Validated liquid chromatographic method and analysis of content of tilianin on several extracts obtained from Agastache mexicana and its correlation with vasorelaxant effect

Ethnopharmacological relevance

To optimize the obtention of tilianin, an antihypertensive flavonoid isolated from Agastache mexicana (Lamiaceae), a medicinal plant used in Mexico for the treatment of hypertension. Also, a validated HPLC method to quantify tilianin from different extracts, obtained by several extraction methods, was developed.

Materials and methods

The aerial parts of Agastache mexicana were dried at different temperatures (22, 40, 50, 90, 100 and 180 °C) and the dry material was extracted with methanol by maceration to compare the content of the active constituent tilianin in the samples. Furthermore, EtOH:H₂O (7:3), infusion and decoction extracts were prepared from air-dried samples at room temperature to compare the content and composition of the different extraction methods. Moreover, an ex vivo vasorelaxant test on endothelium-intact aortic rat rings was conducted, in order to correlate the presence of tilianin with the activity of each extract.

Results

Higher concentration and amounts of tilianin were determined from chromatograms in the obtained methanolic extracts from plant material dried at 90, 50, 40 and 22 °C, followed by 100 °C; however, lower concentrations were observed in dried at 180 °C and EtOH:H₂O (7:3). It is worth to notice that methanolic extracts with higher amount of tilianin were the most potent vasorelaxant extracts, even though these extracts were less potent than carbachol, a positive control used. Finally, decoction, infusion and EtOH:H₂O (7:3) extracts did not show any vasorelaxant effect.

Conclusion

Results suggest that extracts with higher concentration of tilianin possess the best vasorelaxant activity, which allowed us to have a HPLC method for future quality control for this medicinal plant.     

Effect of Vaccinium bracteatum Thunb. leaves extract on blood glucose and plasma lipid levels in streptozotocin-induced diabetic mice

Aim of the study

To investigate the hypoglycemic effects of Vaccinium bracteatum Thunb. leaves (VBTL) extract in streptozotocin-induced diabetic mice.

Materials and methods

After administration of VBTL extract for 4 weeks, the body weight, organ weight, blood glucose (BG), insulin and plasma lipid levels of streptozotocin-induced diabetic mice were measured.

Results

Body weights of diabetic mice treated with VBTL extract were partly recovered. The BG levels of AEG (diabetic mice treated with VBTL aqueous extract) were reduced to 91.52 and 85.82% at week 2 and week 4, respectively (P < 0.05), while those of EEG (diabetic mice treated with VBTL ethanolic extract) were reduced slightly (P > 0.05). The insulin levels of AEG and EEG were obviously higher (P < 0.05) than those of MC (diabetic mice in model control group). Comparing with MC, AEG and EEG had significantly lower (P < 0.05) TC or TG levels and similar HDL-cholesterol or LDL-cholesterol levels. In comparison with non-diabetic control mice, AEG had similar plasma lipid levels except higher LDL-cholesterol level, while EEG had higher TC, TG and LDL-cholesterol levels and lower HDL-cholesterol levels.

Conclusions

Both aqueous and ethanolic extract of VBTL possess a potential hypoglycemic effect in streptozotocin-induced diabetic mice.     

Saponin rich fractions from Polygonatum odoratum (Mill.) Druce with more potential hypoglycemic effects

Aims

The root of Polygonatum odoratum (YuZhu), also a medicinal food has long been used for the treatment of diabetes. The objective of the study was to characterize the anti-diabetic active fractions or compounds in this herb.

Materials and methods

Fractions with a different polarity were prepared by solvent extraction and macroporous absorptive resin (D101) column and their anti-diabetic potentials were evaluated by glucose uptake in HepG2 cells and STZ-induced diabetic rats. In addition, α-glycosidase inhibitory activities of active fractions were measured in vitro and chemical compositions including saponin, total flavonoids and total sugar in the fractions were determined.

Results

The n-buthanol fraction, a saponin-rich fraction obtained by partitioning the ethanol extract with n-buthanol after petroleum ether and acetic ether showed the highest anti-diabetic potential in glucose uptake in HepG2 cells followed by acetic ether fraction which was rich in flavonoids. Further fractionation the saponin-rich fraction using macroporous resin column (D101), polysaccharide, flavonoid and saponin rich fractions were obtained by elution with water, 40% and 60% ethanol, respectively and their anti-diabetic potentials proved by glucose uptake test in HepG2 cells and STZ-induced diabetic rats were in the order of saponin rich fraction > flavonoid rich fraction > polysaccharide rich fraction. Long-term therapy test (60 d) in severe diabetic rats indicated that saponin-rich fraction significantly ameliorated clinical symptoms of diabetes including the elevated blood glucose, body weight loss as well as the increased food and water intake while flavonoid-rich fraction was more potential than saponin-rich fraction to increase superoxide dismutase (SOD) activity and decrease malondialdehyde (MDA) level in rat plasma. Additionally, saponin-rich fraction and flavonoid-rich fraction showed α-glycosidase inhibitory activity with IC₅₀ value of 2.05 ± 0.32 and 3.92 ± 0.65 mg/ml, respectively.

Conclusion

The results suggested that saponin in this herb was more important than flavonoid in exhibiting anti-diabetic activity and flavonoid contributed more to anti-oxidant activity in vivo.     

Hypoglycemic activity of Thai medicinal plants selected from the Thai/Lanna Medicinal Recipe Database MANOSROI II

Ethnopharmacological relevance

Five medicinal plants including Anogeissus acuminata (Roxb. ex DC.) Gills. & Perr. (Combretaceae), Catunaregam tormentosa (Bl. ex DC.) Tirveng (Rubiaceae), Dioecrescis erythroclada (Kurz) Tirveng. (Rubiaceae), Mimosa pudica Linn. var. hispida Bren. (Fabaceae), and Rauwolfia serpentina (L). Benth. ex Kurz. (Apocyanaceae), which have been traditionally used for the treatment of diabetes mellitus and other diseases for several generations by the Thai-Lanna people in the Northern part of Thailand were investigated for their hypoglycemic activity in normoglycemic and alloxan, induced diabetic mice.

Materials and methods

The aqueous extracts of the selected five medicinal plants were tested for their phytochemicals, free radical scavenging activity and hypoglycemic activity on 18 h fasted normoglycemic and alloxan induced diabetic mice over a period of 4 h comparing with the standard anti-diabetic drugs (insulin and glibenclamide) using two way analysis of variance (ANOVA) as analytical tool. Phytochemical analysis was performed using the standard methods while 2,2-diphenyl-1-picrylhydrazine (DPPH) was used to test for free radical scavenging activities of the medicinal plant extracts.

Results

Phytochemicals detected in the extracts were glycosides, xanthones, tannins, alkaloids and saponins. Anogeissus acuminata showed the highest free radical scavenging activity with the IC₅₀ value of 11.00 μg/mL which was 4 folds of the standard ascorbic acid. Significant reduction in fasting blood glucose (FBG) levels of the normoglycemic mice was observed at 4 and 3 h with the extracts of Mimosa pudica (200 mg/kg bw) and Rauwolfia serpentina (100 mg/kg bw), and percentage decreases of 46.15 and 27.94% which were 0.76 and 1.47; 0.53 and 0.91 folds of insulin and glibenclamide, respectively. In alloxan induced diabetic mice, all extracts showed significant (p < 0.05) hypoglycemic activity, with the maximum FBG reduction of 78.96 at 100 mg/kg bw shown by Anogeissus acuminata at the 4 h. The hypoglycemic activity of Anogeissus acuminata was comparable to insulin (1.1 fold), but more potent than glibenclamide (1.76 folds).

Conclusions

Medicinal plants selected from the Thai/Lanna Medicinal Plant Recipe Database MANOSROI II showed hypoglycemic activity in normoglycemic and alloxan induced diabetic mice. This study confirmed the traditional use of these medicinal plants for the treatment of diabetes mellitus and the thiazolidiendiones mimic hypoglycemic effects of the medicinal plants was suggested.     

Neuroprotective effects of Buyang Huanwu decoction against hydrogen peroxide induced oxidative injury in Schwann cells

Ethnopharmacological relevance

Buyang Huanwu decoction (BYHWD) is a traditional Chinese medicine and can be used to promote peripheral nerve regeneration. However the regenerative mechanism of BYHWD remains unclear. The objective of this study was to investigate the protective mechanisms of BYHWD in Schwann cells damaged by hydrogen peroxide (H₂O₂).

Materials and methods

Schwann cells which were derived from neonatal sciatic nerves of rats were used in subsequent experiments. Schwann cells were injured by various concentrations of H₂O₂ (0.25, 0.5 and 1 mM final concentration). BYHWD (600 μg/ml final concentration) was added to the medium either simultaneously or 1 h later after the addition of H₂O₂. Subsequently, methyl thiazolyl tetrazolium (MTT) assay was performed. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were also examined after 12 h. The expression of Caspase 3 and the concentration of intercellular Ca²⁺ ([Ca²⁺]i) were also determined.

Results

Among three concentrations of H₂O₂, 0.5 mM H₂O₂ induced Schwann cells swelled and neuritis disappeared after 12 h. In the presence of BYHWD, MTT assay showed that more cells were viable in comparison with the H₂O₂ injury group. Moreover, the addition of BYHWD has also increased the SOD activity with decreased in MDA level. Furthermore, the concentration of [Ca²⁺]i and expression of Caspase 3 were decreased with the addition of BYHWD in culture.

Conclusions

Our results revealed that BYHWD protected Schwann cells from oxidative injury. The mechanism of BYHWD promoting neural regeneration possibly associated with its anti-oxidative activity.     

Apoptotic activity of ethanol extract from Styrax Japonica Siebold et al Zuccarini in HepG2 cells

Ethnopharmacological relevance

Styrax japonica Siebold et al Zuccarini (SJSZ) has been used to heal inflammation and bronchitis as an herbal plant in Korea.

Aims of the study

The purpose of the present study is to determine whether the ethanol (EtOH) extract of SJSZ induces the programmed cell death (apoptosis) in human hepatoma HepG2 cells.

Materials and methods

It was evaluated cytotoxicity using MTT assay, amount of intracellular reactive oxygen species (iROS) and Ca²⁺ using fluorescence. Activities of apoptotic relevant factors [Bid, cytochrome c, caspase-9, -3, and poly-(ADP-ribose) polymerase (PARP)] were measured by Western blot.

Results

The results in this study indicated that ethanol extract of SJSZ (75 μg/ml) stimulates to increase amount of iROS, Ca²⁺, and the apoptotic relevant factors [Bid, cytochrome c, caspase-9, -3, and poly-(ADP-ribose) polymerase (PARP) in the HepG2 cells.

Conclusion

The results in this study indicated that ethanol extract of SJSZ (75 μg/ml) induces programmed cell death (apoptosis) in the HepG2 cells. Therefore, we speculate that ethanol extract of SJSZ could be used for healing of hepatocarcinoma as one of chemotherapeutic agents.     

Anti-diabetic activity and potential mechanism of total flavonoids of Selaginella tamariscina (Beauv.) Spring in rats induced by high fat diet and low dose STZ

Aim of the study

To evaluate the anti-diabetic effects of the total flavonoids of Selaginella tamariscina (Beauv.) Spring (TFST), and to explore the pertinent mechanism.

Materials and methods

High fat diet and STZ (35 mg/kg) induced diabetic rats were administered with TFST at graded oral doses (100, 200 and 400 mg/kg/day, ig.) for 8 weeks. A range of parameters, including blood glucose and lipid, serum insulin and glucagon, glucose tolerance, were tested to evaluate its anti-diabetic effects. The determination of protein expression of peroxisome proliferator activated receptor γ (PPAR-γ) in adipose tissue and insulin receptor substrate 1 (IRS-1) in hepatic and skeletal muscle tissues was used to study the mechanism of TFST. Moreover, the preliminary study of TFST on the antioxidant activity was performed.

Results

The TFST possessed anti-diabetic activities as shown by the decreased serum levels of fast blood glucose (FBG), glycosylated hemoglobulin A1C (HbA1c), triglyceride (TG), total cholesterol (TC), free fatty acid (FFA), low density lipoprotein-cholesterol (LDL-C) and glucagon, as well as increased serum levels of high density lipoprotein-cholesterol (HDL-C), insulin and C-peptide. TFST also improved the oral glucose tolerance test (OGTT) to a certain degree. Furthermore, TFST increased the protein expression of PPAR-γ in adipose tissue, and increased the protein expressions of IRS-1 in hepatic and skeletal muscle tissues. These benefits were associated with increased superoxide dismutase (SOD) and decreased malondialdehyde (MDA) in serum.

Conclusions

TFST exert beneficial effects on hyperglycosemia and hyperlipoidemia in diabetic rats possibly through regulating the levers of PPAR-γ in adipose tissue and IRS-1 in hepatic and skeletal muscle tissues.     

Evaluation of hypoglycemic activity of total lignans from Fructus Arctii in the spontaneously diabetic Goto-Kakizaki rats

Ethnopharmacological relevance

Fructus Arctii, called “Niubangzi” in China (Great burdock achene in English), is a well-known Chinese Materia Medica. It is the dried ripe fruit of Arctium lappa L. (family Asteraceae) and was included in the Chinese pharmacopoeia for its traditional therapeutic actions. Meanwhile it has been utilized extensively in a number of classical drug formulas as a major component for the treatment of noninsulin-dependent diabetes mellitus. It has also been reported recently that the clinical use of Fructus Arctii resulted in a satisfactory hypoglycemic effect in diabetic patients. The aim of this study was to investigate hypoglycemic activity of total lignans from Fructus Arctii (TLFA) in Goto-Kakizaki (GK) rats, a spontaneous type 2 diabetic animal model, and the mechanism of its hypoglycemic activity.

Materials and methods

Male GK rats and normal Wistar rats were used in this study, GK rats fed twice daily were given TLFA (300 mg/kg) or nateglinide (50 mg/kg) orally before each meal for 12 weeks. Besides common evaluation indexes of hypoglycemic activity such as blood glucose level, oral glucose tolerance test (OGTT), glycated hemoglobin, as well as lipid metabolism parameters such as cholesterol (CHOL), triglycerides (TG), et al., in rat serum. The effects of TLFA on insulin secretion and pancreas tissue sections, the levels of serum glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and the α-glucosidase inhibitory activity of TLFA in vitro were investigated.

Results

TLFA demonstrated stable and long-lasting hypoglycemic activity in GK rats and showed significant improvement in glucose tolerance in glucose fed hyperglycemic GK rats. Both TLFA and nateglinide controlled the glycosylated hemoglobin levels of the experimental animals very well. Stimulation of insulin secretion was proved to be one of the hypoglycemic mechanism of TLFA, promoting the release of GLP-1 should be another one, and ɑ-glucosidase inhibitory activity of TLFA also contributes to its hypoglycemic activity. In this study, we didn't found that TLFA could effect the body weight of GK rats, which was also verified by the changes of biochemical parameters of blood in experimental rats.

Conclusion

The results of this study indicates that TLFA has significant hypoglycemic potential in GK rats, and it may be acting through stimulating insulin secretion, promoting the release of GLP-1, and decreasing intestinal absorption of glucose.     

Comparative biological study of roots,stems, leaves,and seeds of Angelica shikokiana Makino

Ethnopharmacological relevance

Angelica shikokiana has been used as a health food for its anticancer, anti-inflammatory, antibacterial, antiallergic, and blood vessel dilating effects in Japan. It can also be used to prevent and treat hepatitis, diabetes, hyperlipidemia, and arteriosclerosis.

Aim of the study

The present study was designed to compare the biological activities such as melanin synthesis inhibitory, anti-allergy, anti-lipase, anti-bacterial, anti-oxidant, and neuroprotective activities of different parts of the plant that may justify the use of this plant in folk medicine.

Material and methods

The roots, stems, leaves and, seeds of Angelica shikokiana were separately extracted with water and ethanol. Each extract was examined for melanin synthesis inhibitory and anti-allergy activity on B16-melanoma and RBL-2H3 cells using IgE and A23187 as a stimulant for β-hexosaminidase release, respectively. We also evaluated the inhibition of two enzymes, lipase and acetylcholine esterase, and of the bacterial growth of two species, Escherichia coli and Staphylococcus aureaus. The anti-oxidant activity was determined using oxygen radical anti-oxidant capacity, ORAC assay and its relation to the phenolic content was estimated using the Folin–Ciocalteu method. Besides, the protective effect of the extracts against H₂O₂-induced oxidative stress in mouse neuroblastoma, Neuro-2A cells was investigated.

Results

The most active extract exhibiting melanin synthesis inhibition (63%) and at the same time with low cytotoxicity (15%) was the ethanol extract of roots at 20 µg/ml, followed by the ethanol extract of stems (57% inhibition, 5% cytotoxicity). On the other hand, the highest inhibitions of β-hexosaminidase release were recorded for the ethanol extract of leaves with IC₅₀ value of 6.89 µg/ml followed by the water extract of the seeds and leaves with IC₅₀ value of 78.32 and 88.44 µg/ml, respectively. For anti-lipase assay, ethanol extracts of the stems and roots showed the strongest inhibition with IC₅₀ values of 204.06 and 216.24 µg/ml, respectively. None of the examined extracts showed any activity against Escherichia coli. while the ethanol extract of the roots and stems showed moderate inhibition for Staphylococcus aureus with minimum inhibitory concentration of 400 µg/ml. Ethanol extract of the roots showed only 30% inhibition of acetylcholine esterase enzyme. The results of anti-oxidant, phenolic content and protective effect against H₂O₂-induced cytotoxicity assays showed highly correlated data. Ethanol extract of the stems (ORAC value of 1.08 µmol Trolox/ mg and phenolic content 44.25 μg GAE/mg) increased the cell viability of H₂O₂-treated Neuro-2A cells by 28%.     

Anti-hyperglycemic effect of Opuntia streptacantha Lem

Aim of the study

This experiment studied two extracts of Opuntia streptacantha, a plant used by the Mexican population to treat type 2 diabetes, in different assays to contribute to the understanding of the hypoglycemic mechanism of this plant.

Materials and methods

Two different extracts were prepared and tested: the first extract was a filtrate of the traditional liquefied extract (LE) preparation of the cladode; and the second filtrate extract (FE) is a filtered sample of the first. Both extracts contained a newly identified compound for Opuntia (4-hydroxy)-phenyl acetic acid derivate, they were tested on streptozotocin (STZ)-diabetic rats in a series of two tests. The first test was performed to confirm if STZ-diabetic rats presented a hypoglycemic effect after administration of the extracts (LE 135 mg/kg and FE 27 mg/kg). In the second experiment, the extracts were administered before an oral glucose tolerance test (OGTT) to confirm if they have an anti-hyperglycemic effect (LE 135 mg/kg, FE 12 and 27 mg/kg).

Results

The extracts administered to STZ-diabetic rats did not produce a significant hypoglycemic effect compared to the control group, while the same extracts administered before an OGTT produced an anti-hyperglycemic effect compared to the control group.

Conclusions

The filtered, traditional LE of the cladode of Opuntia streptacantha produces an anti-hyperglycemic effect when administered before a glucose challenge, and this anti-hyperglycemic effect is maintained after filtering the extract.Administration of both plants can improve glycemic control by blocking the hepatic glucose output, especially in the fasting state. These data support the traditional use of the plants as “agua de uso”, a cold infusion of the plant consumed over the course of a day.     

Phaleria macrocarpa (Scheff.) Boerl fruit aqueous extract enhances LDL receptor and PCSK9 expression in vivo and in vitro

Ethnopharmacological relevance

Phaleria macrocarpa (Scheff.) Boerl (Pm) has been shown to reduce cholesterol level in vitro and in vivo experiment.

Aim of the study

This study investigated the effects of Pm fruit on weight control and mechanistic basis of its anti-hypercholesterolemic effect in both in vivo and in vitro.

Materials and method

In the in vivo study, thirty six male Sprague Dawley were randomized to six groups. Five groups were induced into hypercholesterolemia by giving 3% cholesterol enriched-diet for 52 days while one group acted as control. The rats were then treated with Pm extract (0, 20, 30 and 40 mg/ml) or simvastatin for 84 days. The following parameters were determined: (1) body weight, (2) blood lipid profile (total cholesterol, triglyceride, HDL and LDL) and (3) hepatic LDL receptor (160 kDa and 120 kDa) and PCSK9 proteins. In the in vitro study, HepG2 cells were cultured in serum-free RPMI supplemented with 0.2% BSA with or without LDL and in the presence of Pm extract (0, 0.1, 2, 40 and 1000 μg/ml) or simvastatin (4.60 μg/ml) for 24 h. The abundance of both LDL receptor and PCSK9 proteins and mRNA were investigated.

Results

Pm extract significantly (P < 0.05) reduced body weight gain, total cholesterol, triglycerides, HDL LDL levels and upregulated hepatic LDL receptor as well as PCSK9 proteins of hypercholesterolemic rats. These results were supported by studies in HepG2 cells whereby Pm extract also significantly upregulated both LDL receptor and PCSK9 at protein and mRNA levels.

Conclusion

This study enhances the potential usage of Pm fruit for controlling the body weight of obese people and for treating hypercholesterolemia.     

Anti-inflammatory and analgesic activity of different extracts of Commiphora myrrha

Aim of the study

This present study was carried out to evaluate the anti-inflammatory and analgesic effects of 85% ethanol extract (EE) of Commiphora myrrha and its different fractions partitioned with petroleum ether extract (EPE), ethyl acetate extract (EEA), n-butanol extract (EBu), and the water extract (ECY). Moreover, the chemical constituents in EPE were analyzed and identified by UPLC-QTOF/MS/MS.

Materials and methods

The anti-inflammatory activities were investigated by utilizing the paw edema mice induced by formalin. In addition, we determined the levels of PGE₂ in the edema paw. While the analgesic activity was examined against thermally and chemically induced nociceptive pain in mice, using the acetic acid and hot-plate test methods. The effects of the administration of dolantin or indomethacin were also studied for references. The components in EPE were analyzed by the ultra-performance liquid chromatography coupled with mass spectrum.

Results

In the anti-inflammatory test, EE inhibited the development of paw swelling induced by formalin significantly. The pharmacological activities of the petroleum ether fraction (EPE) were stronger than the EE extract and other fractions at the dose of 100 mg/kg, and furthermore significantly decreased the levels of inflammatory factor PGE₂ in the edema paw tissue at the fourth hour after formalin injection. It has been also shown that the ethanol extract (EE) significantly reduced acetic acid-induced writhing response in mice at the dose of 200 mg/kg, and 100 mg/kg. The petroleum ether fraction (EPE) showed significant analgesic activity in the model at the dose of 100 mg/kg (p < 0.01), and the ethyl acetate fraction (EEA) exhibited less analgesic activity (p < 0.05). All test samples showed no significant analgesic activity on the hot plate pain threshold in mice. The UPLC-MS/MS chromatogram analysis of EPE stated that EPE contains the ingredients of sesquiterpenes, diterpenes, and diterpenic acids. Moreover, seven main compounds were identified.

Conclusion

These data demonstrated that the EE and EPE posses analgesic and anti-inflammatory activities and may support the fact the traditional application of this herb in treating various diseases associated with inflammatory pain.     

Antibacterial, antioxidant and fibroblast growth stimulation activity of crude extracts of Bridelia ferruginea leaf, a wound-healing plant of Nigeria

Aim of the study

Determination of pharmacological activity relevant to wound healing of Bridelia ferruginea leaf, a traditional medicine used to treat wounds in rural Nigeria.

Materials and methods

Aqueous and ethanolic leaf extracts were tested against bacterial species of relevance to wound infections: Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The ethanolic extracts were assessed for their ability to stimulate the growth of human dermal fibroblasts (FS5) and protect against damage induced by hydrogen peroxide. Antioxidant activity was also assessed using the DPPH assay.

Results

Both aqueous and ethanolic extracts had weak antibacterial activity (MIC > 470 μg/ml). A significant effect (p < 0.001) on the growth of FS5 fibroblasts was observed only at a concentration of 5 μg/ml (28% increase), above which the extracts appeared toxic to the cells. The ethanolic extract offered the highest protection against H₂O₂ damage to FS5 cells, comparable with catalase (82% at 250 μg/ml). The DPPH assay revealed antioxidant activity of the ethanolic leaf extract with IC₅₀ 12.5 ± 0.3 μg/ml comparable to l-ascorbic acid (7.3 ± 0.1 μg/ml).

Conclusion

The antibacterial, modest fibroblast stimulation activity and relatively strong antioxidant activity lend some support to the topical use of Bridelia ferruginea leaf for wound-healing in the traditional medicine of South-western Nigeria.     

The hypoglycemic activity of Lithocarpus polystachyus Rehd. leaves in the experimental hyperglycemic rats

Ethnopharmacological relevance

Leaves of Lithocarpus polystachyus Rehd. are used for the treatment of disorders such as diabetes, hypertension, and epilepsy in folk medicine of South China. The possible antidiabetic effects of the leaves were investigated in experimental type 2 and type 1 diabetic rats.

Materials and methods

Type 2 diabetic rats received orally three different extracts of Lithocarpus polystachyus Rehd. leaves for 4 weeks (aqueous extract [ST-1], ethanol extract [ST-2], flavonoid-rich fraction [ST-3]). At the end of the experiment biochemical parameters were tested and livers and pancreases were excised for histological study. After the comparison of the pharmacological test results of the three extracts, the one which showed the best bioactivity was further studied to confirm its antidiabetes effect on both type 2 and type 1 diabetic rats.

Results

Compared to ST-1 and ST-2, ST-3 had better effects on regulation of blood glucose, glycosylated serum protein, cholesterol, triglyceride, malondialdehyde, superoxide dismutase and attenuation of liver injury in type 2 diabetic rats (p < 0.01 or p < 0.05). ST-3 administration for four weeks also significantly reduced the fasting serum insulin and C-peptide level and improved the insulin tolerance (p < 0.05). In type 1 diabetic rats, ST-3 supplement for three weeks caused significant reduction in fasting blood glucose, total cholesterol, triglyceride, urea nitrogen, creatinine and liver mass, along with significantly inhibiting the decline of insulin level compared to diabetic control (p < 0.05 or p < 0.01).

Conclusion

The flavonoid-rich fraction of Lithocarpus polystachyus Rehd. leaves (ST-3) had better beneficial effect than that of the ethanol or aqueous extract in experimental diabetic rats, which means that the bioactivity of the herbal leaves is probably due to the presence of flavonoids. The results also strongly suggest that the antidiabetic effect of ST-3 was possibly through multiple mechanisms of action including blood lipid and antioxidant mediation. The results indicated that the aqueous flavonoid-rich fraction of Lithocarpus polystachyus Rehd. leaves possessed significant protective activity in type 2 and type 1 diabetes.     

Actions of Artemisia vulgaris extracts and isolated sesquiterpene lactones against receptors mediating contraction of guinea pig ileum and trachea

Aim of the study

The present study evaluates the Philippine medicinal plant Artemisia vulgaris for antagonistic activity at selected biogenic amine receptors on smooth muscle of the airways and gastrointestinal tract in order to explain its traditional use in asthma and hyperactive gut.

Materials and methods

The antagonistic activity of chloroform crude extract (AV-CHCl₃) and methanol crude extract (AV-MeOH) of Artemisia vulgaris was studied against concentration-response curves for contractions of the guinea pig ileum and trachea to 5-hydroxytrptamine (5-HT₂ receptors), methacholine (M₃ muscarinic receptors), histamine (H₁ receptors) and β-phenylethylamine (trace amine-associated receptors, TAAR1).

Results and discussion

The Artemisia vulgaris chloroform (AV-CHCl₃) and methanol (AV-MeOH) extract showed histamine H1 antagonism in the ileum and trachea. Further analysis of AV-CHCl₃ isolated two major components, yomogin and 1,2,3,4-diepoxy-11(13)-eudesmen-12,8-olide. Yomogin, a sesquiterpene lactone, exhibited a novel histamine H1 receptor antagonism in the ileum.

Conclusion

The presence of a specific, competitive histamine receptor antagonist and smooth muscle relaxant activity in Artemisia vulgaris extracts on the smooth muscle in ileum and trachea explains its traditional use in the treatment of asthma and hyperactive gut.     

Hypoglycemic and hypolipidemic effects of Coriandrum sativum L. in Meriones shawi rats

Ethnopharmacological relevance

The use of an aqueous extract of coriander (Coriandrum sativum L.; Apiaceae, Umbelliferae) seeds (CS-extract) in Moroccan traditional treatment of diabetes remains to be experimentally validated.

Aim of the study

The study aim was to investigate potential hypoglycemic (and hypolipidemic) activity of CS-extract after a single oral dose and after daily dosing for 30 days (sub-chronic study) in normal and obese-hyperglycemic-hyperlipidemic (OHH) Meriones shawi rats.

Materials and methods

After a single oral dose of CS-extract (20 mg/kg; predetermined as optimum), plasma glucose, insulin, total cholesterol (TC), and triglycerides (TG) were measured in normal and OHH rats (hypercaloric diet and forced limited physical activity); glibenclamide (GLB; 2.5 mg/kg) was used as reference. In the sub-chronic study, the effect of CS-extract and GLB (at the above doses) on body weight (BW), plasma glucose, insulin, TC, LDL-cholesterol, HDL-cholesterol, TG, urea and creatinine was determined in normal and OHH rats; insulin resistance (IR as HOMA-IR), atherosclerotic and cardioprotective indices were calculated.

Results

A single dose of CS-extract or GLB suppressed hyperglycemia in OHH rats, and normo-glycemia was achieved at 6-h post-dose; there was no effect on lipids, TG or insulin, but IR decreased significantly. The hypoglycemic effect was lower in normal rats. In the sub-chronic study in OHH rats, the test substances (CS-extract > GLB) reduced plasma glucose (normoglycemia on Day 21), insulin and IR, TC, LDL-cholesterol, and TG. Atherosclerotic index decreased while cardioprotective indices increased only by CS-extract, with no effect on BW, urea or creatinine.

Conclusion

Sub-chronic administration of CS-extract in OHH Meriones shawi rats normalized glycemia and decreased the elevated levels of insulin, IR, TC, LDL-cholesterol and TG. Since, the CS-extract decreased several components of the metabolic syndrome and decreased atherosclerotic and increased cardioprotective indices, CS-extract may have cardiovascular protective effect. The present study validates the traditional use of coriander in diabetes.     

Bioassay-guided isolation of neuroprotective compounds from Loranthus parasiticus against H₂O₂-induced oxidative damage in NG108-15 cells

Ethnopharmacological relevance

A parasite plant, Loranthus parasiticus (Loranthaceae), which is generally known as benalu teh (in Malay), Sang Ji Sheng (in Chinese), and baso-kisei (in Japan) distributed in south and southwest part of China, has been used as a folk medicine for the treatment of schizophrenia in southwest China. Loranthus parasiticus has various uses in folk and traditional medicines for bone, brain, kidney, liver, expels wind-damp, and prevents miscarriage.

Aim of the study

The current study was designed to evaluate the neuroprotective activity of Loranthus parasiticus against hydrogen peroxide (H₂O₂)-induced oxidative damage in NG108-15 hybridoma cells, so as to present evidence for the traditional use of this parasite plant in the treatment of oxidative stress related neurodegenerative diseases.

Materials and methods

Dried and ground leaves of Loranthus parasiticus were extracted and fractionated into Loranthus parasiticus ethanol extract (LPEE), Loranthus parasiticus ethyl acetate fraction (LPEAF), and Loranthus parasiticus aqueous fraction (LPAF), which were subjected to neuroprotective activity assessment by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay. Bioassay-guided fractionation and isolation was performed subsequently to identify the most neuroactive compound. Mechanism studies underlying the present neuroprotection model of the isolated neuroactive compound was evaluated by employing 2,7-dichlorofluorescein diacetate (DCFH-DA) for intracellular reactive oxygen species (ROS) measurement, annexin V/propidium iodide (PI) for translocation of membrane phosphatidyleserine to identify cells undergo apoptosis, 5,5′,6,6′-tetrachloro-1,1′,3,3′ tetraethylbenzimidazolylcarbocyanine iodide (JC-1) for mitochondrial membrane potential (MMP) detection, and PI for cell cycle events analysis.

Results

Among those tested extract and fractions (LPEE, LPEAF, and LPAF) in our previous screening, LPAF significantly (P < 0.01) yielded the highest neuroprotective activity with 78.00 ± 1.85% cell viability in a dose dependent manner, supporting a neuroprotective role for LPAF in vitro. AC trimer and (+)-catechin have been isolated from LPAF successfully through bioassay-guided fractionation and isolation approach and (+)-catechin exhibited stronger neuroprotective activity as compared with AC trimer. (+)-Catechin increased cell viability and decreased the level of intracellular reactive oxygen species (ROS) in a dose-dependent manner against H₂O₂-induced oxidative stress in NG108-15 cells. Moreover, (+)-catechin reduced total annexin V positive cells (early and late apoptotic cells), attenuated the collapsed of MMP, and inhibited cell cycle arrested at sub-G₁ population following H₂O₂ insult.

Conclusion

Collectively, the use of Loranthus parasiticus as folk medicine in the treatment of mental disorder was attributed to the presence of proanthocyanidins in this parasite plant. These findings support the traditional use of Loranthus parasiticus which is capable in managing neurological disorder where oxidative stress is implicated.     

Tracheal relaxation of five Ivorian anti-asthmatic plants: role of epithelium and K⁺ channels in the effect of the aqueous-alcoholic extract of Dichrostachys cinerea root bark

Ethnopharmacological relevance

Leaves of Boerhavia diffusa (Nyctaginaceae), Baphia nitida, Cassia occidentalis, Desmodium adscendens (Fabaceae), and root bark of Dichrostachys cinerea (Fabaceae) are used in Ivory Coast for the treatment of asthma. The aim of this study was to evaluate the potential airway relaxant activity of different extracts of these plants.

Materials and methods

Extracts of different polarities (H₂O, EtOH/H₂O, MeOH and CH₂Cl₂) were obtained from these five plants. Their ex vivo relaxant activity was tested in mice isolated trachea precontracted with carbachol (1 μM).

Results

Cumulative concentrations of most extracts induced moderate to strong relaxation, the methanolic extracts being the most potent and the polar extracts the most active at the concentrations used, supporting the traditional use of these five plants as anti-asthmatic remedies. We further investigated the molecular and cellular mechanisms of the mouse trachea relaxant effect of the aqueous-alcoholic extract of Dichrostachys cinerea root bark, the most potent extract. Its effect was not modified in the presence of β-adrenoceptor antagonists (propranolol or ICI 118,551) or a PKA inhibitor (H89). By contrast, it was decreased after depolarization-induced precontraction (with 80 mM KCl), in the presence of some K⁺ channels blockers [4-aminopyridine as voltage-dependent K⁺ (K_v) channel blocker and tetraethylammonium chloride as large conductance Ca²⁺-activated K⁺ (BK_Ca) channel blocker, but not with glibenclamide, an ATP-sensitive K⁺ (K_ATP) channel blocker] or after epithelium removal.

Conclusions

The mouse tracheal relaxant effect of Dichrostachys cinerea EtOH/H₂O extract was independent of β₂-adrenoceptors activation and cAMP/PKA pathway, but dependent on epithelium and K⁺ channels, namely K_v and BK_Ca channels. Further investigation will be required to identify the component(s) responsible for this airways relaxant activity.