Cytotoxicity and Antiviral Activities of Haplophyllum tuberculatum Essential Oils, Pure Compounds, and Their Combinations against Coxsackievirus B3 and B4 #

Haplophyllum tuberculatum is a plant commonly used in folk medicine to treat several diseases including vomiting, nausea, infections, rheumatism, and gastric pains. In the current study, H. tuberculatum essential oils, hydrosols, the pure compounds R -(+)-limonene, S -(-)-limonene, and 1-octanol, as well as their combinations R -(+)-limonene/1-octanol and S -(-)-limonene/1-octanol, were screened for their cytotoxicity on HEp-2 cells after 24, 48, and 72h, and then tested for their activity against Coxsackievirus B3 and B4 (CV-B3 and CV-B4) at 3 different moments: addition of the plant compounds before, after, or together with virus inoculation. Results showed that the samples were more cytotoxic after 72h than after 24h or 48h cell contact. However, the combinations R -(+)-limonene/1-octanol and S -(-)-limonene/1-octanol showed less effect on HEp-2 cells than pure R -(+)-limonene and S -(-)-limonene after 24h, 48h, and 72h. 1-octanol exhibited the highest concentration causing 50% cytotoxicity (CC (50) ) on HEp-2 cells after 24h (CC (50) =93 mu g/mL) and 48h (CC (50) =83 mu g/mL). The antiviral assays showed that the tested samples exhibited potent inhibition of CV-B. IC (50) values ranged from 0.66 mu g/mL to 28.4 mu g/mL. In addition, CV-B3 was more sensitive than CV-B4. Both CV-B strains are more inhibited when cells were pretreated with the plant compounds. The hydrosols have no effect, neither on HEp-2 cells nor on the virus. 1-octanol, S -(-), and R -(+)-limonene/1-octanol had important selectivity indexes over time. Although essential oils had potent antiviral activity, they can be considered for application in the pretreatment of cells. However, 1-octanol and the combinations are within the safety limits, and thus, they can be used as an active natural antiviral agent for CV-B3 and CV-B4 inhibition.