α-VINIFERIN as a potential antidiabetic and antiplasmodial extracted from Dipterocarpus littoralis

Over the past few decades, complementary medicine therapy using medicinal plants have been developed in healthcare. Phytochemical studies about medicinal plants have been conducted to verify their potency as medicinal remedies in modern therapeutics. Dipterocarpus littoralis commonly known as Meranti Jawa in Indonesia is traditionally used to treat diseases such as diarrhea, diabetic and malaria. This study aimed to isolate bioactive compounds from D. littoralis using bioguided fractionation method. The bioactivity measured were antioxidant, antidiabetic, and antiplasmodial activity. Alpha-glucosidase and alpha-amylase assays were applied to estimate the in vitro antidiabetic activity of D. littoralis. The antioxidant activities were determined by using the free radical scavenging assays 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-2″-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Analysis of total flavonoid and phenolic contents were expressed as Quercetin Equivalent (QE) and Gallic Acid Equivalent (GAE), respectively. The in vitro antiplasmodial activity test of methanol extract of D. littoralis was also conducted against Plasmodium falciparum strain 3D7. Purification of the ethyl acetate fraction of the methanol extract of D. littoralis resulted in an oligostilbenes namely α-viniferin (1). The structure of the α-viniferin was characterized by comprehensive spectral analysis including IR, 1D and 2D NMR, and in comparison with the literature data. Compound 1 showed an alpha-glucosidase and alpha-amylase inhibitory activity with IC₅₀ values of 256.17 and 212.79 μg/mL, respectively. The in vitro antiplasmodial activity test against Plasmodium falciparum strain 3D7 at a concentration of 100 μg/mL revealed a strong antiplasmodial inhibitory activity with IC₅₀ value of 2.76 μg/mL. Our findings indicated that α-viniferin (1) which is isolated from D. littoralis extract could be regarded as potential antidiabetic and antiplasmodial resources in the future.

Keywords: ABTS; Alpha-amylase; Alpha-glucosidase; Alpha-viniferin; Antiplasmodial; D. littoralis; DPPH; Natural product chemistry; Pharmaceutical chemistry.