Objective To study the chemical constituents and in vitro antioxidant activity of Euphorbia heterophylla. Methods Comprehensive separation and purification were performed using normal-phase silica gel column chromatography, Sephadex LH-20 gel column chromatography and semi-preparative HPLC. Their structures were elucidated by comprehensive spectroscopic analyses (1D NMR, 2D NMR, HRMS) combined with single-crystal X-ray diffraction. The in vitro antioxidant activities of the isolated compounds were evaluated by DPPH and ABTS methods. Results A total of 18 compounds were isolated from the ethanol extract of E. heterophylla, their structures were elucidated as (3R,5R,8R,9R,13S,14R,17R,18R,21R)-3-hydroxy-21-isopropyl-4,4,9,13,14,17-hexamethyl-cyclopenta[a]chrysen-1(10)-en-2-one (1), β-amyrin ferulate (2), stigmasterol-4-en-3-one (3), isoquercitrin (4), quercetin 3-O-α-L-rhamnoside (5), kaempferol-3-O-α-arabifuranoside (6), kaempferol-3-O-α-L-rhamnoside (7), multiflorin A (8), 4,6-dimethoxyphthalide (9), vanillin (10), p-hydroxybenzaldehyde (11), protocatechuic acid (12), vanillic acid (13), 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl) propan-1-one (14), ferulic acid (15), diethylhexyl adipate (16), 13-propylheptacosane (17) and 1-n-decanoyl hydroxy-benzoic acid (18), respectively. Antioxidant activity evaluation revealed that compounds 5 and 15 exhibited potent DPPH radical scavenging activity, with half maximal inhibitory concentration (IC₅₀) values of (15.88 ± 0.84) μg/mL and (15.95 ± 0.75) μg/mL, respectively. Moreover, compound 15 also exhibited potent ABTS radical scavenging activity, with an IC₅₀ value of (2.54 ± 0.57) μg/mL, outperforming the positive control L-ascorbic acid [(IC₅₀ 12.25 ± 0.82) μg/mL]. Conclusion Compound 1 is a novel fernane-type triterpenoid and named as euheterophyllfernane A, compounds 2—3, 6—11, 14 and 16—18 are isolated from E. heterophylla for the first time.

Euphorbia heterophylla L.  /  fernane-type triterpenoids  /  antioxidant activity  /  euheterophyllfernane A  /  quercetin 3-O-α-L-rhamnoside  /  ferulic acid