Evaluation of radioprotective activities of Rhodiola imbricata Edgew – A high altitude plant

Abstract

The present study reports the radioprotective properties of a hydro-alcoholic rhizome extract of Rhodiola imbricata (code named REC-7004), a plant native to the high-altitude Himalayas. The radioprotective effect, along with its relevant superoxide ion scavenging, metal chelation, antioxidant, anti-lipid peroxidation and anti-hemolytic activities was evaluated under both in vitro and in vivo conditions. Chemical analysis showed the presence of high content of polyphenolics (0.971 +/- 0.01 mg% of quercetin). Absorption spectra analysis revealed constituents that absorb in the range of 220-290 nm, while high-performance liquid chromatography (HPLC) analysis confirmed the presence of four major peaks with retention times of 4.780, 5.767, 6.397 and 7.577 min. REC-7004 was found to lower lipid oxidation significantly (p < 0.05) at concentrations viz., 8 and 80 microg/ml respectively as compared to reduced glutathione, although the optimally protective dose was 80 microg/ml, which showed 59.5% inhibition of induction of linoleic acid degradation within first 24 h. The metal chelation activity of REC-7004 was found to increase concomitantly from 1 to 50 microg/ml. REC-7004 (10-50 microg/ml) exhibited significant metal chelation activity (p < 0.05), as compared to control, and maximum percentage inhibition (30%) of formation of iron-2,2'-bi-pyridyl complex was observed at 50 microg/ml, which correlated well with quercetin (34.9%), taken as standard. The reducing power of REC-7004 increased in a dose-dependent manner. The absorption unit value of REC-7004 was significantly lower (0.0183 +/- 0.0033) as compared to butylated hydroxy toluene, a standard antioxidant (0.230 +/- 0.091), confirming its high reducing ability. Superoxide ion scavenging ability of REC-7004 exhibited a dose-dependent increase (1-100 microg/ml) and was significantly higher (p < 0.05) than that of quercetin at lower concentrations (1-10 microg/ml), while at 100 microg/ml, both quercetin and REC-7004 scavenged over 90% superoxide anions. MTT assay in U87 cell line revealed an increase in percent survival of cells at doses between 25 and 125 microg/ml in case of drug + radiation group. In vivo evaluation of radio-protective efficacy in mice revealed that intraperitoneal administration of REC-7004 (maximally effective dose: 400 mg/kg b.w.) 30 min prior to lethal (10 Gy) total-body gamma-irradiation rendered 83.3% survival. The ability of REC-7004 to inhibit lipid peroxidation induced by iron/ascorbate, radiation (250 Gy) and their combination [i.e., iron/ascorbate and radiation (250 Gy)], was also investigated and was found to decrease in a dose-dependent manner (0.05-2 mg/ml). The maximum percent inhibition of formation of MDA-TBA complex at 2 mg/ml in case of iron/ascorbate, radiation (250 Gy) and both i.e., iron/ascorbate with radiation (250 Gy) was 53.78, 63.07, and 51.76% respectively and were found to be comparable to that of quercetin. REC-7004 (1 microg/ml) also exhibited significant anti-hemolytic capacity by preventing radiation-induced membran...

Radioprotective activity of Gentiana lutea extract and mangiferin

“…Several recent publications report the ability of some herbal constituents to act as radioprotectors (Devipriya et al, 2008;Park et al, 2008;Jagetia and Venkatesha, 2006). Some of the herbal preparations, including Triphala (Jagetia et al, 2002), or Septilin (Jagetia and Baliga, 2004), extracts of Rhodiola imbricata (Arora et al, 2005, Goel et al, 2006, Podophyllum hexandrum (Samanta et al, 2004), Pillea microphilla (Prabhakar et al, 2007), as well as the secondary metabolites such as mangiferin (Jagetia and Baliga, 2005) and naringin (Jagetia et al, 2003) administered to mice intraperitoneally, showed notable protection of normal tissues from irradiation-induced injuries. The present results show that mangiferin can inhibit the irradiationinduced decrease in human PBMC cell survival.…”

Excellence is the Real Enemy of Practicality! Relevance to Radiation Countermeasure Development

“…Particularly, INMAS took the lead in radiation countermeasure development programme and evaluated Indian herbs as the prominent sources of radioprotective molecules. Podophyllum hexandrum, Hippophae rhamnoides, Rhodulla embricata and Tinospora cordifolia was evaluated for their radioprotective efficacy [46][47][48][49][50][51][52] . Apart from that radioprotective efficacy of pure molecules isolated from Podophyllum hexandrum was established at INMAS 53 .…”

Effect ofTinospora cordifoliaon the reduction of ultraviolet radiation‐induced cytotoxicity and DNA damage in PC12 cells

“…Rhodiola imbricata, a high-altitude plant also rich in antioxidants, exhibits both in vitro and in vivo radioprotection via a superoxide ion scavenging process. [30] Recently, Huang et al [28] found that extracts of the leaves of Nelumbo nucifera Gaertn, because of its antioxidant effects, protects animal models against UVB-induced phototoxicity. Polyphenols (mainly phenols and flavonoids) are the major components of plants that showed antioxidant activity.…”