α‐glucosidase, α‐amylase inhibitory potential and antioxidant activity of fragrant black rice (Thai coloured rice)

Abstract

Diabetes mellitus is the most serious metabolic disorder in the world. 1 A recent report from the World Health Organization (WHO) showed that more than 422 million people worldwide have diabetes, especially in low-and middle-income countries. Diabetes mellitus can be divided into two types: insulin-dependent (type 1 diabetes mellitus) and non-insulin-dependent (type 2 diabetes mellitus). The common patients with diabetes are type 2 patients. Type 2 diabetes mellitus is caused by high blood glucose level which is hydrolysed from starch. 2 α-Glucosidase and α-amylase are the group of starch hydrolytic enzymes. The polysaccharides hydrolyse to short oligosaccharides or disaccharides by α-amylase, and finally, the free glucose is released from disaccharides by α-glucosidase. 3 The inhibiting both α-glucosidase and α-amylase has reported by varied plant bioactive compounds. Nazir et al 4 report that the chloroform extract of Elaeagnus umbellata (Thunb.) has shown high inhibitory potential on both α-glucosidase and α-amylase. Capsaicin and dihydrocapsaicin Abstract Coloured rice is the source of bioactive compounds related to medicinal treatment.This study aimed to investigate α-glucosidase and α-amylase inhibitory activity and antioxidant properties of purified coloured rice extract (Thai fragrant black rice). The results reveal that seven purified fractions; rice fractions 1-7 (RF1-RF7) contained several phytochemical compounds especially flavonoids, which were presented in all purified fractions. The percentage inhibition on α-glucosidase and α-amylase of fractions RF1, RF2, RF4, RF5 and RF6 had higher potential than acarbose. RF4, RF5 and RF6 contained the highest inhibition potential, which further determined the IC 50 values, kinetic analysis and antioxidant properties. The IC 50 values of all three fractions indicated that the inhibition potential of purified fraction had higher potential than acarbose, and the highest inhibition potential for both enzymes was obtained from fraction RF5. The kinetic analysis of the three fractions indicated that they are against both enzymes' function in mixed-type inhibition. Moreover, all three fractions also showed good antioxidant activity, and the highest potential was obtained from fraction RF6. This study presents the inhibition efficiency of fragrant black rice extract on α-glucosidase and α-amylase enzymes. The inhibitory activity of rice extract on both enzymes had higher potent than commercial standard drug acarbose.Moreover, the rice extract also shown the high-efficiency antioxidant activity on DPPH and ABTS assay. We suggest the application of these results in the development of anti-diabetes drug for pharmaceutical industry. K E Y W O R D Santioxidant potential, carbohydrate hydrolysis enzyme, Thai fragrant rice, type 2 diabetes mellitus

Biological activity of rice extract and the inhibition potential of rice extract, rice volatile compounds and their combination against α‐glucosidase, α‐amylase and tyrosinase

“…The free‐radical scavenging capacity of plant extract and rice extract has commonly been analysed using DPPH• and ABTS•+ assays (Chaiyasut et al ., 2017; Bari et al ., 2019; Zafar et al ., 2019; Sansenya & Nanok, 2020). The free‐radical scavenging capacity of plant extract is closely related to the phenolic content and flavonoid content (Amri & Hossain, 2018).…”

“…The inhibition potential of rice extract against α‐glucosidase, α‐amylase, and tyrosinase was determined by the modified method of Sansenya & Nanok (2020). AB and KA were used as the standard inhibitors for α‐glucosidase and α‐amylase activity and tyrosinase activity, respectively.…”

Evaluation of Cyanide Content, Volatile Compounds Profile, and Biological Properties of Fresh and Boiled Sliced Thai Bamboo Shoot (Dendrocalamus asper Back.)

“…The presence of phytochemical components, including flavonoids, terpenoid, and reducing sugar, were determined following the method of Sansenya and Nanok (2020) , with modifications. First, the crude methanol extract was dissolved in deionized water to produce 1 mg/mL solutions.…”

Phenolic Compounds and Potential Health Benefits of Pigmented Rice

“…Phenolic compounds have many biological activities, for instance, antioxidant [40,41] and anti-inflammatory properties [42]. Several epidemiological studies suggested that high dietary consumption of polyphenols is associated with decreased risk of a range of diseases including antidiabetic [43,44], cardiovascular disease (CVD) [45], and neurodegenerative diseases [46].…”

“…The potential inhibition against α-amylase activity in black rice samples were higher than those in red and purple rice samples, respectively [13]. In addition, the percentage inhibition on α-glucosidase and α-amylase of fragrant black rice fractions had higher potential than acarbose, a synthetic antidiabetic drug [48]. However, variation in the structure of anthocyanins makes it difficult to determine their effects on Type II diabetes.…”