Enhanced antioxidant and anti-Mycoplasma hyopneumoniae activities of combined Piper sarmentosum and guava leaf extracts

Abstract

Increasing antibiotic resistance in Mycoplasma hyopneumoniae (Mhp) necessitates alternative treatments. Piper sarmentosum extracts (PSE) and guava extracts (GE) show promise due to their antimicrobial and antioxidant properties. This study evaluates the combined in vitro effects of PSE and GE against Mhp and their antioxidant activities. Anti-Mhp activity was assessed using microdilution minimum inhibitory concentration (MIC) and synergy via fractional inhibitory concentration index (FICI), while antioxidant capacity was measured with 2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays for individual extracts, and a 1:1 mixture (based on the results of FICI). Phytochemical profiling used high performance liquid chromatography (HPLC) to quantify main six bioactive compounds. HPLC showed PSE contained vitexin-2-O-rhamnoside (8.58 mg/g) and pellitorine (3.31 mg/g); GE had quercetin-3-O-glucuronide (6.85 mg/g), quercetin (3.72 mg/g), isoquercitrin (0.51 mg/g), and avicularin (1.37 mg/g). PSE (MIC 0.78 mg/mL) and GE (MIC 0.39 mg/mL) exhibited anti-Mhp effects, with their 1:1 combination being additive (FICI=0.75) and reducing MIC to 0.195 mg/mL. This mix also enhanced antioxidant activity by 9.0% in ABTS and 27.0% in FRAP assays. The 1:1 combination of PSE and GE demonstrated superior anti-Mhp activity (additive effect) and enhanced antioxidant properties (synergistic effect) compared to the individual extracts. These findings highlight the potential of these extracts as phytopharmaceutical agents.