against Bacillus subtilis with an IZD of 40mm followed by E.coli (IZD=12mm) and Enterobacter aerogenes (IZD=10mm), while Staphylococcus aureus and Pseudomonas fluorescens were resistant to the betel leaf oil. The antifungal activity was highest against Fusarium oxysporum (93.75%) followed by Penicillium citrinum (87.5%), Aspergillus flavus (81.25%) and Rhizopus stolonifera (antifungal index 75%). The total phenolic content (TPC) was found to be 93.5 mg/g as gallic acid equivalent (GAE). These results showed that betel leaf has potential for use as a food bio-preservative.