Medicinal Plants-Hibiscus, Roselle

Protocatechuic Acid (PCA) or Phenolic Acid Protocatecuic acid isolated from Hibiscus showed antioxidant, anticancer and antihepatocyts effects in experiments on animals and humans.Moreover presence of phenolic acid in the plant structure protect plant itself from pathogenic microorganisms.[18] In one study conducted in it was conluded that the blue and red color of flowers was due to the alkali or alkali-earth phenolic acid that was forming oxonium salts with acids.[16] In ordrer to islolate phenolic acid, ten killogram of flower petals of okra was harvested, them sepatrated into two portions: red and white. Then, 95 percent ethanol and 0.1/HCl-95 percent of ethanol were used to extract white and red portions of plant respectevely. After several steps 1-Butanol was isolated that induced a production of 1 mol of quercetin and glucose.Protocatechuic acid was obtained by the process of alkaline degradation.[18]
Hibiscus anthocyanins (HAs) Cyanidin Delphinidin Isolation of Anthocyanins pigments was studied in 1917 by isolating it from flowers such as poppies, peonies and etc.Different colors that were present in the plants was thought coming from the reaction of anthocyanins. Willstatter was one of the sintists who devided plants and fruit pigments into 3 different groups depending on the type of anthocyanins present. Two of the groups were cyanidin and delphinidin that were isolated from Hibiscus today. Cyannidin is one Anthocyanin that was synthesised by the reaction ofguercetin and magnesium at 35 degree Celcius.Willatter was working on isolation of cyanidin from yellow and red flower pettals that were 0.7 percent and 13-14 percent of the dry weight.[15] Anthocyanins pigments present in the plant as glucosides mixed with sugar.Isolating pigments, flowers have to be boiled in water and then pigments will precipitate (as lead salts) following the process of isolation by adding lead acetate.Lead pigments are filtered, decomposed by two dilute acids (sulfuric acid).later, solutions are boiled for several hours in order to split glucoside and less soluble pigments that filtered out.[19] Today synthesis of anthocyanin genes can be done by such procedures as protein purification, transposon tagging, deffirential screening and etc. Mutation of genes during the synthesis of anthocyanincs was possible, although today mutation causing genes can be isolated. Synthesis starts with malonyl-CoA and p-coumaroyl-CoA. Both coenzymes produce tetrahydroxychalcone from three acetate units and with the help chalcone synthase (CHS).In the next step, colorless niringenin product is produced with the help of chalcone isomerase (CHI) and then converted to dihydrokaempferol (DHK) with the help of flavonone 3-hydroxylase (F3H). In the next step dihydroquercetin (DHQ) and dihydromyrecetin (DHM) are produced when DHK get hdroxylated by flavonoid 3-hydroxylase or flavonoid 3,5-hydroxylase respectevely. In the siries of enzymeatic reactions colorless DHK, DHQ and DHM converted to anthocyanins. In first enzymatic reaction Leucoanthocyanidins are produced with the help of dihydroflavonol 4-reductase(DFR). Two other enzymatic reacions convert Leucoanthocyanidins to red cyanidin and blue delphinidin pigments.[17]
Organic Acids. Ascorbic Acid Organic acids such as ascorbic acid(Vitamin-c), oxalic acid, tartaic and etc. were isolated from the plant Hibiscus. Ascorbic acid was found to convey a greater pharmacoloogical effect indicated in the studies on animals and humans. Hhibiscus cold drink contain great amount of ascorbic acid. In Charles E. Bills article in 1935 ascrbic acid was thought as reducing substance that relatively stable in acid but get easily oxidized in alkaline.Bills obtained extract from lemon juice and converted it to alkaline testing it on lighted photograph that fainted black. Leter he discovered that Vitamin C (l-ascorbic acid) was a substance that apperred in lemon and used it in his other photographic experimetns.[20]