Research Article DPPH Radical Scavenging Potential of Ginger Leaves and Rhizomes Gina Batoy Barbosa1,*, Nonita Picardal Peteros2 1Department of Chemistry, Central Mindanao University, University Town, Musuan, Bukidnon, PHILIPPINES. 2Department of Chemistry, Mindanao State University-Iligan Institute of Technology, Iligan City, PHILIPPINES. Submission Date: 15-09-2018; Revision Date: 19-11-2018; Accepted Date: 20-12-2018 Correspondence: ABSTRACT Dr. Gina Batoy Barbosa, Introduction: Department of Chemistry, Gingers, belonging to the family Zingiberaceae, are popularly known for their Central Mindanao University, beneficial uses in medicine and culinary applications. Aim: This study was conducted to evaluate University Town, Musuan, the DPPH radical scavenging activity of the leaves and rhizomes of Zingiber officinale Rosc., Bukidnon, PHILIPPINES. Curcuma longa L., and Etlingera elatior (Jack) R.M. Smith. Methods: The plant samples were collected from Bukidnon, Mindanao, Philippines. Both water and ethanolic extracts were prepared Phone no: +63-917-426- 8951 separately from its leaves and rhizomes. The extracts were subjected to the determination of Email: ginavbatoy@yahoo. DPPH radical scavenging activity relative to ascorbic acid. Results and Discussion: Leaves, in com general, had higher radical scavenging activity in water than in ethanol extracts. On the other hand, rhizomes had generally higher radical scavenging activity in ethanol than in water extracts except for E. elatior. Among the leaf extracts, E. elatior possessed the highest radical scavenging activity. In both water and ethanol, E. elatior displayed higher radical scavenging activity in its leaves that its rhizomes. Conclusion: Findings of this study suggest the potential of E. elatior leaves as source of antioxidants. Key words: Gingers, Curcuma longa, Etlingera elatior, Zingiber officinale, DPPH. INTRODUCTION Free radicals cause lipid peroxidation and production of fore, have health-promoting e ects in the prevention of [3] highly toxic lipid derivatives, which in turn can modify degenerative diseases. Naturally occurring antioxidant ff cell functions and even may lead to cell death.[1] Cellu- supplements from plants are vital to counter the oxida- [2] lar damage or oxidative injury arising from free radicals tive damage in cells. or reactive oxygen species now appears to be the fun- Thus, an increase in the consumption of dietary anti- damental mechanism underlying a number of human oxidants, which can scavenge free radicals, may be a neurodegenerative disorders, diabetes, inflammation, strategy to prevent free radical-induced damage to viral infections, autoimmune pathologies and digestive biomolecules of lipids, proteins and deoxyribonucleic system disorders.[2] acid, including low density lipoprotein oxidation and An antioxidant, which can quench reactive free radicals, cancer cell initiation, an important beginning stage of [5] can prevent the oxidation of other molecules,[3] pro- carcinogenesis. Antioxidant research is a key topic in [4] tects the body from reactive species[4] and may, there- both the medical and food industry today. The DPPH assay is a very popular[6] and simplest method which is SCAN QR CODE TO VIEW ONLINE considered the first approach to evaluate the antioxidant www.ajbls.com potential of an extract, compound or biological sources. [7] DPPH assay utilizes DPPH● radical, one of the few DOI : stable organic nitrogen radicals, which bears a deep 10.5530/ajbls.2018.7.10 purple color. It is commercially available and does not have to be generated before assay. This assay is based Asian Journal of Biological and Life Sciences, Vol 7, Issue 3, Sep-Dec, 2018 87 Barbosa and Peteros.: DPPH Radical Scavenging Potential of Ginger Leaves and Rhizomes on the measurement of the reducing ability of antioxi- zomes of Curcuma longa, Etlingera elatior and Zingiber offi- dants toward DPPH●. The ability can be evaluated by cinale were evaluated. electron spin resonance or by measuring the decrease of its absorbance.[8] MATERIALS AND METHODS Zingiberaceae plants have received much attention since they produce many complex compounds that are Plant Sampling useful in food as herbs and spices, flavoring and sea- E. elatior plant samples were collected in June 2014 while soning and in the cosmetics and medicinal industries C. longa and Z. officinale were collected in October, 2014 as antioxidant and antimicrobial agents.[9] In Zingib- in Musuan, Maramag, Bukidnon, Philippines. eraceae, it is generally believed that antioxidants and Preparation of plant extracts other secondary metabolites are transported to the rhi- zomes where they are accumulated.[10] This implies that Preparation of plants extracts was done as previously [23] rhizomes would have higher antioxidant activity than reported in Barbosa et al. Briefly, cut plant samples of would other plant parts.[10] Rhizomes of cultivated spe- freshly collected leaves and rhizomes were boiled in suf- cies have been reported to possess radical-scavenging ficient distilled water for five minutes and filtered. The compounds comparable to commercial antioxidants residue left after freeze drying was stored at least -15°C on a weight per weight basis.[10] With these, several past until analysis. This served as the water extract. Etha- antioxidant studies on ginger species were confined to nol extracts were prepared by soaking separately leaves rhizomes.[11-16] The most common Zingiberaceae plant and rhizomes in 95 % ethanol for 48 hrs. The ethanol is the Zingiber officinale, commonly known as ginger. Z. extract obtained after solvent removal in vacuo using a rotary evaporator at 40°C was stored inside refrigerator officinale has shown significant efficacy in nausea, vomit- prior its usage. ing, motion sickness and arthritis and active compounds with antioxidant, anti-mutagenic, antimicrobial and anti- DPPH Radical Scavenging Activity cancer properties have been isolated and require further DPPH radical scavenging activities of the water and [17] scrutiny. Another rhizomatous herbaceous perennial ethanol extracts were determined using the method of plant of the Zingiberaceae family is Curcuma longa L. Lee and Shibamoto.[24] Briefly, various amounts of the Once a native to South Asia, it is now widely cultivated samples (500-, 100-, 50- and 10 µg/mL) were mixed in the tropical and subtropical regions of the world[18] with three mL of methanolic solution of DPPH (0.1 Commonly known as the golden spice turmeric, C. mM). The mixture was shaken vigorously in a vortex longa has been popular because of its component cur- mixer for 10 seconds and allowed to stand in the dark at cumin. Some promising effects have been observed on room temperature for one hour. Absorbance was then patients with cancer, arthritis, ulcerative proctitis, ulcer- measured at 517 nm against methanol as a blank in a ative colitis, psoriasis, atherosclerosis, diabetes, lupus Lasany double beam UV-Vis spectrophotometer (Hary- nephritis, renal conditions, acquired immunodeficiency ana, India). syndrome, gastric inflammation, vitiligo, Crohn’s dis- The DPPH solution alone in methanol was used as con- ease, irritable bowel disease, tropical pancreatitis, trol. Each sample was assayed in triplicate and mean acquired immunodeficiency syndrome and cholecystitis. values were calculated. L-Ascorbic acid was used as [19] Etlingera elatior (Jack) R. M. Smith is a natural species standard. The radical scavenging activity of samples in Sumatra, Indonesia and has been distributed through- corresponds to the intensity of quenching DPPH. The out Southeast Asia. In Peninsular Malaysia, its young percent of DPPH discoloration of the samples was cal- flowers shoots can be eaten raw and used for flavoring culated and results expressed as percentage inhibition in local dishes.[20] It is traditionally used for flavoring[20-21] using the formula shown below: [21] and medicine. % Inhibition = [(Acontrol – Asample) / Acontrol] x 100 Although leaves of ginger species have been used for where Acontrol and Asample are the absorbance values of the food flavoring and in traditional medicine, little research control and test sample, respectively. has been done on their antioxidant properties until The effective concentration of sample required to scav- [22] recent years. It is imperative that scientific attention enge DPPH radical by 50% (EC50) was obtained by lin- should also be given to ginger leaves. In this study, the ear regression analysis of dose-response curve plotting DPPH radical scavenging activity of the leaves and rhi- between % inhibition and concentration. 88 Asian Journal of Biological and Life Sciences, Vol 7, Issue 3, Sep-Dec, 2018 Barbosa and Peteros.: DPPH Radical Scavenging Potential of Ginger Leaves and Rhizomes RESULTS The data in Table 1 shows the percentage inhibition of DPPH radical by the scavenging activity of the ethanol DPPH Radical Scavenging Activity and water extracts of the leaves and rhizomes of the Percentage inhibition represents the DPPH radi- studied Zingiberaceae plants and the EC50 values. The cal scavenging activity of the sample extract. Figure 1 lower the EC50 value, the higher is the radical scavenging depicts a representative concentration-percent (%) inhi- activity of the plant extract. In order to illustrate direct relationship between EC bition curve for the DPPH radical scavenging activity. 50 and antioxidant activity, anti-radical power, 1/EC , Median effective concentration of each extract, that is, 50 was calculated by getting