A high antibacterial efficacy of fruits of litsea cubeba (Lour.) Pers from Nepal. GC-MS and antioxidative capacity analyses

Abstract

Background: Biological activities of the plant materials may vary with different geographic origin. Litsea cubeba fruits are consumed in Nepal as a spice ingredient and are considered to be possessed antibacterial property. Objectives: Aims of this work are: To compare phytoconstituents present in litsea oil by GC-MS analysis, and to evaluate antibacterial and antioxidant activities of the volatile oil and the fruit extracts. Materials and Methods: Hydrodistillation of L. cubeba fruits was performed to obtain litsea oil followed by extractions with boiling methanol. Fractionations of the extract provided hexane, dichloromethane, ethyl acetate and aqueous extracts. The oil and extracts were analysed for the phytochemicals present. They were evaluated by using antibacterial susceptibility, brine-shrimp lethality and antioxidant capacity assays. Results: All together 49 compounds (accounting 93.66%) were identified in the litsea oil by GC-MS. Monoterpenes being dominant components, the oil constituted 15.96% of citral (geranial and neral). Other major constituents were capric acid (12.44%), β-caryophyllene oxide (7.69%), linalool (5.96%), eucalyptol (5.13%) and cis- erpineol (4.22%). Litsea oil, hexane extract and dichloromethane extract displayed very effective antibacterial property. Ethyl acetate extract (LC50 = 21.52 μg mL-1) and litsea oil (LC50 = 31.62 μg mL-1) were found highly cytotoxic against brine-shrimp nauplii. Ethyl acetate (IC50 = 124.57 μg mL-1) and dichloromethane (IC50 = 271.08 μg mL-1) extracts displayed a modest DPPH free radical scavenging activity. Conclusion: Phytoconstituents present in the L. cubeba fruits from Nepal were analysed. Litsea oil and the extracts have displayed high antibacterial and potentially anticarcinogenic activities.