Flowers of Clerodendrum volubile modulates redox homeostasis and suppresses DNA fragmentation in Fe2+ - induced oxidative hepatic and pancreatic injuries; and inhibits carbohydrate catabolic enzymes linked to type 2 diabetes

Abstract

Introduction: Medicinal plants have long been recognized for their roles in the treatment and management of diabetes and its complications. The antioxidative and antidiabetic properties of Clerodendrum volubile flowers were investigated in vitro and ex vivo.

Methods: The flowers were sequentially extracted with solvents of increasing polarity (n-hexane, ethyl acetate, ethanol and water). The concentrated extracts were subjected to in vitro antioxidant assays using the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) scavenging and Ferric reducing antioxidant power (FRAP) protocols. Their inhibitory activities were investigated on α-glucosidase, pancreatic lipases, pancreatic ATPase and glucose-6-phosphatase activities. Their anti-oxidative and anti-apoptotic effects on Fe²⁺-induced oxidative injuries were also investigated in pancreatic and hepatic tissues ex vivo.

Results: The extracts showed potent free radical scavenging activity and significantly (p < 0.05) inhibited all studied enzymes. The GSH level was significantly (p < 0.05) elevated in both tissues with concomitant increase in superoxide dismutase (SOD) and catalase activities as well as reduced levels of malondialdehyde (MDA). The extracts significantly (p < 0.05) suppressed DNA fragmentation in hepatic tissue. These activities were dose-dependent. The ethanol extract showed the best activity and can be attributed to the synergetic effect of its chemical constituents identified via gas chromatography-mass spectroscopy (GC-MS).

Conclusion: These results suggest the antioxidative, antidiabetic and anti-obesogenic potentials of C. volubile flowers.

Keywords: Anti-hyperglycemia; C. volubile; Oxidative stress; Type 2 diabetes.

Fig. 1

Total phenolic contents of the C. volubile flower extracts. Data are presented as mean ± SEM. ^abcValues with different letter above the bars for a given extract are significantly different from each other (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 2

a) DPPH and b) Ferric reducing antioxidant power (FRAP) of C. volubile flower extracts. Data are presented as mean ± SEM. ^abcValues with different letter above the bars for a given concentration are significantly different from each other (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 3

Effect of C. volubile flower extracts on a) pancreatic GSH level; b) hepatic GSH level; c) pancreatic SOD activity d) hepatic SOD activity; e) pancreatic catalase activity; f) hepatic catalase activity; g) pancreatic MDA level and h) hepatic MDA level in oxidative injury. Data are presented as mean ± SEM. ^*Significantly different from untreated sample and ^#Significantly different from normal sample; ^abcValues with different letter above the bars for a given concentration are significantly different from each other (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 4

a) Alpha-glucosidase and b) Pancreatic lipase inhibitory activities of C. volubile flower extracts. Data are presented as mean ± SEM. ^abcValues with different letter above the bars for a given concentration are significantly different from each other (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 5

Effect of C. volubile flower extracts on ATPase activity in oxidative pancreatic injury. Data are presented as mean ± SEM. ^*Significantly different from untreated sample and ^#Significantly different from normal sample (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 6

Effect of C. volubile flower extracts on Glucose-6-Phosphatase activity in oxidative hepatic injury. Data are presented as mean ± SEM. ^*Significantly different from untreated sample and ^#Significantly different from normal sample; ^abValues with different letter above the bars for a given concentration are significantly different from each other (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 7

Effect of C. volubile flower extracts on DNA fragmentation in oxidative injury in a) pancreatic and b) hepatic tissues. Data are presented as mean ± SEM. ^*Significantly different from untreated sample and ^#Significantly different from normal sample (p < 0.05, Tukey’s HSD-multiple range post-hoc test, IBM SPSS for Windows)

Fig. 8

Structures of the compounds identified in the ethanol extract of C. volubile flower

Fig. 9

Proposed antidiabetic and antioxidant mechanisms of C. volubile flower