Efficacy ofPlectranthus glandulosus(Lamiaceae) andCallistemon rigidus(Myrtaceae) Leaf Extract Fractions toCallosobruchus maculatus(Coleoptera: Bruchidae)

Abstract

As part of on-going efforts to use eco-friendly alternatives to chemical pesticides, methanol crude extracts of Plectranthus glandulosus and Callistemon rigidus leaves were sequentially fractionated in hexane, chloroform, ethyl acetate, and methanol to establish the most active fraction(s) against Callosobruchus maculatus in cowpea. Cowpea seeds (25 g) were treated with 0.5, 1, 2, and 4 g/kg of extract to evaluate the contact toxicity and F1 progeny production of the beetles in the laboratory. Mortality was recorded 1, 3, and 7 d postexposure. P. glandulosus hexane fraction was more toxic than the other fractions recording 100% mortality at 4 g/kg, within 7 d with LC50 of 0.39 g/kg. Hexane fraction of C. rigidus showed superior toxicity, causing 100% mortality at 4 g/kg within only 1 d of exposure with LC50 of 1.02 g/kg. All the fractions greatly reduced progeny emergence, with C. rigidus hexane fraction being the best progeny inhibitor. Fractions of P. glandulosus and C. rigidus leaves had sufficient efficacy to be a component of storage pest management package for C. maculatus.

Antiviral Triketone‐Phloroglucinol‐Monoterpene Adducts from Callistemon rigidus

“…The presence of the epoxy group was further confirmed by the HMBCs between H-C(2 0 ) and C(3 0 )/C(4 0 ), and between H-C(1 0 ) and C(4a 0 )/C(9a 0 ), as well as the 1 H, 1 H-COSY spin system of H-C(1 0 )/H-C(2 0 )/H-C(3 0 )/H-C(4 0 )/H-C(4a 0 ) ( Figure 2). In addition, the HMBCs between OH (d(H) 9.75 (1 H, s)) and C (6), between H-C(13)/H-C (14) and C(5), between OH (d(H) 15.33 (1 H, s)) and C(6 0 ), and between H-C (7) and C(7 0 ) suggested these two hydroxy groups were attached at C(5) and C(7 0 ) positions, respectively. Thus, the planar structure of 1 was assigned as shown in Figure 2.…”

“…Thus, the planar structure of 1 was assigned as shown in Figure 2. The relative configuration of 1 was established by the NOESY cross peaks between H-C(9) and H-C (14), between H-C(10) and H-C(18 0 ), between H-C(4a 0 ) and H b -C(4 0 )/H-C(13 0 )/H-C(18 0 ), between H b -C(4 0 ) and H-C(12 0 ), as well as between H-C(2 0 ) and H-C(3 0 ) ( Figure 3). Fortunately, suitable crystals of 1 were obtained in methanol solution, and a single crystal X-ray diffraction experiment (CuK a radiation) was carried out.…”

“…These compounds have attracted the attention of chemists and pharmacologist due to their diverse molecular architectures and biological activities such as cytotoxic, antiviral, antibacterial, and insecticidal effects . Callistemon rigidus , an evergreen shrub of the Myrtaceae family that cultivated in Guangdong and Guangxi provinces of China, had been used as a folk medicine for treating cough and bronchitis . Our previous studies on this plant had led to the isolation of several bioactive phloroglucinol derivatives .…”

“…[9 -12] Callistemon rigidus, an evergreen shrub of the Myrtaceae family that cultivated in Guangdong and Guangxi provinces of China, [13] had been used as a folk medicine for treating cough and bronchitis. [14] Our previous studies on this plant had led to the isolation of several bioactive phloroglucinol derivatives. [15 -17] During our further investigation of the phloroglucinol constituents from this plant, six new phloroglucinol derivatives callistrilones F -K (1 -6) with rare triketone-phloroglucinolmonoterpene skeletons were obtained (Figure 1).…”

An Efflux Pumps Inhibitor Significantly Improved the Antibacterial Activity of Botanicals from Plectranthus glandulosus towards MDR Phenotypes

“…Some compounds including one methoxylated flavonoid derivative, plectranmicin, and one monoterpene derivative, plectranmicinol, together with seven known compounds including 5-hydroxy-3,7,2′,4′tetramethoxyflavone; 5,7-dihydroxy-3,2′,4′-trimethoxyflavone; 7-hydroxy-5,6,4′-trimethoxyflavone; 3-epi-betulinic acid; 3- O - β -D-glucopyranosyl; stigmasterol; β -sitosterol, and 4-epi-fridelin were isolated from the whole plant of the studies species [ 20 ]. Earlier biological studies reported the antinociceptive and anti-inflammatory effects [ 21 ] as well as the antioxidant and insecticidal activities of P. glandulosus [ 22 , 23 ].…”