Efficient Utilization of Plant Resources by Alkaline Extraction

As compared to the studies with hot water extracts of plants, those with alkaline extracts were limited. Both alkaline and hot water extracts from green tea leaf, oolong tea leaf and orange flower were compared for their biological activities. Plant materials were successively extracted first with hot-water and then alkaline solution, or extracted directly with alkaline solution. Viable cell number of HIV-infected and UV-irradiated cells was determined by MTT method. Antibacterial activity against Porphyromonas gingivalis 381 was determined by turbidity assay. Cytochrome P-450 (CYP)3A4 activity was measured by β-hydroxylation of testosterone using human recombinant CYP3A4 (Figure 5). Radical intensity of superoxide and hydroxyl radical was determined by ESR spectroscopy. Alkaline extraction recovered twice as much as dried materials as compared with water extraction. Water extracts showed higher anti-bacterial, CYP3A4 inhibitory and superoxide scavenging activities, whereas alkaline extract showed higher anti-HIV and hydroxyl radical scavenging activity. Both water and alkaline extracts showed comparable anti-UV activity. The present study suggests the usefulness of alkaline extraction for the efficient utilization of the natural resources.