Antiviral activity of Boerhaavia diffusa root extract and the physical properties of the virus inhibitor

Abstract

The aqueous extract of air-dried roots of Boerhaavia diffusa shows broad-spectrum antiviral activity and no phytoxic effects. Infection by four viruses was completely prevented, at treated and nontreated sites, when the extract was applied on two basal leaves of host plants 24 h prior to virus inoculation. This inhibition was completely reversed by the application of actinomycin D on treated leaves within 6 h of extract treatment and partially reversed within 18 h. The crude extract from resistant leaves contained an inhibitor of virus infection.The inhibitor in the root extract was partially active up to a dilution of 1:500, was completely inactivated at 95 °C for 10 min, and survived at room temperature for 20 days. The expression of inhibitory activity was prevented when the treated plants were exposed to temperatures beyond 35 °C. The inhibitory principle in the extract was nondialyzable and insoluble in organic solvents, viz., petroleum ether, solvent ether, chloroform, and benzene. It was adsorbed by animal charcoal, wood charcoal, and celite, and was precipitated by ammonium sulphate (90%), ethanol (50%), and cold trichloroacetic acid (10%). The inhibitor was not sedimented at 120 000 × g for 120 min. Further characterization is being done for positive identification of the inhibitor.

Molecular Characterization of Antiviral Proteins, Isolated from Host Plants, Pretreated with Antiviral Glycoprotein, Isolated from Roots of Boerhaavia Diffusa Plants

“…The glycoprotein stimulated natural viral defense mechanism existing in susceptible plants and provided systemic protection of a very high degree [18]. The systemic resistance inducers (SRIs) present in roots of B.diffusa induced strong systemic resistance in several susceptible hosts against viruses, reacting hypersensitively or systemically, when applied/sprayed 24 hours before virus inoculation or when regularly (weekly) sprayed, by ordinary sprayers, soon after emergence of seedlings [28].By using certain modifiers/spreaders and micro-propagating the plants of B. diffusa on suitable modified MS medium, the antiviral activity has been markedly improved and prolonged [29].…”

“…These proteins show antiviral activity when mixed with virus inoculum and are found to be localized extracellularly in plants [16,17]. On the other hand, some virus inhibitors of plant origin have been reported to induce systemic resistance in non-treated parts of plants also and thereby preventing infection of viruses [6,7,9,[18][19][20][21][22]. One such glycoprotein isolated from B. diffusa roots has prevented virus infection and multiplication in plants [18,19,21].…”

“…On the other hand, some virus inhibitors of plant origin have been reported to induce systemic resistance in non-treated parts of plants also and thereby preventing infection of viruses [6,7,9,[18][19][20][21][22]. One such glycoprotein isolated from B. diffusa roots has prevented virus infection and multiplication in plants [18,19,21]. It has shown very high antiviral activity when mixed with viruses in vitro and provoked the plant system to produce new protein(s) in the treated plants which is the actual virus inhibitory agent (VIA) [19].…”

Prevention and control of viral diseases in watermelon through botanical biopesticides

“…The pulp was stained through two folds of cheese cloth and the homogenate was clarified by centrifugation at 8,000g for 15 minutes. The supernatants obtained following the procedure as described earlier [20,21,23,24], were used for experimental work [16,17].…”

“…Use of such agrochemicals can be avoided by some preventive measures/immunization through antiviral substance of plant origin, botanical biopesticides [15][16][17][18][19]. These substances are nonchemical, nonhazardous, easily biodegradable, did not leave any residual effect on soil, water and environment and are eco-friendly, besides their very low cast [20][21][22][23][24].…”