Flavonoids from Heliotropium subulatum exudate and their evaluation for antioxidant, antineoplastic and cytotoxic activities II

Abstract

The flavonoids are the largest group of phenolic compounds isolated from a wide range of higher plants. These compounds work as antimicrobials, anti-insect agents and protect plants from other types of biotic and abiotic stresses. Various researchers have suggested that flavonoids possessed antioxidant, antineoplastic and cytotoxic activities. The main objective of this study was to test dichloromethane fraction of resinous exudate of Heliotropium subulatum for their antioxidant, antineoplastic and cytotoxic activities, as well as to search new antioxidant and antineoplastic agents for pharmaceutical formulations. Five flavonoids were isolated from resinous exudate of this plant species and screened for their in vitro and in vivo antioxidant models (DPPH radical scavenging, reducing power, superoxide anion scavenging, metal chelating scavenging systems, catalase and lipid peroxidation), antineoplastic (Sarcoma 180), and cytotoxic (Chinese hamster V79 cells) activities. Tricetin demonstrated maximum antioxidant activity against both in vitro and in vivo experimental systems while galangin exhibited maximum inhibition (78.35%) at a dose of 10 µg/kg/day against Sarcoma 180. Similarly, it was found that galangin also showed highest activity (21.1 ± 0.15%) at a concentration of 70 µg/ml to Chinese hamster V79 cells. The observed results suggest that tricetin has a potential to scavenge free radicals in both in vitro and in vivo models while the galangin could be considered as antitumor and cytotoxic agent.

Keywords: Antineoplastic and cytotoxic activity; Antioxidant; Flavonoids; Heliotropium subulatum.

Fig. 1

Structures of isolated flavonoids from resinous exudates of H. subulatum

Fig. 2

In vitro antioxidant activity of the active fraction and the isolated flavonoids from H. subulatum

Fig. 3

Catalase activity of the active fraction and the isolated flavonoids from H. subulatum assessed in the mouse model

Fig. 4

Lipid peroxide activity of the active fraction and the isolated flavonoids from H. subulatum assessed in the mouse model

Fig. 5

Antineoplastic activity of the active fraction and the isolated flavonoids from H. subulatum in Sarcoma 180

Fig. 6

Cytotoxic activity of the active fraction and the isolated flavonoids from H. subulatum in Chinese hamster V79 cells