Comparative Phytochemical Profiles and Antioxidant Potential of Green and Variegated Morphotypes of Alternanthera bettzickiana Under Optimized Extraction Conditions

Abstract

ABSTRACT Alternanthera bettzickiana exhibits considerable morphological diversity, which has contributed to significant inconsistencies in reported phytochemical profiles and bioactivities, as the majority of published studies have not specified the morphotype of the plant material examined. Unlike the green morphotype, which is widely utilized in culinary applications, the variegated (mixed red and green) morphotype has received considerably less attention as an edible vegetable. Furthermore, no validated extraction protocol has been established for this species, despite being a critical determinant of bioactive compound recovery. The present study therefore aimed to optimize extraction conditions and compare the phenolic profiles and antioxidant capacities of both morphotypes. Utilizing Box–Behnken design (BBD)‐based response surface methodology (RSM), the optimized extraction conditions comprised 90% (v/v) aqueous ethanol, a shaking temperature of 50°C, an incubating time of 2 h, and an extract concentration of 10 mg/mL. Under these conditions, the green morphotype exhibited higher total phenolic content (4.95 mg gallic acid equivalent/g dry sample weight (DW)), whereas the variegated morphotype exhibited higher total flavonoid content (31.95 mg quercetin equivalent/g DW) and total anthocyanin content (7.04 mg cyanidin‐3‐O‐glucoside equivalent/g DW). Liquid chromatography‐electrospray ionization‐tandem mass spectrometry identified p‐coumaric acid as the predominant phenolic compound, followed by 3,4‐dihydroxybenzoic acid, in both morphotypes, while rutin was exclusively detected in trace amounts in the green morphotype. The green morphotype also demonstrated significantly higher ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) activities, whereas 2,2‐diphenyl−1‐picrylhydrazyl (DPPH) radical scavenging activities were not significantly different between morphotypes. These findings establish a scientific basis for the future valorization of both morphotypes as functional food ingredients and nutraceutical sources.