Isolation and characterisation of flavonoids from the leaves of medicinal plant Orthosiphon stamineus

Orthosiphon aristatus (Blume) Miq. Extracts attenuate Alzheimer-like pathology through anti-inflammatory, anti-oxidative, and β-amyloid inhibitory activities

ETHNOPHARMACOLOGICAL RELEVANCE

Orthosiphon aristatus (Blume) Miq. (OA) is a traditional folk-herb, which is usually used to treat acute and chronic nephritis, epilepsy, cystitis, and other diseases. Phenols and flavonoids are the main active compound compounds of OA, with proven anti-inflammatory and antioxidant activities.

AIMS OF THIS STUDY

Based on evidenced therapeutic activities, we aimed to investigate the impact of OA on Alzheimer's disease (AD) which is the most common age-related neurodegenerative disease, and the pathological features include accumulation of beta-amyloid (Aβ) and neurofibrillary tangles (NFT).

MATERIALS AND METHODS

OA was extracted with water, methanol, chloroform, and ethyl acetate, and determined its total flavonoid and phenolic contents. Initially, Aβ1-42 based cytotoxicity was induced in BV2 cells and C6 cells to investigate the therapeutic impact of OA therapy by MTT, RT-PCR, Western blot, and ELISA. Further, Aβ1-42 Oligomer (400 pmol)-induced AD mice model was established to evaluate the impact of OA extract on improving learning and memory impairment.

RESULTS

The results showed that the extract of OA could increase cell survival, inhibit the expression of TNF-α, IL-6, IL-1β, COX-2, and iNOS, and increase BDNF levels. We infer that the OA extract may attenuate Aβ-induced cytotoxicity by retarding the production of inflammatory-related factors. In the animal behavior test, the number of mice entering darkroom and the time of arriving at the platform were significantly reduced, indicating the learning and memory-improving ability of OA extract.

CONCLUSIONS

These findings imply that the OA ethanolic extract demonstrated an improving effect on memory and hence could serve as a potential therapeutic target for the treatment of neurodegenerative diseases like AD.

Effect of dietary supplementation with Diuripres® on blood pressure, vascular health, and metabolic parameters in individuals with high-normal blood pressure or stage I hypertension: The CONDOR randomized clinical study

Our aim was to evaluate if a nutritional intervention with a dietary supplement (Diuripres®) containing magnesium, standardized extract of orthosiphon, hawthorn, and hibiscus could positively affect blood pressure (BP), vascular health, and metabolic parameters in 60 individuals with high-normal BP or stage I hypertension. Participants followed a low-fat low-sodium Mediterranean diet for 4 weeks before being randomly allocated to 8-week treatment with two pills each day of either Diuripres® or placebo. Diuripres® significantly decreased systolic BP compared to placebo after 4 weeks (3.1 ± 0.8 mmHg; p < 0.05) and more consistently after 8 weeks (3.4 ± 0.9 mmHg; p < 0.05). At 8-week follow-up, after correction for multiple testing, dietary supplementation with Diuripres® was associated with significant improvements in diastolic BP (-3.1 ± 0.6 mmHg; p < 0.05), aortic BP (-4.3 ± 0.4 mmHg; p < 0.05), and high-sensitivity C-reactive protein (hs-CRP; 0.04 ± 0.01 mg/dL; p < 0.05) in comparison with baseline. The reductions in diastolic BP (--3.8 ± 0.7 mmHg; p < 0.05), aortic BP (-5.2 ± 1.0 mmHg; p < 0.05), and hs-CRP (-0.03 ± 0.01 mg/dL; p < 0.05) were also significant compared to placebo. Therefore, our study shows that dietary supplementation with Diuripres® may be useful in individuals with high-normal BP or stage I hypertension.

Phytochemistry and pharmacology of natural prenylated flavonoids

Prenylated flavonoids are a special kind of flavonoid derivative possessing one or more prenyl groups in the parent nucleus of the flavonoid. The presence of the prenyl side chain enriched the structural diversity of flavonoids and increased their bioactivity and bioavailability. Prenylated flavonoids show a wide range of biological activities, such as anti-cancer, anti-inflammatory, neuroprotective, anti-diabetic, anti-obesity, cardioprotective effects, and anti-osteoclastogenic activities. In recent years, many compounds with significant activity have been discovered with the continuous excavation of the medicinal value of prenylated flavonoids, and have attracted the extensive attention of pharmacologists. This review summarizes recent progress on research into natural active prenylated flavonoids to promote new discoveries of their medicinal value.

A Systematic Review of Orthosiphon stamineus Benth. in the Treatment of Diabetes and Its Complications

(1) Background: Orthosiphon stamineus Benth. is a traditional medicine used in the treatment of diabetes and chronic renal failure in southern China, Malaysia, and Thailand. Diabetes is a chronic metabolic disease and the number of diabetic patients in the world is increasing. This review aimed to systematically review the effects of O. stamineus in the treatment of diabetes and its complications and the pharmacodynamic material basis. (2) Methods: This systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), using the databases ScienceDirect, PubMed, and Web of Science. (3) Results: Thirty-one articles related to O. stamineus and diabetes were included. The mechanisms of O. stamineus in the treatment of diabetes and its complications mainly included inhibiting α-amylase and α-glucosidase activities, antioxidant and anti-inflammatory activities, regulating lipid metabolism, promoting insulin secretion, ameliorating insulin resistance, increasing glucose uptake, promoting glycolysis, inhibiting gluconeogenesis, promoting glucagon-likepeptide-1 (GLP-1) secretion and antiglycation activity. Phenolic acids, flavonoids and triterpenoids might be the main components for hypoglycemia effects in O. stamineus. (4) Conclusion: O. stamineus could be an antidiabetic agent to treat diabetes and its complications. However, it needs further study on a pharmacodynamic substance basis and the mechanisms of effective constituents.

Synthetic Biology towards Improved Flavonoid Pharmacokinetics

Flavonoids are a structurally diverse class of natural products that have been found to have a range of beneficial activities in humans. However, the clinical utilisation of these molecules has been limited due to their low solubility, chemical stability, bioavailability and extensive intestinal metabolism in vivo. Recently, the view has been formed that site-specific modification of flavonoids by methylation and/or glycosylation, processes that occur in plants endogenously, can be used to improve and adapt their biophysical and pharmacokinetic properties. The traditional source of flavonoids and their modified forms is from plants and is limited due to the low amounts present in biomass, intrinsic to the nature of secondary metabolite biosynthesis. Access to greater amounts of flavonoids, and understanding of the impact of modifications, requires a rethink in terms of production, more specifically towards the adoption of plant biosynthetic pathways into ex planta synthesis approaches. Advances in synthetic biology and metabolic engineering, aided by protein engineering and machine learning methods, offer attractive and exciting avenues for ex planta flavonoid synthesis. This review seeks to explore the applications of synthetic biology towards the ex planta biosynthesis of flavonoids, and how the natural plant methylation and glycosylation pathways can be harnessed to produce modified flavonoids with more favourable biophysical and pharmacokinetic properties for clinical use. It is envisaged that the development of viable alternative production systems for the synthesis of flavonoids and their methylated and glycosylated forms will help facilitate their greater clinical application.

Sinensetin: An Insight on Its Pharmacological Activities, Mechanisms of Action and Toxicity

Sinensetin, a plant-derived polymethoxylated flavonoid found in Orthosiphon aristatus var. aristatus and several citrus fruits, has been found to possess strong anticancer activities and a variety of other pharmacological benefits and promising potency in intended activities with minimal toxicity. This review aims to compile an up-to-date reports of published scientific information on sinensetin pharmacological activities, mechanisms of action and toxicity. The present findings about the compound are critically analyzed and its prospect as a lead molecule for drug discovery is highlighted. The databases employed for data collection are mainly through Google Scholar, PubMed, Scopus and Science Direct. In-vitro and in-vivo studies showed that sinensetin possessed strong anticancer activities and a wide range of pharmacological activities such as anti-inflammatory, antioxidant, antimicrobial, anti-obesity, anti-dementia and vasorelaxant activities. The studies provided some insights on its several mechanisms of action in cancer and other disease states. However, more detail mechanistic studies are needed to understand its pharmacological effects. More in vivo studies in various animal models including toxicity, pharmacokinetic, pharmacodynamic and bioavailability studies are required to assess its efficacy and safety before submission to clinical studies. In this review, an insight on sinensetin pharmacological activities and mechanisms of action serves as a useful resource for a more thorough and comprehensive understanding of sinensetin as a potential lead candidate for drug discovery.

Bioassay-guided isolation of anti-inflammatory diterpenoids with highly oxygenated substituents from kidney tea (Clerodendranthus spicatus)

The whole plant of Clerodendranthus spicatus (Thunb.) is one of popular functional food in south of China, named as "kidney tea" and used to ameliorate renal inflammation. In order to verify this potential function and explore the accurate compounds responsible for inflammation, the ethanol extract, fractions, and subfractions of this plant were prepared to evaluate anti-inflammation effect on xylene-induced acute inflammatory mice model, and the results indicated that two subfractions from EtOAc fraction show potential activities. Subsequent bioassay-guided isolation of the bioactive subfractions led to isolation of 25 compounds. Among them, compounds 2, 4, 5, 9-11, 13, 16, 17, and 20-22 inhibited the productions of pro-inflammation factors TNF-α, IL-1β, and IL-8 in lipopolysaccharide (LPS) -induced renal epithelia (HK-2) cells, respectively. Further anti-inflammation evaluation in vivo indicated that the major bioactive compounds 1, 2, 5-7, 17, 21, and 22 from C. spicatus were even better than aspirin. PRACTICAL APPLICATIONS: C. spicatus as a healthy tea has been available in the Chinese market and as a medicine for various disorders such as nephritis, rheumatism, inflammation, gout, and diabetes. Previous pharmacological investigation of the plant revealed the potential anti-inflammatory activities, but the material basis of anti-inflammatory activity remains to be elucidated. In our study, the anti-inflammatory fractions and compounds were obtained by the bioassay-guide isolation and the results showed that the highly oxygenated diterpenoids were major anti-inflammatory compounds, in which 1, 2, 5-7, 17, 21, and 22 were even better than aspirin. This information supported kidney tea as a functional food for treatment of renal inflammation reasonably and may add a new dimension to biological activity of this plant in the field of agriculture as a functional food were cultivated.

Selectivity of Current Extraction Techniques for Flavonoids from Plant Materials

Flavonoids have a broad spectrum of established positive effects on human and animal health. They find an application in medicine for disease therapy and chemoprevention, whence the interest in flavonoids increases. In addition, they are used in food and cosmetic industries as pigments and biopreservatives. Plants are an inexhaustible source of flavonoids. The most important step of plant raw material processing is extraction and isolation of target compounds. The quality of an extract and efficiency of a procedure are influenced by several factors: Plant material and pre-extracting sample preparation, type of solvent, extraction technique, physicochemical conditions, etc. The present overview discusses the common problems and key challenges of the extraction procedures and the different mechanisms for selective extraction of flavonoids from different plant sources. In summary, there is no universal extraction method and each optimized procedure is individual for the respective plants. For an extraction technique to be selective, it must combine an optimal solvent or mixture of solvents with an appropriate technique. Last but not least, its optimization is important for a variety of applications. Moreover, when the selected method needs to be standardized, it must achieve acceptable degree of repeatability and reproducibility.

Assessment of a developed HPLC-MS/MS approach for determining plasma eupatorin in rats and its application in pharmacokinetics analysis

Eupatorin, a bioactive compound extracted from Java tea (Orthosiphon stamineus), possesses potent anti-cancer, anti-inflammatory and vasodilation activities. To date, no pharmacokinetics studies on eupatorin have yet been performed. Here, we established and validated a sensitive and selective LC-MS/MS (liquid chromatography-tandem mass spectrometry) approach for determining plasma eupatorin in rats. Chromatographic fractionation was conducted on a Wonda Cract ODS-2 C18 Column (4.6 mm × 150 mm, 5 μm) with a mobile phase containing aqueous 0.1% formic acid and acetonitrile using a flow rate of 0.8 ml min⁻¹. In multiple reaction monitoring mode, precursor-to-product ion transitions for quantification of eupatorin and the internal standard were set at 343.1 → 328.1 and 252.0 → 155.9, respectively. The intra- and inter-day precision and accuracy were found to be below 6.72% and within ±8.26% in rat plasma, respectively. Meanwhile, all values of the matrix effect, recovery and stability were within the accepted ranges. Furthermore, we carried out the pharmacokinetic analysis using the developed method. The pharmacokinetic study revealed that while the C_max (maximum plasma concentration) of eupatorin and time for reaching the C_max (T_max) were 974.886 ± 293.898 μg L⁻¹ and 0.25 h, respectively, the half-life was 0.353 ± 0.026 h. This study will be of great significance to the research on the pharmacology, clinical pharmacy and drug action mechanism of eupatorin.

Eupatorin, a bioactive compound extracted from Java tea (Orthosiphon stamineus), possesses potent anti-cancer, anti-inflammatory and vasodilation activities.

In vitro antioxidant, antimicrobial and antiproliferative studies of four different extracts of Orthosiphon stamineus, Gynura procumbens and Ficus deltoidea

Background

Medicinal plants are important source of drugs with pharmacological activities. Therefore, there is always rising demands to discover more therapeutic agents from various species. Orthosiphon stamineus, Gynura procumbens and Ficus deltoidea are high valued medicinal plants of Malaysia contain rich source of phenolic and flavonoid compounds. The aims of the present study were to evaluate anti-oxidant, antimicrobial and anti-proliferative effects on A549, HeGP2 and MCF7 cell lines of four different extracts of Orthosiphon stamineus, Gynura procumbens and Ficus deltoidea.

Methodology

The leaves of all selected plants were extracted with methanol, chloroform, ethyl acetate and butanol separately with simple cold maceration. Antioxidant activity of all crude extracts were quantitatively measured against DPPH and Ferric Reducing Assay. Antimicrobial evaluation was done by Microdilution and MTT assay and antipoliferative activity of all extracts of selected plant were evaluated against A549, HePG2 and MCF7 cell lines.

Results

Results showed that methanol extract exhibited highest percentage free radical scavenging activity of almost all extracts of selected plants. Antimicrobials results showed chloroform and methanol extracts of O. stamineus extract were the two most active extracts against resistant MRSA but not S. aureus. Only methanol extract of G. procumbens showed antimicrobial activity against the tested pathogens. Chloroform and methanol extracts of F. deltoidea elicited antimicrobial activity against S. aureus but not MRSA. Antiproliferative activity against three tested cell lines results showed that ethyl acetate extract of O. stamineus showed good effect whereas methanol extract of F. deltoidea and G. procumbens exhibited good antiproliferative activity.

Conclusions

The results of the present investigation demonstrated significant variations in the antioxidant, antimicrobial and antiproliferative effects of different solvent extracts. These data could be helpful in isolation of pure potent compounds with good biological activities from the extracts of plants.

Identification of Metabolites of Eupatorin in Vivo and in Vitro Based on UHPLC-Q-TOF-MS/MS

Eupatorin is the major bioactive component of Java tea (Orthosiphon stamineus), exhibiting strong anticancer and anti-inflammatory activities. However, no research on the metabolism of eupatorin has been reported to date. In the present study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with an efficient online data acquisition and a multiple data processing method were developed for metabolite identification in vivo (rat plasma, bile, urine and feces) and in vitro (rat liver microsomes and intestinal flora). A total of 51 metabolites in vivo, 60 metabolites in vitro were structurally characterized. The loss of CH2, CH2O, O, CO, oxidation, methylation, glucuronidation, sulfate conjugation, N-acetylation, hydrogenation, ketone formation, glycine conjugation, glutamine conjugation and glucose conjugation were the main metabolic pathways of eupatorin. This was the first identification of metabolites of eupatorin in vivo and in vitro and it will provide reference and valuable evidence for further development of new pharmaceuticals and pharmacological mechanisms.

Orthosiphon stamineus as a potential antidiabetic drug in maternal hyperglycemia in streptozotocin-induced diabetic rats

Background

Maternal hyperglycemia is associated with increased risk of adverse outcomes for both mother and offspring. Insulin is the standard treatment of hyperglycemia with the aim to reduce risks of complications, however, due to several restrictions, the search for more effective drugs from traditional medicinal plants continues.

Methods

The antidiabetic effects of Orthosiphon stamineus (O . stamineus ) in non-pregnant and pregnant streptozotocin-induced Sprague Dawley rats were identified. The effect of different concentrations of O. stamineouson insulin level using isolated pancreatic islets in response to low and high concentrations of glucose was identified. Oral glucose tolerance test was performed in both pregnant and non-pregnant rats prior to and after treatment with O. stamineus (0.1 g/100 g of body weight). O. stamineus was given orally daily for 2 weeks in non-pregnant and 10 days in pregnant rats.

Results

Oral glucose tolerance test indicated that treatment with O. stamineus in non-pregnant and pregnant rats significantly reduced blood glucose level and stimulated glucose-induced insulin secretion. No mortality was recorded throughout the study and no signs of toxicity during the experimental period including in both mother and foetus. For plasma analysis, the interactions of peptides such as GLP-1 and ghrelin level might contribute to the glucose lowering effect by O. stamineus via stimulation of insulin. The incubation of islets showed that O . stamineussignificantly stimulated insulin release in response to high glucose.

Conclusion

O. stamineus could be a potential source of a specific oral hypoglycaemic agent to treat glucose intolerance in pregnancy.

Orthosiphon stamineus Leaf Extract Affects TNF-α and Seizures in a Zebrafish Model

Epileptic seizures result from abnormal brain activity and can affect motor, autonomic and sensory function; as well as, memory, cognition, behavior, or emotional state. Effective anti-epileptic drugs (AEDs) are available but have tolerability issues due to their side effects. The Malaysian herb Orthosiphon stamineus, is a traditional epilepsy remedy and possesses anti-inflammatory, anti-oxidant and free-radical scavenging abilities, all of which are known to protect against seizures. This experiment thus aimed to explore if an ethanolic leaf extract of O. stamineus has the potential to be a novel symptomatic treatment for epileptic seizures in a zebrafish model; and the effects of the extract on the expression levels of several genes in the zebrafish brain which are associated with seizures. The results of this study indicate that O. stamineus has the potential to be a novel symptomatic treatment for epileptic seizures as it is pharmacologically active against seizures in a zebrafish model. The anti-convulsive effect of this extract is also comparable to that of diazepam at higher doses and can surpass diazepam in certain cases. Treatment with the extract also counteracts the upregulation of NF-κB, NPY and TNF-α as a result of a Pentylenetetrazol (PTZ) treated seizure. The anti-convulsive action for this extract could be at least partially due to its downregulation of TNF-α. Future work could include the discovery of the active anti-convulsive compound, as well as determine if the extract does not cause cognitive impairment in zebrafish.

Isolated mangiferin and naringenin exert antidiabetic effect via PPARγ/GLUT4 dual agonistic action with strong metabolic regulation

In this study, we isolated two compounds from the leaves of Salacia oblonga (SA1, mangiferin and SA2, naringenin), and their structures were confirmed by infrared spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry. SA1 and SA2 were orally administered to streptozotocin-induced diabetic rats at 50 and 100 mg/kg daily for 15 days. Blood glucose level, serum lipid profile, oxidative stress parameters, histopathology, docking, molecular parameters, and NMR-based metabolic perturbation studies were performed to investigate the pharmacological activities of SA1 and SA2. Results suggested that both compounds reduced blood glucose level, restored body weight, and normalized lipid concentrations in the serum and oxidative stress biomarkers in the liver and pancreas. In addition, the docking study on several diabetes-associated targets revealed that both compounds had a strong binding affinity towards peroxisome proliferator-activated receptor gamma (PPAR_γ) and glucose transporter type 4 (GLUT4). Further real-time reverse transcription polymerase chain reaction and western blot analyses were performed to confirm the gene and protein expression levels of PPAR_γ and GLUT4 in the pancreatic tissues. Data obtained from the molecular studies showed that both compounds exhibited antidiabetic effects through dual activation of PPAR_γ/GLUT4 signaling pathways. Finally, the NMR-based metabolic studies showed that both compounds normalized the diabetogenic metabolites in the serum. Altogether, we concluded that SA1 and SA2 might be potential antidiabetic lead compounds for future drug development.

Cancer chemoprevention through dietary flavonoids: what's limiting?

Flavonoids are polyphenols that are found in numerous edible plant species. Data obtained from preclinical and clinical studies suggest that specific flavonoids are chemo-preventive and cytotoxic against various cancers via a multitude of mechanisms. However, the clinical use of flavonoids is limited due to challenges associated with their effective use, including (1) the isolation and purification of flavonoids from their natural resources; (2) demonstration of the effects of flavonoids in reducing the risk of certain cancer, in tandem with the cost and time needed for epidemiological studies, and (3) numerous pharmacokinetic challenges (e.g., bioavailability, drug–drug interactions, and metabolic instability). Currently, numerous approaches are being used to surmount some of these challenges, thereby increasing the likelihood of flavonoids being used as chemo-preventive drugs in the clinic. In this review, we summarize the most important challenges and efforts that are being made to surmount these challenges.

New Diterpenoids from Clerodendranthus spicatus

Two new diterpenoids, neoorthosiphonones B and C (1 and 2), and one known diterpenoid, were isolated from the aerial parts of Clerodendranthus spicatus. Their structures including absolute configurations were determined by comprehensive spectroscopic analyses and X-ray crystallographic methods. No compound was found to inhibit fibronectin production at the concentration of 20 μM.

LC-ESI-MS/MS Identification of Biologically Active Phenolic Compounds in Mistletoe Berry Extracts from Different Host Trees

A new, rapid, sensitive and selective liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed to determine the content of flavonoid aglycones and phenolic acids in mistletoe berries (Viscum album L.) harvested from six different Polish host trees. Additionally, the total phenolic content (TPC) and total flavonoid content (TFC) as well as an antioxidant and antiproliferative activity were evaluated for the first time. The plant material was selectively extracted using ultrasound assisted maceration with methanol/water (8:2) solution. The obtained TPC and TFC results varied from 7.146 to 9.345 mg GA g⁻¹ and from 1.888 to 2.888 mg Q g⁻¹ of dry extracts, respectively. The LC-ESI-MS/MS analysis demonstrated the highest content of phenolic acids in mistletoe berries from Populus nigra ‘Italica’ L. and flavonoid aglycones in mistletoe berries from Tilia cordata Mill. (354.45 µg and 5.955 µg per g dry extract, respectively). The moderate antioxidant activity of investigated extracts was obtained. The studies revealed that the examined extracts decreased the proliferation of human colon adenocarcinoma cells line LS180 in a dose-dependent manner without cytotoxicity in the human colon epithelial cell line CCD 841 CoTr. Moreover, the obtained results suggest considerable impact of polyphenols on the anticancer activity of these extracts.

Isolated flavonoids from Ficus racemosa stem bark possess antidiabetic, hypolipidemic and protective effects in albino Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ficus racemosa (FR) has been used for thousands of years in Ayurvedic system of medicine in India and is closely associated with prevention, treatment and cure of various human ailments like obesity and diabetes. It is popularly known as gular. A vast and wide range of chemical compounds like polyphenols, friedelane-type triterpenes, norfriedelane type triterpene, eudesmane-type sesquiterpene including various glycosides had been isolated from this plant. However, no detail studies related to isolation of flavonoids has been reported previously with their antidiabetic, hypolipidemic and toxicological consequences.

AIM OF THE STUDY

The present study was undertaken to evaluate antidiabetic, hypolipidemic and toxicological assessments of flavonoids isolated from Ficus racemosa (FR) stem bark.

MATERIALS AND METHODS

We isolated four flavonoids from stem bark of FR and structures were confirmed by Infrared spectroscopy (IR), Nuclear Magnetic Resonance (NMR) (both 1D and 2D), mass spectroscopy (MS). Later, these flavonoids were administered to streptozotocin (STZ) rats once in a day for a period of seven days at 100mg/kg dose. We measured blood glucose level and body weight changes at different days (1st, 3rd, 5th and 7th days). Serum lipid profiles were also estimated to investigate the hypolipidemic potential of flavonoids in the similar experiment. Various oxidative stress parameters in pancreas and liver and hepatic biomarker enzymes in plasma were also determined to investigate the toxicity potential of isolated flavonoids. Finally, we performed docking studies to find out the mechanism of action.

RESULTS

Our results collectively suggested that four flavonoids reduced blood glucose level and restored body weight, signifying antidiabetic action. There were reduction of other lipid profile parameters and increase of high density lipoprotein (HDL) during administration of flavonoids, also signifying hypolipidemic action. Various oxidative stress biomarkers and hepatic enzymes levels were also normalized with respect to diabetic control at the same time. Docking studies revealed that isolated flavonoids showed their antidiabetic potential via binding to PPARγ and GLUT1 receptors.

CONCLUSION

The isolated four flavonoids demonstrated good antidiabetic, hypolipidemic and antioxidant properties in STZ diabetic rats which supported the use of FR stem bark as useful supplementary drug for future antidiabetic therapy.

Genotoxicity, acute and subchronic toxicity studies of nano liposomes of Orthosiphon stamineus ethanolic extract in Sprague Dawley rats

Background

Orthosiphon stamineus (OS) Benth is a medicinal plant and native in Southeast Asia. Pharmacological effects of OS are attributed to the presence of lipophilic flavones. However; lipophilic compounds suffer from poor aqueous solubility which limits the OS oral bioavailability and therapeutic applications. Therefore, OS was prepared in nano formulation form using liposomes from soybean phospholipids. The aim of the present study is to evaluate the in vitro genotoxicity and in vivo oral toxicity of nano liposomes of OS ethanolic extract (OS-EL).

Methods

In the acute toxicity study Sprague Dawley female rats were given a single dose of the OS-EL at 5000 mg/kg/day orally and screened for two weeks after administration. In the subchronic study, three different doses of OS-EL were administered for 28 days. Mortality, clinical signs, body weight changes, hematological and biochemical parameters, gross findings, organ weights, and histological parameters were monitored during the study. Genotoxicity was assessed using the Ames test with the TA98 and TA100 Salmonella typhimurium strains. High-performance liquid chromatography was performed for identification and quantification of the major marker compounds in OS-EL. Heavy metal detection was performed using an atomic absorption spectrometer.

Results

The acute toxicity study showed that the LD₅₀ of the extract was greater than 5000 mg/kg. In the repeated dose 28-day oral toxicity study, the administration of 250 mg/kg, 500 mg/kg, and 1000 mg/kg/day of OS-EL per body weight revealed no significant difference in food and water consumptions, bodyweight change, haematological and biochemical parameters, relative organ weights, gross findings or histopathology compared to the control group. The Ames test revealed that the OS-EL did not have any potential to induce gene mutations in S. Typhimurium.

Conclusions

Analyses of these results with the information of signs, behaviour, and health monitoring could lead to the conclusion that the long-term oral administration of OS-EL for 28 days does not cause sub-chronic toxicity.