Chemodiversity of Clausena excavata (Rutaceae) and related species: Coumarins and carbazoles

Chemical constituents and biological effects of essential oils of Clausena genus (Rutaceae): A review

Clausena is a genus of Rutaceae family commonly used in traditional medicine. This report aims to provide the brief review on the chemical components and bioactivities of essential oils (EOs) isolated from Clausena plants. The phyto-chemicals of EOs obtained from different plant parts of Clausena species are characterized by several chemical groups such as oxygenated sesquiterpene, oxygenated monoterpene, monoterpene hydrocarbons, sesquiterpene hydrocarbons, etc. In addition, the studied oils also possess the antimicrobial, insecticidal and larvicidal activities.

Phytochemical Analysis and Evaluation of Antioxidant and Biological Activities of Extracts from Three Clauseneae Plants in Northern Thailand

This study established the DNA barcoding sequences (matK and rbcL) of three plant species identified in the tribe Clauseneae, namely Clausena excavata, C. harmandiana and Murraya koenigii. The total phenolic and total flavonoid contents, together with the biological activities of the derived essential oils and methanol extracts, were also investigated. Herein, the success of obtaining sequences of these plant using two different barcode genes matK and rbcL were 62.5% and 100%, respectively. Both regions were discriminated by around 700 base pairs and these had resemblance with those of the Clausenae materials earlier deposited in Genbank at a 99–100% degree of identity. Additionally, the use of matK DNA sequences could positively confirm the identity as monophyletic. The highest total phenolic and total flavonoid content values (p < 0.05) were observed in the methanol extract of M. koenigii at 43.50 mg GAE/g extract and 66.13 mg QE/g extract, respectively. Furthermore, anethole was detected as the dominant compound in C. excavata (86.72%) and C. harmandiana (46.09%). Moreover, anethole (26.02%) and caryophyllene (21.15%) were identified as the major phytochemical compounds of M. koenigii. In terms of the biological properties, the M. koenigii methanol extract was found to display the greatest amount of antioxidant activity (DPPH; IC₅₀ 95.54 µg/mL, ABTS value 118.12 mg GAE/g extract, FRAP value 48.15 mg GAE/g extract), and also revealed the highest α-glucosidase and antihypertensive inhibitory activities with percent inhibition values of 84.55 and 84.95. Notably, no adverse effects on human peripheral blood mononuclear cells were observed with regard to all of the plant extracts. Furthermore, M. koenigii methanol extract exhibited promise against human lung cancer cells almost at 80% after 24 h and 90% over 48 h.

Chemical constituents of Clausena lenis

Phytochemical examination of Clausena lenis Drake (Rutaceae), collected in Thailand, led to the isolation of seven coumarins, four furoquinolines, two amides, and one flavonoid glycoside. Four of these compounds, one coumarine derivative named as gravelliferone A (3), two furoquinoline derivatives (kokusagenin A (8) and B (9)) and one amide, clausenalansamide H (13), are reported for the first time. Compound 3 was isolated from the root bark, compound 8 from the stem bark and compounds 9 and 13 from the leaves. The molecular structures of all isolated compounds were established by means of NMR experiments combined with mass spectrometry. Preliminary tests of the lipophilic stem bark extract against various human pathogenic bacteria strains revealed promising effects against Staphylococcus aureus ATCC 43300.