Extractive Contents and DPPH-Scavenging Activities of Bamboo Leaf Extracts from Gigantochloa atter, Dendrocalamus asper, and Gigantochloa verticillata

Extractive Contents and DPPH-Scavenging Activities of Bamboo Leaf Extracts from Gigantochloa atter, Dendrocalamus asper, and Gigantochloa verticillata

Rini Pujiarti,

Sri Suryani,

Sigit Sunarta,

Ganis Lukmandaru,

Brandon Aristo Verick Purba

【 Summary】

In this study, we investigated the extractive contents, phenolic content, and DPPH-scavenging activity of leaf extracts of 3 commonly cultivated bamboo species (Gigantochloa atter, Dendro- calamus asper, and G. verticillata) from Tlogoadi Village, Yogyakarta, Indonesia. Extractions were successively done by reflux, using n-hexane, ethyl acetate, methanol, and hot water. The ex- tracts were subjected to the following procedures: phytochemical screening for alkaloids, saponins, and tannins; a colorimetric assay for total phenolic and flavonoid contents; and a DPPH radical- scavenging capacity assay. Results showed that hot water produced the highest yields of G. atter (3.62%) and D. asper (3.16%), while n-hexane produced the highest yield of G. verticillata (2.46%).

Phytochemical screening detected saponins in the hot-water extract of G. atter, and tannins were present in the ethanol (70%, v v

) extract of all 3 bamboo species. Total phenolic and flavonoid contents were highest in the ethyl-acetate extract of D. asper (26.09 mg gallic acid equivalents g

) and G. verticillata (92.67 mg quercetin equivalents g

), respectively. The hot water-soluble extract of G. verticillata showed the lowest 50% inhibitory concentration of 662.41 µg ml

. The present study indicates that the 3 bamboo leaf extracts can potentially be used as natural sources of anti- oxidants and phytochemicals, especially the polar extract of G. verticillata with its high flavonoid content and mild DPPH-scavenging activity.

Key words: phytochemical screening, phenolic, antioxidant, flavonoid, successive extraction.

Pujiarti R, Suryani S, Sunarta S, Lukmandaru G, Purba BAV. 2020. Extractive content and DPPH-scavenging activity of bamboo leaf extracts from Gigantochloa atter, Dendrocala- mus asper, and Gigantochloa verticillata. Taiwan J For Sci 35(1):1-12.

1)

D e p a r t m e n t o f F o r e s t P r o d u c t Te c h n o l o g y, F a c u l t y o f F o r e s t r y , U n i v e r s i t a s G a d j a h M a d a , Yogyakarta, Indonesia. Jl. Agro, No.01, Bulaksumur, Yogyakarta 55281, Indonesia..

2)

Corresponding author, e-mail:[email protected] 通訊作者。

Received August 2019, Accepted February 2020. 2019年8月送審 2020年2月通過。

研究報告

三竹種

(Gigantochloa atter, Dendrocalamus asper, Gigantochloa verticillata)竹葉萃取物含量

及清除

DPPH自由基活性

Rini Pujiarti

Sri Suryani

Sigit Sunarta

Ganis Lukmandaru

Brandon Aristo Verick Purba

摘 要

本 研 究 旨 在 調 查 印 度 尼 西 亞 日 惹 特 區 Tlogoadi村三種常見栽培竹種( Gigantochloa atter,

驗方法是採用回流法，依序使用正己烷、乙酸乙酯、甲醇和熱水進行萃取。萃取物之生物鹼、皂苷和單 寧含量透過植物化學篩選程序測定，總酚、類黃酮含量及和DPPH自由基清除能力則透過比色法測定。

研究結果顯示，

別為 3.62，3.16和2.46%。植物化學篩選檢測結果，皂苷可在G. atter以熱水萃取，以乙醇(70%, v/v)萃取 可在三竹種中取得單寧。總酚和類黃酮含量以乙酸乙酯萃取，含量最高分別是

g及G. verticillata的92.67 mg QE/g。G. verticillata的熱水溶性萃取產物顯示IC

值最低，為 662.41μg/ ml。

總結，本研究顯示三種竹葉萃取物具備被用來萃取抗氧化劑和植物化學物質天然來源的潛力，尤其是

verticillata含有高含量的類黃酮和溫和清除DPPH自由基活性的極性萃取產物。

關鍵詞：植物化學篩選、酚類、抗氧化劑、類黃酮、連續提取。

Pujiarti R、Suryani S、Sunarta S、Lukmandaru G、Purba BAV。2020。三竹種(Gigantochloa atter, Dendrocalamus asper, Gigantochloa verticillata)竹葉萃取物含量及清除DPPH自由基活

性。台灣林業科學35(1):1-12。

INTRODUCTION

Bamboos are large lignocellulosic plants in the family Gramineae. They are distributed in many tropical, subtropical, and temperate countries such as Indonesia, Brazil, China, Africa, Australia, Japan, and India. Bamboo is an important non-wood forest product (NWFP), since some parts of the stem are ex- tensively utilized (Agustino et al. 2011). The plant is often used as an ornamental and to provide environmental service; the main stem is used as a construction material for build- ing houses and bridges. Generally, bamboo

is used in furniture and handicrafts because

it is cheap and lightweight (Benton 2015). In

Indonesia, there are about 7 genera and more

than 60 known species of bamboo. Legi (Gi-

gantochloa atter), Petung (Dendrocalamus

asper), and Wulung bamboo (G. verticillata)

are bamboo species cultivated especially on

Java island, Indonesia. Gigantochloa atter

and D. asper are mostly utilized for construc-

tion, while G. verticillata is mostly used for

handicrafts and musical instruments (Rifai

1995).

Bamboo has been used as medicine since ancient times. The leaves of some bamboo species are used to treat stomach heat, colds, and arthritis (Hossain and Islamm 2015). Sev- eral compounds, such as flavones, phenolic acids, quinones, glycosides, and fatty acids, are found in bamboo leaf extracts (Gong et al. 2014). Previous studies found some bio- activity in leaf extracts of various species.

Fatty acids and their derivatives found in G.

apus leaves exhibited antibacterial activity against pathogenic Escherichia coli (Mulyono et al. 2013). Further, fatty acids are never mentioned in term of antioxidant activity.

The diverse chemical structures of alkaloids and saponins are thought to contribute to the antioxidant activity. Leaves of Bambusa arundinacea are known to exhibit antileprotic and anticoagulation activities, and they are also utilized to alleviate hemoptysis symp- toms (Khare 2007). Meanwhile, an extract of leaves of Phyllostachys nigra bamboo was shown to exhibit antioxidant activity, and it is used as a standardized food antioxidant in China (Hu et al. 2000, Gong et al. 2014).

Antioxidants are molecules, ions, or stable radicals that are able to prevent the oxi- dation of other molecules; oxidation can be caused by the activities of free radicals such as reactive oxygen species (ROS) and reac- tive nitrogen species (RNS) (Pinchuk et al.

2012). Some radical reactions are suspected of causing oxidative stress, which can lead to various diseases such as diabetes, arterioscle- rosis, aging disorders, and cancers (Halliwell and Aruoma 1991, Apak et al. 2007, Pinchuk et al. 2012). Further, antioxidant agents are often used as additives by the food industry to preserve products for longer periods (Caro- cho and Ferreira 2013). In recent times, both synthetic and natural antioxidants have been used in many kinds of industries. However, some common synthetic antioxidants, such as

butylated hydroxyl anisole (BHA) and butyl- ated hydroxy toluene (BHT), were associated with toxicity and carcinogenicity (Ito et al.

1985, Kahl and Kappus 1993, Caleja et al.

2017). This concern has increased interest in naturally derived antioxidants as safer alter- natives than synthetic antioxidants, as well as increasing the popularity of products that use natural antioxidants (Kumar and Pruthi 2014, Carocho and Ferreira 2013).

Due to limited information on leaf ex- tracts of G. atter, D. asper, and G. verticilla- ta, the purpose of this study was to investigate the extractive contents of G. atter D. asper, and G. verticillata leaves by analyzing total phenolic (TPC) and flavonoid contents (TFC), and qualitatively detecting certain compounds and antioxidant activities. The information obtained by this research is expected to en- courage people to explore the possibility of using bamboo leaf extracts as a source of natural antioxidants.

MATERIALS AND METHODS Preparation of bamboo leaf extracts

Fresh young bamboo leaves of G. atter, D. asper, and G. verticillata were harvested from Tlogoadi Village, Sleman, Yogyakarta, Indonesia (175 m in elevation). Young leaves that had a lighter green color and were lo- cated near or at the tip of bamboo stems were selected from 2 m in height of the trunk.

These were further dried at room tempera- ture, milled, sieved with a 20~40 mesh, and analyzed for moisture content following the ASTM D 4442-92 (Reapproved 03).

Successive extraction

Powdered leaf samples of each species

(50 g in dry weight; DW) were successively

extracted by reflux, using the solvents, n-

hexane, ethyl acetate, methanol, and hot

water, for 6 h for each solvent. Meanwhile, ethanol (70%, v v

) extraction (48 h, cold extraction) was conducted separately as a control. The extracts were filtered and evaporated before being stored separately in bottles. The extracted contents were calcu- lated based on the leaf DW, and all analyses were run in triplicate.

Phytochemical screening for alkaloids, saponins, and tannins

The n-hexane, ethyl-acetate, methanol, hot-water, and ethanol 70% extracts were subjected to phytochemical screening fol- lowing methods described by Pochapski et al. (2011) with slight modifications. Phyto- chemical screening was then used to iden- tify some classes of secondary metabolites (Table 2). Each test was replicated 3 times.

Result are presented as a summary of the replications.

Screening for alkaloids

Alkaloids were screened by adding 50 mg of extract to 5 ml of a chloroform-ammo- nia mixture; this was then filtered into a test tube. A few drops of 2 M H

SO

were added to the filtrate and shaken to form 2 layers. Af- ter that, the top layer (which was clear) was placed in a glass container. Drops of Meyer reagent were added to the top layer. If a white precipitate formed, then the extract was posi- tive for alkaloids.

Screening for saponins

In total, 50 mg of an extract was dis- solved in 5 ml of water in a test tube. After heating for about 5 min, the extract was filtered and shaken. After shaking, if a vis- ible froth appeared that did not disappear for 10 min and remained stable after add- ing 2 N HCl, then the extract was positive for saponins.

Screening for tannins

Methanol (5 ml) was added to dissolve 50 mg of an extract in a test tube. After heat- ing the tube, the extract was filtered through filter paper (8µm pore size). To the filtrate was added 5~10 drops of 1% FeCl

. If the fil- trate became dark blue or dark green, then the extract was positive for tannins.

Colorimetric assay for TPC and TFC The assay for the TPC was carried out using Folin-Ciocalteau reagent according to the method described by Baba and Malik (2015) with slight modifications. An aliquot (0.5 ml) of the extract was diluted with meth- anol to a concentration 1 mg ml

. Folin-Cio- calteau reagent at 2.5 ml that had been diluted 10 times was added to diluted extracts, and the solution was further incubated for 2 min at room temperature. After incubation, 2 ml of Na

CO

(7.5%) was added and the solution was incubated for 30 min. The absorbance was analyzed using an ultraviolet-visible (UV-VIS) spectrophotometer at a wavelength of 765 nm. Furthermore, a blank test was also carried out with no extract. A calibration curve was prepared using gallic acid with the same procedure. The TPC was expressed as milligrams gallic acid equivalents (GAE) per gram of sample. All analyses were run in trip- licate, and average values are reported.

The TFC was measured using an alu- minum chloride assay method described by Diouf et al. (2009) with slight modifications.

An aliquot (2 ml) of the extract at a concen- tration of 1 mg ml

was added to 2 ml of 2%

AlCl

.6H

O. After being incubated for 1 h

at 20℃, the absorbance was analyzed with a

UV-VIS spectrophotometer at a wavelength

of 415 nm. Furthermore, a blank test was car-

ried out with no extract. A calibration curve

was made using quercetin with the same pro-

cedure, and the TFC was expressed as mil-

ligrams quercetin equivalents (QE) per gram of sample. All analyses were run in triplicate, and the average is reported.

Scavenging activity of 2,2-diphenyl- 1-picrylhydrazyl (DPPH) radicals

The antioxidant activity was analyzed using a DPPH-scavenging capacity assay described by Gong et al. (2014) with slight modifications. An aliquot (0.1 ml) of an ex- tract at various concentrations (250, 500, 1000, and 2000 μg ml

) was added to 5 ml of a DPPH solution. The mixture was shaken by hand and incubated in a dark place for 30 min. A blank determination was done without the addition of the extract. The absorbance was analyzed using a UV-VIS spectropho- tometer at 516 nm. Inhibition was calculated using the following equation:

Inhibition (%) = ((A

- A

)×100) /A

where A

is the absorbance of the blank, and A

is the absorbance of the sample. The antioxidant activity was expressed as the con- centration that can inhibit DPPH radicals by 50% (IC

) using a graph function created for the inhibition. In this experiment, gallic acid and catechin were used as positive controls of natural antioxidants. All analyses were run in triplicate, and their average was calculated.

Statistical analysis

Data were analyzed using SPSS soft-

ware (vers. 25, IBM, New York, NY, USA).

A two-way analysis of variance (ANOVA) at a confidence level of 95% was used to deter- mine the effects of bamboo species (G. atter, G. verticillata, and D. asper) and solvents (n- hexane, ethyl acetate, methanol, and hot wa- ter). Thereafter, a post-hoc test was performed using Tukey’s honest significant difference (HSD) method to determine the significance level of the data.

RESULTS

Extraction yield, TPC, and TFC

Extractive yields of leaf extracts of the 3 bamboo species (G. atter, D. asper, and G. verticillata) were determined using sol- vents with successively increasing polarity.

Each extract, except for the n-hexane-soluble extract, was analyzed with colorimetric as- says. Extraction yields are shown in Table 1.

Gigantochloa verticillata revealed the high- est soluble extract with n-hexane (2.46%), ethyl acetate (1.68%), and total extractive yield (8.81%), while G. atter had the high- est yields of soluble extracts with methanol extraction (2.58%), hot water (3.62%), and 70% ethanol (4.96%). Further, the TPC and TFC are shown in Figures 1 and 2. The ANOVA revealed a significant difference in the interaction of the two factors of TPC (p <

0.05) and TFC (p < 0.01). The highest TPC

Table 1. Percentage of extraction yield with successive extraction

Bamboo species Extraction yield (%)

n-hexane ethyl acetate Methanol hot water Total extractive

ethanol 70%

G. atter

0.93 0.91 2.58 3.62 8.04 4.96

D. asper 1.76 1.43 2.12 3.16 8.47 4.75

G. verticillata 2.46 1.68 2.40 2.27 8.81 4.58

Data shown are mean from three replication

1)

Total extractive yield is a sum of the successive extraction yield.

2)

n-hexane – hot water extractions were done successively, ethanol 70% extraction were done separately.

and TFC were found in the ethyl acetate- soluble extract of D. asper (26.09 mg GAE g

) and G. verticillata (92.67 mg QE g

), re- spectively. Meanwhile, TPCs were found to be lower in methanol- and hot water-soluble extracts, and no flavonoids were measured in the hot water-soluble extracts.

Phytochemical screening for alkaloids, saponins, and tannins

Amounts of alkaloids, saponins, and tan- nins detected in leaf extracts of the 3 bamboo species (G. atter, D. asper, and G. verticil- lata) are shown in Table 2. Saponins, tannins, or alkaloids were not detected in ethyl-acetate or methanol extracts of the 3 bamboo species.

The presence of saponins was only detected in the hot-water extract of G. atter. Tannins were detected in the ethanol (70%) extracts of all 3 bamboo species.

25.64 23.36 22.85 23.22

26.09 23.45 23.42 23.94

25.50 23.42 24.37 24.85

20 21 22 23 24 25 26 27

Total Phenolic Content (mg G AE/g)

G. atter D. asper G. verticillata

bc c bc

ab ab

ab a ab ab

ab bc b

Ethyl acetate Methanol Hot water Ethanol 70%

Fig. 1. A: Total phenolic content of ethyl acetate, methanol, hot water, and ethanol 70 soluble extract.

84.03 20.80 0.00 3.50

84.23 22.58 0.00 5.18

92.67 18.49 0.00 17.18

0 20 40 60 80 100 120

Ethyl acetate Methanol Hot water Ethanol 70%

Total Flavonoid Content (mg QE/g)

G. atter D. asper G. verticillata

c c d

b b b

a a a a a

b

Fig. 2. Total flavonoid content G. atter, D. asper, and G. verticillata on ethyl acetate,

methanol, hot water, and ethanol 70 soluble extract.

Table 2. Phytochemical screening for saponin, tannin, and alkaloid

Classes of Tests G. atter

compounds

Ethyl acetate Methanol Hot water Ethanol 70%

Saponin Frothing (-) (-) (+) (-)

Tannin Ferric chloride (-) (-) (-) (+)

Alkaloid Mayer (-) (-) (-) (-)

Ethyl acetate Methanol Hot water Ethanol 70%

Saponin Frothing (-) (-) (-) (-)

Tannin Ferric chloride (-) (-) (-) (+)

Alkaloid Mayer (-) (-) (-) (-)

Ethyl acetate Methanol Hot water Ethanol 70%

Saponin Frothing (-) (-) (-) (-)

Tannin Ferric chloride (-) (-) (-) (+)

Alkaloid Mayer (-) (-) (-) (-)

The results are average from three replications. (-) = no presence; (+) = presence of compound.

DPPH radical-scavenging capacity The DPPH radical-scavenging assay is a method that depends on the ability of a compound to reduce DPPH radicals. A hydrogen atom that has been donated by a donor compound or antioxidant forms a non- radical form of DPPH-H. The antioxidant activity of the extract was expressed as the IC

value as shown in Figure 3. The highest antioxidant activity is shown by the lowest IC

value. In general, mild antioxidant activi- ties were exhibited by polar solvents (ethyl acetate, methanol, hot water, and 70% etha- nol). Meanwhile, n-hexane-soluble extracts showed low antioxidant activity. Gallic acid and quercetin were used as positive controls, and a comparison showed respective values of 92.51 and 169.05 µg ml

. An ANOVA of the antioxidant activity of various polar solvents showed a significant interaction between the various species and solvent factor (p = 0.032).

Tukey’s HSD test showed that polar- soluble extracts had no significant antioxidant activity, except for the ethyl acetate-soluble

extract of G. verticillata which was signifi- cantly milder. The ethanol (70%)-soluble ex- tract of G. verticillata showed the highest an- tioxidant activity with an IC

value of 566.79 µg ml

. Compared to the positive controls, the extract showed mild antioxidant activity (Ethanol soluble extract of G. verticillata IC

was ±6.12 and ±3.35 times the IC

values of gallic acid and quercetin, respectively).

DISCUSSION

Successive extraction is a method used

to extract a broad range of compounds using

solvents with increasing polarity from non-

polar (n-hexane) to polar (hot water). G.atter

showed the highest yield of polar compounds,

while G. verticillata showed the highest yield

of apolar compounds. The apolar n-hexane-

soluble extracts showed a dark color, and it

was assumed to contain phenolics, albeit to a

lesser extent. The highest yield of polar com-

pounds was obtained using 70% ethanol in all

species. Further, TPCs of the 3 bamboo spe-

cies were higher in semi-polar (ethyl acetate) extracts, while the polar extractive showed lower amounts with no significant difference among the solvents. Meanwhile, TFCs of the 3 species declined as the polarity of the solvent increased, and flavonoids were not present in hot water-soluble extracts. These results indicate that the 3 bamboo leaf extracts with relatively low polarity were dominated by phe- nolic compounds as seen with quercetin. This was in alignment with a previous study on the ethyl acetate-soluble peel extract of Citrus hys- trix, where the amount of phenolic compounds varied based on the polarity of the solvent used (Wijaya et al. 2017).

Phytochemical screening detected that saponins were present in the hot-water ex- tract of G. atter. Saponins are glycosides that consist of an aglycone, either a choline steroid or triterpenoid, and a sugar side chain

that attaches through a bond in C3 (Vicken et al. 2007). Previous studies explained some of the benefits of ingesting saponins by humans because of the hypocholesterolemic, immunostimulatory, antioxidant, and anticar- cinogenic properties they possess (Coffie et al. 2014). However, glycosidation of pheno- lics lowers the antioxidant potency (Merrilon et al. 1997; Hopia and Heinonen 1999). In some cases, saponins are also known to be toxic at high doses, as they have hemolytic properties (Price et al. 1987). Therefore, their detection in the hot-water extract of G.

atter could indicate additional health benefits to humans. However, their safety and toxic- ity should be further studied before they are applied to human diets.

Tannins were detected by phytochemi- cal screening in 70% ethanol-soluble ex- tracts. Tannins are hydrophilic polyphenol

4988 .7 8 1450 .1 7 2504 .9 3 1993 .1 2 1825 .0 7

3869 .1 8 1566 .1 7 1459 .9 1 1039 .7 2 1017 .2 0

4446 .5 5 4085 .0 0 1674 .2 4 662 .4 1 566 .7 9

169.05 92.51

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000

IC

(µ g/ m l)

ab b

a a

a ab

b a ab

c c c

ab ab c

G. atter D. asper G. verticillata

Control

n‐hexane ethyl acetate methanol hot water ethanol 70% Quercetin Gallic acid Fig. 3. IC

(inhibitory concentration to scavenge the DPPH radical by 50 ) of G. atter, D.

asper, and G. verticillata on ethyl acetate, methanol, hot water, and ethanol 70 soluble

extract. Quercetin and gallic acid were used as positive control. Lower value indicates

stronger antioxidant activity.

compounds with large molecular weights of 500 to 3000. They have the capacity to form insoluble complexes with proteins, cellulose, pectin, and gelatin (Swain and Bate-Smith 1962, Lekha and Lonsane 1997). The tannins present in G. atter, D. asper, and G. verticil- lata are suggested to be proanthocyanidins (condensed tannins), because hydrolysable tannins are only found in dicotyledonous plants (Sule et al. 2005). Proanthocyanidins are known to have a wide range of benefi- cial health properties such as antioxidative, anticancer, and health-promoting activities against some diseases such as Alzheimer’s disease and cardiovascular disease (Sato and Matsui 2012). Hot-water extracts of the 3 spe- cies of bamboo can potentially be used as di- etary supplements with those beneficial prop- erties. A portion of the flavonoids found in the successive extraction process was suspected of having a proanthocyanidin monomeric unit (flavan-3-ols), while condensed tannins with larger molecular weights were dissolved in ethanol (70%). This was further detected in the phytochemical screening.

Compared to previous studies, results of the DPPH-scavenging capacity assay showed similarities between the antioxidant activities of the hot-water and ethanol (70%) extracts from G. verticillata leaves and the antioxidant activity of ferulic acid (±4.84-fold gallic ac- id’s IC

), a natural antioxidant found in many plant parts including bamboo shoots (Villano et al. 2007, Kumar and Pruthi 2014). This re- sult did not statistically different from the hot water-soluble extracts of G. atter and D. asper.

Therefore, it can be deduced that the polar leaf extracts of the 3 bamboo species, especially that from G. verticillata, can potentially be used as a natural source of antioxidants.

Flavonoids are one of the main function- al components in leaf extracts of some other bamboo species. Some of the flavonoids were

identified as flavone C-glucosides, including isoorientin, vitexin, orientin, and isovitexin (Zhang et al. 2005). However, in this study, although the ethyl acetate-soluble extract of the 3 bamboo species showed high TPC and TFC values, their antioxidant activities were fairly low. Furthermore, the hot water-soluble extracts of the 3 bamboo species generally showed preponderant antioxidant activity even though no flavonoid content was detect- ed. A similar trend was also observed in bark extracts of Shorea macroptera and Neobala- nocarpus heimii, as they had high total phe- nolics but low antioxidant activity (Kawamura et al. 2011). Pietarinen et al. (2006) who reviewed the antioxidant properties of bark extracts from several species suggested syn- ergism of the polyphenols, or there may be minor compounds that strongly contribute to the activity compared to the predominant compounds. This result therefore indicates that the antioxidant activity of the 3 bamboo species was not attributable to flavonoids that could be measured by the methods applied in this research. In the hot water-soluble extract, we suspect that long-chain proanthocyanidins contributed more to the antioxidative proper- ties of the 3 bamboo extracts because their presence was detected during phytochemical screening. Further identification should be done to determine what compounds are re- sponsible in the antioxidant activity observed in the hot-water extract

CONCLUSIONS

The maximum recovery of polar extracts

of G. atter, D. asper, and G. verticillata was

achieved using ethanol (70%). The highest

yield of polar extracts was shown by G. atter,

while G. verticillata was observed to have

the highest yield of apolar extracts. The high-

est TPC and TFC were shown with the ethyl

acetate-soluble extract. Dendrocalamus asper had the highest TPC, while G. verticillata had the highest TFC. Phytochemical screening detected saponins in the hot water-soluble ex- tract of G. atter, while tannins were detected in the ethanol (70%)-soluble extract of all 3 bamboo species. Higher antioxidant activity was shown by the 70% ethanol-soluble ex- tract of G. verticillata, followed by D. asper, and the G. verticillata leaf extract exhibited effective DPPH radical-scavenging activity. It contained high amounts of TPC and TFC.

Results of this research indicate that leaf extracts from these 3 bamboo species exhib- ited good concentrations of phenolic com- pounds, mild DPPH-scavenging activity, and the presence of some beneficial phytochemi- cal compounds. Some bioactivity can be expected especially from the polar (hot water and ethanol 70%) extracts of G. verticillata leaves. Hopefully, results of this research can be used as a reference for more in-depth stud- ies of the extracts from these 3 bamboo spe- cies as sources of natural antioxidants from non-wood forest products. Future research should be focused on the identification and more-specific quantification of the phenolic compounds, as well as investigation of their antioxidant activities using different types of radicals.

ACKNOWLEDGMENTS

This research was funded by In Search of Balance Scholarship, Norway.

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