A Lanosteryl Triterpene from Protorhus longifolia Improves Glucose Tolerance and Pancreatic Beta Cell Ultrastructure in Type 2 Diabetic Rats.

Type 2 diabetes remains one of the leading causes of death worldwide. Persistent hyperglycemia within a diabetic state is implicated in the generation of oxidative stress and aggravated inflammation that is responsible for accelerated modification of pancreatic beta cell structure. Here we investigated whether a lanosteryl triterpene, methyl-3ß-hydroxylanosta-9,24-dien-21-oate (RA-3), isolated from Protorhus longifolia can improve glucose tolerance and pancreatic beta cell ultrastructure by reducing oxidative stress and inflammation in high fat diet and streptozotocin-induced type 2 diabetes in rats. In addition to impaired glucose tolerance, the untreated diabetic rats showed increased fasting plasma glucose and C-peptide levels. These untreated diabetic rats further demonstrated raised cholesterol, interleukin-6 (IL-6), and lipid peroxidation levels as well as a destroyed beta cell ultrastructure. Treatment with RA-3 was as effective as metformin in improving glucose tolerance and antioxidant effect in the diabetic rats. Interestingly, RA-3 displayed a slightly more enhanced effect than metformin in reducing elevated IL-6 levels and in improving beta cell ultrastructure. Although the involved molecular mechanisms remain to be established, RA-3 demonstrates a strong potential to improve pancreatic beta cell ultrastructure by attenuating impaired glucose tolerance, reducing oxidative stress and inflammation.

Testicular Dysfunction Ameliorative Effect of the Methanolic Roots Extracts of Maytenus procumbens and Ozoroa paniculosa.

The traditional use of medicinal plants in the management of sexual dysfunctions has a long history. This study investigated testicular dysfunction ameliorative effect of the methanolic roots extracts of Maytenus procumbens and Ozoroa paniculosa in a butanol-induced testicular dysfunction rat model. The rats in respective experimental groups were orally administered with the extract at 50 and 250 mg/kg bw, daily for 28 days. The cytotoxicity of the extracts was evaluated against HEK293, MCF-7, and HT29 cell lines. The extracts exhibited moderate (LC50 30.3-330.2 µg/mL) to weak (LC50 200.8-438.4 µg/mL) cytotoxicity level on the cancer and normal cells, respectively. While relatively lower serum testosterone levels and total sperm count along with decreased numbers of spermatogonia were noted in the untreated group, all these parameters were improved in the groups treated with the extracts at 250 mg/kg. Improved histomorphological changes of the testes were also observed when compared to the untreated group. While the extracts (at 250 mg/kg) increased serum reduced glutathione content and decreased malondialdehyde content, a relatively higher serum creatinine level was also observed in the treated animals group. The results indicate that the two plant extracts have potential to ameliorate testicular dysfunction.

Cardioprotective potential of a lanosteryl triterpene from Protorhus longifolia.

CONTEXT: The current rapid increase in the incidence of cardiovascular events indicates a need for the discovery of more effective cardioprotective agents. OBJECTIVE: This study evaluated the cardioprotective potential of a lanosteryl triterpene from Protorhus longifolia (Benrh.) Engl. stem bark. MATERIALS AND METHODS: Spectroscopic data analysis was used to confirm the structure of methyl-3ß-hydroxylanosta-9, 24-dien-21-oate (RA-3). The cardioprotective effect of RA-3 in isoproterenol-induced myocardial injury in hyperlipidemic rats was investigated. Rats were divided into the normal diet (ND) fed and high fat diet (HFD) fed groups. The HFD rats were further subdivided into three groups. The experimental group was orally administered with RA-3 (100 mg/kg) for 15 days. The rats were then injected with isoproterenol (85 mg/kg) to induce myocardial injury. At the end of the experiment, hearts and blood tissues were collected and used for histology and biochemical assays, respectively. RESULTS: RA-3 exhibited a cardioprotective effect as it minimized myocardial injury in HFD rats. Few lesions of acute hyaline degeneration and reduced fat deposition were observed in the heart tissue of the triterpene pretreated rats. Lactate dehydrogenase (LDH) activity was decreased in the blood of the RA-3 pretreated rats (44.1 mU/mL) compared to the untreated group (64.8 mU/mL). Increased glutathione (GSH) content and catalase (CAT) activity along with lower levels of malondialdehyde (MDA) in the triterpene pretreated animals (120.8 nmol/µL) than in the non-treated HFD fed rats (143.6 nmol/µL) were also observed. DISCUSSION AND CONCLUSION: The cardioprotective effect exhibited by RA-3 indicates its potential use in the management of cardiovascular diseases (CVD) and related health problems.

In vivo antihyperglycemic activity of a lanosteryl triterpene from Protorhus longifolia.

Control of postprandial hyperglycemia is crucial in the management of diabetes mellitus. Despite the use of the current hypoglycemic drugs, incidence of diabetes and related diseases continue to increase. This study aimed at evaluating the in vivo antihyperglycemic activity of methyl-3ß-hydroxylanosta-9,24-dien-21-oate (RA-3), a lanosteryl triterpene isolated, and characterized from Protorhus longifolia stem bark. Spectroscopic data analysis was used to establish and verify the structure of the triterpene. The antihyperglycemic activity of the triterpene was evaluated in an STZ-induced diabetes rat model. The experimental animals were orally administered with RA-3 (100 mg/kg body weight) daily for 14 days. An oral glucose tolerance test was also performed. The animals were euthanized and biochemical analysis of antioxidant status, some glycolytic enzymes and glycogen content were conducted on serum and liver samples, respectively. RA-3 exhibited hypoglycemic activity by reducing blood glucose levels by 37%. The triterpene also improved glucose tolerance in the diabetic rats. Relatively higher hepatic glycogen content, hexokinase and glucokinase activity with a decrease in glucose-6-phosphatase activity were observed in the triterpene-treated diabetic group when compared with the diabetic control group. The triterpene treatment further increased antioxidant status of the diabetic animals; increased activity of superoxide dismutase and catalase were observed along with a decrease in malondialdehyde content. The results indicate potential pharmaceutical effects of lanosteryl triterpene in the management of diabetes mellitus.

Evaluation of the anti-Listeria potentials of some plant-derived triterpenes.

BACKGROUND: Listeriosis is a fatal disease caused by pathogenic Listeria bacteria and it is most prevalent in immune-compromised individuals. The increase in numbers of immune-compromised individuals against a background of Listeria antibiotic resistance, limits listeriosis treatment options. This therefore calls for research into substitute treatments, of which, medicinal plants derived compounds offer a viable alternative. METHODS: The broth microdilution assay was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of three plant triterpenes namely 3ß-hydroxylanosta-9,24-dien-21-oic acid, methyl-3ß-hydroxylanosta-9,24-dien-21-oate and 3ß-acetylursolic acid, against Listeria monocytogenes, Listeria ivanovii and Listeria grayi species. The chequerboard method was used to assess the interactions between the triterpenes and conventional antibiotics: ampicillin, neomycin, gentamicin and penicillin G. The lactate dehydrogenase membrane damage method was used to assess the triterpenes' membrane damaging potentials against the Listeria bacteria. RESULTS: The triterpenes' MIC values were found to range from 0.185 to 1.67 mg/ml while, the MBC determination assay results revealed that the test triterpenes were bacteriostatic against the Listeria bacteria. The interactions involving 3ß-hydroxylanosta-9,24-dien-21-oic acid were mainly additive with ampicillin and synergistic with neomycin, gentamicin and penicillin G. The interactions involving methyl-3ß-hydroxylanosta-9,24-dien-21-oate were mainly antagonistic with ampicillin, indifferent with neomycin, ranging from synergistic to indifference with gentamicin and synergistic with penicillin G. The interactions involving 3ß-acetylursolic acid were mainly indifferent with ampicillin, synergistic with neomycin and gentamicin while ranging between synergistic and additive with penicillin G. The low levels of cytosolic lactate dehydrogenase released from the cells treated with 4× MIC concentration of the triterpenes in comparison to that of cells treated with 3% Triton X-100 proved that membrane damage was not the mode of action of the triterpenes. CONCLUSION: This study therefore shows the potential that these plant triterpenes have in listeriosis chemotherapy especially as shown by the favourable interactions they had with penicillin G, one of the antibiotics of choice in listeriosis treatment.

In vitro antilisterial properties of crude methanol extracts of Garcinia kola (Heckel) seeds.

Crude methanol extracts of Garcinia kola (Heckel) seeds were screened for their antilisterial activities against 42 Listeria bacteria isolated from wastewater effluents. The extract had activity against 45% of the test bacteria and achieved minimum inhibitory concentrations (MICs) ranging between 0.157 and 0.625 mg/mL. The rate of kill of the extract was determined against four representative Listeria species in the study, and the results showed that the highest percentage of bacteria cells were killed after the maximum exposure time of 2 h at the highest concentration of 4 × MIC value, with the maximum number of bacteria cells killed being for L. ivanovii (LEL 30) 100%, L. monocytogenes (LAL 8) 94.686%, L. ivanovii (LEL 18) 60.330%, and L. grayi (LAL 15) 56.071% We therefore conclude that the nature of inhibition of the crude methanol extracts of Garcinia kola seeds can be either bactericidal or bacteriostatic depending on the target Listeria species and can also differ among same species as evidenced by L. ivanovii strains LEL 30 and LEL 18.

In vitro anti-listerial activities of crude n-hexane and aqueous extracts of Garcinia kola (heckel) seeds.

We assessed the anti-Listerial activities of crude n-hexane and aqueous extracts of Garcinia kola seeds against a panel of 42 Listeria isolates previously isolated from wastewater effluents in the Eastern Cape Province of South Africa and belonging to Listeria monocytogenes, Listeria grayi and Listeria ivanovii species. The n-hexane fraction was active against 45% of the test bacteria with zones of inhibition ranging between 8-17 mm, while the aqueous fraction was active against 29% with zones of inhibition ranging between 8-11 mm. The minimum inhibitory concentrations (MIC) were within the ranges of 0.079-0.625 mg/mL for the n-hexane extract and 10 to >10 mg/mL for the aqueous extract. The rate of kill experiment carried out for the n-hexane extract only, revealed complete elimination of the initial bacterial population for L. grayi (LAL 15) at 3× and 4× MIC after 90 and 60 min; L. monocytogenes (LAL 8) at 3× and 4× MIC after 60 and 15 min; L. ivanovii (LEL 18) at 3× and 4× MIC after 120 and 15 min; L. ivanovii (LEL 30) at 2, 3 and 4× MIC values after 105, 90 and 15 min exposure time respectively. The rate of kill activities were time- and concentration-dependant and the extract proved to be bactericidal as it achieved a more than 3log(10) decrease in viable cell counts after 2 h exposure time for all of the four test organisms at 3× and 4× MIC values. The results therefore show the potential presence of anti-Listerial compounds in Garcinia kola seeds that can be exploited in effective anti-Listerial chemotherapy.

In-vitro antagonistic characteristics of crude aqueous and methanolic extracts of Garcinia kola (Heckel) seeds against some Vibrio bacteria.

The methanolic and aqueous extracts of Garcinia kola seeds were screened for their anti-Vibrio activities against 50 Vibrio isolates obtained from wastewater final effluents in the Eastern Cape Province, South Africa. The crude extracts at 10 mg/mL exhibited appreciable inhibitory activities against most of the test Vibrio isolates, with zones of inhibition ranging from 10-19 mm for methanol extract and 8-15 mm for the aqueous extracts. The minimum inhibitory concentrations (MIC) of the methanol extract varied from 0.313 to 2.5 mg/mL while that for the aqueous extract was 10 mg/mL for all the susceptible Vibrio isolates. Rate of kill assay of the methanolic extracts against three selected Vibrio species showed bacteriostatic activities against all of them achieving 58% and 60% (Vibrio vulnificus AL042); 68% and 69% (Vibrio parahaemolyticus AL049); and 70% and 78% (Vibrio fluvialis AL040) killing of the test bacteria at 3× and 4 ×MIC values, respectively, after 2 h exposure time. We conclude that Garcinia kola seeds hold promise as a potential source of therapeutic compounds of relevance in Vibrio infections management.