Characterization of Unsaponifiable Matter in Unripe Pistacia atlantica Fruits: Evaluation of Antioxidant Activity and α ‐Amylase Inhibitory Effect

This study provides a comprehensive characterization of the unsaponifiable matter (USM) in oils extracted from Pistacia atlantica fruits during prematurity phases (unripe and semiripe stages) from two distinct biogeographical regions in Algeria (Sougaa and Bousdraya). Notably, quantitative analysis revealed substantial variations in bioactive compound concentrations: tocopherols ranged from 3.10 to 17.88 mg α TE/g USM, sterols from 844.45 to 871.36 mg β S/g USM, and carotenoids from 15.22 to 20.76 mg β CE/g USM, demonstrating the significant phytochemical richness of early developmental stages. The USM components were quantified using validated spectrophotometric methods, with parallel evaluation of antioxidant and α ‐amylase inhibitory activities. The most remarkable finding was the exceptional antioxidant potency of semiripe fruits from Bousdraya (BRF), showing IC 50 = 0.49 mg/mL, representing one of the strongest antioxidant activities reported for Pistacia species unsaponifiable fractions. The unripe sample from Sougaa (SRC) exhibited the highest USM yield (10.45%) along with superior carotenoid and sterol concentrations. Furthermore, semiripe fruits from Sougaa (SRF) demonstrated the strongest α ‐amylase inhibition (34.58 μmol acarbose Eq/g USM), highlighting their potential for diabetes management applications. Correlation analysis revealed a strong negative relationship between tocopherol content and antioxidant activity ( r = −0.92), confirming their role as primary radical scavengers. The results provide crucial insights for developing functional ingredients for nutraceutical and pharmaceutical industries targeting oxidative stress and glycemic control. Initial stages of Pistacia atlantica fruit development represent an underappreciated source of valuable bioactive compounds. These results clearly indicate that an optimal harvesting strategy must consider both geographic origin and phenological stage, depending on the desired functional profile (e.g., semiripe BRF for strong antioxidant activity, immature SRC for maximum USM, and carotenoid/sterol yield). The key role in this activity was confirmed by a strong, statistically significant, negative correlation between tocopherol content and the IC 50 value ( r = −0.92). However, the highest alpha‐amylase inhibition activity, significantly different from the immature samples ( p < 0.05), was achieved by semiripe samples from Sougaa (SRF, 34.58 p.m. 1.33 mµmol AACE/g USM) and BRF, suggesting that other, statistically uncorrelated ( r approx. 0.01 for tocopherols) compounds are responsible for this effect. In terms of content, the immature sample from Sougaa (SRC) was statistically superior in terms of carotenoid and sterol content. These findings definitively confirm that the selection of harvest site and time is critical for maximizing the functional quality of the oil.