INTRODUCTION:

Skin, an architecturally marvelous structure has a surface area of 1.5 to 2 m². It is pliable yet tough, allowing it to take constant punishment from the external environment. Sunlight is one such factor that affects the skin constantly and in the process causing damage. Skin has the intrinsic properties to protect itself from the sun, in form of melanin.¹

Exposed sun UV light is classified into three types, by its wavelengths as UV-A, UV-B and UV-C. The dimensions of their wavelength are roughly 400-320nm for UV-A, 320-290nm for UV-B and 209-200nm for UV-C. Although it may be observed that the shorter wavelength and the lower the number, the greater the energy level of the light and the more damage it can do.²

Direct exposure to UV-C for a length of time would destroy the skin. Fortunately, UV-C is completely absorbed by gases in the atmospheres before it reaches the ground. In any time the longer wavelength of UV-B and UV-A pass right through the atmosphere. The molecules in sunscreen absorb most of UV-Band prevent it from reaching the skin just as the molecules of the atmospheres absorbs UV-C and prevent it from reaching the ground.²

Various herbal formulation and chemicals are available to block various ranges of UV rays and always prevent all types of skin from various damages. Our study is to find out such flowers that are widely used as sunscreen from ancient time.

The Hibiscus rosa-sinensis Linn ( Malvaceae ) is a glabrous shrub widely cultivated in the tropics as an ornamental plant and has several forms with varying colours of flowers . Known colloquially as the Chinese hibiscus, China rose and shoe flower is an evergreen flowering shrub native to East Asia. It is widely grown as an ornamental plant throughout the tropics and subtropics. The flowers are large, generally red in the original varieties, and firm, but generally lack any scent. Numerous varieties, cultivars, and hybrids are available, with flower colors ranging from white through yellow and orange to scarlet and shades of pink, with both single and double sets of petals. In medicine, however the red flowered variety is preferred.³ The leaves and flowers are observed to be promoters of hair growth and aid in healing of ulcers. ^{4, 5, 6} Flowers have been found to be effective in the treatment of arterial hypertension and to have significant antifertility effect according to traditional texts it is well accepted that the leaves and flowers of Hibiscus rosa-sinensis have hair growth promoting and antigreying properties.^5,6

MATERIALS AND METHOD:

Hibiscus rosa-sinensis Linn flower were freshly obtained from nursery at Bijapur; and they were botanical authenticated at Dept. of botany A.S.P College, Bijapur (K.S). The petals of flower are separated, cleaned by distilled water, cut into small pieces and dried by circulating cool air. A 100 g powered petals were extracted with 150ml of 90% ethanol by maceration. The extracts were evaporated to dryness on steam bath. The general flavonoid identification test was performed on the extract.⁷

Test 1: To dry extract, add 5ml of 95% ethanol, few drop of concentrated hydrochloric acid and 0.5 g of magnesium turning. The finally pink colour observed. (Shinoda test)

Test 2: To a small quantity of extract, add lead acetate solution, it shows yellow coloured precipitate is formed.

EXPERIMENTAL WORK:

Preparation of sample

The sample preparations were carried out by 10 mg% w/v concentration dissolving into the 100 ml of distilled water (10 mg/100ml). The UV absorption spectrum for the extract was obtained in ranges of 200-400 nm using double beam UV-Vis Spectrophotometer model Shimadzu-1700.

The figure 1 indicates scanning absorption spectra of the extract in given range and figure 2 indicate digital monitor display reading of absorption spectra of the extract which is directly taken from spectrophotometer.

Figure 1: scanning indicates absorption spectra of the extract

Figure 2: Digital monitor display reading of absorption spectra of the extract

RESULT:

The UV scanning absorption spectra of the extract showed very strong absorption (1.26) with λ _max at 200nm and λ _max at 280nm with absorbance of ~0.3. The graph if extract also showed a plateau in range of 300-400 nm with moderate absorbance of ~0.2-0.1.

DISCUSSION:

The result obtained were showed the ability of extract to absorb UV radiation and hence proved its UV protection ability. The extract showed a prominent absorbance at 200-250nm, while good absorbance at range of 260-320nm and moderate absorbance was reported at range of 300-380nm.

Qualitatively investigation indicates that presence of flavonoid in the extract. This flavonoids are coloured compound pigment found in various leaves and flower amongst the natural source. They are well known for their attractive colours and pharmacological activities, it absorbs light and helps to protect as photosensitive substances in the flower and leaves. Thus it play key role in defense mechanisms in plant. The absorption of UV radiation is a main characteristic for identification of flavonoids in natural source. Due to presence of these flavonoids the result showed strong to moderate absorbance of UV radiation along the whole ranges. The present study is essential for collection of similar data for different plant and there flowers, as well as other parts. This proved activity of plant showed its importance and prophylactic utility in anti- solar formulation. This will be a better, cheaper and safe alternative to harmful chemical sunscreens that used now a day in the industry.

ACKNOWLEDGEMENT:

We are also thankful to the Principal Prof Dr. N. V. Kalyane and Management of B.L.D.E.A college of Pharmacy, Bijapur for providing the necessary facilities to carry out this work.

REFERENCES:

1. Lu H, Edwards C, Gaskell S, Pearse A, Marks R. Melanin content and distribution in the surface corneocyte with phototypes, Br J Dermatology 1996;135:263-7.

2. Saraf S, Ashawat M. Anti solar activity of flower extract of R. damascena and T. erecta Linn. Planta indica 2005; 1:26-7.

3. Adhirajan , N., Kumar, T. R., Shanmugasundaram, N.& Babu, M., In vivo and in vitro evaluation of hair growth potential of Hibiscus rosa-sinensis Linn, Journal of Ethnopharmacology, Vol-88, 2003, 235-239

4. Nadkarni, A. K., Indian Materia Medica, Bombay, 1954, 631.

5. Ali, M. & Ansari, S. H., Hair care and herbal drugs, Indian Journal of Natural products , Vol-13, 1997, 3-5.

6. Kurup, P. N. & Joshi, P., Handbook of Medicinal plants, New Delhi, 1979, 86.

7. Khandelwal KR. Practical pharmacognocy. 12^th ed. Pune: Nirali Prakashan; 2004

Received on 15.10.2010 Modified on 23.10.2010

Research J. Pharm. and Tech. 4(3): March 2011; Page 472-473