Introduction: Natural colorants are widely used in food and beverage products due to increasing consumer demand for natural ingredients (Katz & Williams 2011). Anthocyanin is one of the most commonly utilized water-soluble natural colorants and a subclass of flavonoids (Mercadante & Bobbio 2007). They are typically extracted from the red and blue parts of certain plants, including fruits, vegetables, flowers, and leaves. The color stability of anthocyanin is strongly dependent on the pH of the surrounding aqueous phase and they are more stable in acidic rather than in neutral or alkaline solutions. The rate of degradation is affected by many factors including pH, light, temperature, oxygen, enzymes, and ingredient interactions (Malien-Aubert et al. 2001). Besides, anthocyanin also has anti-oxidant and bioactive properties linked to certain health benefits e. g. antidiabetic, anti-inflammatory, and anti-cancer effects (Tzulker et al. 2007, Olaleye 2007). The stability of anthocyanin color can be enhanced by co-pigmentation phenomenon where the anthocyanin molecule reacts with other natural plant substances through weak interactions forming an enhanced and stabilized color (Gordillo et al. 2012). Co-pigmentation is a solution phenomenon in which pigments and co-pigment molecules form molecular complexes. These cause the pigments to exhibit high color intensity than would be expected from their original. This interaction prevents water attack on the flavylium cation. The most common co-pigments are flavonoids, polyphenolic compounds, alkaloids, amino acids and organic acids (Mazza & Brouillard 1990). HIBISCUS SABDARIFFA is a tropical plant, which belongs to the Malvaceae fam. It is rich in anthocyanins, minerals, pectin. The major reported anthocyanins are delphinidin-3-glucoside, delphinidin-3-sambubioside, and cyanidin-3-sambubioside chiefly responsible for their color and antioxidant properties (Pau-Ling et al. 2002, Jadhav & Bhujbal 2019). Phytochemicals, these natural components, may be able to inhibit the chemical degradation of the anthocyanins and to prolong their color stability. For this reason, many investigations have been carried out to improve the stability of anthocyanins. Therefore, they can be used more widely in food products (Eiro & Heinonen. 2002, Talcott et al. 2003, Clemente & GallI 2011, Jadhav & Bhujbal 2019). The present study is carried out to extract anthocyanins from HIBISCUS saddariffa and to improve its stability by copigmentation by four polyphenols (green tea extract, rosemary extract, rose extract, sage extract and in the presence of ascorbic acid). The color stability of anthocyanins is determined by evaluation of the amount anthocyanins, destructive index and total polyphenol during storage at elevated temperature in the presence of light and ascorbic acid in order to accelerate the degradation of anthocyanin pigments. Material and methods: In order to extract HIBISCUS saddariffaas, a rich source of anthocyanins, the sepals of this plant were used. First, a weighed amount (6 g) of HIBISCUSsepal was dissolved in Methanol and water in a ratio of 0. 5 to 1. 5 as a solvent system. Then, it was kept in an orbital shaker at 40 ℃ for 4 hours to complete anthocyanin pigment extraction. The extract was filtered using whatman No. 1 filter paper and concentrated by rotary evaporator at 60℃ to reach 12 brix. In order to prepare other phytochemical extracts (green tea, rosemary, sage and rose), a weighed amount of (260 g) of each phytochemical was dissolved in deionized water and stirred until fully hydrated. Next, 30% w/w of each extract were added to the HIBISCUS extraction (as a source of anthocyanins) as well as 0. 05% w/w ascorbic acid. The pH of the solutions was then adjusted to pH2 using 1 M citric acid. Then, the amount of anthocyanin compounds was determined using pH change method. Besides, destructive index of anthocyanins was evaluated by using absorbance at 420 nm divided by the absorbance at 520 nm. The total amount of polyphenolic compounds of treatments by the folinciocalteu reagents was investigated. For this aim, all experiments were analyzed in triplicate in a completely randomized design using the Minitab 16 software using one-way analysis of variance Duncan's test. Result and discussion: The color stability of anthocyanin in the sample reduced in the presence of ascorbic acid. In the absence of ascorbic acid, the anthocyanin color was stable over seven days. The color fading caused by the presence of ascorbic acid had been proposed to occur through two main mechanisms: (a) a condensation reaction between anthocyanin and ascorbic acid and/or (b) autoxidation of ascorbic acid generating free radicals (e. g., hydrogen peroxide) that cleave the flavylium core of the anthocyanins (Mercadante & Bobbio 2007). In addition, the polyphenols extracts in the presence of ascorbic acid increased the anthocyanin content compared to the control and treatment sample (T2) and also increased the stability of anthocyanin content during storage. Among the co-pigments used (polyphenols extracts), T3 treatment, which contained 30% w/w green tea, had the highest amount of anthocyanin compounds (260/49 mg / l), which could be due to the phenomenon of co-pigmentation. In other words, the higher anthocyanin stability upon green tea addition was due to co-pigmentation, inhibited the ability of water molecules to attack the flavylium ion and caused color loss (Kopjar et al. 2014). According to the obtained results of Degradation index, treatment (T3) with addition of ascorbic acid and green tea extract had the lowest, while the sample (T2) with the addition of ascorbic acid only had the highest degradation index. Those results were in correspondence with the results for anthocyanin content. After preparation, samples with green tea extract addition had the highest anthocyanin content and the lowest degradation index, which means that anthocyanins were more stable. During storage, degradation of anthocyanin occurred and the destructive index increased (Piliž ota et al. 2012). In terms of total phenolic content, under the defined conditions, T3 treatment containing of green tea extract (30% w/w) had more phenolic compounds than other treatments (5. 78 mg/l) and T2 treatment containing ascorbic acid had the lowest polyphenol content (2. 85 mg/l). Whereas T3 treatment had more polyphenolic compounds than other samples, anthocyanins and polyphenol structures could be more exposed to each other and more effective copigmentation occurred. Conclusion: The results revealed that by using plant extract/polyphenol, solutions could significantly increase the stability of anthocyanins. Among these extracts, green tea extract was the most effective extract in inhibiting the destruction of anthocyanins.

Emerging community concerns and a growing environmental consciousness throughout the globe have forced the material scientists to synthesize new green polymer composite materials and processes for their better end uses. In the present research paper fabrication of HIBISCUS SABDARIFFA (HS) fibre reinforced phenolic resin matrix based polymer composites have been reported. Resorcinol-formaldehyde (RF) resin polymer matrix based composites have been fabricated through compression moulding technique developed in our laboratory. Mechanical properties such as tensile strength, flexural strength, compressive strength and wear resistance, etc. of fibre reinforced polymer composites have been investigated as a function of fibre loading (in terms of weight). The reinforcing of the polymeric resin with HIBISCUS SABDARIFFA fibre was accomplished in particle size of 200 (micron). The entire polymer composites fabricated showed a general trend of increase in properties with fibre loading up to 30% and beyond this loading the properties decrease. Fibre/matrix interaction has been analyzed from the mechanical data and morphological (SEM) studies. Thermal (TGA/DTA/DTG) studies have also been carried out on polymeric resorcinol-formaldehyde (RF) resin, HIBISCUS SABDARIFFA fibre and particle reinforced (P-Rnf) biocomposites.

Nootropic acitivity of calyces of HIBISCUS SABDARIFFA Linn.  was studied in mice. Elevated plus maze and passive avoidance paradigm were employed to evaluate learning and memory parameters. Scopolamine (0.4 mg/kg, i.p.) used to induce amnesia in mice. The aqueous extracts of calyces of HIBISCUS sab-darrifa (HS-100 and 200 mg/kg, p.o.) significantly attenuated amnestic deficits induced by scopolamine (0.4 mg/kg, i.p.)  and natural aging. HS (100 and 200 mg/kg) decreased the transfer latencies and increased step down latencies significantly in the aged mice and scopolamine induced amnesic mice as compared with Piracetam (200 mg/kg, i.p.). To delineate the possible mechanism through which H. sab- dariffa elicits the anti-amnesic effects, we studied its influence on central cholinergic activity by estimating the whole brain acetylcholinesterase activity. H. SABDARIFFA significantly decreased acetyl cholinesterase activity in mice. The results indicate that, the aqueous extract of calyces of H. SABDARIFFA might prove to be a useful memory restorative agent in the treatment of dementia seen in elderly. The underlying mechanism of action can be attributed to its anti acetylcholinesterase property.

In recent years, the consumption of healthy drinks has increased due to the increase in consumer awareness. In this research, the production of HIBISCUS tea probiotic dietary drinks based on stevia and inulin sweeteners was investigated. In order to prepare probiotic drinks, Lactiplantibacillus plantarum bacteria, HIBISCUS tea at levels of 2.5, 5 and 7%, inulin at levels of 2, 4, 6% and stevia at levels (0.1, 0.2 and 0.3 percent) were used and pH, acidity, brix, formalin index, turbidity, total phenol, antioxidant activity (DPPH, FRAP, ABTS), sensory characteristics of the samples were investigated on day 1 and total microbial count and survival of probiotics on days 1, 3 and 15. According to the obtained results, at the highest levels of HIBISCUS tea and the lowest levels of inulin, the pH of the samples decreased significantly and the acidity increased (p<0.05). At the highest levels of HIBISCUS tea and inulin, Brix, Turbidity and formalin index of samples increased significantly (p<0.05). In the highest levels of HIBISCUS tea, inulin and stevia, total phenol and antioxidant activity and population of probiotics in the samples increased significantly (p<0.05). Sample H5, I4, S0.2 and sample H5, I6, S0.2 obtained the highest sensory score compared to other samples (p<0.05). Due to the higher sensory scores, antioxidant activity and proper survival of probiotics, sample H5, I4, S0.2 was selected as the best sample.

HIBISCUS SABDARIFFA L., belonging to the Malvaceae family, has been long used as herbal medicine, food, beverage, flavouring, and colouring agents. This study aims to review and document the evidence regarding the potential use of H. SABDARIFFA as ethnomedicine in some countries and its bioactive constituents and therapeutic properties. The electronic databases were used to search for the relevant information to the aims of this review up to March 2022. The high usage of H. SABDARIFFA as traditional medicine is due to its easy accessibility and low price. The plant is often used to treat intestinal problems, stomach disorders, and blood or liver toxicities. The plant contains phenolic compounds, including anthocyanins, flavonoids, and phenolic acids. The in vivo, in vitro, and clinical studies provide evidence that H. SABDARIFFA possesses therapeutic effects such as antihypertensive, antihyperlipidemic, antioxidants, antimicrobial, and antitumor activities. The studies provided scientific evidence for the statement of H. SABDARIFFA and its bioactive constituents in treating various diseases.

Roselle is an important medicinal and industrial plant of the family of Malvaceae, and is planted in vast areas of Sistan and Baluchestan. In a laboratory study, the effect of varying temperatures on seed germination of HIBISCUS SABDARIFFA was investigated and minimum, optimum and maximum temperatures for its germination were determined in a completely randomized design with four replications. For this purpose, temperatures 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50°C were considered in each treatment. Cardinal temperatures for germination were determined consistent with three models (i.e., Intersected-lines Model, Five-Parameters Beta Model and Quadratic Polynomial Model). The traits measured were germination percentage, speed of germination and mean germination time. The temperature effect on all the measured traits was significant. The results of the regression analysis showed that the best model in terms of cardinal point of this plant is the Five-Parameters Beta Model. Given the results of this model, the minimum and the optimal temperatures for the germination of Roselle are 4.04°C, and 29.83°C, respectively.