Evaluation of antithyroid potential of Luffa acutangula peel extract and its chemical constituents as identified by HR-LC/MS

Abstract

Although some reports are there indicating the medicinal values of fruit peels, on vegetable peels investigations are meager. The present study is an attempt to explore the hitherto unknown potential of Luffa acutangula peel extract in T₄-induced hyperthyroid female mice. Animals were made hyperthyroid by administering pre-standardized dose of l-thyroxin (l-T₄ at 0.5 mg/kg/day) for 12 consecutive days and then the effects of the test peel extract at 25 and 50 mg/kg for 15 days were studied on the changes in serum thyroid hormones, glucose, different lipids; hepatic lipid peroxidation (LPO); enzymatic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, and in reduced glutathione. The main chemical constituents of the extract were identified by high resolution liquid chromatography mass spectrometry. Administration of the test peel extract to the hyperthyroid mice at both the test doses decreased the levels of serum thyroid hormones, glucose and tissue LPO suggesting its antithyroid, antihyperglycemic and antiperoxidative potential. These positive effects were also supported by an improved lipid profile as well as liver histology. LC-MS analyses revealed the presence of kaempferol-3-O-rutinoside, kameferol-O-neohesporoside, quercetin, cinnamic acid ethyl ester, caffeic acid derivatives such as 4-O-caffeyol quinic acid, 3-sinapoylquinic acid and 4,5-dihydroxyprenyl caffeate, orientin and sinapic acid. It is presumed that the antithyroid and anti-hyperglycemic actions of the test plant extract could be the result of antioxidative properties of these phytochemicals.

Keywords: Catalase; Hyperglycemia; Lipid peroxidation; Liver histology; Superoxide dismutase; Thyrotoxicosis.

Fig. 1

Effects of L. accutangula peel extract on the alterations in serum concentrations of T₃ (ng/mL) and T₄ (ng/mL) in euthyroid and in l-thyroxin (l-T₄)-induced thyrotoxic mice. Each bar represents the mean ± SEM, n = 7. Ctrl, Control; T₃, triidothyronine; T₄, thyroxine. ^aP < 0.001 as compared to the respective control values. ^xP < 0.001 and ^yP < 0.01, as compared to the respective values of l-T₄ treated animals. D1, 25 mg/kg and D2 50 mg/kg

Fig. 2

a Effects of L. accutangula peel extract on the alterations in hepatic LPO (nm of MDA formed/h/mg protein). b. SOD (units per mg protein, CAT (µM of H₂O₂ decomposed per min per mg protein), GPx (μ moles of GSH oxidized/mg protein) and GSH (μM GSH per mg protein) in liver tissues. Each bar represents the mean ± SEM, n = 7. Ctrl, Control; T3, triidothyronine; T₄, thyroxine. ^aP < 0.001 as compared to the respective control values. ^xP < 0.001, ^yP < 0.01 and ^zP < 0.5 as compared to the respective values of l-T₄ treated animals. D1, 25 mg/kg and D2 50 mg/kg

Fig. 3

Effects of L. accutangula peel extract on the alterations in serum glucose and different lipids. Each bar represents the mean ± SEM, n = 7. Ctrl, Control; l-T₄, l-thyroxine. ^aP < 0.001 as compared to the respective control values. ^xP < 0.001, ^yP < 0.01 and ^zP < 0.5 as compared to the respective values of l-T₄ treated animals. GLU, glucose; CHOL, cholesterol; HDL, high density lipoprotein and TG, triglyceride. D1, 25 mg/kg and D2 50 mg/kg

Fig. 4

Representative photographs (×10) from the control and treated animals. While control (CTRL) shows normal hepatic cells, arranged regularly and radially around central vein showining normal architecture, in l-T₄ treated group, disruption of central vein, loss of cellular boundaries, inflammatory cell infiltration around the portal vein were observed. T4 + 25 mg/kg of peel extract (PE-D1) animal shows presence of normal hepatocytes around central vein exhibiting near normal liver architecture, and in l-T₄ + 50 mg/kg of peel extract (PE-D2) only moderate damage in hepatocytes with intact central vein (CV) was noticed. In T₄ + PTU treated animal also, only a moderate damage in hepatocytes with clear CV is seen. H. hepatocyte and IFC, inflammatory cell