Please find the below summary of Aquilaria (agarwood) backed up with scientific research.

1) Anti-allergic(anti-anaphylaxis):

Tree Part: Stem

" We investigated the effects of the aqueous extract of Aquilaria agallocha Roxb. (Thymelaeaceae) on the immediate hypersensitivity reactions. The aqueous extract of Aquilaria agallocha stems showed inhibitory effects on passive cutaneous anaphylaxis, anaphylaxis induced by compound 48/80, and histamine release from rat peritoneal mast cells (RPMC). The morphological examination also clearly showed that the extract prevented the degranulation of RPMC in rats. The level of compound 48/80-induced intracellular cAMP in RPMC, when the extract was added, significantly increased about 8-fold at 10 s compared with that of basal cells. These results suggest that the aqueous extract of Aquilaria agallocha stems inhibits the immediate hypersensitivity reaction by inhibition of histamine release from mast cells. " 
Effect of the aqueous extract of Aquilaria agallocha stems from the immediate hypersensitivity reactions. Available here

A: Fresh isolated RPMC (rat peritoneal mast cells)

B: Compound 48:80  (a potent histamine liberator), induced allergy in RPMC  in A

C: in the presence of the aqueous extract of Aquilaria agallocha stems (10 mg: ml) plus compound 48:80 (C). Magnifications700

Excessive production of histamine in the body can generate allergic and inflammatory responses. The release of histamine, one of the potential mediators of allergic reactions may lead to the constriction of respiratory airways, which involved in early asthmatic responses (Liu et al., 1990). The presence of individual chemical constituents like flavonoids in the leaf extracts possess antihistaminic, antiallergic and mast cell degranulation properties (Kumar et al., 2011). Chemical compounds such as genkwanin and luteolin in Aquilaria leaves have potentials in relieving cough and soothing asthma ( Wang, 2008;  Lin et al., 2012). The ethanol extract of A. Sinensis leaves antihistaminic activity, which significantly prolongs asthma latency that is caused by the presence of excessive histamine, as shown in a laboratory experiment ( Wu et al., 2013).

2) Anti-diabetic(anti-hyperglycemic)

Tree part: Leaf

Below is the 2016  journal research article:

Efficacy of the Aquilaria malaccensis leaves active fraction in glucose uptake in skeletal muscle on diabetic Wistar rats.

It can be concluded that either AFEA or AFEC( (fraction of ethanol-water/AFEA and fractions of ethyl acetate/AFEC)) (0.01 g/kg b.w.) potential to increase the level of GLUT4 24.5% and 20.6% respectively in skeletal muscle tissue of diabetic rats model.

The ethanolic extract of A. Sinensis leaves been shown to possess hypoglycemic effects. Tests on the hypoglycemic effect are often carried out using diabetic mice/rats. The extract significantly reduces the blood glucose levels; this may be due to the blood sugar-lowering activity of 2α-hydroxy ursolic acid ( Mei et al., 2013). Furthermore, the methanol and water extracts from A. Sinensis leaves have an anti-hyperglycemic activity similar to effects exerted by insulin ( Pranakhon et al., 2011). Fractions of ethanol-water and ethyl acetate of A. malaccensis leaves also improve glucose uptake by elevating levels of glucose transporter type 4 (GLUT4), a regulator of whole-body glucose homeostasis. The extracts are known to exhibit increased GLUT4 level more than pioglitazone ( Said et al., 2016). Chemical compounds in ethanol extract of A. Sinensis leaves such as mangiferin, iriflophenone 2-O-α-L-rhamnopyranoside, iriflophenone 3-C-β-D-glucoside and iriflophenone 3,5-C-β-D-diglucopyranoside demonstrate a vigorous α-glucosidase inhibitory activity. These compounds act as an antidiabetic agent and reduce the blood glucose level by controlling carbohydrate absorption from the intestine ( Feng et al., 2011).

Iriflophenone 3-C-[sz]-glucoside (IPG) is active in lowering fasting blood glucose with a potency comparable to that of insulin (Ratree. Pranakhon, Chantana. Aromdee, Patchareewan. Pannangpetch 2015)

 3) Anticancer

Tree part: Shoot and callus

Figure 1. Stages of callus growth in A. malaccensis Lam.a. Initiation of callus, b&c; Growth of the callus; d. Cell death

In Aquilaria, cucurbitacin I that is found in A. malaccensis callus and shoot, can inhibit cancer cells, displays cytotoxicity against MDA-MB-468 human breast cancer cells, and indirectly interrupts actin dynamics ( Knecht et al., 2010). Chemical constituent like isocorydine, an aporphine alkaloid in A. Sinensis leaves ( Nie et al., 2009) is known to possess anticancer activity (Zhong et al., 2014). The results from in vitro and in vivo experiments demonstrated that the effectiveness of anticancer activities could be improved significantly by modifying the chemical structure of isocorydine. For instance, isocorydine derivatives like 8-amino-isocorydine and 6α,7-dihydrogen-isocorydione could prevent the growth of human lung (A549), gastric (SGC7901) and liver (HepG2) cancer cell lines in vitro. Isocorydione and 8-acetamino-isocorydine have also been shown to prevent the growth of murine sarcoma S180 tumour and murine hepatoma H22-induced tumours, respectively (Zhong et al., 2014). Another chemical constituent, squalene, which is a polyunsaturated triterpene that belongs to the terpenoid family can inhibit the development of various tumours and enhances the immune response to various associated antigens (Reddy and Couvreur, 2009). 1-hexacosanol found in A. Sinensis' leaves also possesses antitumor effect ( Wei and Bin, 2011). Gastrointestinal infections and tumour growth could be prevented with the presence of glycosides moieties like saponins, anthraquinones, cardiac glycosides and flavonoids (Abubakar, 2009).

Tree part: infected part (agarwood oil)

Research Article  

In vitro antimetastatic activity of Agarwood (Aquilaria crassna) essential oils against pancreatic cancer cells

Agarwood essential oil on apoptosis and in vitro metastasis of pancreatic cancer cells. These findings suggest that the EOs exhibited significant antimetastatic activities based on the strong inhibitory effect in proliferation, migration and colony formation. Thus, further investigation on the active principles of the extract could probably lead to the discovery of promising chemotherapeutic agents against pancreatic cancer.

Tree part: stem bark

Research Article

Separation and Fractionation of Aquilaria MalaccensisOil Using Supercritical Fluid Extraction and tThe Cytotoxic Properties of the Extracted Oil

" The finding of this study reveals that the supercritical extraction yield of A. Malaccensis increases with increasing pressure and temperature. Supercritical extract of A. Malaccensis is an effective cytotoxic agent. Its toxicity increased with temperature increment up to 50ºC and lowering the pressure to 20.7 MPa. The first 10 min fraction of supercritical extraction possesses potent toxicity towards HCT116 cancer cells with an IC 50 of 4 ug/ml. This result demonstrates that temperature is an effective factor for the extraction yield and for the extracting of cytotoxic compound" 

4) Anti-inflammatory/anti- nociceptive/analgesic/ antipyretic

Tree part: Aquilaria leaves

Research Article

Full text available below

Anti-inflammatory effects of the ethyl acetate extract of Aquilaria crassna inhibits LPS-induced tumour necrosis factor-alpha production by attenuating P38 MAPK activation.

"Ethyl acetate extract of Aquilaria crassna inhibits TNF- gene expression and secretion in LPS induces hPBMCs. This inhibitory effect apparently resulted from selectively attenuating p38 MAPK activation." 

"Alkaloids have the potential to treat toothache, colic, severe headache, rheumatism, and pains during pregnancy (Aniszewski, 2015). Studies on leaves and flowers of Psychotria colorata extracts using formalin, acetic acid-induced writhing, and tail-flick tests proved that alkaloids in the leaves and flowers of P. colorata extracts demonstrated an analgesic activity ( Malairajan et al., 2006). The detection of alkaloids in Aquilaria leaves extracts indicates its potential use as an analgesic agent for pain relief. Polyphenolic compounds like flavonoids exhibit anti-inflammatory activities by decreasing the release of inflammatory mediators and stabilizing cell membranes ( Kumar and Pandey, 2013;  Martini et al., 2014), and friedelan-3-one also exhibits anti-inflammatory (Wei and Bin, 2011). A. Sinensis is reportedly shown to have anti-inflammatory activity through xylene-induced edema model, carrageenan-induced edema model, and carboxymethylcellulose sodium-induced leukocyte migration model ( Zhou et al., 2008). This could be due to the flavonoids presence in the leaves ( Wang et al., 2008; Qi et al., 2009; Feng et al., 2011;  Ito et al., 2012). Ethanolic extract of A. agallocha (synonym A. malaccensis) leaves the potential as an anti-arthritic agent ( Rahman et al., 2016). Generally, rheumatoid arthritis is caused by the denaturation of protein due to the production of auto-antigens in certain rheumatic diseases. The presence of chemical constituents such as glycosides, tannins, terpenoids, oleic acids, terpenes and phenolic compounds in the extracts are thought to restrain heat-induced protein denaturation (Rahman et al., 2016)"

5) Laxative effects: Constipation relief

Tree Part: Leaves

Leaves of A. Sinensis have the ability to improve intestinal movement function ( Li et al., 2013). Mangiferin and genkwanin-5-O-β-premeveroside found in ethanol extracts of both A. Sinensis and A. crassna, promote contraction tension of the small intestine in mice, resulting in increased number and weight of stool beads ( Kakino et al., 2010, Kakino and Hara, 2016).

6) Antihyperlipidemic agents: lower cholesterol level 

Tree Part: Leaves

Mangiferin, has lipid-lowering effect, a polyphenol compound which is useful in the treatment of hyperlipidemia, a genetic disorder that results in a high level of lipids. The aqueous extract of A. sinensis leaves has been shown to lower total triglyceride and total cholesterol content in a laboratory experiment ( Wu et al., 2012). Mangiferin is also one of the main compound found in Aquilaria Crassna

Mangiferin in agarwood tea significantly lower levels of uric acid in the blood (cause solid crystals to form within joint, known as "Gout"). Please see the 2017 research below from Agarwood, Science Behind the Fragrance

7) Effect on Central Nervous System

Tree part: Wood Heartwood Oil

Ethanol extractat100 mg/mL significantly induced the brain-derived neurotrophic.

Factor (BDNF)exonIII–V mRNA expression in rat cortical cells, indicating an improved brain function.

Benzene extract showed reduced spontaneous motility, the prolonged effect on hex-barbiturate-induced sleeping time as well as reduced rectal temperature and acetic writhing <=== Anti-depression effects.

The scent is provocative, smelling agarwood oil has a positive effect on your brain, improves your olfactory, brings more alertness and concentration.