Khong Heng Yen

Chemical compositions, antioxidant and antimicrobial activities of essential oils of Piper caninum Blume.

Chemical composition, antioxidant and antimicrobial activities of the fresh leaves and stems oils of Piper caninum were investigated. A total of forty eight constituents were identified in the leaves (77.9%) and stems (87.0%) oil which were characterized by high proportions of phenylpropanoid, safrole with 17.1% for leaves and 25.5% for stems oil. Antioxidant activities were evaluated by using β-carotene/linoleic acid bleaching, DPPH radical scavenging and total phenolic content. Stems oil showed the highest inhibitory activity towards lipid peroxidation (114.9 ± 0.9%), compared to BHT (95.5 ± 0.5%), while leaves oil showed significant total phenolic content (27.4 ± 0.5 mg GA/g) equivalent to gallic acid. However, the essential oils showed weak activity towards DPPH free-radical scavenging. Evaluation of antimicrobial activity revealed that both oils exhibited strong activity against all bacteria strains with MIC values in the range 62.5 to 250 μg/mL, but weak activity against fungal strains. These findings suggest that the essential oils can be used as antioxidant and antimicrobial agents for therapeutic, nutraceutical industries and food manufactures.

Chemical composition and biological activities of essential oil of Beilschmiedia pulverulenta

Abstract Context: The ethnopharmacological study of Beilschmiedia indicates that several species are used for the treatment of various ailments. Objective: This is the first study of the chemical composition of Beilschmiedia pulverulenta Kosterm (Lauraceae) essential oil and its antioxidant, antimicrobial, antityrosinase, anti-inflammatory, and anticholinesterase activities. Materials and methods: The antioxidant activities were evaluated by β-carotene, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric-reducing antioxidant power (FRAP), and phenolic content at different concentrations. The antimicrobial activities against Gram-positive and Gram-negative bacteria and fungi were revealed by disk diffusion and microdilution. The antityrosinase and anti-inflammatory activities were assayed against mushroom tyrosinase and lipoxygenase enzymes. The anticholinesterase activity was analyzed using acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Results: Forty-two components were detected in B. pulverulenta oil with eugenol (45.3%) being the major component. The oil phenolic content and the FRAP were 660.1 mg gallic acid/g and 604.0 mg ascorbic acid/g, respectively. The oil gave an IC50 value of 94.5 µg/mL and an inhibition of 93.9% in DPPH and β-carotene, respectively. The antimicrobial activity showed that the oil had strong activity against all Gram-positive bacteria with an minimum inhibitory concentration (MIC) value each of 62.5 µg/mL and moderate against all fungi with MIC and minimum bactericidal concentration (MBC) values each of 125 µg/mL. The oil showed significant antityrosinase and anti-inflammatory activities with 67.6 and 62.5% inhibition, respectively. In addition, the oil had moderate AChE (56.5%) and BChE (48.2%) activities. Discussion and conclusion: The results show that the oil could potentially be used for nutraceutical industries, food manufactures, and therapeutic agents against various diseases such as inflammation and rheumatism.

Essential oil compositions of Malaysian lauraceae: A mini review

Essential oils have been largely employed for human need due to their antibacterial, antifungal and insecticidal activities. At present, approximately 3000 essential oils are known, 300 of which are commercially important. Essential oils or some of their components are used in perfumes and make-up products, sanitary products, dentistry, agriculture, as food preservers and additives, and as natural remedies. The essential oil compositions of Malaysian Lauraceae family have been investigated for many years. In the recent years, studies on the essential oils of the species have been progressing and many of them have reported interesting pharmacological activities. In this article, we summarized and updated the chemical compositions and biological activities of Malaysian Lauraceae. Throughout our literature review, only four genera which are Lindera, Beilschmiedia, Litsea, and Cinnamomum have been studied for their essential oil compositions in Malaysia. They were found to contain mainly safrole, eugenol, linalool, camphor, benzyl benzoate or cinnamaldehyde as major components. There were significant priorities to find out the details of the chemical compositions of the essential oils from Malaysian Lauraceae. Therefore, more clinical studies on the toxicity of the essential oil of the species are also crucial to ensure their safety and to assess their eligibility to be used as the sources of modern medicines.

Antioxidant and Anti-tyrosinase Activities from Piper officinarum C.DC (Piperaceae)

The present study was carried out to evaluate antioxidant and anti-tyrosinase activities from Piper officinarum stems, as well as investigation of its chemical constituents. In a series of in vitro assays, antioxidant (DPPH radical scavenging and total phenolic content) and anti-tyrosinase (mushroom tyrosinase) activities of various extracts of stem were evaluated. The isolation and purification of the constituents were carried out on the extracts using various chromatographic methods and identified by direct comparison of their spectroscopic data with respective published data. The results showed that the methanol extracts showed the highest DPPH (80.0%) at 1 mg/ml, as well as total phenolic content (50.5%). Phytochemical analysis of the stem extracts have isolated five compounds identified as 4-allyl resorcinol (1), aristolactam AII (2) aristolactam BII (3), stigmast-4-en-3-one (4) and 6-hydroxystigmast-4-en-3-one (5). Compound (1), (2) and (3) showed significant activity towards DPPH radical scavenging (I%=17.3-28.1%), while (2), (3) and (4) demonstrated potent inhibitory effects against tyrosinase mushroom (I% = 11.1 - 24.4%). The results showed that the stem extracts has significant antioxidant activity that may help to discover new chemical classes of natural antioxidant substances.

Chemical Composition and Antimicrobial Activity of Essential Oil of Piper muricatum Blume (Piperaceae)

Abstract: The essential oil isolated by hydrodistillation from fresh whole plant parts of Piper muricatum Blume (Piperaceae) was analyzed by GC and GC-MS. Forty components were identified, representing 90.8 % of the total oil. The major components were aromadendrene (16.2 %), β-caryophyllene (8.8 %), germacrene D (7.9 %), γ-cadinene (7.9 %), elemol (5.4 %), γ-elemene (4.9 %) and bicyclogermacrene (4.4 %). The antimicrobial evaluation revealed that the essential oil had moderate activity towards Gram positive bacteria, Bacillus cereus and Streptococcus mutans each with MIC value of 250 µg/mL.

Chemical compositions and antibacterial activity of the leaf and stem oils of Piper porphyrophyllum (Lindl). N.E. Br.

The essential oils obtained by hydrodistillation from the fresh leaf and stem of Piper porphyrophyllum N.E. Br. were analyzed by GC and GC/MS. Thirty four constituents were identified in the leaf oil, while thirty eight constituents were identified in the stems oil. The most abundant components in the leaf oil included bicyclogermacrene (14.7 %), α-copaene (13.2 %) and β-phellandrene (9.5 %) while sabinene (15.5 %), bicyclogermacrene (12.3 %) and α-copaene (8.1 %) were the main constituents in the stem oil. The evaluation of antibacterial activity by using micro-dilution method revealed that both oils were moderately active against all the Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Pseudomonas aeruginosa, Pseudomonas putida and Escherichia coli) with minimum inhibitory concentration (MIC) values in the range 125-1000 µg/ml.

Xanthone from Garcinia eugenifolia (Clusiaceae)

Studies on the twigs of Garcinia eugenifolia have led to the isolation of one xanthone 5,9-dihydroxy-8-methoxy-2,2-dimethyl-7-(3-methylbut-2-enyl)pyrano[3,2-b]xanthen-6(2H)-one (1) and one triterpenoid, sitosterol (2). Meanwhile, studies on the leaves of Garcinia eugenifolia provided another triterpenoid, friedelin (3). The structures of these compounds were determined by spectroscopic methods such as 1H NMR, 13C NMR, mass spectrometry (MS) and by comparison with previous studies. The hexane and ethyl acetate extracts of Garcinia eugenifolia indicated strong cytotoxicity towards the HL-60 cell line with IC50 values of 1.9 µg/ml and 2.5 µg/ml respectively. However, the methanol extract gave moderate inhibitory activities (IC50<10 µg/ml) towards HL-60 cell line.

Structure based Pharmacophore modeling, Virtual screening and Molecular Docking of Potential Phytochemicals against HSP70 -

Article history: Received on: 03/08/2016 Accepted on: 12/02/2017 Available online: 30/08/2017 Previous studies showed that Artocarpus species are rich in phenolic compounds, including flavonoids, stilbenoids and arylbenzofurons. Furthermore, compounds from Artocarpus species exhibited diverse biological activities including antibacterial, antitubercular, antiviral, antifungal, antiplatelet, antiarthritic, tyrosinase inhibitory and cytotoxicity. However, there is no phytochemical investigation on the Artocarpus odoratissimus from Sarawak. Thus, it would be interesting to develop a chemical profile of such Sarawakian species. Various chromatographic methods, such as liquid vacuum chromatography, radial chromatography and column chromatograpy were employed to isolate the chemical constituents from the different parts, namely root, bark and leaves of Artocarpus odoratissimus. The isolation and purification using different solvents system ratio of hexane and ethyl acetate (10:0, 8:2, 6:4, 4:6, 2:8, 0:10) and ethyl acetate and methanol (8:2) have led to two flavonoids; pinocembrin (1) and pinostrobin (2), and six triterpenoids; α-amyrin acetate (3), ß-amyrin acetate (4), traxateryl acetate (5), hexyl dodecanoate (6), ß-sitosterol (7) and stigmasterol (8). The structures (1) – (8) were elucidated using various spectroscopic analysis, which included the Mass Spectroscopy (MS), Infrared (IR) spectroscopy, Ultra-violet (UV) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy, as well as by comparison with the reported data. Although the occurrence of compounds 1 and 2 were widely distributed in many of the plant species, but it was uncommon to the Artocarpus species which could be of chemotaxonomic significance to the genus Artocarpus.

Nutritional Content, Antioxidant and Antibacterial Activities of Litsea Garciae

In Sarawak, Litsea garciae are known as “Engkala”. The tree of ‘Engkala’ can grow in inland riparian forest and secondary forest. This medium-sized tree have long brittle spreading branches and the leaves lanceolate or obovate often with unequal side (asymmetric) and non-hairy. This seasonal fruit turn pink, or pinkish, greenish white when it is ripping depending on the variety. It is used as antidote against scorpion, centipede and snake bite by Bidayuh and Iban communities. It is also used to treat muscular pains, sprained ankles and knees, skin disease and blood in stools. The metanolic leaves, barks and fruits extracts of L. garciae were tested for its nutritional value, antioxidant and antibacterial activities. The nutritional values, such as N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, B, moisture, ash, protein, carbohydrates and fat were determined based on MS677 and ICP-AES. The antioxidant assay was carried out using DPPH, free radical scavenging activity while the antibacterial assays were carried out using minimum inhibitory concentration (MIC) and disk diffusion method against five bacteria. The findings showed that L. garciae is a good source of carbohydrate and protein. In addition, it is also demonstrated weak activities towards antioxidant and antibacterial. The phytochemistry study on this plant is being carried out to identify bioactive compounds. Preliminary results suggest that L. garciae is rich in stearic acid. This common saturated fatty acids derived from plants may be used in the production of biodegradable soaps and cosmetics such as shampoo and shaving cream products.

Cytotoxic and antioxidant properties of borneo Garcinia species (Clusiaceae)

There are several local Malaysian Garcinia species which have ethnobotanical uses but so far very few studies have been carried out to link these folkloric uses with the phytochemistry of these plant species. It would be interesting therefore, to develop phytochemical data of two such Sarawakian species which are Garcinia eugenifolia and Garcinia nitida which have not been reported before. The methanol extract from the G. eugenifolia leaves exhibited moderate antioxidant activity with EC50 values of 66 and 51 respectively, when compared to ascorbic acid with EC50 values of 15.32 µg/mL. This crude also showed weak cytotoxic activity to HeLa with IC50 values of 71 and 40 µg/mL respectively. However, the leaves extracts of G. nitida showed good cytotoxic activity with IC50 values of 4 and 7 µg/mL respectively towards both cell lines.