Antimicrobial activity of in vitro melastoma decemfidum plant extract and isolation of partial chalcone synthase gene / Nurul Huda Che Isa

Melastoma decemfidum {M. decemfidum) is a medicinal plant that belongs to the family Melastomataceae. It can grow wild, but difficult to find as compared to other species of Melastomataceae. This plant was reported to produce bioactive flavonoids, having antimicrobial activities. The flavonoid biosynthesis pathway involves a key enzyme called chalcone synthase (CHS). The present study was aimed to determine the antimicrobial activities of different concentrations of extracts and to isolate and amplify the CHS gene from in vitro M. decemfidum plant. The antimicrobial activities were determined using agar disc diffusion method against tested microorganisms which include Gram positive bacteria {Staphylococcus aureus), Gram negative bacteria {Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium) and fungi {Candida albicans and Aspergillus brasiliensis). Genomic DNA was extracted and a partial CHS gene was amplified using designed primers. Finding showed that S. aureus was the most sensitive towards leaves and whole plant extracts, while A. brasiliensis were resistant to both extracts (leaves and whole plant extract). The range of MIC values for the leaves and whole plant extracts were 50 to 200 mg/ml. While the MBC and MFC range from 100 to 200 mg/ml. The amplified PCR products with the approximate size of 136 and 140 nucleotide base pairs were obtained from leaves and whole plant extract. This is the first report to describe the isolation of CHS gene from in vitro M. decemfidum.