Anti-herpes virus activities of bioactive fraction and isolated pure constituent of Mallotus peltatus: an ethnomedicine from Andaman Islands

Abstract

BackgroundViral infections, particularly the infections caused by herpes simplex virus (HSV), represent one of the most serious public health concerns globally because of their devastating impact. The aim of this study was to evaluate the antiviral potential of methanolic crude extract of an ethnomedicine Mallotus peltatus, its active fraction and pure compound, against HSV-1 F and HSV-2 G.ResultThe cytotoxicity (CC50, the concentration of 50% cellular toxicity), antiviral effective concentration (EC50, the concentration required to achieve 50% protection against virus-induced cytopathic effect), plaque reduction and the selectivity index (SI, the ratio of CC50 and EC50) was determined. Results showed that the crude methanolic extract of M. peltatus possessed weak anti-HSV activity. In contrast, the active fraction A and isolated ursolic acid from fraction A exhibited potent antiherpesvirus activity against both HSV-1 (EC50 = 7.8 and 5.5 μg/ml; SI = 22.3 and 20) and HSV-2 (EC50 = 8.2 and 5.8 μg/ml, and SI = 21.2 and 18.97). The fraction A and isolated ursolic acid (10 μg/ml) inhibited plaque formation of HSV-1 and HSV-2 at more than 80% levels, with a dose dependent antiviral activity, compared to acyclovir. The time response study revealed that the anti-HSV activity of fraction A and isolated ursolic acid is highest at 2–5 h post-infection. Moreover, the time kinetics study by indirect immunofluorescence assay showed a characteristic pattern of small foci of single fluorescent cells in fraction A- treated virus infected cells at 2 h and 4 h post-infection, suggesting drug inhibited viral dissemination. Further, the PCR study with infected cell cultures treated with fraction A and isolated ursolic acid at various time intervals, failed to show amplification at 48–72 h, like acyclovir treated HSV-infected cells. Moreover, fraction A or isolated ursolic acid showed no interaction in combination with acyclovir.ConclusionThis study revealed that bioactive fraction A and isolated ursolic acid of M. peltatus has good anti-HSV activity, probably by inhibiting the early stage of multiplication (post-infection of 0–5 h), with SI value of 20, suggesting its potential use as anti-HSV agents.

Determination of antioxidant activity, phenolic contents and antiviral potential of methanol extract of <i>Euphorbia spinidens</i> Bornm (Euphorbiaceae)

“…This may indicate that the extract probably interferes with post-absorption and early stages of HSV-1 replication. Similarly, it has been reported that the crude methanol extract of Mallotus peltatus leaves and Cuminum cyminum L seeds inhibited HSV-1 replication in the early stage and adsorption, respectively [21,22]. These results, together, might indicate that some herbal extracts are able to interact with this virus in the intracellular stages of replication.…”

“…This experiment, in which HSV-1 infected cells were treated with different doses of the extract at 1 h before and 24 h after the infection, was carried out according to previously described procedures with minor modifications [21]. In brief, approximately, 5 × 10 5 Vero cells/well were seeded onto 96-well plates with final volume of 100 µL per well and cultured for 24 h at 37 °C.…”

“…(1) where At and As refer to the absorbance of the test and control, respectively [21]. The 50 % cytotoxic concentration (CC 50 ) was defined as the cytotoxic concentration of the crude extract by regression analysis.…”

“…Virus stock was prepared by infection of confluent monolayer Vero cells in 75 cm 2 culture flasks using DMEM medium with 2 % FBS, at 37 °C in 5 % CO 2 . Virus titer was determined by cytopathic effect (CPE) of HSV-1 in Vero cells and was expressed as the 50 % Tissue Culture Infective Dose (TCID 50 ) per ml using the formula of Spearman-Karber [21].…”

Anti-HSV type-1 activity of olive leaves extract crude form acting as a microemulsion dosage form

“…The cell monolayer sheet was stained with 0.1% crystal violet staining solution for at least 15 min, then removed by aspiration and rinsing with distilled water, then the absorbance was measured with microplate reader (Bio-Rad 550) at wavelength of 490 nm. The viral inhibition rate was calculated according to the study of Bag et al (2012) and Dargan (1998) as follows:…”