Screening of medicinal plants containing phenolic compounds as a vaccine adjuvant and preparation of crude extract solution

Abstract

The objectives of this study were to screen the medicinal crude extracts for an immunopotentiators and to prepare the mixed solution of the model antigen and the crude extract in injectable solvent system. The eleven crude plant extracts at the concentration of 1, 10, 50 and 100 µg/ml (except for the crude extract from stems of Derris reticulata, which was tested at the concentration of 1, 10, 50 and 74.25 µg/ml). The crude extracts were incubated with the peripheral blood mononuclear cells (PBMCs) for 72 hrs at normal culturing condition. The effect of all crude extracts on the PBMCs viability was determined. Three crude extracts i.e. crude extract from root barks of Artocarpus gomezianus, crude extract from heartwood of Dalbergia cultrata and crude extract from stem barks of Erythrina variegate were not toxic to the PBMCs at all concentration tested. Four crude extracts i.e. crude extract from stems of Artocarpus altilis, crude extract from heartwood of Artocarpus heterophyllus, crude extract from root barks of Broussonetia papyriferra and crude extract from root barks of Morus alba were toxic to PBMCs at the concentration of 100 µg/ml. Four crude extracts i.e. crude extract from flowers of Azadirachta indica, crude extract from stems of Derris reticulata, crude extract from stems of Derris scandens and crude extract from stems of Pithecolobium dulce were toxic to PBMCs at almost all of the concentrations tested and were excluded from the study. The effect of seven crude extracts to the proliferation of PBMCs was determined. Two crude extracts i.e. crude extract from root barks of Artocarpus gomezianus and crude extract from heartwood of Dalbergia cultrata showed the stimulatory effect on the proliferation of PBMCs at the concentration of 100 µg/ml. Two crude extracts i.e. crude extract from stem barks of Erythrina variegata (100 µg/ml) and crude extract from heartwood of Artocarpus heterophyllus (50 µg/ml) tended to decrease the proliferation PBMCs without causing a decrease in viability of PBMCs. The effect of crude extracts on the maturation of monocyte-derive dendritic cells (MoDCs) was determined. The crude extract from root barks of Artocarpus gomezianus induced the maturation of MoDCs. In the preparation of crude extract from root barks of Artocarpus gomezianus and model antigen solution, the crude extract could be dissolved in the solvent system consisting of 10 % ethanol, 8% propylene glycol, 30 % PEG 400 and 2 % tween 80 in water at the concentration of 29.72 mg/ml. In this solvent system, the model antigen aggregated to be a suspension with the particle size smaller than 50 µm. However, the aggregates could be redispersed by agitation.