The present study aimed to examine the chemical compositions of the essential oils of Beilschmiedia madang and their antioxidant, antibacterial, antifungal, anticholinesterase and anti-tyrosinase activities. The major constituents of the essential oils of leaf and bark of B. madang were δ-cadinene (17.0 and 20.5 %), β-caryophyllene (10.3 and 6.7 %), α-cubebene (11.3 and 15.6 %), and α-cadinol (5.8 and 10.6 %). The essential oils were screened for their antioxidant activities using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, β-carotene/linoleic acid bleaching, and total phenolic content. The bark oil showed the highest β-carotene/linoleic acid bleaching (90.3 % ± 0.2) and DPPH radical scavenging (IC50 212.0 µg/mL), while the highest phenolic content was exhibited by the leaf oil (94.5 % ± 0.3 mg GA/g). The antibacterial and antifungal activities were investigated by the disc diffusion and micro dilution method. The leaf and bark oils showed moderate activity towards Bacillus subtilis and Staphylococcus aureus with minimum inhibitory concentration (MIC) value 125 µg/mL. For antifungal assay, the bark oil showed strong activity towards Aspergillus niger and Aspergillus fumigatus with MIC value 62.5 µg/mL. Anticholinesterase and anti-tyrosinase activities were evaluated against Ellman method and mushroom tyrosinase, respectively. The results showed that leaf oil gave significant percentage inhibition (I%: acetylcholinesterase 55.2 %, butyrylcholinesterase 60.4 %, tyrosinase 53.1 %).

Introduction The genus Knema (Myristicaceae) is commonly found in tropical countries like Asia, Africa, and Australia. It comprises approximately 60 species in Southeast Asia but the evergreen forests in Thailand carries at least 12 species of this genus. 1 They are tropical trees with characteristic red resin in their bark, usually referred to by a word meaning 'blood' in their local names. Some Knema species are used for medical purposes where the barks and seeds are used in traditional medicine for treatment of diseases pertaining to skin or mouth and throat sores. The seeds of K. corlicosa are employed to prepare medicinal salves. 2-3 Previously, the genus Knema also contains a variety of natural compounds including acetophenone, substituted stilbene, lignan, flavonoid, alkyl/acyl resorcinol, and phenylalkylphenol derivatives. 4-8 Plants in this genus exhibited antibacterial, antinematodal, cytotoxicity, and acetylcholinesterase inhibitory activities. 9-12 Given that the genus is reported to be rich in health benefits, this review paper aims to phytochemically and pharmacologically investigate the different Knema species through previous literature that had reported its extraction, isolation, structural characterization, and description of biological activity of individual compounds. The SciFinder Scholar database was used to search for a substructure and was done via keyword searches in PubMed, Medline, and Scopus. The results indicated that to date, there have been citations of 12 species in this perspective. Each plant would get a discussion on its phytochemistry and pharmacognosy and listed in alphabetical order. Phytochemical Studies Since 1978, compounds 1-97 (Figure 1) have been isolated from the plants of the genus Knema. Their structures were shown below, and their names and corresponding plant sources were discussed below. A literature survey revealed that only twelve species of Knema genus have been investigated worldwide which are K.

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.

This study was designed to investigate the antioxidant and antimicrobial activities of the essential oils from Piper officinarum C. DC. GC and GC/MS analysis of the leaf and stem oils showed forty one components, representing 85.6% and 93.0% of the oil, respectively. The most abundant components in the leaf oil were β-caryophyllene (11.2%), α-pinene (9.3%), sabinene (7.6%), β-selinene (5.3%) and limonene (4.6%), while β-caryophyllene (10.9%), α-phellandrene (9.3%), linalool (6.9%), limonene (6.7%) and α-pinene (5.0%) were the main components of the stem oil. The antioxidant activities were determined by using complementary tests: namely β-carotene-linoleic acid, DPPH radical scavenging and total phenolic assays. The stems oil showed weak activity (IC 50 = 777.4 µg/mL) in the DPPH system, but showed moderate lipid peroxidation inhibition in the β-carotene-linoleic acid system (88.9 ± 0.35%) compared with BHT (95.5 ± 0.30%). Both oils showed weak activity against P. aeruginosa and E. coli with M IC values of 250 µg/mL.

The chemical composition of the essential oil and antioxidant and anti-inflammatory activities of the extracts from Piper miniatum were determined. GC and GC-MS analysis of the essential oil resulted in the identification of 64 components, accounting for 89.2% of the total. The major components were caryophyllene oxide (20.3%) and α-cubebene (10.4%). The antioxidant activity was evaluated by β-carotene/linoleic acid bleaching, DPPH radical scavenging and total phenolic content. In the β-carotene assay, the n-hexane extract showed the highest inhibition activity with 42.7%, while the oil gave 91.3%. The essential oil and extracts were tested for anti-inflammatory activity by using the TPA-induced mouse ear edema model and lipoxygenase assays. The essential oil exhibited significant activity in both models as an anti-inflammatory agent. The n-hexane extract showed strong activity with inhibition of 85.9% in the TPA-induced mouse ear edema model, while the chloroform extract showed the highest activity with 94.2% in the lipoxygenase assay.