Structure elucidation and complete NMR spectral assignments of four new diterpenoids from Smallantus sonchifolius

Yacon as an alternative host plant for Encarsia formosa mass-rearing: validating a multinomial theorem for bootstrap technique in life table research

BACKGROUND

Yacon (Smallanthus sonchifolius) is a broadleaf host plant suitable for rearing the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Here, the possibility of using yacon as an alternative host plant for production of the parasitoid, Encarsia formosa Gahan, one of the most important natural enemies of whiteflies, was explored. Data on the demographic characteristics, parasitism rate, and host-feeding rate were collected and analyzed using the TWOSEX-MSChart, CONSUME-MSChart, and TIMING-MSChart computer programs, and then contrasted with comparable data from the more commonly utilized host plant, tobacco.

RESULTS

Higher fecundity (F) (190.13 eggs/female) and more oviposition days (O_d ) (16.60 days) were observed in E. formosa when yacon was used as the host plant for rearing T. vaporariorum, compared with when tobacco was used (F = 150.13 eggs/female, O_d = 15.27 days). The intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R₀ ) were significantly higher in E. formosa parasitizing T. vaporariorum reared on yacon compared with those parasitizing tobacco-reared T. vaporariorum. Furthermore, the net host-feeding rate (C₀ = 40.87 prey/parasitoid), net killing rate (Z₀ = 239.73 prey/parasitoid), and finite killing rate ( υ  = 0.2560/day) for E. formosa on yacon-reared whiteflies were significantly higher than those from tobacco-reared whiteflies.

CONCLUSION

Our results showed that yacon is more suitable than tobacco as a host plant for mass-rearing E. formosa for biological control programs to manage whiteflies. An innovative application of the multinomial theorem for calculating the exact probability of bootstrap samples in life table research was also introduced. © 2021 Society of Chemical Industry.

Anti-diabetes Constituents in Leaves of Smallanthus sonchifolius

The inhibitory effect of smallanthaditerpenic acids A, B, C and D previously isolated from leaves of Smallanthus sonchifolius (yacon) on α-glucosidase were examined and their IC50 were determined to be 0.48 mg/mL, 0.59 mg/mL, 1.00 mg/mL, and 1.17 mg/mL respectively. In addition, a rapid, reliable RP-HPLC method for the analysis of chlorogenic acid, caffeic acid, and smallanthaditerpenic acids A and C in yacon leaves was established, and the variation in their contents in leaves from plants cultivated in different places and collected at different times of the year were compared. The established analytical method for determining smallanthaditerpenic acids A and C, chlorogenic acid and caffeic acid presented good results and could be used as a method for the quality control of S. sonchifolius leaves.

New Compounds from Leaves of Smallanthus sonchifolius

A new octadecatrienoic acid and a new benzyl glycoside, along with a known compound, were isolated from the leaves of Smallanthus sonchifolius. The structures of the two new compounds were elucidated as 13(R)-hydroxy-octadeca-(9E,11E,15Z)-trienoic acid (1) and benzyl alcohol 7-O-α-L-arabinopyranosyl(1″→2′)-β-D-glucopyranoside (2) on the basis of spectroscopic analysis and chemical evidence. The known compound was identified as 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trienoic acid (3) by comparison of its spectral data with that reported. Compound 3 was isolated for the first time from the title plant.