Tumbuhan bungur (Lagerstroemia loudonii T.B.) termasuk dalam famili Lytrharceae. Famili Lythraceae telah diketahui memiliki aktivitas farmakologi sebagai antidiabetes, antiinflamasi, antimikroba, serta antiobesitas. Daun dan buah bungur (Lagerstroemia loudonii T.B.) memiliki aktivitas dalam menghambat alfa-glukosidase. Berdasarkan teori khemotaksonomi didalam tumbuhan, kemungkinan bagian lain dari tumbuhan bungur memiliki aktivitas dan kandungan kimia yang sama, sehingga dilakukan pengujian aktivitas penghambatan terhadap alfa-glukosidase pada bagian kulit batang bungur. Ekstraksi simplisia dilakukan dengan cara maserasi selama 24 jam menggunakan pelarut etanol 96%. Proses fraksinasi menggunakan cara Ekstraksi Cair-Cair (ECC) dengan pelarut n-heksana, etil asetat dan air. Pengujian aktivitas penghambatan alfa-glukosidase secara in vitro menggunakan metode kolorimetri dengan alat spektrofotometer UV-VIS pada panjang gelombang 400,4 nm dengan substrat p-nitrofenil-α-D-glukopiranosid (PNPG). Akarbose digunakan sebagai pembanding. Hasil penelitian menunjukkan bahwa ekstrak, fraksi air, fraksi etil asetat dan fraksi n-heksana memiliki nilai IC50 berturut-turut sebesar 240,53±0,47 μg/ml, 186,111±1,02 μg/ml, 79,479±0,52 μg/ml dan 113,101±0,46 μg/ml. Nilai IC50 akarbose adalah sebesar 10,457±1,48 μg/ml. Ekstrak dan fraksi-fraksi (air,etil asetat dan n-heksana) kulit batang bungur mampu menghambat aktivitas enzim α-glukosidase. Aktivitas yang paling baik ditunjukan oleh fraksi etil asetat dengan nilai IC50 sebesar 79,479±0,52 μg/ml.
Bungur (Lagerstroemia loudonii T.B.) is included in the Family Lytrharceae. The Lythraceae has been known to have pharmacological activity as antidiabetic, anti-inflammatory, antimicrobial, and antiobesity. Leaves and fruits of bungur (Lagerstroemia loudonii T.B.) have activities to inhibit alpha-glucosidase. Based on the chemotaxonomy theory in plants, it is possible that other parts of the bungur plant have the same chemical activity and content, Hence the study to evalute the inhibitory activity against alpha-glucosidase was carried out on its bark stem.The extraction of dried powder material was carried out by maceration for 24 hours using 96% ethanol. The extract was fractionated by Liquid-Liquid Extraction (ECC) method with n-hexane, ethyl acetate and water. The In vitro study of alpha-glucosidase inhibition activity using a colorimetric method with a UV-VIS spectrophotometer at a wavelength of 400.4 nm with a p-nitrophenyl-α-D-glucopiranoside (PNPG) substrate was performed. Akarbose was used as a standard drug.The results showed that extract, water fraction, ethyl acetate fraction and n-hexane fraction showed IC50 values of 240.53 ± 0.47 μg / ml, 186.111 ± 1.02 μg / ml, 79.497 ± 0.52 μg/ ml and 113.101 ± 0.46 μg / ml, respectively. The IC50value of bungur was 10.457 ± 1.48 μg / ml. Extracts and fractions (water, ethyl acetate and n-hexane) of bark stem were able to inhibit the activity of α-glucosidase. Theethyl acetate fraction showed the strongestactivity with IC50 value of 79,479 ± 0.52 μg / ml
