Chemical constituents, antioxidant and cytotoxic properties of Aglaia oligophylla Miq. and Kaempferia angustifolia Rosc.

Natural products are chemical substances produced by plants, microbial sources and other living organisms. Some natural products are used for medicinal purpose due to their distinctive pharmacological active properties. Aglaia oligophylla Miq. belong to the genus Aglaia under the Meliaceae family whilst Kaempferia angustifolia Rosc. is a species from the genus of Kaempferia under the Zingiberaceae family. The genera are recognized for their versatile medicinal properties including antioxidant, anti-malarial, antiviral, antimicrobial and anti-tumor. However, there are limited studies on cytotoxicities and antioxidant properties of A. oligophylla and K. angustifolia. Therefore, the objective of the studies is to investigate the phytochemistry, antioxidant and cytotoxic properties of A. oligophylla and K. angustifolia. The elucidation and assignation of structure of the pure compound were carried out using spectroscopic methods such as UV (Ultra-violet), IR (Infrared Spectroscopy), NMR (Nuclear Magnetic Resonance), and MS (Mass Spectrometry) and as well as comparison with published data. Column chromatographic separation and purification of trunks and stem bark of A. oligophylla furnished three new compounds and three know compounds. The trunks of A. oligophylla afforded two new compounds identified as 20S,24R-epoxy-3-oxo-A-dinor-5α-dammaran-31-al (oligophyllin) (101) and 5-hydroxy-7-methoxy-2-[(5’S,6’S,8’S,11’R)-12’-(5’,6’,8’,9’-tetramethyl-11’-hydroxycyclonon-9’-enyl)-phenyl]-4H-1-benzopyran-4-one (oligolin A) (102) whilst the stem of A. oligophylla obtained 20S,24S-epoxy-25-hydroxy-4-propyl-2-secodammarane-2-oic acid (oligophyllic acid) (105) as new compound. Meanwhile, three known compounds namely cabraleone (104), β-sitosterol (98) and stigmasterol (103) were isolated from the trunks and stem bark of A. oligophylla. Phytochemical investigaton on rhizomes of K. angustifolia afforded six known compounds which were boesenboxide (89), crotepoxide (94), flavokawain A (92), kaempfolienol (96), β-sitosterol (98) and zeylenol (95). Various chromatography techniques such as thin layer, gravity column and centrifugal thin layer have been used to isolate these compounds. The extracts and chemical constituents of the plants were evaluated for antioxidant potential using in vitro assays such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP) and β-carotene-linoleate bleaching assays. The comparison of the antioxidant properties of the extracts from A. oligophylla in DPPH assay revealed that the methanol extract from the stem bark showed the strongest antioxidant property. The ethyl acetate extract of the trunks of A. oligophylla exhibited the strongest antioxidant property among the extracts in ABTS and CUPRAC assays with the values of 96.97 and 1696.48 mg TE/g respectively whilst the methanol extract from the trunks showed the strongest antioxidant activity among the extracts in FRAP assay with the value of 1312.03 mg TE/g. The comparison of the antioxidant properties of the extracts and chemical constituents from A. oligophylla in β-carotene-linoleate bleaching assay indicated ethyl acetate extract from the trunks of the plant showed the strongest antioxidant property with the value of 88.77 %. The comparison of the antioxidant properties of the extracts and chemical constituents from K. angustifolia revealed that the methanol extract presented the strongest antioxidant in DPPH assay with the value of 607.29 mg TE/g whilst flavokawain A (92) showed the strongest antioxidant property in ABTS, CUPRAC and FRAP assays with the values of 42.01, 1470.19 and 780.77 mg TE/g respectively. Meanhwile, boesenboxide (89) showed the strongest antioxidant property in β-carotene-linoleate bleaching assay with the value of 98.31 %. The extracts and phytochemicals of both plants were also subjected to cytotoxicity screening against hormone dependent human breast adenocarcinoma (MCF-7), hormone independent human breast adenocarcinoma (MDA-MB-231) and Swiss mouse embryo fibroblast (3T3-L1) cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Characterisation of cellular morphology was done using inverted light microscope. The chloroform extract from the trunks of A. oligophylla showed the strongest cytotoxicity against MCF-7 cell line with the IC50 value of 35.45 μg/mL whilst oligolin A (102) from A. oligophylla displayed the strongest cytotoxic effect against MDA-MB-231 cell line with the IC50 value of 14.23 ± 0.48 μg/mL. The oligolin A (102)-treated MDA-MB-231 cell underwent morphological change such as cell shrinkage, nuclear compaction and membrane blebbing which further support the cytotoxicity result of the compound. Oligolin A (102) showed insignificant cytotoxicity against 3T3-L1 cell line. The flavokawain A (92) from K. angustifolia showed the strongest cytotoxicity against MCF-7 and MDA-MB-231 cell lines with IC50 values of 53.98 and 22.48 μg/mL respectively. The results pinpointed the potential compounds isolated from A. oligophylla and K. angustifolia as the possible candidates for the breast cancer treatment and therapy.

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