Synergistic Antibacterial Effects of Combined Phytochemicals of Endophytic Fungi Extracts and Its Pure Compounds Isolated from Sungkai (Peronema canescens) Leaves

Abstract

In previous research, we reported the isolation of endophytic fungi from sungkai leaves (Peronema canescens) and the isolation of pure compounds accompanied by antioxidant and antibacterial activities. The development of drugs from natural ingredients is often effective at high concentrations. This can lead to adverse side effects caused by higher concentrations of a single ingredient. This limitation can be overcome by using a combination of pure extracts/compounds which allows for synergistic interactions with strong bioactivity at fairly low concentrations. It was discovered that mixtures of bioactive substances were more likely to prevent illness than single active molecules. The purpose of this study is to examine the interaction between endophytic fungus isolated from leaves (P. canescens) and purified chemicals that have significant antibacterial activity. Providing endophytic fungal extracts was carried out by re-isolating eight endophytic fungi from sungkai leaves, morphological characterization, cultivation and extraction. Isolation of endophytic fungi was carried out using the surface sterilization method, characterization using microscopic and macroscopic techniques, and extraction using the maceration method. Isolation of compounds using the column chromatography method and analysis using NMR spectroscopy. However, this study used five pure compounds from endophytic fungal extracts taken from stock compounds. Each endophytic fungi extract (PD1-PD8) and pure compound (C1-C5) were tested for antibacterial activity with the disc diffusion method using four test bacteria, namely, E. coli, S. typhi, B. subtilis, and S. aureus. Next, a combination of two and three component blends was carried out in a 1:1 ratio and the antibacterial activity was determined. The best combination of extracts is PD4+PD5+PD8 which comes from an additive effect and the best combination of pure compounds is C1+C2 which comes from an additive and synergistic effect. The additive and synergistic effects that occur in the combination of PD1+PD2 extract and the pure compound C3+C4 combination can apparently be used as an alternative formula compared to the single extract or the single pure compound. Thus, this combination formula is expected to help avoid undesirable side effects due to higher doses of single ingredients which need to be proven by in vivo tests.