Chemical profile, antiproliferative and antibacterial activities and docking studies of essential oil and hexane fraction of hydrosol from fresh leaf of Plectranthus amboinicus (Lour.) Spreng.

Abstract

Essential oils are commonly extracted from plants by hydrodistillation in which an aqueous phase called hydrosol is obtained. Like essential oil, this by-product of distillation can be a source of natural bioactive molecules with health benefits. This study aimed at the investigation of the chemical profile, antiproliferative and antibacterial activities of essential oil and hexane fraction of hydrosol from Plectrunthus amboinicus (family Lamiacease) fresh leaf cultivated in Sudan. Essential oil was obtained by hydrodistilation and hexane fraction (HF) was derived from hydrosol by liquid -liquid extraction. Results showed that the phenolic monoterpene thymol (72.9%) was the dominant component of the essential oil while the HF was characterized by the presence of long-chain (n-C29 to n-C68) alkanes (91.4%). The HF showed highest antiproliferative activity against the colon cancer HT29 (IC50 9.2 mu g/mL) and HCT116 (IC50 7.7 mu g/mL) cell lines. The essential oil exerted best antibacterial activity with highest inhibition (22.0-22.3 mm) and minimum inhibitory concentration (31 mu g/mL) against the Gram positive bacteria Bacillus subtilis and Staphylococcus aureus. In silico study showed that the major components of the oil displayed higher docking scores than those present in the HF suggesting an antagonistic effect by other molecules in the essential oil. In conclusion, beside the essential oil, the hydrosol possesses promising bioactive composition suggesting that it could be exploited for further therapeutic applications.