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SECTION I: MOLECULAR GENETIC ENGINEERING AND BIOCHEMICAL TECHNOLOGY 77isolation and structural elucidation of two main flavonoids from the Caatinga green propolis. The isolated compounds have been further subjected to antioxidative, antimicrobial and mosquito larvicidal activities. 2. MATERIALS AND METHODS 2.1. Plant materialsGreen propolis was collected from Remanso-Brazil on June, 2021. Botanical identification was confirmed by the taxonomist Milton Groppo, Department of Biology, University of Sao Paulo. A voucher specimen (SPFR: 15118) has been deposited in the Department of Biology, University of Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil. 2.2. Chromatographic separationUsing a Soxhlet apparatus, 150 g of green propolis powder was submerged in 4 x 2L x 4 hours of 90% EtOH. The crude extract (38.52 g) was obtained by evaporating the mixed extract at 45 oC under decreased pressure. Following silica gel column chromatography (40-63 %u00b5m), this extract was eluted using hexane-acetone (1:0 to 0:1, v/v) to yield 13 fractions, GP1-GP13. Three sub-fractions, GP61-GP63, were obtained by fractionating the fraction GP6 (2.17 g) using a Sephadex LH-20 column and eluting it with 100% MeOH. Using preparative HPLC-UV at%u03bbmax 280 and 338 nm, the sub-fraction GP61 (1.1 g) was further purified and eluted with acetonitrile-water (8:1, v/v, 0.1% formic acid) to provide compound 2 (130 mg). The fraction GP8 (5.15 g) was then separated into four sub-fractions GP81-GP84, by using normal silica gel column chromatography [CHCl3-EtOAc (30:1-1:1, v/v)]. Compound 1 (77.4 mg) was purified from the sub-fraction GP81 (2.11 g), using the same condition.