Biological Activities And Identification Of Chemical Constituents From The Leaves Of Melaleuca Bracteata And Callistemon Viminalis

The chemical constituents from the leaves of Melaleuca bracteata and Callistemon viminalis as well as their biological activities were investigated.The silica gel column chromatography,C₁₈ reversed-phase silica gel column chromatography,and Sephadex LH-20 gel column chromatography were used as iso lating and purifying methods.The spectral analysis methods including NMR,HRESI,CD,and IR were used directly to indentify the acquired 21 natural compounds,including three newly-discovered compounds.The biomimetic total synthesis towards the novel compounds Melaleucins A-C?1-3?were conducted to confirm their biosynthetic pathway and to establish a concise methodology to access their analogous efficiently.All of the isolated compounds were tested the antimicrobial and insecticidal activities,and a few of them have been revealed as promising lead compounds of pesticide and antibacterial agent.It can rationally infer that aboundant of active chemical constituents from leaves of Melaleuca bracteata and Callistemon viminalis were antimicrobial and insec t resistant.Phytochemical study on the leaves of Melaleuca bracteataresulted in the isolation of ten compounds including three new neolignans,named Melaleucins A-C?1-3?.Among them,the Melaleucin B shares a rarely occurring nor-neolignan skeleton,and both Melaleucins B and C bear a novel aldehyde moiety,which might be response for the delicate fragrance of M.bracteata.Their structures were extensively characterized by spectral data interpretation and biomimetic total synthesis.Moreover,their biosynthetic pathway with oxidative radical coupling and Michael addition as critical reaction was also confirmed.The antimicrobial activity evaluation revealed that new compound Melaleucin A exhibited considerable antimicrobial activity towards methicillin-resistant staphylococcus aureus.Also seven known compounds methyl eugenol?4?,3,4,5-trimethoxy-benzoic acid methyl ester?5?,3'-methoxymiliumollin?6?,vomifoliol?7?,betulinic acid?8?,?-sitostenone?9?and?-sitosterol?10?are acquired.Compound 4 and one fraction is tested for insect resistance.We investigate the chemical constituents and their biological activities from the leaves of Callistemon viminalis,which were isolated and purified by silica gel column chromatography,Sephadex LH-20 column chromatography,as well as C₁₈ reversed phase column chromatography.Their structures were elucidated by organic spectroscopic methods.Their insecticidal activity was evaluated by stomach toxicity method.Eleven compounds were isolated and purified from ethyl acetate fraction of volume fraction 95%ethanolic extract from the leaves of Callistemon viminalis.Their structures were identified as 3,3',4'-tri-O-methylellagic acid?15?,quercetin?16?,sideroxylin?17?,kaempferol?18?,5-hydroxy-7,4?-dimethoxy-6-methylflavone?19?,farrerol?20?,methyl gallate?21?,protocatechuic acid?22?,gallic acid?23?,2,6-dihydroxy-4-methoxyisovalerophenone?24?,succinic acid?25?.Compounds 15-23,25 were isolated from Callistemon viminalis for the first time.Compound 24 was showed potent insecticidal activity to Spodoptera exigua.