Nutritional and bioactive composition of Clausena indica (Dalzell) Oliv. Leaves and fruits from selected northern mountainous provinces of Vietnam

Clausena indica (Dalzell) Oliv., a perennial shrub of the family Rutaceae, is widely distributed in northern Vietnam, where the species serves as both a traditional condiment and a medicinal resource. This study investigated the nutritional and bioactive composition of C. indica leaves and fruits collected from Lang Son, Cao Bang, and Bac Kan provinces under two soil conditions: feralit (mountain) and limestone soils. Quantitative analyses were performed for mineral elements (Ca, Mg, Fe, Na, K), proximate nutrients (protein, lipid, carbohydrates), total flavonoids, total polyphenols, essential oils, vitamins, and amino acids. The results revealed that both leaves and fruits were rich in minerals and bioactive compounds, with significant variation among ecological sites and soil types. Leaves contained higher levels of protein (8.65–9.56%), total sugars (19.40–21.38%), flavonoids (10.54–11.63 mg/100 g), and polyphenols (12.36–13.63 mg/100 g) than fruits, whereas fruits were richer in carbohydrates and vitamin C (157.8–174.0 mg/100 g). Overall, samples from limestone soils exhibited slightly higher concentrations of most nutrients and bioactive constituents than those from feralit soils. These findings provide scientific evidence for the nutritional potential and ecological adaptability of C. indica, supporting its potential use in food, nutraceutical, and medicinal applications in mountainous regions of Vietnam.