Medicinal plants of Southeast Asia with anti-α-glucosidase activity as potential source for type-2 diabetes mellitus treatment

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus, a widespread chronic illness, affects millions worldwide, and its incidence is increasing alarmingly, especially in developing nations. Current pharmacological treatments can be costly and have undesirable side effects. To address this, medicinal plants with antidiabetic effects, particularly targeting α-glucosidase for controlling hyperglycaemia in type-2 diabetes mellitus (T2DM), hold promise for drug development with reduced toxicity and adverse reactions.

AIM OF THIS REVIEW

This review aims to succinctly collect information about medicinal plant extracts that exhibit antidiabetic potential through α-glucosidase inhibition using acarbose as a standard reference in Southeast Asia. The characteristics of this inhibition are based on in vitro studies.

MATERIALS AND METHODS

Relevant information on medicinal plants in Southeast Asia, along with α-glucosidase inhibition studies using acarbose as a positive control, was gathered from various scientific databases, including Scopus, PubMed, Web of Science, and Google Scholar.

RESULTS

About 49 papers were found from specific counties in Southeast Asia demonstrated notable α-glucosidase inhibitory potential of their medicinal plants, with several plant extracts showcasing activity comparable to or surpassing that of acarbose. Notably, 19 active constituents were identified for their α-glucosidase inhibitory effects.

CONCLUSIONS

The findings underscore the antidiabetic potential of the tested medicinal plant extracts, indicating their promise as alternative treatments for T2DM. This review can aid in the development of potent therapeutic medicines with increased effectiveness and safety for the treatment of T2DM.

Phytochemical analysis, antioxidant, α-glucosidase inhibitory activity, and toxicity evaluation of Orthosiphon stamineus leaf extract

Ocimum aristatum, commonly known as O. stamineus, has been widely studied for its potential as an herbal medicine candidate. This research aims to compare the efficacy of water and 100% ethanolic extracts of O. stamineus as α-glucosidase inhibitors and antioxidants, as well as toxicity against zebrafish embryos. Based on the study findings, water extract of O. stamineus leaves exhibited superior inhibition activity against α-glucosidase, ABTS, and DPPH, with IC50 values of approximately 43.623 ± 0.039 µg/mL, 27.556 ± 0.125 µg/mL, and 95.047 ± 1.587 µg/mL, respectively. The major active compounds identified in the extract include fatty acid groups and their derivates such as linoleic acid, α-eleostearic acid, stearic acid, oleanolic acid, and corchorifatty acid F. Phenolic groups such as caffeic acid, rosmarinic acid, 3,4-Dihydroxybenzaldehyde, norfenefrine, caftaric acid, and 2-hydroxyphenylalanine and flavonoids and their derivates including 5,7-Dihydroxychromone, 5,7-Dihydroxy-2,6-dimethyl-4H-chromen-4-one, eupatorin, and others were also identified in the extract. Carboxylic acid groups and triterpenoids such as azelaic acid and asiatic acid were also present. This study found that the water extract of O. stamineus is non-toxic to zebrafish embryos and does not affect the development of zebrafish larvae at concentrations lower than 500 µg/mL. These findings highlight the potential of the water extract of O. stamineus as a valuable herbal medicine candidate, particularly for its potent α-glucosidase inhibition and antioxidant properties, and affirm its safety in zebrafish embryos at tested concentrations.

Development of Bangle Rhizome and Purple Sweet Potato Flour Biscuit and Its in vivo Antioxidant Activity in High-Fat Diet-Induced Rats

Bangle rhizome and purple sweet potato could be used as functional food to overcome health problems such as hyperlipidemia. The anti-hyperlipidemic, nutritional properties of the above-said root vegetables could be formulated into a more community-preferred food in the form of biscuits. For this reason, this study aims to formulate biscuits from the mixed flour of bangle rhizome and purple sweet potato. Next, the prepared product's antioxidant activity and lipid-lowering properties are tested in vivo in high-fat diet-induced Wistar rats. In this study, bangle rhizome and purple sweet potato were turned into flour and formulated into three types of biscuits comprising different ratios of bangle rhizome and purple sweet potato flour (5:39 % w/w (F1), 3:41 % w/w (F2), and 2:42 % w/w (F3)). The study found that the baked products showed good organoleptic and physical properties, yielding golden- to brown-colored biscuits with a distinctive aroma and vaguely bitter after-taste, with F3 showing the highest hardness (8.94 0.18). The proximate analysis test showed that the biscuits achieved three of the six SNI 01-2973-2011 quality requirements. The best formula (F3) exhibited acceptable in vivo antioxidant catalase (5.12 0.16 U/mL) and glutathione peroxidase activity (64.44 2.11 U/mg) in high-fat diet Wistar rats tested for 28 days. The F3 formula was deemed the best, yielding biscuits with low moisture content and good crispiness. The formulated biscuits increased catalase's antioxidant activity (285.47%) and glutathione peroxidase (265.08%) more than the negative control. Hence, the study demonstrated that bangle rhizome and purple sweet potato-containing biscuits were potentially useful functional foods for improving antioxidant activity in high-fat diet-induced Wistar rats.

Sweet Potato (Ipomoea batatas L.) Leaves Ethanol Extract Increases Endogenous Antioxidant Activities in Hyperlipidemic Rats

Consumption of high-fat foods can induce the formation of free radicals and trigger oxidative stress. The leave of sweet potato (Ipomoea batatas L.) has been reported to be a potent antioxidant in vitro. This study investigates the effect of ethanol extract of purple sweet potato leaves on the endogenous antioxidant activity in hyperlipidemic rats. The sweet potato leaves were oven-dried and extracted using 70% ethanol in a ratio of 1:7 w/v for 24 h, followed by vacuum evaporation. The five groups of test animals were created: normal control-which was given a standard diet, negative control (high-fat diet (HFD) for 14 days), and three treated groups which treated with HFD for 14 days and start for the same time treated with sweet potato leaves extract (SPLE) at the doses of 100, 200, and 400 mg/kg BW for 28 days. The antioxidant activity was measured from liver homogenate on the 29th day. Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) activities, and malondialdehyde (MDA) levels were quantified using spectrophotometry. The high-performance liquid chromatography (HPLC) analysis found rutin as a major chemical content of the SPLE. HFD significantly (p<0.05) decreased the activity of endogenous antioxidants (SOD, CAT, and GSH-Px) and increased the MDA level significantly (p<0.05) compared with the normal group. On the contrary, the treatment with the SPLE significantly (p<0.05) increased the activity of SOD, CAT, and GSH-Px and lowered MDA levels significantly (p<0.05) in a dose-dependent manner compared to the negative control. SPLE increase the activities of endogenous enzymatic antioxidants in hyperlipidemic rats.

Zingiber cassumunar Roxb. extract increase the reactive oxidant level and interleukins expression in vitro

Zingiber cassumunar Roxb. (bangle) has a variety of active compounds, including curcumin and phenylbutenoid. Bangle rhizoma reported exhibiting immunomodulatory activities. This research aims to determine the mechanism of bangle extract as an immunomodulator by the secretion of Reactive Oxygen Intermediate (ROI), Nitric Oxide (NO), and interleukin (IL-10 and IL-14) expression level. Bangle extract (Zingiber cassumunar Roxb.) was made by the maceration method using 96% ethanol solvent. This research was administered in vitro using macrophage cells from male mice with Balb/C strain divided into 2 groups: normal control and treatment group (receiving 25, 50, and 100 ppm of extract). The administration of bangle extract can function as an immunomodulator by an increase of ROI in 25 and 50 ppm of the extract significantly than the control group (p <0.05), the treatment groups decrease NO level (p <0.05), it also was found to increase expression of IL-10 and IL-14 expression levels (p <0.05). Zingiber cassumunar Roxb. extract was potentially to be developed as an immunomodulator.

Isolation and identification of Bengle (Zingiber cassumunar roxb) as a stimulant in phagocytic activity of macrophages

Immunomodulators are pharmacological agents that modify or regulate the immune system through stimulating the functioning of the immune system and, at the same time, inhibiting excessive immune responses. This study was conducted to determine the active compound in Z. cassumunar that is responsible for increasing the immune system based on the parameters of phagocytic activity. The isolation method began with fractionation, which involved extraction with ethanol and successive fractionation with hexane and chloroform. Z. cassumunar extract, hexane fraction, and chloroform fraction were tested on mice macrophage cells for their phagocytic functions. The phagocytic activity of macrophages was measured by active phagocytic cells (averagely 39.194 ±1.597, 27.923 ±2.941, and 62.090 ±6.947) and phagocytic index (in a row, averagely 47.513 ±2.844, 41.129 ±7.195, and 101.527 ±10.555). The results showed that the Z. cassumunar extract,  hexane fraction, and chloroform fraction exhibited more significant phagocytic activities of macrophages (p <0.05) compared with the normal group. Since the chloroform fraction showed the best result, this fraction was further separated by column chromatography. This procedure yielded five sub-fractions, namely F1, F2, F2C, F3, and F4. Based on the phagocytic activity testing, the results were as follows: (1) the active phagocytic cells of F1, F2, F2C, F3 and F4 were 18.860 ±3.191, 27.077 ±4.482, 15.749 ±3.026, 64.333 ±1.780, and 44.943 ±2.944, respectively, and (2) the phagocytic indices were 30.0249 ±3.4231, 44.5969 ±8.3646, 24.5597 ±5.4487, 102.7447 ±1.0806, and 76.5007 ±4.7293. Because F3 produced the best result, this subfraction was then identified using 1H-NMR and 13C-NMR. The identification results showed that F3 was (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-ol as an active compound.