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Anti-hyperglycemic and Anti-hypercholesterolemicEffects of Aloe vera Leaf Gel in Hyperlipidemic Type 2Diabetic Patients: A Randomized Double-Blind Placebo-Controlled Clinical Trial Hasan Fallah Huseini1, Saeed Kianbakht1, Reza Hajiaghaee2, Fataneh Hashem Dabaghian3 1 Department of Pharmacology and Applied Medicine, Research Institute of Medicinal Plants, ACECR, Karaj, Iran2 Department of Pharmacognosy and Pharmacy, Research Institute of Medicinal Plants, ACECR, Karaj, Iran3 Research Institute for Islamic and Complementary Medicine, Tehran University of Medical Sciences, Tehran, Iran drugs in treatment of 30 patients were evaluated Diabetes mellitus type 2 with dyslipidemia is a and compared with the placebo group (n = 30).
common disease. Previous studies suggest that The aloe gel lowered the fasting blood glucose, aloe (Aloe vera L.) leaf gel may positively affect HbA1c, total cholesterol, and LDL levels signifi- the blood glucose and lipid levels in dyslipidemic type 2 diabetic patients. Thus, in this randomized p = 0.004, respectively) without any significant ef- fects on the other blood lipid levels and liver/kid- with hyperlipidemic (hypercholesterolemic and/ ney function tests (p > 0.05) compared with the or hypertriglyceridemic) type 2 diabetic patients placebo at the endpoint. No adverse effects were aged 40 to 60 years not using other anti-hyper- reported. The results suggest that aloe gel may be lipidemic agents and resistant to daily intake of a safe anti-hyperglycemic and anti-hypercholes- two 5 mg glyburide tablets and two 500 mg met- terolemic agent for hyperlipidemic type 2 diabet- formin tablets, the efficacy and safety of taking aloe gel (one 300 mg capsule every 12 hours for 2 rently, there is renewed interest in the plant- based medicines and functional foods modulating Type 2 diabetes mellitus (T2DM) is common physiological effects in the prevention and cure of Downloaded by: Tel Aviv University. Copyrighted material.
worldwide [1]. Type 2 diabetic patients frequently diabetes. The plant kingdom is a wide field to have dyslipidemia [increased low-density lipo- search for natural effective oral anti-hyperglyce- mic agents that have slight or no side effects.
(VLDL) and triglycerides, and decreased high- More than about 1200 plant species have been re- density lipoprotein (HDL)]. The lipid changes are corded to be used empirically for their alleged attributed to increased free fatty acid flux second- anti-hyperglycemic activity [12]. Aloe (Aloe vera ary to insulin resistance. Dyslipidemia is one of L., Liliaceae family) is a popular traditional reme- the major risk factors for premature cardiovascu- dy for numerous diseases such as diabetes melli- lar morbidity and mortality in the T2DM patients tus in several cultures [13, 14]. A variety of phar- [2, 3]. Multiple anti-hyperglycemic and anti-hy- macological effects have been demonstrated for perlipidemic drugs with different mechanisms aloe leaf preparations [13]. For example, aloe gel are often needed for effective treatment of hyper- lowered the blood triglycerides level in a mouse lipidemic type 2 diabetic patients [4, 5]. Conven- model of T2DM [15]. Further, aloe gel reduced tional anti-hyperglycemic and anti-hyperlipi- the blood cholesterol, triglycerides, LDL and VLDL demic drugs have limited efficacies and impor- levels, but increased the blood HDL level in strep- Culture and Research (ACECR)Kavosh Boulevard, Supa tant adverse effects. Thus, more efficacious and tozocin-induced diabetic rats [16]. A controlled safer anti-hyperglycemic and anti-hyperlipidemic clinical trial (n = 60) indicated decreased blood to- agents are needed [6, 7]. Plants have played a sig- tal cholesterol, triglycerides, and LDL levels after nificant role in maintaining human health and 12 weeks of two different doses of aloe gel in two improving the quality of life for thousands of groups of hyperlipidemic patients compared with years [8]. Herbal supplements may be effective in baseline. Since this trial was available as an ab- Fax: + 98 26 14 76 40 [email protected] prevention and treatment of diseases [9–11]. Cur- stract only, neither intergroup comparisons nor Huseini HF et al. Anti-hyperglycemic and Anti-hypercholesterolemic … Planta Med 2012; 78: 311–316 randomization nor blinding were mentioned [17]. Reports on the for different concentrations of acemannan applied. 10 µL of each effects of aloe in the animal models of diabetes have been incon- of the sample solutions was spotted in triplicate on HPTLC plates.
sistent [18–22]. Two nonrandomized clinical trials (n = 76 and Chromatograms were developed, scanned, and the peak areas re- n = 40) are available from the same investigation group that re- corded. The amount of acemannan in the sample was calculated ported decreased fasting blood glucose and triglycerides levels, by the calibration curve of acemannan.
but no change in the cholesterol level after 6 weeks of juice madefrom aloe gel in type 2 diabetic patients. The blood lipid levels Preparation of the aloe gel powder and placebo capsules were not the primary outcomes in the trials [21, 23]. Case reports The aloe gel powder as the drug and toast powder as the placebo of five type 2 diabetic individuals reported decreases in fasting were separately filled into oral gelatin capsules with identical ap- blood glucose and glycosylated hemoglobin (HbA1c) levels [18].
pearance by using a hand-operated capsule-filling machine (Sci- No adverse effects were reported in these trials [17, 18, 21, 23].
entific Instruments and Technology Corporation). The aloe cap- The trials had methodological drawbacks such as lack of random- sules contained 300 mg of the aloe gel powder. Toast powder ization, lack of double-blindness, small sample size, and lack of was chosen as the placebo, because its appearance was relatively power calculation [13, 14]. The preliminary data suggest a poten- tial effect of aloe in glycemic control and hyperlipidemia; howev-er, further information is needed [13, 14].
In conclusion, further and better trials are needed to define the Inclusion criteria: Iranian male and female type 2 diabetic outpa- clinical efficacy and safety of aloe in the treatment of diabetes tients aged 40 to 60 years; patients with fasting blood levels of mellitus and hyperlipidemia more precisely. Thus, the efficacy glucose between 150 mg/dL to 200 mg/dL and HbA1c between and safety of aloe gel in the treatment of hyperlipidemic (hyper- 7 % to 9 % despite taking two 5 mg glyburide tablets and two cholesterolemic and/or hypertriglyceridemic) type 2 diabetic pa- 500 mg metformin tablets every day; patients using two 5 mg tients were evaluated and compared with placebo in the study glyburide tablets and two 500 mg metformin tablets every day; newly diagnosed patients with fasting blood LDL and/or triglyc-erides levels above 100 mg/dL and 150 mg/dL, respectively.
Exclusion criteria: Patients taking other anti-hyperglycemic and anti-hyperlipidemic agents; patients receiving insulin therapy; patients with cardiac, renal, hepatic, hematological diseases, hy- Aloe and preparation of the aloe leaf gel powder pothyroidism, tachycardia, vertigo, and seizure; patients with a The freshly harvested whole aloe leaves obtained from the Re- history of gallstones or gall bladder surgery; patients using estro- search Institute of Medicinal Plants (Karaj, Iran) were washed in gen, steroid, beta-blocker, and thiazide; pregnant women; wom- a suitable bactericide (chlorhexidine). 1 inch of the leaf base, 2 in- en planning pregnancy; breast-feeding women.
ches of the tapering point, and sharp spines located along the leafmargins were removed by a knife. The skin was carefully sepa- rated from the parenchyma. The filets were extensively washed Sixty-seven Iranian male and female outpatients (thirty-three with distilled water to remove the exudates from their surfaces, patients in the aloe group and thirty-four patients in the placebo then the filets were ground to a liquid, and the pulp was removed group) were recruited according to the inclusion and exclusion by filtering. The gel obtained was treated with activated carbon criteria. Thirty patients in each group finished the trial which to decolorize the gel and remove aloin and anthraquinones, was the sample size calculated to estimate 25 mg/dL difference which have laxative effects. The resultant gel was then freeze- of total cholesterol between the groups, considering type I er- dried so that a pure powder was produced [24].
ror = 0.05 and 80 % power. The CONSORT flowchart describing Downloaded by: Tel Aviv University. Copyrighted material.
the progress of the patients through the trial is shown in Determination of the acemannan content of the gel l" Fig. 1. The demographic data of the subjects who finished the The acemannan content of the gel powder was analyzed by A group of thirty patients took the aloe capsules at the dose of HPTLC according to the method described previously [25]. A one 300 mg capsule every 12 hours by the oral route for 2 stock solution of acemannan (1000 mg/mL) was prepared in months, and another concurrently parallel group of thirty pa- water. Different concentrations of the stock solution (10, 20, 40, tients took the placebo capsules orally every 12 hours for 2 and 80 mg/mL) were obtained by water dilution. 10 µL of each of months. The dosage of the aloe gel was based on the results of a them were spotted in triplicate on TLC plates so as to obtain con- dose finding study. Block randomization was used for treatment centrations of 100, 200, 400, and 800 ng per spot of acemannan, allocation. The study was double-blind. Further, the patients were recommended to restrict intake of carbohydrates and fatty The data of peak areas versus acemannan masses were treated by foods such as rice, confectionery, red meat, pies, cream pies, eggs, the linear least square regression method. 1 mg of aloe powder and fatty dairy products from two months before the beginning dissolved in 10 mL of water was used for quantification of ace- of the trial onward. All the subjects recorded the names and mannan. 10 µL of each of the concentrations of standard solu- amounts of the daily consumed foods for 3 days every week. To tions were spotted in triplicate on HPTLC plates. Chromatograms monitor the patientsʼ compliance with the allocated treatments, were developed for 10 cm using n-butanol: n-propanol: glacial the patients returned any capsules left and were asked questions acetic acid: water (30: 15: 10: 5 v/v/v/v). After development, the about taking the capsules on their monthly visit. The treatment, plates were sprayed with anisaldehyde sulfuric acid reagent, and diet, and physical activity of the patients completing the trial re- the spots were detected by heating the plate at 105–110 °C for mained unchanged throughout the study. At the beginning and 3 min. The sprayed plates were scanned at 600 nm. The calibra- also the end of the study, the fasting (after fasting for 12 hours) tion curve of acemannan was obtained by plotting peak areas blood levels of glucose, HbA1c, creatinine, BUN (blood urea nitro- Huseini HF et al. Anti-hyperglycemic and Anti-hypercholesterolemic … Planta Med 2012; 78: 311–316 The CONSORT flowchart describing the progress of the patients through the trial.
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gen), AST (aspartate aminotransferase), ALT (alanine aminotrans- istered in the Iranian Registry of Clinical Trials with the number ferase), AP (alkaline phosphatase), GGT (γ-glutamyl transpepti- dase); total, direct, and indirect bilirubins; triglycerides, totalcholesterol, VLDL, LDL, and HDL in the aloe and placebo groupswere determined with standard enzymatic kits produced by the Pars Azmoon company and an auto analyzer (Hitachi 902). The glucose, HbA1c, and lipid levels were the primary outcome varia- Linearity was shown for acemannan between 100 and 800 ng/ bles. The other blood parameter levels were the secondary out- spot by 4 different concentrations of the acemannan standard.
come variables. The baseline homogeneity of the blood parame- The equation y = 1.943 x + 7.103 (R2 = 0.999) with the applied ace- ter means across the aloe and placebo groups was analyzed by mannan mass x and the area y was obtained (l the Mann-Whitney U test, and p values below 0.05 were consid- of acemannan was determined in the gel powder.
ered as significant. At the end of the study, the data of the pa- No adverse effects were reported. The groups were matched in tients in the aloe and placebo groups were also compared by the regard to demographic data (age, gender, duration of diabetes, Mann-Whitney U test and p values below 0.05 were considered " Table 1). The baseline blood levels of as significant. All statistical analyses were per-protocol analyses.
all parameters were not significantly different between the two All participants were requested to report any adverse effects.
Written informed consent was obtained from the patients. The The aloe gel lowered the glucose, HbA1c, total cholesterol, and medical ethics committee of the Ebne Sina Research Institute af- LDL levels significantly (p = 0.036, p = 0.036, p = 0.006, and filiated with the ACECR approved the protocol (approval number p = 0.004, respectively) without any significant effects on the oth- and date: 492/51/29 and 23 Nov. 2008). Further, the trial was reg- er parameter levels (p > 0.05) compared with the placebo group Huseini HF et al. Anti-hyperglycemic and Anti-hypercholesterolemic … Planta Med 2012; 78: 311–316 the subjects who finished the trial.
The fasting blood parameter levels before and after intervention and their changes during the study.
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a P < 0.05, significant (Mann-Whitney U test); SD, standard deviation; ↓ decrease; ↑ increase " Table 2). The percentages of endpoint reduc- tions of the glucose, HbA1c, total cholesterol, and LDL levels in the aloe group compared with the baseline levels were 4.8 %, The results suggest that aloe gel improves glycemic control and 8.07 %, 8.35 %, and 4.48 %, respectively. The box plots of decreases lowers the blood levels of total cholesterol and LDL, but does not (before intervention – after intervention) in the glucose, HbA1c, affect the other blood lipid levels and does not cause any hepatic, total cholesterol, and LDL levels of the aloe and placebo groups renal, or other adverse effects in the hyperlipidemic type 2 dia- betic patients. The improved glycemic control agrees with theprevious trials [18, 21, 23]. However, the effects on the lipid pro-file have some discrepancies with the earlier trials [17, 21, 23].
Huseini HF et al. Anti-hyperglycemic and Anti-hypercholesterolemic … Planta Med 2012; 78: 311–316 Box plot of decreases (before intervention – after intervention) in Box plot of decreases (before intervention – after intervention) in the fasting blood glucose (FBG) levels (mg/dL) of the aloe (group 1) and the blood glycosylated hemoglobin (HbA1c) levels (percent) of the aloe (group 1) and placebo (group 2) groups.
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Box plot of decreases (before intervention – after intervention) in Box plot of decreases (before intervention – after intervention) in the blood total cholesterol levels (mg/dL) of the aloe (group 1) and placebo the blood low-density lipoprotein (LDL) levels (mg/dL) of the aloe (group 1) The total cholesterol and LDL lowering effects of the aloe gel in vious studies reporting the triglycerides lowering effect of aloe the present trial agree with the previous study reporting the total gel [17, 21, 23]. The lack of the aloe gel effects on the triglyceride cholesterol and LDL lowering effect of aloe gel [17] but disagree and HDL levels in the present trial could be due to the small num- with the earlier reports showing no effect of aloe gel on the cho- lesterol level [21, 23]. Further, the lack of the aloe gel effect on the The only bioactive that was identified and quantified in the aloe triglycerides level in the current trial is inconsistent with the pre- gel used in the present trial was a mucopolysaccharide named Huseini HF et al. Anti-hyperglycemic and Anti-hypercholesterolemic … Planta Med 2012; 78: 311–316 acemannan. Further, the bioactives and mechanisms involved in 9 Fugh-Berman A. Herbs and dietary supplements in the prevention and the anti-hyperglycemic and anti-hypercholesterolemic actions of treatment of cardiovascular disease. Prev Cardiol 2000; 3: 24–32 10 Tapsell LC, Hemphill I, Cobiac L, Patch CS, Sullivan DR, Fenech M, Roo- the aloe gel were not investigated in the study presented here.
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