Photobiology division is dedicated for the phototoxicity evaluation and identification of mechanism of xenobiotics with particular emphasis to health care products (Drugs and Cosmetics) and environmental pollutants by using reactive oxygen species (ROS), DNA damage, Linoliec acid peroxidation and other photochemical methods under the exposure of ambient doses of UVA /UVB in laboratory conditions and in natural condition under sunlight. Red blood corpuscles (RBC) photohaemolysis is also used for the phototoxicity assessment. We are using different rodent (L-929 and NIH 3T3 mouse fibroblast cell lines) and human cell line (A-431 Human epidermal skin cell line) for phototoxicity evaluation. In vitro systems are used for the initial screening of different chemicals as high throughput system. These systems for phototoxicity evaluation are as per the Organization for economic cooperation and development (OECD guide lines). We have also established laboratory cultured Spirodela polyrhiza as an alternate model for phototoxicity of aquatic pollutants by using visible injury symptoms and biochemical parameters. Currently we are pursuing our research on UV induced gene expression by various xenobiotics.
 

• Phototoxicity evaluation of xenobiotics (Drugs & Environmental pollutants) by using in vitro and in vivo systems.

• Evaluation of possible mechanism of phototoxicity of different xenobiotics.

• To study the photodegradation of chemicals and identification of its photodegraded products.

• Identification of photosensitive genes by using human cell lines and other cell lines.

• Phototoxicity evaluation of non-steroidal anti-inflammatory drugs (in vitro) 
  Nonsteroidal anti-inflammatory drugs (NSAIDs) have been assessed for the phototoxic potential (diclofenac, flurbiprofen and ibuprofen) using L929, mouse fibroblast cell line and compaired the results with OECD approved NIH3T3, cell line and RBC photohemolysis test at the ambient intensities of UV-A, UV-B and natural sunlight. Sunlight exposure was found most effective followed by UV-B and UV-A. Diclofenac showed most photocytotoxic effect followed by flurbiprofen and ibuprofen. In conclusion, L929 cell line was found more sensitive than NIH3T3 cell line. Phototoxic effects induced by UVR may have importance with regard to clinical photosensitization of NSAIDs. 

• Use of L-929 cell line for phototoxicity assessment 
  L-929 sensitivity towards UV radiation was studied under UVA (0.5 to 3.0 mW/cm²), UVB (0.2 to 1.4 mW/cm²) and sunlight (30 -180 min), in order to use it as an alternate in vitro test system for phototoxic assessment. MTT assay was adopted for quantitative assessment of cell viability. Cell viability was studied in cultured L-929 and NIH-3T3 cells under the exposure of toxic insult of UVR alone and in combination with chlorpromazine (an antipsychotic drug). Chlorpromazine was assessed for phototoxic potential under UVA (1.5 mW/cm²), UVB (0.8 mW/cm²) and sunlight exposure (30 min), a dose dependent phototoxic response was observed. The study suggests the suitability of L929, as an in vitro alternative test system for the phototoxicity assessment along with OECD approved NIH-3T3 cell line. 

• Phototoxicity assessment of ciprofloxacin by using cell line 
  Ciprofloxacin is a widely used fluoroquinolone drug with broad spectrum antibacterial activity. Clinical experience has shown incidences of adverse effects related to skin, hepatic, central nervous system, gastrointestinal and phototoxicity. Generation of ROS like singlet oxygen (¹O₂) and superoxide anion radical (O₂^.-) under the exposure of UVA (320-400 nm), UVB (290-320 nm) and natural sunlight (from 12 to 2 PM) was studied. The results showed that ciprofloxacin was producing ROS by Type I and Type II photochemical reactions, interacted photochemically with nucleic acid moiety and reduced cell viability in a dose and time dependent manner. Further, the UV-induced photooxidation of linoleic acid accorded the involvement of ROS in the manifestation of drug phototoxicity. The data suggests that sunlight exposure should be avoided after the intake of drug to minimize the phototoxic effects. 

• Spirodela polyrhiza: An alternate system for phototoxicity assessment of chemicals/industrial and municipal waste water
  An aquatic plant Spirodela polyrhiza (duckweed) was developed for the phototoxicity assessment of chemicals, industrial waste water (IWW) and municipal waste water (MWW). It is a simple test system for determining aquatic toxicity of pesticides, herbicides, and other chemicals, approved by international agencies. IWW from distillery, paper, pesticide formulation and tannery industry and MWW from sewage canal were assessed for phototoxicity. The Study revealed that the contaminants in IWW and MWW show additional phototoxicity. 

• E. coli: A new alternate system for Phototoxicity assessment of drugs and cosmetic products
  A gram negative bacteria E.coli (Dh5 strain) was developed as an alternate test system for phototoxicity assessment. Eight drugs (antibiotics) and cosmetic products (eight face creams) were assessed for their phototoxicity. UVA radiation induced phototoxicity of these compounds was tested by agar gel diffusion assay and decrease in colony forming units (CFU) was taken as an end point of phototoxicity. E.coli may also be used as an additional alternative test system for phototoxicity assessment of the chemical agents like that of existing alternate models, as a battery of test systems is required to conclude the toxic/phototoxic potential of a chemical agent.

FIRST TIER (Physicochemical properties) 
a. Solubility, pH, conductivity 
b. Absorption spectra (UV/Vis) 

SECOND TIER (in vitro system)
a. ROS generation (photochemically and in vitro) 
b. RBC photohemolysis 
c. Spirodela polyrhiza (Lemna) 
d. Cell lines (L-929, NIH-3T3 and A-431) 
e. Identification of marker photosensitive genes  
f. Photogenotoxic potential of xenobiotics (chromosomal aberrations and micronucleus assays) 

THIRD TIER (in vivo system) 
Determination of phototoxicity by using in vivo systems (higher lab animals). 
a. Guinea pig (skin patch test)

RBC                       L929


      NIH3T3                   S. polyrhiza  
 

• Cell culture of mouse fibroblast cell line (NIH-3T3 and L929) and Human skin cell line A431

• Maintained culture of Spirodela polyrhiza

• CO₂ incubators

• Spectrophotometers

• UV-A, UV-B and UV-C irradiation systems

• Sensitive radiometers

• Laminar flow

• -30°C freezer

• Lyophilizer

• Cooling centrifuge

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