Bioactive proanthocyanidins are the main inhibitors of starch hydrolases in unripe and ripe Malay cherry fruits. Proanthocyanidins from both unripe and ripe fruits showed stronger inhibition of α-amylase with IC₅₀ values of 3.54 ± 0.03 and 1.19 ± 0.02 μg/mL, respectively, than that of α-glucosidase. The structural fingerprints of proanthocyanidins were identified using high-performance liquid chromatography electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses. Results showed the subunits of proanthocyanidins were (epi)catechins and (epi)gallocatechins, and they formed tetramers to dodecamers in unripe fruits and tetramers to hexadecamers in ripe fruits. The mean degree of polymerization (mDP) of proanthocyanidins was found to increase from 8 to 18 as fruit ripened. Larger proanthocyanidins (higher mDP values) in ripe fruits exerted significantly stronger inhibition of α-amylase and α-glucosidase than less polymerized proanthocyanidins in unripe fruits, indicating the dependence of inhibition on mDP. Total phenolics and total proanthocyanidins significantly decreased as fruit ripened.

具有生物活性的原花色素是未成熟和成熟的马来樱桃果实中淀粉水解酶的主要抑制剂。未成熟和成熟果实中的原花青素对IC _50的抑制作用都强于α-淀粉酶的值分别比α-葡萄糖苷酶的3.54±0.03和1.19±0.02μg/ mL高。原花色素的结构指纹使用高效液相色谱电喷雾电离质谱和基质辅助激光解吸/电离飞行时间质谱分析进行鉴定。结果表明，原花青素的亚基是（epi）儿茶素和（epi）gallocatechins，它们在未成熟的水果中形成十二聚体到十二聚体，而在成熟的水果中形成六聚体到六聚体。发现原花青素的平均聚合度（mDP）随着果实成熟而从8增加至18。成熟果实中较大的原花青素（较高的mDP值）比未成熟果实中聚合度较低的原花青素对α-淀粉酶和α-葡萄糖苷酶的抑制作用强得多，表明抑制对mDP的依赖性。随着果实成熟，总酚和总原花青素显着下降。