Biological activities and LC-MS/MS profiling of methanolic extract of Opuntia monacantha Haw. (Cactaceae)

Abstract

Opuntia monacantha Haw. (Cactaceae) is a cochineal prickly pear with various medicinal uses. Its cladodes are consumed widely by local community in Mexico due its nutritional value and therapeutics effects. However, the cactus only known as an ornamental plant in Malaysia. To date, limited numbers of scientific studies have been conducted to explore its medicinal properties. Hence, the present study was carried out to evaluate the cytotoxicity and antioxidant of the cladodes of O. monacantha crude methanolic extract (MEOM), as well as phytoconstituents profiling. The cladodes of O. monacantha was extracted using maceration method with methanol in ratio (sample:methanol, 1:20L for 72hrs), followed by concentrated by means of rotary evaporator to obtain the crude methanol extract of the cladodes. Afterwards, the MEOM was tested for its toxicity using brine shrimp lethality test (BSLT), antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolics content (TPC) and total flavonoids content (TFC). Finally, chemical compounds were identified using UHPLC-Q-TOF/MS. According to Meyer and Clarkson toxicity criterion, the BSLT assay showed the extract possessed significant low toxicity LC50 of 1367.91 ppm. As for the antioxidant activity, the results exhibited that the extract could be categorized as having moderate antioxidant activity with IC50 value of 3.764 mg/mL DPPH activity, contain the TPC at 4.222±0.339 mg GAE/g extract, while no flavonoids were detected. According to the library of UHPLC-MS spectra, it has been identified the extract contain 22 potential active compounds from the cladodes of MEOM. The strongest peak identified as isoliquiritin, a flavonoid glycoside compound which possibly contribute to the moderate antioxidant activity. The findings are in agreement to the traditional uses of cladodes among natives in Mexico which were consumed safely and used for its various therapeutics values. Besides, the plant can be explored further as it has a potential to be developed into alternative-natural products in treating various discomforts and ailments with no side effects.