Comparative in vitro evaluation of phytochemical composition, antioxidant, and protein-denaturation inhibitory activities of five Vietnamese medicinal plants

Abstract. Thao TTP, Tu PTC, Men TT, Ngan NTT, Van TTB. 2026. Comparative in vitro evaluation of phytochemical composition, antioxidant, and protein-denaturation inhibitory activities of five Vietnamese medicinal plants. Biodiversitas 27 (9): d270925. https://doi.org/10.13057/biodiv/d270925. Medicinal plants are important sources of bioactive compounds with antioxidant and anti-inflammatory properties that may have applications in food, pharmaceutical, and aquaculture industries. This study comparatively evaluated the phytochemical composition, antioxidant activity, and anti-inflammatory potential of five medicinal plants commonly found in Vietnam, namely guava (Psidium guajava), breadfruit (Artocarpus altilis), pennywort (Centella asiatica), billy goat weed (Ageratum conyzoides), and Vietnamese coriander (Persicaria odorata). Significant differences in phytochemical composition were observed among the extracts. Guava leaf extract contained the highest concentrations of total polyphenols (447.62±32.47 mg GAE/g extract), flavonoids (364.76±7.43 mg QE/g extract), saponins (283.14±0.45 mg ACE/g extract), and polysaccharides (354.17±16.67 mg GE/g extract). Antioxidant activity was assessed using Ferric Reducing Antioxidant Power (FRAP), ABTS radical scavenging, Total Antioxidant Capacity (TAC), and Reducing Power (RP) assays. Guava exhibited the strongest antioxidant activity in the FRAP, ABTS, and reducing power assays, whereas Vietnamese coriander exhibited the strongest Total Antioxidant Capacity (TAC). In contrast, billy goat weed generally showed the weakest antioxidant performance. Interestingly, Vietnamese coriander exhibited the strongest total antioxidant capacity among the plant extracts (A0.5=592.83±49.37 µg/mL) despite its relatively low polyphenol content, suggesting the contribution of non-phenolic antioxidants. Protein-denaturation inhibitory activity, evaluated using the inhibition of bovine serum albumin denaturation, revealed that guava and breadfruit extracts exhibited the strongest inhibitory effects, with IC₅₀ values of 93.89±2.06 and 94.48±3.71 µg/mL, respectively, whereas Vietnamese coriander exhibited the weakest protein-denaturation inhibitory activity (IC₅₀>3000 µg/mL). Under the experimental conditions used, guava and breadfruit exhibited the strongest antioxidant and protein-denaturation inhibitory activities among the tested extracts. However, because the study was limited to preliminary in vitro assays, further research should focus on phytochemical characterization, toxicity assessment, and in vivo validation before practical applications can be recommended.