Open Access
Open Peer Review

This article has Open Peer Review reports available.

How does Open Peer Review work?

Phytochemicals from Mangifera pajang Kosterm and their biological activities

  • Sadikah Ahmad1,
  • Mohd Aspollah Sukari1Email author,
  • Nurussaadah Ismail1,
  • Intan Safinar Ismail1,
  • Ahmad Bustamam Abdul2,
  • Mohd Fadzelly Abu Bakar3,
  • Nurolaini Kifli4 and
  • Gwendoline C L Ee1
BMC Complementary and Alternative MedicineThe official journal of the International Society for Complementary Medicine Research (ISCMR)201515:83

https://doi.org/10.1186/s12906-015-0594-7

Received: 17 July 2014

Accepted: 28 February 2015

Published: 26 March 2015

Abstract

Background

Mangifera pajang Kosterm is a plant species from the mango family (Anacardiaceae). The fruits are edible and have been reported to have high antioxidant content. However, the detailed phytochemical studies of the plant have not been reported previously. This study investigates the phytochemicals and biological activities of different parts of Mangifera pajang.

Methods

The plant samples were extracted with solvents of different polarity to obtain the crude extracts. The isolated compounds were characterized using spectroscopic methods. The extracts and isolated compounds were subjected to cytotoxicity tests using human breast cancer (MCF-7), human cervical cancer (HeLa) and human colon cancer (HT-29) cells. The free radical scavenging activity test was conducted using the DPPH assay. Antimicrobial activity tests were carried out by using the disc diffusion method.

Results

Phytochemical investigation on the kernel, stem bark and leaves of Mangifera pajang led to the isolation of methyl gallate (1), mixture of benzaldehyde (2) and benzyl alcohol (3), mangiferonic acid (4), 3β-hydroxy-cycloart-24-ene-26-oic acid (5), 3β,23-dihydroxy-cycloart-24-ene-26-oic acid (6), lupeol(7) lupenone(8), β-sitosterol(9), stigmasterol(10), trans-sobrerol(11) and quercitrin (12). Crude ethyl acetate and methanol extracts from the kernel indicated strong cytotoxic activity towards MCF-7 and HeLa cells with IC50 values of less than 10 μg/mL, while petroleum ether, chloroform and ethyl acetate extracts of the stem bark showed strong to moderate activity against MCF-7, HeLa and HT-29 cancer cell lines with IC50 values ranging from 5 to 30 μg/mL. As for the antimicrobial assays, only the ethyl acetate and methanol extracts from the kernel displayed some inhibition against the microbes in the antibacterial assays. The kernel extracts showed highest free radical scavenging activity with IC50 values of less than 10 μg/mL, while the ethyl acetate and methanol extracts of leaves displayed only weak activity in the DPPH assays.

Conclusions

Phytochemical investigations on various parts of Mangifera pajang have identified terpenoids and a flavonol derivative as major constituents. Bioassay studies have indicated that the crude extracts and isolated compounds have potential as naturally-derived anticancer and antimicrobial agents, besides possess high free radical scavenging activity.

Keywords

Mangifera pajang Bambangan Phytochemicals Cytotoxicity DPPH Antimicrobial

Background

Mangifera pajang Kosterm is also known as ‘bambangan’; a plant species from the mango group which can be found in Borneo Island (Malaysia – Sabah and Sarawak, Brunei, and Indonesia – Kalimantan) [1]. Unlike commercial mangoes (Mangifera indica), the fruit of Mangifera pajang are rarely eaten as it is unpopular among the public in Peninsula Malaysia and it is relatively unknown as antioxidant source. The fruits are ovoid and light-brown coloured, while the peels are thick which constitute approximately 27% of the whole bambangan fruit. The bambangan fruit is also about three times larger than its more common counterpart, mango [2,3]. The pulp is fibrous, juicy, has a specific aromatic flavour and strong smell and can be eaten fresh while the peel is used for cooking curries [3]. In Sabah, the kernel and flesh are used to make ‘jerok bambangan’ among Kadazans, the young leaves are sold as vegetables in Sarawak, while the thick rind can be sun-dried and preserved to be used for preparation of ‘sambel’ [4]. Previous studies of the fruit parts (peel, pulp and kernel) have reported high antioxidant and cytotoxic activity towards cancer cell lines [5,6]. However, there are no reports on the isolation of chemical constituents from the kernel, leaves and stem bark of the plant. In continuation of our research on local underutilised medicinal plants, we wish to report herein on the phytochemical properties and biological activities of Mangifera pajang.

Methods

Plant collection

The plant was collected from Sabah, Malaysia and was identified by Dr Mohd Fadzelly Abu Bakar from Universiti Tun Hussein Onn Malaysia (UTHM). The voucher specimen was deposited at the herbarium, BORNEENSIS, Universiti Malaysia Sabah. The plant samples (kernel, leaves and stem bark) were air-dried and ground into a fine powder prior to being used.

Extraction and isolation

The ground kernel (180 g), leaves (500 g) and stem bark (330 g) of Mangifera pajang were extracted successively, each three times with petroleum ether, chloroform, ethyl acetate and methanol respectively for three days, for each extract by cold maceration method. Small portions of each crude extract were put aside for bioassays and the rest were fractionated using the column chromatographic method. From the kernel of the plant, β-sitosterol (9) (7 mg) and a yellow oil containing mixture a of benzaldehyde (2) and benzyl alcohol (3) were obtained from petroleum ether (12.26 g) and chloroform extracts (1.30 g) while isolation work on the methanol extract (21.95 g) gave methyl gallate (1) (1.15 g). Various crude extracts; petroleum ether (18.08 g), chloroform (3.59 g), ethyl acetate (1.24 g) and methanol (5.04 g) extracts from stem bark of Mangifera pajang were fractionated using column chromatography which afforded mangiferonic acid (4) (3.10 g), 3β-hydroxy-cycloart-24-ene-26-oic acid (5) (2.27 g) and 3β,23-dihydroxy-cycloart-24-ene-26-oic acid (6) (10 mg), lupeol (7) (3.15 g), β-sitosterol (9) (9 mg), stigmasterol (10) (5 mg) and trans-sobrerol (11) (14 mg). In addition, fractionation of the leaves extract gave lupeol (7) (20 mg), lupenone (8) (16 mg), methyl gallate (1) (11 mg) and quercitrin (12) (1.29 g). The structures of the isolated compounds were elucidated using spectroscopic methods including infrared spectroscopy (IR), mass spectrometry (MS), and nuclear magnetic resonance spectroscopy (NMR).

Methyl gallate (1): white solid, C8H8O5,m.p. 190–192°C (lit. m.p 188–189°C) [7]. IR (UATR, cm−1) νmax: 3347, 3100, 2850, 1686, 1441, 1466.EI-MS m/z (% intensity):184 (M+, 45). 1H and 13C NMR spectral data were in good agreement with the published data [7].

Mixture of benzaldehyde (2) and benzyl alcohol (3): yellow oil, IR (UATR, cm−1) νmax: 3400, 1739, 1457. EI-MS m/z (% intensity) of benzaldehyde (C7H6O): 106 (M+, 90). EI-MS m/z (% intensity) of benzyl alcohol (C7H8O):108 (M+, 77).

Mangiferonic acid (4): white solid, C30H46O3, m.p.185-188°C (lit. m.p. 188–192°C) [8]. IR (UATR, cm−1) νmax: 3306, 3067, 1681, 1642, 1454, 1376, 1106.EI-MS m/z (% intensity):454 (M+, 38).1H and 13C NMR spectral data were in good agreement with the published data [8].

3β-Hydroxy-cycloart-24-ene-26-carboxylic acid (5): white solid, C30H48O3, m.p. 175–177°C (lit. m.p. 177–178°C) [8]. IR (UATR, cm−1) νmax: 3361, 2933, 2867, 1683, 1634, 1447, 1372, 1020. EI-MS m/z(% intensity):456 (M+, 9).1H and 13C NMR spectral data were in good agreement with the published data [8].

3β,23-Dihydroxy-cycloart-24-ene-26-oic acid (6): white needle-shaped crystals, C30H48O4, m.p. 276-278°C (lit. m.p 279–281°C) [9]. IR (UATR, cm−1) νmax: 3318, 3101, 2933, 2870, 1670, 1439, 1374, 1043. EI-MS m/z(% intensity):472 (M+, 6). 1H and 13C NMR spectral data were in good agreement with the published data [9].

Lupeol (7): white solid, C30H50O, m.p 199-210°C (lit. m.p 212-213°C) [10]. IR (UATR, cm−1) νmax: 3308, 2925, 2858, 1639, 1455, 1377, 1034. EI-MS m/z(% intensity):426 (M+, 7). 1H and 13C NMR spectral data were in good agreement with the published data [10].

Lupenone (8): Colourless needle-shaped crystals, C30H48O, m.p. 166–168°C (lit. m.p 168-170°C) [11]. IR (UATR, cm−1) νmax: 2938, 2861, 1702, 1643, 1451, 1380, 869. EI-MS m/z(% intensity):424 (M+, 43). 1H and 13C NMR spectral data were in good agreement with the published data [11].

β-Sitosterol (9): white needle-shaped crystals, C29H50O, m.p. 133–135°C (lit. m.p 136-138°C) [12]. IR (UATR, cm−1) νmax: 3413, 2935, 2860, 1673, 1455, 1372, 1047. EI-MS m/z(% intensity):414 (M+, 49). 1H and 13C NMR spectral data were in good agreement with the published data [13].

Stigmasterol (10): colourless needle-shaped crystals, C29H48O, m.p. 168 to 170°C (lit. m.p 167 - 169°C) [14]. IR (UATR, cm−1max: 3429, 2928, 2857, 1711, 1460, 1375, 1058. EI-MS m/z (% intensity):412 (M+, 10). 1H and 13C NMR spectral data were in good agreement with the published data [10].

Trans-sobrerol (11): white needle-shaped crystals, C10H18O2, m.p. 130 to 132°C (lit m.p 130–133°C) [15]. IR (UATR, cm−1) νmax: 3413, 2935, 2865, 1673, 1455, 1372, 1047.EI-MS m/z (% intensity):170 (M+, 1).1H and 13C NMR spectral data were in good agreement with the published data [15].

Quercitrin (12): yellow solid, C21H20011, m.p. 188–190°C (lit. m.p 179–182°C) [16]. IR (UATR, cm−1) νmax: 3429, 1653, 1599, 1498, 1062, 814. EI-MS m/z (% intensity):302 (M+- Rham). 1H and 13C NMR spectral data were in good agreement with the published data [16].

Cytotoxic assays

Various crude extracts of Mangifera pajang were screened for cytotoxic activity against MCF-7 (human breast cancer), HeLa (human cervical cancer) and HT-29 (human colon cancer) cells according to the method described previously [17]. The stock solutions of 100 mg/mL were prepared by using dimethyl sulphoxide (DMSO) of concentrations ranging from 0.1 μg/mL – 30.0 μg/mL. Working solutions were made up by two fold dilution of the stock and 20 μL of each concentration was added to each well in triplicates. The control wells of the untreated population were treated with highest concentration DMSO as the negative control. After 3 days, the cell viability was determined by introducing 20 μL of MTT solution (5 mg/mL in PBS) to each well, followed by 4 hours of incubation. The blue formazan crystals that formed were dissolved in DMSO and the absorbance was read using the Elisa reader with wavelength of 570 nm and a reference wavelength of 630 nm. The cytotoxic activity was determined by the IC50 values, which were defined as the concentration of the test samples that resulted in a 50% reduction of absorbance or a measure of 50% concentration of tested samples that was required to inhibit the growth of cancer cells. Extracts and isolated compounds that indicated IC50 values < 10 μg/mL, are considered to have significant cytotoxic activity against that particular cell line.

DPPH assay

The scavenging activity of the crude extracts and constituents were determined by using 1,1- diphenyl-2-pycrylhydrazyl (DPPH) according to a procedure described previously [18]. DPPH was used as the stable free radical agent while DMSO was used as the blank. The sample was dissolved in DMSO in the ratio of 1:1 (w/v) and diluted to achieve concentrations of 500, 250, 125, 62.50, 31.25, 15.63 and 7.81 μg/mL. The IC50 values were determined by plotting the percentage of inhibition against sample concentration, ranging from 500 to 7.81 μg/mL. The IC50 values are defined as the amount of antioxidants needed to decrease the initial concentration of DPPH by 50%.

Antibacterial and antifungal assays

All crude extracts from Mangifera pajang (kernel, leaves and stem bark) were subjected to antibacterial and antifungal assays towards several targeted microbes including Methicillin resistant staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Salmonella choleraesuis and Bacillus subtilis for antibacterial screening while Candida albican, Aspergillus ochraceaus and Sacchoromyces cerevisiae were used for antifungal screening. The assays were carried out using the disc diffusion method [17]. This involved placing paper discs of 6 mm in diameter that contained the samples onto a plate where the microbes were growing. Ampicillin (Gram-negative Bacteria) and Streptomycin (Gram-positive Bacteria) standards were used for the bacteria while nystatin was used as the positive control for the fungi. The plates were inverted and incubated at 30-37°C for 18–24 hours for bacteria and 24–48 hours for fungi or until sufficient growth had occurred. After incubation, each plate was examined. The diameters of the zones of complete inhibition were measured.

Results and discussion

Isolated constituents

Phytochemical investigations on the kernel, stem bark and leaves of Mangifera pajang have afforded several classes of constituents including aromatic esters, cycloartane and lupane triterpenes, a monoterpene, steroids and a flavonol glycoside.
  • An aromatic ester; methyl gallate (1) and a mixture of benzaldehyde (2) and benzyl alcohol (3) together with β-sitosterol (9) have been isolated from the kernel. Cycloartane triterpenes; mangiferonic acid (4), 3β-hydroxy-cycloart-24-ene-26-oic acid (5) and 3β,23-dihydroxy-cycloart-24-ene-26-oic acid (6), lupeol (7), β-sitosterol (9), stigmasterol (10) and a monoterpene identified as trans-sobrerol (11) were obtained from the stem bark. Meanwhile lupane triterpenes; lupeol (7) and lupenone (8) together with methyl gallate (1) and a flavonol glycoside; quercitrin (12) have been isolated from the leaves. The structure of compounds shown in Figure 1 were elucidated using spectroscopic analysis (IR, EIMS and NMR) and also by comparison with reported data [7-16].

  • Compound (1) was reported previously from ripe bambangan peel using HPLC-DAD and TSQ-ESI-MS analysis [19]. The compound was obtained from the methanol extracts of the kernel and leaves and which appeared as a white amorphous solid with m.p. of 190-192°C. Compound (2) and (3) were obtained as a yellow oily mixture from the petroleum ether and chloroform extracts of the kernel respectively. GCMS analysis of the oil suggested the presence of mixture of benzaldehyde (2) and benzyl alcohol (3). Molecular ion peaks at m/z 106 and 108 corresponded to benzaldehyde (2), C7H6O and benzyl alcohol (3), C7H8O, respectively.

  • Compounds (4), (5), and (6) which belong to cycloartane type triterpenes were obtained from the non-polar extracts of the stem bark. These compounds were previously isolated from Mangifera indica [8,9] and this is the first reported isolation of the compounds from Mangifera pajang.

  • Two lupane triterpenes, lupeol (7) and lupenone (8) were obtained from the extracts of the stem bark and leaves of Mangifera pajang. Lupeol (7) was obtained both from the stem bark and leaves while lupenone (8) was isolated only from the leaves. The EI-MS spectra of the compounds show molecular ion peaks at m/z 426 and 424 which corresponded to molecular formulae C30H50O (lupeol) and C30H48O (lupenone), respectively. Compound (9) and (10) which were identified as β-sitosterol and stigmasterol have also been isolated from the kernel and stem bark. The identities of the compounds were confirmed by comparing its physical and spectral data with the literature values [13,14].

  • Compounds (11) and (12) were identified as trans-sobrerol and quercitrin, respectively. Compound (11) is a monoterpene while compound (12) is a flavonol glycoside and both compounds have never been isolated from the genus Mangifera. Compound (11) was isolated from chloroform extract of the stem bark and appeared as white needle crystals with a melting point of 130 - 132°C and the spectral data were in good agreement with the published data [15]. Meanwhile, compound (12) was obtained from the ethyl acetate and methanol extracts of the leaves and appeared as a yellow solid with a melting point of 188 - 190°C. The compound was identified by comparison of its spectral data with that available literature of the compound isolated previously from the leaves of Myrsine seguinii [16].

Figure 1

Isolated constituents from Mangifera pajang: methyl gallate (1), mixture of benzaldehyde (2) and benzyl alcohol (3), mangiferonic acid (4), 3β-hydroxy-cycloart-24-ene-26-oic acid (5), 3β,23-dihydroxy-cycloart-24-ene-26-oic acid (6), lupeol (7), lupenone (8), β -sitosterol (9), stigmasterol (10), trans -sobrerol (11), quercitrin (12).

Cytotoxicity of crude extracts and isolated compounds

All crude extracts from the kernel, stem bark and leaves were subjected to cytotoxic screening against MCF-7, HeLa and HT-29 cancer cells and the results are summarized in Table 1.
  • Ethyl acetate and methanol extracts of the kernel showed strong cytotoxic activity towards MCF-7 and HeLa cell lines with IC50 values less than 10 μg/mL, and displayed strong to moderate activities towards the HT-29 cell line. In addition, petroleum ether and chloroform extracts of the stem bark also showed high cytotoxic activity towards MCF-7, HeLa and HT-29 cells with IC50 values of less than 15 μg/mL. In contrast, the ethyl acetate extract of the stem bark and the petroleum ether extract of the leaves displayed rather weak activity with IC50 values of more than 20 μg/mL. Similarly, most of the extracts from the leaves were not active with IC50 values being more than 30 μg/mL. Previous studies on the cytotoxic activity of Mangifera pajang have been reported on the ethanolic extract of its kernel towards MCF-7 (hormone-dependent breast cancer cells) and MDA-MB-231 (non-hormone dependent breast cancer cells) with IC50 values of 23 and 30.5 μg/mL, respectively [20]. For cytotoxic screening of the isolated compounds in this work, only six compounds with sufficient amounts were selected for the anticancer tests. Cytotoxic assay of the compounds against MCF-7 cell line (Table 1) indicated strong activity as shown by methyl gallate (1) with an IC50 value of 10.5 ± 0.29 μg/mL. Meanwhile, 3β-hydroxy-cycloart-24-ene-26-oic acid (5) displayed moderate cytotoxic activity towards MCF-7 with an IC50 value of 13.03 ± 0.81 μg/mL. In contrast, weak cytotoxic activities were shown by lupeol (7), lupenone (8) and quercitrin (12) with IC50 values of 25.02 ± 0.71 , 27.01 ± 0.34 and 25.04 ± 0.72 μg/mL respectively, while mangiferonic acid (4) was inactive with IC50 > 30 μg/mL.

  • The results from cytotoxic tests of the chemical constituents of the plant against human cervical cancer (HeLa) cells (Table 1) indicated strong activity as was implicated by 3β-hydroxy-cycloart-24-ene-26-oic acid (5) with the IC50 value 6.27 ± 0.61 μg/mL. Apart from that, moderate activities were demonstrated by quercitrin (12), mangiferonic acid (4) and lupeol (7) with IC50 values of 11.93 ± 0.63, 16.51 ± 0.55 and 13.09 ± 0.80 μg/mL respectively. Other isolated constituents, methyl gallate (1) and lupenone (8) showed no activity with IC50 values > 30 μg/mL.

  • Meanwhile, cytotoxic tests against human colon cancer (HT-29) cell (Table 1) indicated very strong cytotoxic activity shown by a flavonol glycoside, quercitrin (12) with IC50 values of 3.82 ± 0.91 μg/mL. In addition, methyl gallate (1) and mangiferonic acid (4) have also demonstrated moderate cytotoxic activity with IC50 values of 18.07 ± 0.37 and 18.03 ± 0.75 μg/mL, respectively. However, no cytotoxic activity were shown by 3β-hydroxy-cycloart-24-ene-26-oic (5), lupeol(7) and lupenone (8) where the IC50 values were more than 30 μg/mL.

  • Some of the isolated compounds have been reported to show cytotoxic activities against several cancer cell lines. Methyl gallate (1) was shown to possess weak anticancer effects (IC50 value of more than 70 μg/mL) against human cervix adenocarcinoma cells (HeLa) and human fibroblast cells (L-132) [21]. However, a study by Lee et al. [22] demonstrated that methyl gallate (1) successfully enhanced antitumor effects through modulation of CD4+ CD25+ Treg cell functions, delaying tumour growth even though this compound was known to have low anticancer activity.

  • Mangiferonic acid (4) reported by Li et al. [23] showed insignificant anticancer activity with IC50 values of around 100 μg/mL towards three murine cancer cell lines (colon 26-L5 carcinoma, B16-BL6 melanoma and Lewis lung carcinoma) and also towards three human cancer cell lines (lung A549 adecarcenoma, cervix HeLa adecarcinoma and HT-1080 fibrosarcoma).

  • Meanwhile, anticancer activities of lupeol (7) as reviewed by Gallo and Sarachine, [24] found that lupeol (7) exhibited weak cytotoxicity in human melanoma SK-MEL-2, human lung carcinoma A549 and murine melanoma B16-F10 cells. Lupeol (7) also inhibited the proliferation of MDA-MB-231 human breast cancer cells and has been tested previously against many different numbers of cancer cells and showed range of activities towards the tested cells according to Gallo and Sarachine, [24]. These findings further corroborated with that reported in this work [25], where lupeol (7) and lupenone (8) exhibited weak cytotoxicity with IC50 values more than 30 μg/mL against human colorectal cancer (HT-29) and mammary breast cancer (MDA-MB) cell lines. However, lupeol (7) was slightly toxic against the normal cell line (3 T3) with an IC50 value of 38.92 μg/mL while lupenone (8) did not demonstrate any cytotoxic effect against the 3 T3 cell line with IC50 values of more than 100 μg/mL [26]. Meanwhile, quercitrin (12) was found to have a weak inhibitory effect on the human prostate cancer cell line PC-3 [26].

Table 1

Cytotoxicity of Mangifera pajang isolates against various cancer cell lines

Mangifera pajang

Cytotoxic activities (IC50μg/mL)

 

MCF-7

HeLa

HT-29

Kernel (crude extracts)

   

Petroleum ether

>30

>30

5.51 ± 0.98

Chloroform

15.60 ± 1.03

>30

23.06 ± 0.75

Ethyl acetate

3.99 ± 0.47

6.68 ± 0.46

14.40 ± 0.52

Methanol

4.12 ± 0.20

5.40 ± 0.53

4.94 ± 0.36

Stem bark (crude extracts)

   

Petroleum ether

5.80 ± 0.23

11.8 ± 0.45

12.67 ± 0.82

Chloroform

11.26 ± 1.08

17.48 ± 0.62

12.11 ± 0.39

Ethyl acetate

>30

29.84 ± 1.03

15.01 ± 0.52

Methanol

>30

>30

>30

Leaves (crude extracts)

   

Petroleum ether

>30

23.78 ± 0.73

23.19 ± 0.31

Chloroform

>30

>30

>30

Ethyl acetate

>30

>30

>30

Methanol

13.17 ± 0.49

>30

>30

Isolated compounds

   

Methyl gallate (1)

10.53 ± 0.29

>30

18.07 ± 0.37

Mangiferonic acid (4)

>30

16.51 ± 0.55

18.03 ± 0.75

3β-hydroxy-cycloart-24-ene-26-oic acid (5)

13.03 ± 0.81

6.27 ± 0.61

>30

Lupeol (7)

25.02 ± 0.71

13.09 ± 0.80

>30

Lupenone (8)

27.01 ± 0.34

>30

>30

Quercitrin (12)

25.04 ± 0.72

11.93 ± 0.63

3.82 ± 0.91

*Standard

3.36 ± 0.02

4.93 ± 0.51

2.04 ± 0.03

*MCF-7: Tamoxifen, HeLa: Cisplatin, HT-29: 5-Fluorouracil.

IC50 > 30: Inactive, <10 μg/mL: highly active, 10 to 20 μg/mL: moderately active, 20 to 30 μg/mL: weakly active.

Structure-activity relationships

The moderate to strong anticancer activities of the constituents of the plant have contributed to the overall cytotoxic properties of the plant extracts.
  • Among the tested crude extracts, the methanol extract from kernel was the most potent with IC50 values less than 6 μg/mL for the three cancer cell lines. This may due to the presence of the cytotoxic methyl gallate (1) constituent. Methyl gallate (1) which is an ester (Figure 1), has a carbonyl and three hydroxyl groups attached to a benzene ring which probably synergistically enhanced the anticancer properties of the compound [21]. Meanwhile, mangiferonic acid (4) and 3β-hydroxy-cycloart-24-ene-26-oic acid (5) which were isolated from the hexane and ethyl acetate extracts of the stem bark of the plant, displayed various ranges of cytotoxicity against the three cancer cell lines. In the current study, 3β-hydroxy-cycloart-24-ene-26-oic acid (5) was more cytotoxic compared to mangiferonic acid (4). In contrast to the results described by Li et al. [23], the anticancer potency of the cycloartane skeleton was suggested to be depending on the substituent at C-3; in order of α-OH > C = O > β-OH [23].

  • Quercitrin (12) obtained from extracts of leaves in polar solvents showed good anticancer activity with IC50 values around 10 μg/mL for HeLa and HT-29 cancer cell lines but simultaneously reduced the cytotoxicity of the crude extracts, suggesting the antagonistic effect of quercitrin (12). Quercitrin (12) is a glycoside of quercetin with a rhamnose group attached to the hydroxyl group at C-3. However, the glycoside substituent on the ring did not enhance the cytotoxicity of quercitrin (12) as its parent flavonol structure; quercetin significantly inhibited human prostate cancer cell line PC-3 cell proliferation, whereas quercitrin (12) itself did not have any antiproliferation effect on the cancer cells [26].

  • In addition, lupeol (7) and lupenone (8) together with most of leaf extracts exhibited weak cytotoxicity towards all cancer cell lines. Lupeol (7) is slightly more cytotoxic compared to lupenone (8) due to the presence of a hydroxyl group at C-3.

DPPH free radical scavenging activity

  • Free radical scavenging activity was determined by DPPH assay (summarized in Table 2); where ethyl acetate and methanol extracts from the kernel showed high radical scavenging activity with IC50 values of less than 10 μg/mL, while polar (ethyl acetate and methanol) extracts of the leaves showed moderate to weak radical scavenging activity with IC50values 100 to 200 μg/mL. Previous studies have reported high scavenging activity of the fruit parts (peel, pulp and kernel) of Mangifera pajang [5], but antioxidant studies were not reported on its leaves and stem bark.

  • Further DPPH screening assay on the isolated compounds indicated that methyl gallate (1) showed the highest radical scavenging activity with IC50 values of 6.24 ± 0.30 μg/mL, while mangiferonic acid (4), 3β-hydroxy-cycloart-24-ene-26-oic acid (5), lupeol (7) and lupenone (8) were not active with IC50 > 300 μg/mL. The strong scavenging activity of methyl gallate (1) was also reported previously [27], where they reported IC50 values of 2.8 μg/mL for methyl gallate in the DPPH free radical assay. However till date, there has been no previous report on free radical scavenging activity of mangiferonic acid (4) and 3β-hydroxy-cycloart-24-ene-26-oic acid (5).

Table 2

DPPH free radical scavenging activity of isolates of Mangifera pajang

Samples (Mangifera pajang)

Crude extracts/compounds

IC50(μg/mL)

Kernel

Petroleum ether

>300

 

Chloroform

>300

 

Ethyl acetate

7.28 ± 0.30

 

Methanol

8.84 ± 1.04

Stem bark

Petroleum ether

>300

 

Chloroform

>300

 

Ethyl acetate

>300

 

Methanol

>300

Leaves

Petroleum ether

>300

 

Chloroform

>300

 

Ethyl acetate

104.05 ± 1.02

 

Methanol

186.26 ± 0.99

Isolated compounds

(1)

6.24 ± 0.3

 

(4), (5), (7), (8)

>300

Standard

Ascorbic acid

6.69 ± 0.02

>300 μg/mL: Inactive, <10 μg/mL: highly active, 50 to 150 μg/mL: moderately active, 150 to 300 μg/mL: weakly active.

Antimicrobial activity

The results of the agar diffusion assay indicated that most of the crude extracts did not show significant inhibition activity towards targeted microbes. Some crude extracts of different parts of the plant displayed either weak or moderate activities with inhibition zones between 6 and 13 mm.
  • In this study, only the isolated compound methyl gallate (1) demonstrated strong antibacterial activity towards MRSA with an inhibition zone of 21.5 mm, as compared with an inhibition zone of 23.0 mm given by the standard compound (streptomycin). In addition, methyl gallate (1) also exhibited moderate antimicrobial activities towards P. aeruginosa, S. choleraesuis and B. subtilis with inhibition zones 12.0, 15.5, and 12.5 mm, respectively. This was in agreement with previous reports on the potent antimicrobial properties of methyl gallate (1) [27] which showed high MIC (Minimum Inhibitory Concentration) values (MICs 17.5 - 48.3 μg/mL) towards B. subtilis; Streptomyces viridochromogenes; S. aureus; Escherichia coli; Mucor miehei; Candida albicans. Meanwhile, there were no inhibition zones shown by quercitrin (12), mangiferonic acid (4), 3β-hydroxy-cycloart-24-ene-26-oic (5) and lupeol (7) towards the targeted microbes.

  • As for the antifungal tests, none of extracts and isolated compounds showed activity against Candida albican, Aspergillus ochraceaus and Sacchoromyces cerevisiae. To our knowledge, this is the first antimicrobial activity study reported on Mangifera pajang.

Conclusions

Extracts of the kernel, stem bark and leaves of Mangifera pajang have demonstrated potential cytotoxic activity towards MCF-7, HeLa and HT-29 cancer cells, and the extract of kernel also displayed strong free radical scavenging activity. These are assumed to be due to the presence of bioactive constituents that were isolated including cycloartane and lupane triterpenes, together with the major constituent, methyl gallate. The plant species, Mangifera pajang could become a potential source for natural anticancer (especially for breast, liver and colon cancers) and antioxidant agents. In particular, the major isolated constituent, methyl gallate could become a potential anticancer, antioxidant and antimicrobial agent.

Declarations

Acknowledgements

Special thanks to staffs of Department of Chemistry (UPM), UPM-MAKNA Cancer Research Laboratory, Microbial Culture Collection Unit (UNiCC) Laboratory, and Institute of Bioscience for the technical assistance and facilities provided.

Authors’ Affiliations

(1)
Department of Chemistry, Faculty of Science, Universiti Putra Malaysia
(2)
UPM-MAKNA Cancer Research Laboratory, Institute of Bioscience, Universiti Putra Malaysia
(3)
Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia
(4)
PAP Rashidah Sa’adatul Bolkiah Institute of Health Science, Universiti Brunei Darussalam

References

  1. Abu Bakar MF, Mohamed M, Rahmat A, Fry J. Phytochemicals and antioxidant activity of different parts of bambangan (Mangifera pajang) and tarap (Artocarpus odoratissimus). Food Chem. 2009;113:479–83.View ArticleGoogle Scholar
  2. Ajila CM, Naidu KA, Bhat SG, Prasada Rao UJS. Bioactive compounds and antioxidant potential of mango peel extract. Food Chem. 2007;105:982–8.View ArticleGoogle Scholar
  3. Ibrahim M, Prasad KN, Ismail A, Azlan A, Abd Hamid A. Physiochemical composition and antioxidant activities of underutilized Mangifera pajang fruit. Afr J Biotechnol. 2010;9(28):4392–7.Google Scholar
  4. Kostermans AJGH, Bompard JM. The mangoes: Their botany, nomenclature, horticulture and utilization. London: Academic Press; 1993.Google Scholar
  5. Khoo HE, Prasad KN, Ismail A, Esa NM. Carotenoids from Mangifera pajang and their antioxidant capacity. Molecules. 2010;15:6699–712.View ArticleGoogle Scholar
  6. Abu Bakar MF, Mohamad M, Rahmat A, Burr SA, Fry JR. Cytotoxicity and polyphenol diversity in selected parts of Mangifera pajang and Artocarpus odoratissimus fruits. Nutri Food Sci. 2010;48:1688–97.Google Scholar
  7. Ekaprasada MT, Nurdin H, Ibrahim S. Dachriyanus: antioxidant activity of methyl gallate isolated from leaves of toonasureni. Indo J Chem. 2009;9(3):457–60.Google Scholar
  8. Escobedo-Martínez C, Lozada MC, Hernandez-Ortega S, Villarreal ML, Gnecco D, Enríquez RG, et al. 1H and 13C NMR characterization of new cycloartane triterpenes from Mangifera indica. Magn Res Chem. 2012;50:52–7.View ArticleGoogle Scholar
  9. Anjaneyulu V, Ravi K, Prasad KH, Connolly JD. Triterpenoids from Mangifera indica. Phytochemistry. 1989;28(5):1471–7.View ArticleGoogle Scholar
  10. Jain PS, Bari SB. Isolation of lupeol, stigmasterol and campasterol from petroleum ether extract of woody stem of Wrightia tinctoria. Asian J Plant Sci. 2010;9(3):163–7.View ArticleGoogle Scholar
  11. Jamal AK, Yaacob WA, Din L. A chemical study on Phyllanthuscolumnaris. Eur J Sci Res. 2009;28(1):76–81.Google Scholar
  12. Manoharan KP, Benny TKH, Yang D. Cycloartane type terpenoid from the rhizomes of Polygonum bistorta. Phytochemistry. 2005;66(19):2304–8.View ArticlePubMedGoogle Scholar
  13. Kamboj A, Saluja AK. Isolation of stigmasterol and β-sitosterol from petroleum ether extract of aerial parts of Ageratum conyzoides (Asteraceae). Int J Pharm Pharmaceut Sci. 2011;3(1):94–6.Google Scholar
  14. Domínguez XA, Sanchez H, Merijanian BA, Rojas PM. Stigmasterol, friedooleanan-3β-ol and baccharis oxide from Bacciiarissalicifolia. Phytochemistry. 1972;11:2628.View ArticleGoogle Scholar
  15. Wang Q, Li Y, Chen Q. Synthetic communications: a convenient, large scale synthesis of trans-(+)-sobrerol. Int J Rapid Commun Synthetic Org Chem. 2003;33(12):2125–34.Google Scholar
  16. Zhong XN, Otsuka H, Ide T, Hirata E, Takushi A, Takeda Y. Three flavonol glycosides from leaves of Myrsine seguinii. Phytochemistry. 1997;45(5):943–6.View ArticleGoogle Scholar
  17. Mackeen MM, Ali AM, El-Sharkawy SH, Manap MY, Salleh KM, Lajis NH, et al. Antimicrobial and cytotoxic properties of some Malaysian traditional vegetables. Int J Pharmacognosy. 1997;35:174–8.View ArticleGoogle Scholar
  18. Saha K, Lajis NH, Israf DA, Hamzah AS, Khozirah S, Khamis S, et al. Evaluation of antioxidant and nitric oxide inhibitory activities of selected Malaysian medicinal plants. J Ethnopharmacol. 2004;92:263–7.View ArticlePubMedGoogle Scholar
  19. Hassan FA, Ismail A, Abdul Hamid A, Azlan A, Al-Sheraji SH. Characterization of fibre-rich powder and antioxidant capacity of Mangifera pajang K. fruit peels. Food Chem. 2011;126:283–8.View ArticleGoogle Scholar
  20. Abu Bakar MF, Mohamad M, Rahmat A, Burr SA, Fry JR. Cytotoxicity, cell cycle arrest, and apoptosis in breast cancer cell lines exposed to an extract of the seed kernel of Mangifera pajang (bambangan). Food Chem Toxicol. 2010;48:1688–97.View ArticlePubMedGoogle Scholar
  21. Fiuza SM, Gomes C, Teixera LJ, Girao da Cruz MT, Cordeiro MNDS, Milhazes N, et al. Phenolic acid derivatives with potential anticancer properties – a structure-activity study. Part 1: Methyl, propyl and octyl esters of caffeic and gallic acids. Bioorg Med Chem. 2004;12:3581–9.View ArticlePubMedGoogle Scholar
  22. Lee SH, Kim JK, Kim DW, Hwang HS, Eum WS, Park J, et al. Antitumor activity of methyl gallate by inhibition of focal adhesion formation and Akt phosphorylation in glioma cells. Biochimica et Biophysica Acta. 2013;1830(8):4017–29.View ArticlePubMedGoogle Scholar
  23. Li F, Awale S, Tezuka Y, Kadota S. Cytotoxic constituents of propolis from Myanmar and their structure-activity relationship. Biol Pharm Bull. 2009;32(12):2075–8.View ArticlePubMedGoogle Scholar
  24. Gallo MBC, Sarachine MJ. Biological activities of lupeol. Int J Biomed Pharm Sci. 2009;3(1):46–66.Google Scholar
  25. Al Muqarrabun LMR, Ahmat N, Aris SRS, Shamsulrijal N, Baharum SN, Ahmad R, et al. A new sesquiterpenoid from Scaphium macropodun (Miq.) Beumee. Nat Prod Res. 2014;28(9):597–605.View ArticlePubMedGoogle Scholar
  26. Xu R, Zhang Y, Ye X, Xue S, Shi J, Pan J, et al. Inhibition effects of apoptosis of flavonoids on the prostate cancer cell line PC-3 in vitro. Food Chem. 2013;138:48–53.View ArticlePubMedGoogle Scholar
  27. Choi YH, Han SS, Lee HO, Baek SH. Biological activity of bioactive components from Acer ginnala Max. Bull Korean Chem Soc. 2005;26(9):1450–2.View ArticleGoogle Scholar

Copyright

© Ahmad et al.; licensee BioMed Central. 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Advertisement