Volatile compounds from two pineapples varieties (Tainong No.4 and No.6) were isolated by headspace solid phase microextraction (HS-SPME) and identified and quantified by gas chromatography-mass spectrometry (GC/MS). In the Tainong No. 4 and No. 6 pineapples, a total of 11 and 28 volatile compounds were identified according to their retention time on capillary columns and their mass spectra, and quantified with total concentrations of 1080.44 µg·kg⁻¹ and 380.66 µg·kg⁻¹ in the Tainong No.4 and No. 6 pineapples, respectively. The odor active values (OAVs) of volatile compounds from pineapples were also calculated. According to the OAVs, four compounds were defined as the characteristic aroma compounds for the Tainong No. 4 pineapple, including furaneol, 3-(methylthio)propanoic acid methyl ester, 3-(methylthio)propanoic acid ethyl ester and δ-octalactone. The OAVs of five compounds including ethyl-2-methylbutyrate, methyl-2-methylbutyrate, 3-(methylthio)propanoic acid ethyl ester, ethyl hexanoate and decanal were considered to be the characteristic aroma compounds for the Tainong No. 6 pineapple.

PISTILLATA (PI)-like genes are crucial regulators of flowering in angiosperms. A homologue of PI, designated as AcPI (Genbank accession number HQ717796), was isolated from pineapple cultivar Comte de Paris by reverse transcriptase polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The cDNA sequence of AcPI is 907 bp in length and contains an open reading frame of 594 bp, which encodes a protein of 197 amino acids. The molecular weight was 2.29 kDa and the isoelectric point was 9.28. The alignment showed that AcPI had a high identity with CsPIC2 (78.6%), AoPI (77.4%), OrcPI (75.7%) and HPI2 (72.4%). Quantitative real-time polymerase chain reaction (qRT-PCR) analyses in different tissues showed that the expression pattern of AcPI was different from the B-class genes in eudicots. AcPI was expressed in all the tissues investigated. The expression level was very low in fruit stems, bracts, leaves and sepals, high in petals and carpels, and moderate in apical meristems, flesh and stamens. The qRT-PCR analyses in different stages indicated that the expression of AcPI reached the highest level at 40 days after flower inducement, when the multiple fruit and floral organs were forming. It proved the important role of AcPI in floral organs and fruit development. The 35S::AcPI transgenic Arabidopsis plants flowered earlier and had more inflorescences or branches than wild type plants.

This paper investigated the best extraction process of total flavonoids from Piper sarmentosum Roxb. leaves. The optimal extraction solvent was first determined to be ethanol, and then the effects of ethanol concentration, extraction temperature, extraction time and the ratio of liquid to solid on the extraction yield of total flavonoids were determined by single factor method. Based on the above experiments, the orthogonal experimental design of three factors and three levels was established. The best extraction conditions of total flavonoids from Piper sarmentosum Roxb. leaves were concluded: extraction time 1.5h, liquid-solid ratio 175:1, ethanol concentration 75%, extraction time 1.5h, and the effect of solid-liquid ratio was greater than that of ethanol concentration, and the effect of ethanol concentration was greater than that of time. Furthermore, the antioxidant properties of total flavonoids were also determined from P. sarmentosum leaves in the regions of Suixi, Lianjiang, and Cunjin based on the DPPH, FRAP and MCC methods.

In the present research, single-factor experiments and a three-variable, five-level central composite design were performed to study on the ionic liquids-based ultrasoni-assisted extraction of total flavonoids from Manilkara zapota leaves. The optimum parameters were: 0.95 M [C 4 MIM]Br, liquid/ solid ratio 33.1:1 mL•g-1 , extraction duration 30.3 min. Under the optimal conditions, the average extraction yields of total flavonoids were 12.42%.